___________________

OCS Study

MMS 2005-070

Final Report

December 2005

U.S. Department of the Interior

Minerals Management Service

Pacific OCS Region

Survey of Invertebrate and Algal Communities

on Offshore Oil and Gas Platforms

in Southern California
_______________ OCS Study 

MMS 2005-070 

Survey of Invertebrate and Algal Communities 

on Offshore Oil and Gas Platforms 

in Southern California 

Final Report 

December 2005 

Prepared for: 

U.S. Department of the Interior 

Minerals Management Service 

Pacific OCS Region 

770 Paseo Camarillo 

Camarillo, California 93010 

Telephone: (805) 389-7810 

Prepared by: 

Continental Shelf Associates, Inc. 

759 Parkway Street 

Jupiter, Florida 33477 

Telephone: (561) 746-7946
iii 

DISCLAIMER 

This report was prepared under Contract 1435-01-98-CT-30865 between the Minerals 

Management Service (MMS), Pacific OCS Region, Camarillo, CA and Continental Shelf 

Associates, Inc., Jupiter, FL. This report has been technically reviewed by the MMS and has 

been approved for publication. Approval does not signify that the contents necessarily reflect 

the views and policies of the MMS, nor does mention of trade names or commercial products 

constitute endorsement or recommendation for use. It is, however, exempt from review and 

compliance with MMS editorial standards. 

REPORT AVAILABILITY 

Printed copies of this report may be obtained from the Public Information Office at the 

following address: 

 U.S. Department of the Interior 

 Minerals Management Service 

 Pacific OCS Region 

 770 Paseo Camarillo 

 Camarillo, California 93010 

 Telephone: (805) 389-7810 

An Adobe Acrobat version of this report may be accessed online at: 

www.mms.gov/omm/pacific

CITATION 

Suggested citation: 

Continental Shelf Associates, Inc. 2005. Survey of invertebrate and algal communities on 

offshore oil and gas platforms in southern California: Final report. Prepared for the U.S. 

Department of the Interior, Minerals Management Service, Pacific OCS Region, 

Camarillo, CA. December 2005. OCS Study MMS 2005-070. 232 pp. plus appendices. 

ABOUT THE COVER 

Photographic images acquired during diver and remotely operated vehicle surveys at select 

California platforms. Clockwise from upper left: 

 View of unidentified ophiuroids, Metridium senile, Pisaster ochraceus, and calcareous 

worm tubes at 122 m water depth, Platform Hidalgo 

 View of Mytilus spp., Metridium senile, Balanus spp., and Ophiothrix spiculata at 4 m water 

depth, Platform Habitat 

 View of Corynactis californica, Ophiothrix spiculata, and encrusters at 41 m water depth, 

Platform Habitat 

 View of Metridium senile, turf, bare metal, and Galathea californiensis at 177 m water 

depth, Platform Harvest 

 View of Metridium senile, Amphipholis spp., and turf at 152 m water depth, Platform Gail 
v 

TABLE OF CONTENTS 

Page 

LIST OF TABLES.......................................................................................................................................... vii 

LIST OF FIGURES..........................................................................................................................................xi 

LIST OF PHOTOS.........................................................................................................................................xv 

EXECUTIVE SUMMARY ........................................................................................................................ES-1 

1.0 Introduction.........................................................................................................................................1 

2.0 Materials and Methods ............................................................................................................... 5 

 2.1 Review of Platform Information....................................................................................... 5 

 2.2 Platform Selection and Inspection Videotape Review .................................................. 5 

 2.3 Field Surveys..................................................................................................................... 12 

 2.3.1 Operational Procedures...................................................................................... 13 

 2.3.2 Platform Leg Selection ........................................................................................ 13 

 2.3.3 Sampling Procedures .......................................................................................... 13 

 2.4 Sample Analyses............................................................................................................... 15 

 2.4.1 Quantitative Slide and Videotape Analysis..................................................... 15 

 2.4.2 Voucher Collections ............................................................................................ 16 

 2.4.3 Scraping Collections............................................................................................ 16 

 2.4.4 Growth Thickness Measurements..................................................................... 17 

 2.5 Data Analyses ................................................................................................................... 17 

3.0 Results.......................................................................................................................................... 19 

 3.1 Inspection Videotape Review ......................................................................................... 19 

 3.2 Field Surveys..................................................................................................................... 19 

 3.3 Platform Characterization – Photographic Interpretation.......................................... 25 

 3.3.1 Platform Gail ........................................................................................................ 26

 3.3.2 Platform Grace ..................................................................................................... 34 

 3.3.3 Platform Harvest ................................................................................................. 40 

 3.3.4 Platform Hidalgo................................................................................................. 50 

 3.3.5 Platform Habitat .................................................................................................. 58 

 3.3.6 Platform Irene ...................................................................................................... 61 

 3.4 Diablo and Nifty Rocks – Photographic Interpretation .............................................. 67 

 3.4.1 Physical Characteristics ...................................................................................... 67 

 3.4.2 Community Description..................................................................................... 67 

 3.5 Random Point Count Analysis ....................................................................................... 74 

 3.6 Statistical Analysis of Photographic Data ..................................................................... 80 

 3.6.1 Whole Slide Analysis Photographic Data ........................................................ 80 

 3.6.2 PointCount’99® Photographic Data ................................................................. 86 

 3.6.3 Diablo and Nifty Rocks and Comparable Platform Zones............................ 89 

 3.7 Scraping Analysis ............................................................................................................. 92 
vi 

TABLE OF CONTENTS 

(Continued) 

Page 

3.8 Statistical Analysis of Scraping Data ............................................................................. 94 

3.9 Wet Weight Determinations ......................................................................................... 101 

 3.10 Individual Mussel Measurements................................................................................ 104 

 3.11 Growth Thickness Measurements................................................................................ 104 

4.0 Discussion ................................................................................................................................. 107 

 4.1 Overview and Historical Perspective .......................................................................... 107 

 4.2 Study Limitations ........................................................................................................... 109 

 4.3 Comparisons Between Adjacent Platform Legs......................................................... 110 

 4.3.1 Platform Gail ...................................................................................................... 111 

 4.3.2 Platform Grace ................................................................................................... 113 

 4.3.3 Platform Harvest ............................................................................................... 116 

 4.3.4 Platform Hidalgo............................................................................................... 118 

 4.3.5 Summary of Comparisons for Adjacent Platform Legs ............................... 120 

 4.4 Comparisons Between Platforms ................................................................................. 121 

 4.4.1 Rank Order of Dominant Taxa ........................................................................ 121 

 4.4.2 Density Comparisons........................................................................................ 130 

 4.4.3 Percent Cover Comparisons ............................................................................ 134 

 4.4.4 Comparison of Percent Cover Data: PointCount’99® vs. QSA................... 136 

 4.4.5 Clustering Analyses .......................................................................................... 141 

 4.5 Depth Distribution of Platform-Associated Biota...................................................... 145 

 4.6 Scraping Analysis ........................................................................................................... 153 

 4.7 Growth Thickness Measurements................................................................................ 158 

 4.8 Platform vs. Natural Hard Bottom – Comparisons of Biota..................................... 160 

 4.9 Summary.......................................................................................................................... 162 

5.0 List of Preparers........................................................................................................................ 173 

6.0 Literature Cited ........................................................................................................................ 175 

APPENDICES........................................................................................................................................ 177

Appendix A Detailed Operational, Sampling, and Safety Procedures and 

Vessel Modifications ........................................................................................A-1

Appendix B Randomization of Photoquadrats .................................................................. B-1

Appendix C Data Appendix: Whole Slide Analysis .......................................................... C-1

Appendix D Scraping Data – Platforms Harvest and Gail................................................D-1

Appendix E Data Appendix: PointCount’99® Analysis ................................................... E-1 
vii 

LIST OF TABLES 

Table Page 

2-1 Summary of California OCS candidate platforms, designated units or fields, 

and platform water depth and installation date by geographic area (Adapted 

from: U.S. Department of the Interior, Minerals Management Service, 2005) ..................... 8 

2-2 Summary of sampling conducted during the analysis of invertebrate and algal 

communities on offshore oil and gas platforms in southern California ............................... 9 

3-1 Characteristics of platform biotic zones as determined during inspection 

videotape analysis....................................................................................................................... 20 

3-2 Summary of platform legs and rocky outcrops sampled during the analysis of 

invertebrate and algal communities on offshore oil and gas platforms in 

southern California ..................................................................................................................... 24 

3-3 Dominant taxa (or physical characteristics) on Leg A1 of Platform Gail 

identified during quantitative slide analysis .......................................................................... 27 

3-4 Dominant taxa (or physical characteristics) on Leg B1 of Platform Gail 

identified during quantitative slide analysis .......................................................................... 28 

3-5 Dominant taxa (or physical characteristics) on Leg C1 of Platform Grace 

identified during quantitative slide analysis .......................................................................... 35 

3-6 Dominant taxa (or physical characteristics) on Leg C4 of Platform Grace 

identified during quantitative slide analysis .......................................................................... 37 

3-7 Dominant taxa (or physical characteristics) on Leg B1 of Platform Harvest 

identified during quantitative slide analysis .......................................................................... 43 

3-8 Dominant taxa (or physical characteristics) on Leg B2 of Platform Harvest 

identified during quantitative slide analysis .......................................................................... 45 

3-9 Dominant taxa (or physical characteristics) on Leg A1 of Platform Hidalgo 

identified during quantitative slide analysis .......................................................................... 51 

3-10 Dominant taxa (or physical characteristics) on Leg B1 of Platform Hidalgo 

identified during quantitative slide analysis .......................................................................... 53 

3-11 Dominant taxa on Leg A1 of Platform Habitat identified during quantitative 

slide analysis................................................................................................................................ 59 

3-12 Dominant taxa on Leg A1 of Platform Irene identified during quantitative slide 

analysis ......................................................................................................................................... 64 
viii 

LIST OF TABLES 

(Continued) 

Table Page 

3-13 Dominant taxa on natural substrate of Diablo and Nifty Rocks identified 

during quantitative slide analysis ............................................................................................ 69 

3-14 Dominant taxa on the six platforms as determined by PointCount’99® analysis............. 76 

3-15 Designations of zones used in the clustering analysis of photographic data..................... 81 

3-16 Summary of the most common taxa identified, their relative abundance, 

frequency of occurrence, and mean relative abundance per occurrence, as 

determined from scraping samples collected at Platform Harvest...................................... 95 

3-17 Summary of the most common taxa identified, their relative abundance, 

frequency of occurrence, and mean relative abundance per occurrence, as 

determined from scraping samples collected at Platform Gail ............................................ 97 

3-18 Summary species list for scraping samples used in the correspondence analysis ............ 99 

3-19 Summary of weight measurements for scraping samples from Platform 

Harvest ....................................................................................................................................... 103 

3-20 Summary of mussel measurements of scraping samples collected from 

Platform Harvest....................................................................................................................... 105 

3-21 Summary of growth thickness measurements...................................................................... 106 

4-1 Comparison of taxa between Legs A1 and B1 of Platform Gail based on the 

results of quantitative slide analysis ...................................................................................... 112

4-2 Comparison of taxa between Legs C1 and C4 of Platform Grace based on the 

results of quantitative slide analysis ...................................................................................... 114

4-3 Comparison of taxa between Legs B1 and B2 of Platform Harvest based on the 

results of quantitative slide analysis ...................................................................................... 117

4-4 Comparison of taxa between Legs A1 and B1 of Platform Hidalgo based on the 

results of quantitative slide analysis ...................................................................................... 119

4-5 Summary of rankings for each of the top 12 taxa (based on density) identified 

during quantitative slide analysis, by platform leg ............................................................. 122 

4-6 Summary of rankings for each of the top 12 taxa (based on percent cover) 

identified during quantitative slide analysis, by platform leg ........................................... 126 
ix 

LIST OF TABLES 

(Continued) 

Table Page 

4-7 Comparison of average rankings – density vs. percent cover – for the dominant 

taxa, all platforms...................................................................................................................... 129 

4-8 Minimum, maximum, and average densities of select dominant taxa (based on 

numerical abundance) by platform ....................................................................................... 131 

4-9 Minimum, maximum, and average coverage of select dominant taxa (based on 

percent cover) by platform ...................................................................................................... 135 

4-10 Comparison of dominant taxa on the six platforms – PointCount’99® vs. QSA – 

based on percent cover estimates ........................................................................................... 137 

4-11 Comparison of biotic zones and species/taxon presence by depth at six 

platforms .................................................................................................................................... 146 

4-12 Taxa identified during the analysis of scraping samples from the intertidal, 

barnacle, and mussel zones of platforms Gail and Harvest................................................ 155 

4-13 Presence and depth of occurrence of species found both on platforms and 

natural hard bottom areas ....................................................................................................... 161 

4-14 Taxa identified during the photographic analysis of six California platforms 

and Diablo and Nifty Rocks. ................................................................................................... 163 
xi 

LIST OF FIGURES 

Figure Page 

1-1 Southern California Planning Area, including currently designated fields or 

units (Adapted from: U.S. Department of the Interior, Minerals Management 

Service, 2001) .............................................................................................................................. 2 

2-1 Santa Maria Basin OCS operations (Adapted from: U.S. Department of the 

Interior, Minerals Management Service, 2001)...................................................................... 6 

2-2 East Santa Barbara Channel OCS operations (Adapted from: U.S. Department 

of the Interior, Minerals Management Service, 2001)........................................................... 7 

2-3 Location of Diablo Rock, Santa Cruz Island, California..................................................... 10 

2-4 Location of Nifty Rock, San Miguel Island, California....................................................... 11 

3-1 Zonation patterns evident from videotape analysis of (a) Platform Gail and 

(b) Platform Grace, as viewed from an outboard perspective .......................................... 21 

3-2 Zonation patterns evident from videotape analysis of (a) Platform Harvest 

and (b) Platform Hidalgo, as viewed from an outboard perspective............................... 22 

3-3 Zonation patterns evident from videotape analysis of (a) Platform Habitat 

and (b) Platform Irene, as viewed from an outboard perspective.................................... 23 

3-4 Density and depth distribution of the six numerically dominant taxa on 

Leg A1 of Platform Gail determined from quantitative slide analysis ............................ 32 

3-5 Density and depth distribution of the six numerically dominant taxa on 

Leg B1 of Platform Gail determined from quantitative slide analysis............................. 33 

3-6 Density and depth distribution of the six numerically dominant taxa on 

Leg C1 of Platform Grace determined from quantitative slide analysis.......................... 41 

3-7 Density and depth distribution of the six numerically dominant taxa on 

Leg C4 of Platform Grace determined from quantitative slide analysis.......................... 42 

3-8 Density and depth distribution of the six numerically dominant taxa on 

Leg B1 of Platform Harvest determined from quantitative slide analysis ...................... 48 

3-9 Density and depth distribution of the six numerically dominant taxa on 

Leg B2 of Platform Harvest determined from quantitative slide analysis ...................... 49 

3-10 Density and depth distribution of the six numerically dominant taxa on 

Leg A1 of Platform Hidalgo determined from quantitative slide analysis .................... 56 
xii 

LIST OF FIGURES 

(Continued) 

Figure Page 

3-11 Density and depth distribution of the six numerically dominant taxa on 

Leg B1 of Platform Hidalgo determined from quantitative slide analysis...................... 57 

3-12 Density and depth distribution of the six numerically dominant taxa on 

Leg A1 of Platform Habitat determined from quantitative slide analysis ...................... 63 

3-13 Density and depth distribution of the six numerically dominant taxa on 

Leg A1 of Platform Irene determined from quantitative slide analysis........................... 68 

3-14 Density and depth distribution of the six numerically dominant taxa at 

Diablo and Nifty Rocks determined from quantitative slide analysis............................. 75 

3-15 Dendrogram of count data from the quantitative slide analysis, by platform 

leg............................................................................................................................................... 82 

3-16 Dendrogram of percent cover data from the quantitative slide analysis, by 

platform leg .............................................................................................................................. 84 

3-17 Dendrogram of count data from the quantitative slide analysis, by biotic zone 

for all platforms........................................................................................................................ 85 

3-18 Dendrogram of percent cover data from the quantitative slide analysis, by 

biotic zone for all platforms ................................................................................................... 87 

3-19 Dendrogram of PointCount data, by platform leg.............................................................. 88 

3-20 Dendrogram of PointCount data, by biotic zone for all platforms................................... 90 

3-21 Dendrogram of count data from the quantitative slide analysis – platform 

legs versus natural outcrops .................................................................................................. 91 

3-22 Dendrogram of percent cover data from the quantitative slide analysis – 

platform legs versus natural outcrops.................................................................................. 93 

3-23 Correspondence analysis results, as determined through the comparison of 

mussel and barnacle zones for each of the six platforms and Diablo and Nifty 

Rocks........................................................................................................................................ 102 

4-1 Generalized depth distribution of dominant species present at platforms Gail 

and Grace ................................................................................................................................ 150 

4-2 Generalized depth distribution of dominant species present at platforms 

Harvest and Hidalgo............................................................................................................. 151 
xiii 

LIST OF FIGURES 

(Continued) 

Figure Page 

4-3 Generalized depth distribution of dominant species present at platforms 

Habitat and Irene ................................................................................................................... 152 

4-4 Mussel thickness at platforms Harvest and Irene............................................................. 159 

4-5 Generalized depth distribution of select biota – all platforms ........................................ 168 
xv 

LIST OF PHOTOS

Photo Page 

1 View of (1) Metridium exilis, (2) Corynactis californica, and (3) tan and yellow 

encrusting sponges at -47 m (-153 ft), Leg B1, Platform Gail ............................................... 29 

2 View of (1) Metridium senile, (2) Amphipholis spp., and (3) turf at -152 m (-500 ft), 

Leg B1, Platform Gail ................................................................................................................. 29 

3 View of (1) Mytilus spp., (2) Metridium senile, and some (3) Metridium exilis at 

-1 m (-4 ft), Leg B1, Platform Gail ............................................................................................. 31 

4 View of (1) Corynactis californica, (2) tan encrusting sponge, and (3) Metridium 

farcimen at -51 m (-168 ft), Leg A1, Platform Gail ................................................................... 31 

5 View of (1) Mytilus spp., (2) Balanus spp., and (3) filamentous red algae at -2 m 

(-8 ft), Leg C1, Platform Grace................................................................................................... 38 

6 View of (1) Corynactis californica, (2) filamentous red algae, and (3) encrusting 

sponges at -19 m (-61 ft), Leg C1, Platform Grace .................................................................. 38 

7 View of (1) Paracyathus stearnsii, (2) Coenocyathus bowersi, and (3) Metridium 

farcimen at -53 m (-174 ft), Leg C1, Platform Grace................................................................. 39 

8 View of (1) Paracyathus stearnsii, (2) Ophiothrix spiculata, (3) Asterina miniata, and 

turf at -74 m (-242 ft), Leg C1, Platform Grace........................................................................ 39 

9 View of (1) Mytilus spp., (2) Metridium senile, (3) Balanus spp., and 

(4) filamentous red algae at -2 m (-6 ft), Leg B1, Platform Harvest ..................................... 46 

10 View of (1) Metridium senile, (2) tan branching bryozoan colonies, (3) red 

encrusters, and (4) unidentified ophiuroids at -90 m (-294 ft), Leg B2, 

Platform Harvest......................................................................................................................... 46 

11 View of (1) Balanus nubilus, (2) Metridium senile, and (3) turf at -47 m (-153 ft), 

Leg B2, Platform Harvest........................................................................................................... 47 

12 View of (1) Metridium senile, (2) turf, (3) bare metal, and (4) Galathea californiensis

at -177 m (-580 ft), Leg B2, Platform Harvest .......................................................................... 47 

13 View of (1) Metridium senile, (2) Anthopleura elegantissima (rosy morph), and 

(3) Strongylocentrotus purpuratus at -14 m (-45 ft), Leg B1, Platform Hidalgo..................... 54 

14 View of (1) Mytilus spp. and associated fauna at -2 m (-6 ft), Leg B1, 

Platform Hidalgo ........................................................................................................................ 54 
xvi 

LIST OF PHOTOS

Photo Page 

15 View of (1) unidentified ophiuroids, (2) Metridium senile, (3) Pisaster ochraceus, 

and (4) Leucetta losangelensis at -30 m (-99 ft), Leg A1, Platform Hidalgo ........................... 55 

16 View of (1) Metridium senile, (2) turf, (3) various encrusters, and (4) calcareous 

worm tubes at -122 m (-399 ft), Leg B1, Platform Hidalgo ................................................... 55 

17 View of (1) Mytilus spp., (2) Metridium senile, (3) Balanus spp., and (4) Ophiothrix 

spiculata at -4 m (-13 ft), Leg A1, Platform Habitat................................................................. 60 

18 View of (1) Mytilus spp., (2) filamentous red algae, (3) Metridium senile,

(4) Balanus spp., and (5) Anthopleura elegantissima (rosy morph) at -5 m (-18 ft), 

Leg A1, Platform Habitat........................................................................................................... 60 

19 View of (1) Corynactis californica, (2) Ophiothrix spiculata, and encrusters at -41 m 

(-134 ft), Leg A1, Platform Habitat ........................................................................................... 62 

20 View of (1) undescribed zoanthid anemones (Palythoa) at -82 m (-269 ft), 

Leg A1, Platform Habitat........................................................................................................... 62 

21 View of (1) Mytilus californianus, (2) Metridium senile, (3) Tetraclita squamosa, and 

other barnacles at -1 m (-4 ft), Leg A1, Platform Irene .......................................................... 65 

22 View of (1) Mytilus californianus, (2) Metridium senile, (3) Anthopleura 

elegantissima (rosy morph), and (4) Pisaster ochraceus at -9 m (-31 ft), Leg A1, 

Platform Irene.............................................................................................................................. 65 

23 View of (1) Metridium senile and (2) encrusting sponges at -44 m (-145 ft), Leg A1, 

Platform Irene.............................................................................................................................. 66 

24 View of (1) Metridium farcimen (and possibly M. senile), (2) Asterina miniata, and 

(3) calcareous worm tubes at -71 m (-232 ft), Leg A1, Platform Irene ................................. 66 

25 View of (1) yellow staghorn bryozoa, (2) Strongylocentrotus purpuratus, 

(3) S. franciscanus, (4) Urticina spp., (5) a solitary Anthopleura spp., and (6) turf 

at -14 m (-45 ft), Diablo Rock..................................................................................................... 71 

26 View of (1) Paracyathus stearnsii, (2) Balanophyllia elegans, (3) an encrusting alga 

(Lithothamnion), and turf at -17 m (-55 ft), Nifty Rock .......................................................... 71 

27 View of (1) Mytilus californianus, (2) filamentous red algae, (3) an encrusting 

alga (Lithothamnion), (4) Anthopleura xanthogrammica, and (5) A. elegantissima at 

-8 m (-25 ft), Diablo Rock ........................................................................................................... 72 

28 View of (1) Corynactis californica, (2) an encrusting alga (Lithothamnion), and 

(3) Chthalamus spp. at -15 m (-50 ft), Diablo Rock .................................................................. 72 
xvii

LIST OF PHOTOS 

(Continued) 

Photo Page 

29 View of (1) Anthopleura elegantissima, (2) filamentous red algae, and 

(3) Strongylocentrotus purpuratus at -11 m (-35 ft), Diablo Rock............................................ 73 

30 View of (1) a Bossiella-type coralline alga at -14 m (-45 ft), Nifty Rock ............................... 73 
Executive Summary 

ES-1 Introduction 

 During the 23-year period between 1967 and 1989, 24 oil and gas production facilities 

were installed in Federal waters offshore California, including the Santa Maria Basin, the Santa 

Barbara Channel, and San Pedro Bay. Most of the platforms were installed to produce oil and 

gas, with only two facilities installed for oil and/or gas processing. To date, only one of these 

facilities has been decommissioned and removed, leaving 23 oil and gas platforms currently on 

the southern California outer continental shelf (OCS). 

 While more than 1 billion barrels of oil and 1.3 trillion cubic feet of gas have been 

produced from these operations (through March 2003), production volumes from Federal 

waters offshore California are presently reflecting a general decrease over time. Given the 

projected life expectancy of production operations at these facilities (i.e., projected 

decommissioning and removal of several platforms in the next several years), the Minerals 

Management Service (MMS) has a vested regulatory mandate and scientific interest in properly 

characterizing platform-associated communities. As with most biological systems, there are 

recognized data gaps in our knowledge of marine ecosystems. In particular, the invertebrate 

and algal populations found in association with California’s offshore oil and gas platforms have 

not been fully characterized. To address these information gaps as they pertain to 

platform-associated communities, this study had four specific objectives: 

(1) Determine abundance, density, and depth distribution/vertical zonation 

characteristics of invertebrate and algal communities on selected platforms and 

natural reefs; 

(2) Quantify biomass production estimates of invertebrate and algal communities on 

platforms (and natural reefs, where practical); 

(3) Conduct the research using methods that are similar or complementary to those 

being used in related studies; and 

(4) Evaluate and discuss the relative importance of platform-associated invertebrate 

and algal communities to the ecology of the region. 

ES-2 Methods

Platform Selection and Inspection Videotape Review 

 All platforms on the California OCS were considered as potential sampling sites during 

the platform selection process. Criteria for selection included a consideration of water depth 

and geographic location. Considering mesoscale oceanographic conditions, the platforms 

found within the Santa Barbara Channel and Santa Maria Basin regions were identified as 

optimal candidates for study. Further, water depths in which these facilities are found range 

from relatively shallow to deep (i.e., shallowest at Platform Gina in 29 m of water; deepest at 

Platform Harmony in 365 m of water). Eight platforms were identified as preferred sampling 

locations – platforms Irene, Hidalgo, Harvest, and Hermosa in the Santa Maria Basin, Platform 

Hondo in the western Santa Barbara Channel, and platforms Grace, Gail, and Habitat in the 

eastern Santa Barbara Channel (Figure ES-1). 

ES-1
123o 122o 121o 120o 119o 118o 

San Luis Obispo

Santa Maria

Lompoc

Gaviota Santa

Barbara Carpinteria

Ventura

Oxnard

Port Hueneme

Los

Angeles

Santa

Monica

Long 

Beach

Huntington Beach

Newport Beach

Laguna Beac

O

Figure ES-1. Locations sampled during the survey of invertebrate and algal communities on offshore oil and gas platforms 

including several naturally occurring rock outcrops. 

Cal

Lege

= Sou

Plan

= Des

0 50 Nautical Miles0 60 Kilometers

25

30

Santa Rosa

Island

Santa Cruz

Island

San Miguel

Island

Santa Barbara 

Island

Santa Catalina

Island

San Clemente

Island

San Nicolas 

Island

Begg Rock

Santa 

Barbara 

Channel

San Pedro

Bay

Santa 

MariaBasin

CAVERN

UNIT

Port

Hueneme

Santa Cruz Island

POINTHUENEME UNIT

GAIL

GINA

Anacapa Island

Santa Rosa

Island

HABITAT

C

FEDERAL ECOLOGICAL PRESERVE

BUFFER ZONE

State

Waters

State

Waters

SANTA CLARA

UNIT

PITAS POINT UNIT

HILLHOUSE

B A

HENRY

HOGAN

HOUCHIN

SANTA BARBARA

OIL AND GAS

SANCTUARY

CHANNEL ISLANDS NATIONAL

MARINE SANCTUARY BOUNDARY

Ventura

Oxnard

GRACE GILDA

Ventura

County

Santa Barbara

Carpinteria

Go Santa Barbara County leta

HOLLY

Santa Maria

Orcutt

Lompoc

Santa Barbara

County

Point

Arguello

Point

Conception

LION ROCK

UNIT

POINT SAL

UNIT

PURISIMA

POINT UNIT

SANTA

MARIA UNIT

POINTPEDERNALESUNIT

Surf

TRANQUILLON

RIDGE UNIT

ROCKY

POINT UNIT

BONITO

UNIT

POINT

ARGUELLO

UNIT

HIDALGO

HARVEST

HERMOSA

SWORD

UNIT

State Waters

State

Waters San Luis Obispo

County

Vandenberg

Air Force

Base

IRENE

PACIFIC

OCEAN

CALIFORNIA

San Miguel Islan

N

R

Harris

Point

Crook

Point

Judith

Rock

Point

Bennett

Castle

Rock

Diablo

Rock

Santa Cruz Island

West

Point

Black

Point

Kinton

Point

Morse

Point Gull

Island

Bowen

Point
Study platform locations were considered representative of the diversity of the 

California OCS – including platforms in both shallow and deep water, and within potentially 

different biogeographic regimes. Among these eight facilities, four primary platforms were 

selected for more intense sampling – Grace, Gail, Hidalgo, and Harvest; at each of these primary 

platforms, two outer legs were photographed and videotaped. Four additional secondary 

platforms were also selected – Hondo, Hermosa, Habitat, and Irene; at these locations, only 

single outer legs were slated for photographic and videotape characterization. Platforms Grace 

and Hidalgo are both located in relatively shallow water (i.e., 97 to 131 m), with one platform in 

the Santa Barbara Channel and the other in the Santa Maria Basin. Platforms Gail and Harvest 

are located in intermediate to deep waters (i.e., 206 to 225 m), with one platform in the Santa 

Barbara Channel and the other in the Santa Maria Basin. For the secondary platforms, 

platforms Habitat and Irene are located in relatively shallow water depths (i.e., 74 to 88 m) 

either within the Santa Barbara Channel or Santa Maria Basin. Due to operational restrictions 

and/or weather constraints, platforms Hondo and Hermosa were not sampled. Also of interest 

to this study effort were the invertebrate and algal communities found in association with 

naturally occurring rock outcrops or pinnacles. Only a limited number of suitable candidate 

sites were identified, most of which occur off the northern Channel Islands. Diablo and 

Nifty Rocks (Figure ES-1) were selected for sampling using similar quantitative photographic 

techniques. 

Sampling emphasized collection of 35-mm slide transparencies (i.e., photoquadrats) and 

high resolution color video, each of which was collected via diver (from the intertidal zone to 

24 m subsurface) and ROV (from 24 m subsurface to the seafloor) at platforms and rock 

outcrops. In addition, “scraping” collections (i.e., removal of all epibiota within a prescribed 

area) and thickness/depth measurements (i.e., measurement from the outer portion of the 

community inward to the platform leg) were also completed at several platforms, as detailed in 

Table ES-1. 

Table ES-1. Summary of sampling conducted during the analysis of invertebrate and algal 

communities on offshore oil and gas platforms in southern California. 

Platform and 

Leg(s) Sampled 

Diver 

Video 

Diver 

Photos 

ROV 

Video 

ROV 

Photos Scraping Growth 

Primary Platforms (2 legs per platform) 

Gail – Legs A1, B1 + + + + + - 

Grace – Legs C1, C4 + + + + - - 

Harvest – Legs B1, B2 + + + + + + 

Hidalgo – Leg A1, B1 + + + + - - 

Secondary Platforms (1 leg per platform) 

Habitat – Leg A1 + + + + - - 

Irene – Leg A1 + + + + - + 

Offshore Rocks/Pinnacles 

Diablo Rock + + - - - - 

Nifty Rock + + - - - - 

Key: + = data collected; - = no sampling required; ROV = remotely operated vehicle. 

ES-3
After primary and secondary platforms were identified, biologists reviewed MMS 

inspection videotapes to establish preliminary biotic zonation patterns along the outer portions 

of the legs of each platform to be sampled. Depth and range characteristics of these biotic zones 

were used in determining where discrete samples (e.g., photographs, scrapings) were to be 

taken during subsequent field surveys. 

Field Surveys 

 Field surveys were completed in several phases between 1998 and 2000. A preliminary 

survey was conducted in October 1998 to test the various diver and ROV systems. Full surveys 

at six platforms were completed between October 1999 and November 2000. All surveys were 

completed using the R/V Dawn, a 30-m (100-ft) research vessel. Scientific divers and a Phantom 

HD2 ROV were employed to collect high resolution color video and 35-mm slide transparencies 

from one or two platform legs. The depth at which each photograph was collected was 

predetermined using a randomized sampling approach. Divers also collected 0.0625-m2

scraping samples from select platform legs. 

Sample Analyses 

 Sample analyses included videotape review, quantitative slide analysis (QSA), and point 

count analysis. QSA (also called whole slide analysis) entailed projection of the 35-mm slide 

image onto a large screen and the taxonomic identification and enumeration of biota present 

(i.e., abundance [individual counts] and percent cover). QSA encompassed complete 

identification of specimens within each slide (i.e., taxonomic identification of all biota to the 

lowest practical taxon). QSA protocols called for identification of biota within 15 photographs 

(i.e., 0.0625-m2 photoquadrats) per biotic zone for each platform leg and rock outcrop/pinnacle 

sampled. Following completion of the whole slide analysis, all 35-mm slide transparencies 

were digitized to facilitate error checking and as a prelude to completion of point count 

analysis. During point count analysis, digital images were processed using PointCount’99® 

software to identify biota present beneath 50 randomly placed points. 

 Scraping samples from the mussel and barnacle/scallop zones of platforms Gail and 

Harvest were analyzed. Total sample weight and mussel weight measurements were made on 

scraping samples. Individual mussels from Platform Harvest were measured and weighed. 

Whole scraping samples were subsequently sorted into major phylogenetic groups, identified to 

the lowest practical taxon, and categorized as to relative abundance. 

 Growth thickness measurements were completed by divers during sampling operations 

at platforms Harvest and Irene. A hand-held ruler was used at varying water depths and the 

thickness of the biota present (e.g., from the outer edge of the mussel bed to the platform leg) 

was measured and recorded. 

ES-4
Data Analyses 

 Six basic questions related to community composition, intra- and inter-platform 

variability, and zonation patterns were addressed in the analysis of the data with the overall 

purpose to determine density, percent cover, and depth distribution/vertical zonation 

characteristics of invertebrate and algal communities on selected platforms: 

 What benthic biota live on platforms? 

 Do platform benthic biota differ between legs (primary platforms)? 

 Do platform benthic biota differ between platforms (all platforms sampled)? 

 Do platform benthic biota differ between depth zones? 

 Do platform benthic biota differ between oceanographic regions? 

 Do platform benthic biota differ between platforms and pinnacles? 

 To evaluate how benthic biota differ between zones, estimates of percent cover (and 

available count data) for individual biotic zones were used in a separate cluster analysis. The 

replicates within each biotic zone were pooled at individual platform legs, providing a means to 

evaluate the occurrence and similarities of the biotic zones. There was no weighting for the 

analysis of biotic zones. 

 A reduced portion of the data set was also analyzed to compare platform legs to the 

pinnacles. Because there was no distinct vertical zonation evident at the pinnacles, the data 

were pooled over the pinnacle and individual platform legs for the applicable depth zones. 

Specifically, only the samples occurring within the 5 to 17 m depth range from the platforms 

were used in this portion of the data analysis because these correspond to the depth range of the 

biota sampled at the pinnacles. 

ES-3 Results and Discussion 

Inspection Videotape Review 

 Four to six distinct biotic zones (i.e., zonation patterns) were evident, depending upon 

platform depth (Table ES-2). As platform depth increased, the total number of biotic zones 

increased. Platforms in shallower water (e.g., platforms Grace, Hidalgo, Habitat, and Irene) 

exhibited four or five zones, while the deeper platforms (e.g., platforms Gail and Harvest) 

possessed additional vertical substrate for a sixth platform-associated community. 

Based on inspection videotape review, several observations of platform-associated 

community structure were noteworthy: 

 Mytilus was always present, therefore there was always a mussel zone whose 

vertical extent and lower boundary were quite variable; 

 Barnacles were typically present above and/or below the mussel zone; 

 Encrusters (e.g., sponges) were routinely present at depth, often in conjunction with 

various cnidarian species (e.g., Metridium, Corynactis, Paracyathus); and 

 Beneath the intertidal, barnacle, and mussel zones, considerable variability in faunal 

composition was suggested. 

ES-5
Table ES-2. Characteristics of platform biotic zones as determined during inspection 

videotape analysis. 

Biotic Zone Zone Depth 

(m [ft] subsurface) 

Vertical Extent 

(m [ft]) 

Primary Platforms – 

Platform Gail 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Mytilus 1.8 to 12.1 (6 to 40) 10.3 (34) 

 Barnacle/Scallop 12.1 to 48.8 (40 to 160) 36.7 (120) 

 Corynactis/Encruster 48.8 to 115.8 (160 to 380) 67.0 (220) 

 Vase sponge/Encruster 115.8 to 192.0 (380 to 630) 76.2 (250) 

 Encruster/Sea Star/Cup Coral 192.0 to 225.2 (630 to 739) 33.2 (109) 

Platform Grace 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Mytilus 1.8 to 13.7 (6 to 45) 11.9 (39) 

 Barnacle/Scallop 13.7 to 27.4 (45 to 90) 13.7 (45) 

 Anemone/Encruster 27.4 to 70.1 (90 to 230) 42.6 (140) 

 Encruster/Sea Star 70.1 to 96.9 (230 to 318) 26.8 (88) 

Platform Harvest 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Mytilus 1.8 to 25.9 (6 to 85) 24.1 (79) 

 Barnacle/Corynactis 25.9 to 50.3 (85 to 165) 24.4 (80) 

 Anemone/Encruster 50.3 to 105.2 (165 to 345) 54.9 (180) 

 Vase Sponge/Encruster 105.2 to 169.2 (345 to 555) 64.0 (210) 

 Metridium/Sea Star 169.2 to 205.7 (555 to 675) 36.6 (120) 

Platform Hidalgo 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Mytilus 1.8 to 19.8 (6 to 65) 18.0 (59) 

 Barnacle 19.8 to 32.0 (65 to 105) 12.1 (40) 

 Metridium/Encruster 32.0 to 109.7 (105 to 360) 77.7 (255) 

 Sponges/Encruster 109.7 to 132.3 (360 to 434) 22.5 (74) 

Secondary Platforms – 

Platform Habitat 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Mytilus 1.8 to 18.3 (6 to 60) 16.5 (54) 

 Corynactis 18.3 to 54.9 (60 to 180) 36.6 (120) 

 Metridium/Encruster 54.9 to 88.4 (180 to 290) 33.5 (110) 

Platform Irene 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Barnacle/Algae 1.8 to 10.7 (6 to 35) 8.8 (29) 

 Mytilus 10.7 to 25.9 (35 to 85) 15.2 (50) 

 Corynactis/Encruster 25.9 to 73.4 (85 to 242) 47.9 (157) 

ES-6
Photographic Analysis 

 Based on the identification and enumeration of all flora and fauna present in each 

photoquadrat, 149 taxa (i.e., species level or higher) were identified (Table ES-3) on the six 

platforms. An additional 24 taxa were observed on the rock outcrops, for a total of 173 taxa 

identified at all sites sampled. During QSA, 821 photographs were characterized completely. 

The composite species list included representatives from several invertebrate phyla – mollusks 

(e.g., Mytilus), cnidarians (e.g., Metridium, Corynactis, Anthopleura), crustaceans (e.g., Balanus), 

polychaetes (e.g., worm tubes), echinoderms (e.g., Ophiothrix), and minor phyla (i.e., sponges, 

bryozoans, tunicates). Green, brown, and red algae were also identified. Fifty-five taxa total 

were identified during PointCount’99® analysis in which 883 photographs from six platforms 

were evaluated. 

 Photographic analysis of all species present (i.e., quantitative slide analysis) provided an 

estimate of both total density and percent cover for all specimens present on each photograph 

(image area: 0.0625 m2). Individual counts were important as a means of identifying numerical 

dominants, determining relative species densities, and as one basis for comparing platform legs. 

Estimates of percent cover were important for those species where individual counts were more 

difficult to acquire or where counts were not truly representative (e.g., with colonial taxa or 

major “community formers”). Percent cover estimates were also used in a comparison of 

platform legs. 

 Total density and percent cover estimates were used to rank dominant taxa. For the 

primary platforms, density and percent cover of dominant taxa were compared between 

adjacent legs, providing an indication of intra-platform variability. For both primary and 

secondary platforms, density and percent cover were used to compare taxa, providing an 

indication of inter-platform variability. 

Platform Gail

 This 8-legged platform is located in 225 m (739 ft) of water in the eastern Santa Barbara 

Channel. Legs A1 and B1 were sampled at Platform Gail from the intertidal zone to the base of 

each platform leg. Based on complete analysis of 196 photographs from both legs, 74 total taxa 

were identified, of which 41 percent (30) were monospecific taxa (i.e., species level 

identification). Remaining taxa were identified primarily to genus level, with a few specimens 

enumerated at higher taxonomic levels. Only five floral taxa (i.e., filamentous red algae, 

including Polysiphonia, Neoptilota, Antithamnion; Codium; encrusting coralline algae; filamentous 

green algae; foliose red algae) were among the 74 total taxa observed. One undifferentiated 

assemblage (turf) and one physical characteristic (bare metal) were also observed at Platform 

Gail. There were also indications that the upper portions (i.e., within the upper 8 m) of both 

legs of Platform Gail had been recently cleaned. Density-dominant species included Corynactis 

californica, Metridium exilis, Metridium senile, filamentous red algae, Ophiothrix spiculata, and 

Mytilus spp. Percent cover dominants included Corynactis californica, Mytilus spp., Metridium 

senile, Anthopleura elegantissima (rosy morph), and Metridium exilis. 

ES-7
Table ES-3. Taxa identified during the photographic analysis of six California platforms and Diablo and N

Dominant species or taxa, as determined via ranking of the top 12 taxa by density or percent cotype; dominant species shown separately for platforms (P), rock outcrops (R), or both (P+R). 

FLORA: Algae: 

Alga, brown, blade Alga, brown, clump Alga, coralline, encrusting Alga, encrusting (Lithothamnion) (R) 

Alga, green clump Alga, green clump (Codium-like) (R) Alga, green encrusting (P) Alga, green filamentous Algae, red filamentous (P+R) Algae, red foliose (P) Bossiella spp. (R)Codium spp. Corallina spp. (P) 

Egregia spp. Rhodymenia ?lobata Rhodymenia spp. 

Ulva lactuca (P) 

Note: Algae broadly characterized due to limitations of 

photographic resolution and interpretation. 

FAUNA: Crustaceans:  Barnacles (Cirripedia): 

Balanus nubilus (P)Balanus spp. (P+R)

Barnacle, unidentifiedChthalamus spp. (R) 

Pollicipes polymerus (P)Tetraclita squamosa (P)

 Decapod crabs (Decapoda): 

Cancer antennarius Cancer spp.Hemigrapsus nudus 

 Galatheid crabs (Galatheidae): 

Galathea californiensis

Echinoderms:  Sea stars (Asteroidea): 

Asterina miniata (=Patiria) 

Dermasterias imbricate Henricia leviuscula Henricia sanguinolenta Orthasterias koehleri Pisaster brevispinusPisaster giganteus Pisaster ochraceus (P)

Poraniopsis inflata Pycnopodia helianthoides Stylasterias forreri 

 Urchins (Echinoidea): 

Allocentrotus fragilis Lytechinus pictusStrongylocentrotus franciscanus

Strongylocentrotus purpuratus (R)

 Brittle stars (Ophiuroidea): 

Amphipholis spp. (P)Ophiocantha diplasia Ophiothrix spiculata (P+R)

Ophiuroid, unidentified (P) 

 Holothuroids (Holothuroidea): 

Dendrochirotida, unidentified (R) 

Parastichopus californicus 

 Crinoids (Crinoidea); 

Florometra serratissima 

Mollusks: 

Bivalves (Pelecypoda): 

Anomiidae, unidentified Bivalve, nestling, unidentified Chama arcana Crassadoma gigantea Mytilidae, unidentified Mytilus californianus (P+R)

Mytilus spp. (P) 

 Gastropods (Gastropoda

Aeolid (SF Aeolid

Aeolidia papillosa? Aeolidioidea, un

Anisodoris nobilisArchidoris monterCalliostoma spp.Cypraea spadicea Dialula sandiegensDorid, white, uniDorid, yellow, un

Doridacea, unideFlabellina iodinea

Gastropoda, unidHermissenda crassPleurobranchaea caSerpulorbis spp.Triopha catalina

 Chitons (Polyplacophora

Chiton, unidentif

Polychaetes:

Eudistylia polymSabellidae/Serpu

duster worm

Protula superba Salmacina spp. 

Serpulidae, unideSpionidae, unideSpirobranchus sppTube worm, douTube worm, singWorm tubes, calcWorm tubes, pla
Table ES-3. Taxa identified during the photographic analysis of six California platforms and Diablo and N

Dominant species or taxa, as determined via ranking of the top 12 taxa by density or percent cotype; dominant species shown separately for platforms (P), rock outcrops (R), or both (P+R) (c

Cnidarians:  Anthozoans (Actiniaria): 

Actiniaria, brown Actiniaria, pink Amphianthus californicus Anemone, pink Anemone, unidentified Anthopleura elegantissima 

(rosy morph) (P+R)

Anthopleura spp. Anthopleura spp. (whitish, no rose) (P) Anthopleura xanthogrammica (R)

Anthozoa, unidentified Astrangia spp. 

Balanophyllia elegans (R)

Coenocyathus bowersi (P)

Corynactis californica (P+R)

Cup coral, white, unidentified Desmophyllum dianthus (P) Epiactis prolifera? Gorgonian, unidentified Metridium exilis (P)

Metridium farcimen (P)

Metridium senile (P+R)

Metridium spp. (P) Metridium spp., dark or Feather Duster Palythoa (tan zoanthid) (P) Palythoa (tan) Paracyathus stearnsii (P)Urticina spp. Zoanthid (Palythoa) (P) Zoanthid, colonial tan (P) Zoanthid, solitary tan 

Hydrozoans: 

Hydrozoa, colony Hydrozoa, tan clump Plumularia spp. (P) Eudendrium spp.? Hydroid, pink Hydroid, tan (P) Hydroid, tan branching (P) 

Hydroid, white 

Minor Phyla:  Sponges (Porifera): 

Cliona spp., yellow Halichondria panicea (P)Leucetta losangelensis (P)

Leucilla nuttingiLeucetta spp. (P) Sponge, gray encrusting (P) Sponge, green encrusting (P) Sponge, orange encrusting (P) Sponge, orange round Sponge, purple encrusting Sponge, tan cup (P) Sponge, tan encrusting (P) Sponge, tan foliose encrusting Sponge, tan globose Sponge, unidentified (R) 

Sponge, white encrusting (P) Sponge, white finger Sponge, yellow encrusting (P) Staurocalyptus spp. (P)

 Bryozoans (Bryozoa): 

Bryozoa, staghorn, yellow (R) Bryozoa, tan branching (P) Bryozoa, white branching Bugula spp. Crisia/Filicrisia spp. Hippodiplosia spp. 

Tunicates (Urochordata, A

Amaroucium spp.Aplidium spp. Botrylloides spp. Halocynthia igabojStyela spp. Tunicate, encrusTunicate, encrusTunicate, globulaTunicate, solitaryUrochordata, uni

Fishes (Osteichthyes): 

Oxylebius pictus Sebastes spp. 

Undifferentiated Assembl

Algae/hydrozoa Bryozoa turf (P) Encruster, blue (Encruster, gray Encruster, green Encruster, lavendEncruster, orange Encruster, pink Encruster, red (PEncruster, tan (PEncruster, white Encruster, yellow Turf (P+R) 

Physical Characteristics: 

Bare metal (P) Line (P) 

Total: 173 taxa, including uassemblages and encrusterscharacteristics
 In terms of unique characteristics, Platform Gail (1) exhibited an unusual trend, 

specifically notable in the species identified within the anthozoan mix – the presence of dense 

colonies of Metridium exilis; (2) a Desmophyllum dianthus zone evident along the lower portions 

of both Legs A1 and B1; and (3) Corynactis californica, usually a dominant species at depth, was 

supplanted by M. exilis on Leg B1. 

 The top three density-dominant taxa common to both legs on Platform Gail (i.e., 

Corynactis californica, Metridium exilis, and Metridium senile) exhibited considerable between-leg 

variation in terms of total counts, average density per occurrence, and frequency of occurrence. 

Percent cover estimates of the dominant taxa (or physical characteristics) on Platform Gail also 

exhibited considerable variability between adjacent legs. Depth of distribution among the 

dominant taxa was also variable between the two platform legs. Photo ES-1 shows several of 

the dominant taxa evident on Platform Gail. 

Photo ES-1. (1) Mytilus spp., (2) Metridium senile, and several (3) Metridium exilis

at -1 m (-4 ft), Leg B1, Platform Gail.

1

3

2

Platform Grace 

This 12-legged platform is located in 97 m (318 ft) of water in the eastern Santa Barbara 

Channel. Legs C1 and C4 were sampled at Platform Grace. Based on analysis of 

150 photographs, 61 total taxa were identified, of which 36 percent (22) were monospecific taxa 

(i.e., species level identification). Remaining taxa were identified to genus level or higher. Only 

two floral taxa (i.e., filamentous red algae, including Polysiphonia, Neoptilota, Antithamnion; Ulva 

lactuca) were among the 61 total taxa observed. Two undifferentiated assemblages (turf, 

bryozoa turf) and two physical characteristics (bare metal, line) were also observed at Platform 

Grace. While mussel harvesting had occurred recently at Platform Grace, cleaned areas were 

ES-10
avoided during photographic sampling. Density-dominant taxa included Corynactis californica, 

Paracyathus stearnsii, Mytilus spp., and Ophiothrix spiculata. Percent cover dominants included 

Mytilus spp., Corynactis californica, turf, Anthopleura elegantissima (rosy morph), Metridium senile, 

and filamentous red algae. 

 Platform Grace exhibited well-defined Mytilus and Corynactis zones, abundant 

ophiuroids, a prominent barnacle community, and a broadly distributed anthozoan community 

(Metridium, Corynactis, Anthopleura). Many of the dominant species were also present on most 

other platforms (e.g., filamentous red algae, Balanus spp.). In terms of unique characteristics, 

Platform Grace exhibited the following trends: (1) prominent Mytilus and Corynactis 

communities, with no apparent overlap between the two species; and (2) a prominent 

Paracyathus community beginning in the lower portions of the Corynactis community and 

extending to the base of the platform. Photo ES-2 shows several of the dominant taxa evident 

on Platform Grace. 

Photo ES-2. (1) Mytilus spp., (2) Balanus spp., and (3) filamentous red algae at 

-2 m (-8 ft), Leg C1, Platform Grace. 

1

2

3

The top three density-dominant taxa common to both legs on Platform Grace (i.e., 

Corynactis californica, Paracyathus stearnsii, and Mytilus spp. on Leg C1; Corynactis californica, 

Mytilus spp., and Ophiothrix spiculata on Leg C4) exhibited moderate between-leg variation in 

terms of total counts, average density per occurrence, and frequency of occurrence. Percent 

cover estimates of dominant taxa Platform Grace also exhibited moderate variability between 

adjacent legs. Depth of distribution among the dominant taxa was also variable between the 

two platform legs. 

ES-11
Platform Harvest 

 This 10-legged platform is located in 206 m (675 ft) of water in the southern Santa Maria 

Basin. Legs B1 and B2 were sampled at Platform Harvest. Based on complete analysis of 

178 photographs from both legs, 53 taxa were identified, of which 34 percent (18) were 

monospecific taxa (i.e., species level identification). Remaining taxa were identified primarily to 

genus level, with several specimens enumerated at higher taxonomic levels. Only three floral 

taxa (i.e., foliose red algae; Egregia; filamentous red algae, including Polysiphonia, Neoptilota, 

Antithamnion) were among the 53 total taxa observed. One undifferentiated assemblage (turf) 

and two physical characteristics (bare metal, line) were also observed at Platform Harvest. 

There was no indication that recent cleaning activity had occurred at this platform. 

Density-dominant taxa included Metridium senile, an unidentified ophiuroid (probably 

Ophiothrix spiculata), Mytilus spp., and Leucetta. Percent cover dominants included Metridium 

senile, Metridium farcimen, turf, a red encruster, Leucetta losangelensis, and Mytilus spp. 

Photo ES-3 shows several of the dominant taxa evident on Platform Harvest. 

Photo ES-3. (1) Mytilus spp., (2) Metridium senile, (3) Balanus spp., and 

(4) filamentous red algae at -2 m (-6 ft), Leg B1, Platform Harvest.

1

2

3

4

The top three density-dominant taxa common to both legs on Platform Harvest (i.e., 

Metridium senile, an unidentified ophiuroid [probably Ophiothrix spiculata], and Mytilus spp. on 

Leg B1; Metridium senile, an unidentified ophiuroid, and Leucetta on Leg B2) exhibited moderate 

between-leg variation in terms of total counts, average density per occurrence, and frequency of 

occurrence. Percent cover estimates of dominant taxa on Platform Harvest also exhibited 

considerable variability between adjacent legs. 

ES-12
Platform Hidalgo 

 This 8-legged platform is located in 131 m (430 ft) of water in the southern Santa Maria 

Basin. Legs A1 and B1 were sampled at Platform Hidalgo. Based on analysis of 

141 photographs, 53 total taxa were identified, of which 37 percent (21) were monospecific taxa 

(i.e., species level identification). Only four floral taxa (i.e., foliose red algae; Egregia; 

filamentous red algae, including Polysiphonia, Neoptilota, Antithamnion; Rhodymenia) were among 

the 53 total taxa observed. One undifferentiated assemblage (turf) and two physical 

characteristics (bare metal, fishing line) were also observed. There was no indication that recent 

cleaning activity had occurred at Platform Hidalgo. Density-dominant taxa included Metridium 

senile, an unidentified ophiuroid, Mytilus spp., Balanus nubilus, Metridium farcimen, Balanus spp., 

and calcareous worm tubes. Percent cover dominants included Mytilus spp., Metridium senile, 

Leucetta losangelensis, and Anthopleura elegantissima (rosy morph). Photo ES-4 shows Mytilus 

spp. and associated fauna present on Platform Hidalgo. 

Photo ES-4. (1) Mytilus spp. and associated fauna at -2 m (-6 ft), Leg B1, 

Platform Hidalgo.

1

The top three density-dominant taxa common to both legs on Platform Hidalgo (i.e., 

Metridium senile, an unidentified ophiuroid, and Mytilus spp. on Leg A1; Metridium senile, 

Mytilus spp., and an unidentified ophiuroid on Leg B1) exhibited moderate between-leg 

variation in terms of total counts, average density per occurrence, and frequency of occurrence. 

Percent cover estimates of dominant taxa on Platform Hidalgo also exhibited considerable 

variability between adjacent legs. 

ES-13
Comparisons of Adjacent Legs – Summary 

 Among the four primary platforms sampled, there were varying numbers of common 

and unique dominant and subdominant taxa present on adjacent legs. When the top 

12 density-dominant taxa were considered, relatively high numbers of co-occurring dominants 

were evident at platforms Harvest and Gail, followed by Hidalgo and Grace. In all cases, the 

numbers of dominant taxa unique to a particular platform leg ranged from zero to two, 

suggesting a relatively strong similarity in community composition between adjacent platform 

legs. Two taxa, Metridium senile and Mytilus spp., were noted numerical dominants on all of 

the primary platform legs. Other dominant taxa which were consistently common to adjacent 

platform legs included Balanus spp., Ophiothrix spiculata or unidentified ophiuroids, and 

calcareous worm tubes. Turf, representing an aggregation of smaller flora and fauna (including 

protozoa, hydrozoa, bryozoa, and algae) that co-occur with one another, was included among 

the density co-dominants on three of the four primary platforms, while bare metal co-occurred 

on all adjacent legs and was a dominant feature on platforms Harvest and Hidalgo. 

 In terms of percent cover, there were interesting differences evident between adjacent 

platform legs. On Platform Gail, Corynactis californica, Metridium exilis, and Mytilus spp. 

contributions to percent cover were significantly different between the legs sampled, while 

contributions from bare metal and Metridium senile increased accordingly. On Platform Grace, 

percent cover estimates of dominant taxa exhibited moderate variability between adjacent legs. 

Percent cover contributions from Mytilus spp., turf, and filamentous red algae were comparable 

between the two legs sampled, while those from Corynactis californica were considerably 

different. 

On Platform Harvest, percent cover dominants Metridium senile and turf exhibited 

similar contributions between legs, while significant variability was evident between legs for 

the red encruster, Mytilus spp., and Leucetta losangelensis. On Platform Hidalgo, moderate 

variability in percent cover dominants was evident between adjacent legs. Contributions from 

Mytilus spp., Metridium senile, and Leucetta losangelensis were similar between legs, while those 

from Corynactis californica and Anthopleura elegantissima (rosy morph) were noticeably different. 

 There were several other interesting observations which resulted from a comparison of 

adjacent legs. Corynactis californica and Anthopleura elegantissima (rosy morph) were normally 

present on the adjacent legs of primary platforms, however, Corynactis was noticeably and 

completely absent from Leg B1 of Platform Hidalgo and A. elegantissima (rosy morph) was 

absent from Leg A1 of Platform Hidalgo and Leg B1 of Platform Gail. 

Platform Habitat

This 8-legged platform is located in 88 m (290 ft) of water in the central Santa Barbara 

Channel. Leg A1 was sampled at Platform Habitat. Based on complete analysis of 

70 photographs, 42 taxa were identified, of which 36 percent (15) were monospecific taxa 

(i.e., species level identification). Only three floral taxa (i.e., filamentous red algae, including 

Polysiphonia, Neoptilota, Antithamnion, etc.; the coralline alga Corallina; Ulva) were among the 

42 total taxa observed. One undifferentiated assemblage (turf) and one physical characteristic 

ES-14
(bare metal) were also observed. There was no indication that recent cleaning activity had 

occurred at Platform Habitat. 

Density-dominant taxa included Corynactis californica, Mytilus spp., Metridium senile, 

Ophiothrix spiculata, Balanus nubilus, and the rosy morph form of Anthopleura elegantissima. 

Dominant taxa in terms of percent cover included Corynactis californica, Mytilus spp., a zoanthid 

(Palythoa), the rosy morph form of Anthopleura elegantissima, and filamentous red algae. In 

terms of unique characteristics, Platform Habitat exhibited the following: (1) an intermittent 

Mytilus zone; (2) a broadly distributed anthozoan community (Metridium, Corynactis, 

Anthopleura); and (3) dense aggregations of an unidentified zoanthid. Photo ES-5 shows several 

of the dominant taxa evident on Platform Habitat. 

Photo ES-5. (1) Mytilus spp., (2) Metridium senile, (3) Balanus spp., and 

(4) Ophiothrix spiculata at -4 m (-13 ft), Leg A1, Platform Habitat.

1

2

3

4

Platform Irene 

 This 8-legged platform is located in 74 m (242 ft) of water in the southern Santa Maria 

Basin. Leg A1 was sampled at Platform Irene. Based on complete analysis of 64 photographs, 

39 taxa were identified, of which nearly 41 percent (16) were monospecific taxa (i.e., species 

level identification). Remaining taxa were identified primarily to genus level, with a few 

specimens enumerated at higher taxonomic levels. Only four floral taxa (i.e., filamentous red 

algae, including Polysiphonia, Neoptilota, Antithamnion, etc.; a small red foliose alga, a green 

encrusting alga; Ulva) were among the 39 total taxa observed. One undifferentiated assemblage 

(turf) and one physical characteristic (bare metal) were also observed. There was no indication 

that recent cleaning activity had occurred at Platform Irene. 

ES-15
 Dominant taxa, based on total density, included Metridium senile, Mytilus californianus, 

Tetraclita squamosa, Balanus spp., Anthopleura elegantissima (rosy morph), and calcareous worm 

tubes. In terms of percent cover, prevalent species included Metridium senile, Mytilus 

californianus, Tetraclita squamosa, and three encrusting sponge species (i.e., gray encrusting, tan 

encrusting, and yellow encrusting). Photo ES-6 shows several of the dominant taxa evident on 

Platform Irene. 

Photo ES-6. (1) Mytilus californianus, (2) Metridium senile, (3) Anthopleura 

elegantissima (rosy morph), and (4) Pisaster ochraceus at 

-9 m (-31 ft), Leg A1, Platform Irene.

1

2

3

4

Diablo and Nifty Rocks

These two natural rock outcrops are located offshore of the northern Channel Islands. 

Diablo Rock is several kilometers to the west of Diablo Point, off the northern coastline of Santa 

Cruz Island, within the waters of the western Santa Barbara Channel; water depths at the base 

of this feature are approximately 33 m (108 ft). Nifty Rock is several kilometers east-southeast 

of Harris Point, off the northwestern point of San Miguel Island; water depths at the foot of this 

rock outcrop are approximately 15 m (50 ft). Forty-four taxa were identified from the 

photographic analysis of 22 photographs acquired at Diablo and Nifty Rocks. Fourteen of these 

taxa were monospecific (i.e., species level identification). Of the 44 taxa present, 24 taxa were 

unique to the rock outcrops (i.e., 20 taxa common to both the rock outcrops and the platforms). 

Seven floral taxa (i.e., filamentous red algae, Bossiella spp., an encrusting alga [Lithothamnion], 

two different green clump algal types [one of which was Codium-like], an unidentified brown 

alga, and a brown clump alga) were among the 44 total taxa observed. Density-dominant taxa 

included Corynactis californica, Chthalamus spp., Balanus spp., Anthopleura xanthogrammica, 

ES-16
Ophiothrix spiculata, and Mytilus californianus. Percent cover dominants included Corynactis 

californica, filamentous red algae, encrusting green alga (Lithothamnion), Chthalamus spp., turf, 

and a composite of encrusters. Photo ES-7 shows several of the dominant taxa evident at 

Diablo Rock. 

Photo ES-7. (1) Mytilus californianus, (2) filamentous red algae, (3) an 

encrusting alga (Lithothamnion), (4) Anthopleura xanthogrammica, 

and (5) A. elegantissima at -8 m (-25 ft), Diablo Rock.

1

2

3

4

5

Comparisons Between Platforms 

 Combining dominant taxa from both density and percent cover determinations into a 

composite listing produced 60 taxa, undifferentiated assemblages (i.e., turf, bryozoa turf), and 

physical characteristics (e.g., bare metal). A comparison of average rankings (i.e., density vs. 

percent cover) for the dominant taxa at all platforms is provided in Table ES-4. 

 Thirty-four numerically dominant species or taxa were present on one or more of the 

six platforms evaluated. Two taxa, Metridium senile and Mytilus spp., were identified as 

numerical dominants on all ten platform legs evaluated. Four other taxa – Balanus spp., 

calcareous worm tubes, turf, and a yellow encrusting sponge – were either density-dominants 

or present (as sub-dominants) on all ten platform legs. Corynactis californica and Anthopleura 

elegantissima (rosy morph) were present on nine of the ten legs as dominant taxa, while Balanus 

nubilus and bare metal were either dominants or present on nine of the platform legs. Other 

taxa present on a majority of the platform legs included unidentified ophiuroids, Ophiothrix 

spiculata, Metridium farcimen, filamentous red algae, Leucetta/Leucetta losangelensis, Paracyathus 

stearnsii, and plain worm tubes. 

ES-17
Table ES-4. Comparison of average rankings – density vs. percent cover – for the dominant taxa, all platform

Taxon Density Percent Cover Frequency (%) Taxon Density 

Metridium senile 2.90 3.33 100 Zoanthid, colonial tan ND Mytilus spp. 3.80 2.78 100 Tetraclita squamosa 8.00 Balanus spp. 6.00 ND 100 Coenocyathus bowersi 9.00 Worm tubes, calcareous 8.00 6.00 100 Metridium spp. 9.00 Turf 9.29 7.00 100 Tunicate, encrusting translucent 10.00 Sponge, tan encrusting ND 9.00 100 Sponge, cup tan ND Bare Metal 11.50 7.88 100 Zoanthid, tan (Palythoa) ND Sponge, yellow encrusting 11.00 10.25 100 Sponge, orange encrusting ND Corynactis californica 2.89 4.00 90 Desmophyllum dianthus 6.50 Ophiuroid, unidentified 3.80 ND 90 Protula superba 10.00 Balanus nubilus 8.00 ND 90 Zoanthid (Palythoa) ND Encruster, yellow ND 8.00 90 Hydroid, tan ND Anthopleura elegantissima (rm) 6.25 6.57 80 Sponge, tan foliose ND Ophiothrix spiculata 5.86 7.00 70 Tunicate, tan encrusting ND Metridium farcimen 8.00 5.33 70 Sponge, gray encrusting ND Filamentous red algae 8.20 6.00 70 Encruster, lavender ND Foliose red algae ND 11.00 70 Encruster, blue ND Leucetta/Leucetta losangelensis 7.50 5.60 60 Alga, encrusting green ND Encruster, tan ND 8.67 60 Ulva spp. ND Hydroid, tan branching ND 9.00 60 Halichondria panicea ND Paracyathus stearnsii 5.00 10.00 60 Bryozoa turf ND Sponge, white encrusting ND 11.00 60 Cliona spp., yellow ND Worm tubes, plain 11.50 ND 60 Triopha catalinae 8.00 Pollicipes polymerus 12.00 ND 50 Botrylloides spp. ND Eudistylia polymorpha 9.00 ND 40 Sponge, tan globose ND Encruster, red 11.50 4.00 40 Anthozoa, unidentified ND Pisaster ochraceus 12.00 ND 40 Anthopleura spp. (whitish, no rose) 10.00 Bryozoa, tan branching ND 11.00 40 Corallina spp. 10.00 Metridium exilis 3.67 3.50 30 Staurocalyptus sp. 11.00 Mytilus californianus 4.50 5.00 30 Amphipholis spp. 12.00 Note: ND = not determined; rm = rosy morph. 
 While a number of density-dominant taxa were present at all platforms, considerable 

variability was evident among platform sub-dominants. For example, Metridium exilis at 

Platform Gail and Desmophyllum (Desmophyllum dianthus) at Platform Gail were among the 

platform’s numerical dominants, yet were either extremely limited or not evident at the 

remaining platforms. Metridium exilis only occurred elsewhere on a single platform leg – 

Platform Grace, Leg C4 (i.e., this species was not encountered at the remaining four platforms). 

Desmophyllum, the sixth or seventh most abundant species (by density) at Platform Gail, was not 

encountered at any of the other platforms sampled. 

 Other dominant taxa that occurred exclusively at the southern platforms (i.e., Gail, 

Grace, Habitat) included the brittlestar Amphipholis, coralline alga (Corallina), the sponge 

Staurocalyptus, and the nudibranch Triopha catalinae. Similarly, several species were absent from 

platforms in the eastern Santa Barbara Channel (i.e., Grace, Gail), but nearly always present on 

those in the Santa Maria Basin (i.e., Harvest, Hidalgo, Irene), including the gooseneck barnacle 

Pollicipes polymerus, a red encruster, and the starfish Pisaster ochraceus. 

 In terms of percent cover, forty dominant species, taxa, or physical characteristics were 

noted. Six taxa (or undifferentiated “assemblages” such as turf) were present on all ten 

platform legs. Metridium senile and turf were percent cover dominants on all ten platform legs. 

Tan encrusting and yellow encrusting sponges and calcareous worm tubes were dominants or 

sub-dominants on all ten platform legs evaluated. Mytilus spp. was a major contributor to 

percent cover on nine of the ten legs evaluated. While percent cover estimates for Mytilus spp. 

were not determined on Platform Irene, Mytilus californianus was recognized as a dominant 

contributor to percent cover on Irene, indicating that mussels were percent cover dominants on 

all platform legs. Corynactis californica and Anthopleura elegantissima (rosy morph) were percent 

cover dominants or sub-dominants on eight legs and present (but coverage not determined) on 

another leg, for a total of nine platform legs. Corynactis was absent from a single leg on 

Platform Hidalgo, while Anthopleura was absent from a single leg on Platform Gail. 

Bare metal was also a percent cover dominant or sub-dominant, as a physical 

characteristic, on nine of the platform legs, being absent from Platform Irene. Other taxa which 

were contributors to percent cover on a majority of the platform legs included a yellow 

encruster, Ophiothrix spiculata, filamentous red algae, a white encrusting sponge, Metridium 

farcimen, foliose red algae, a tan encruster, Leucetta/Leucetta losangelensis, a tan branching 

hydroid, and Paracyathus stearnsii. 

For many of the taxa, the average density and average percent cover rank 

determinations were comparable, particularly for the most frequently observed species 

(e.g., Metridium senile; Mytilus spp.; calcareous worm tubes; Corynactis californica; Anthopleura 

elegantissima [rosy morph]). This comparability underscores the fact that these species were not 

only present at all of the platforms, but present as dominant taxa in terms of individual counts 

and/or percent cover. Further, individual counts and percent cover estimators are viable 

mechanisms, both separately and jointly, in determining relative importance of a species to 

platform community structure. 

ES-19
 Among the numerically dominant (i.e., density-dominant) taxa, cnidarians 

(i.e., Metridium senile, Anthopleura elegantissima (rosy morph), Corynactis californica), mussels 

(i.e., Mytilus californianus; Mytilus spp. complex), barnacles (i.e., Balanus nubilus, Balanus spp., 

Tetraclita squamosa), worm tubes (calcareous and plain), and ophiuroids (Ophiothrix spiculata; 

ophiuroids, unidentified) represented the most prominent and consistent community-formers 

present on the platforms studied. Several of the density-dominant taxa were also noted as 

significant fauna elements when percent cover was determined. The major taxa, 

undifferentiated assemblages, or physical characteristics evaluated for percent cover 

(i.e., coverage-dominant) included cnidarians (i.e., Metridium senile, Anthopleura elegantissima

[rosy morph], Corynactis californica; Metridium farcimen), mussels (i.e., Mytilus californianus; 

Mytilus spp. complex), turf, calcareous worm tubes, sponges (tan encrusting, yellow encrusting, 

Leucetta/Leucetta losangelensis), bare metal, encrusters (yellow), ophiuroids (Ophiothrix spiculata), 

and algae (filamentous red algae, foliose red algae). These taxa represented the most prominent 

and consistent community-formers present on the platforms studied. 

 Major findings pertinent to dominant platform-associated taxa included the following: 

 Metridium senile – the highest ranked species observed overall, a numerical (density) 

dominant of platforms Harvest, Hidalgo, and Irene, and ranking within the top four 

at platforms Gail, Grace, and Habitat. Average densities ranged from 10.8 to 

330.9 individuals/0.0625 m2 (maximum: 510 individuals/0.0625 m2 at Platform 

Irene) and average coverage ranged from 3.7 to 66.0 percent (maximum: 98 percent 

at Platform Irene). This species exhibited a wide depth distribution and was found 

at nearly all depths of a platform. 

 Mytilus spp. – the second highest ranked species observed and the most prominent 

taxon between the intertidal and the upper few tens of meters of a platform leg. 

Mytilus spp. or Mytilus californianus consistently ranked in the top six among density 

dominants, and usually was the second or third most abundant taxa (by density) at 

the platforms sampled. Average densities ranged from 24.3 to 117.8 individuals 

/0.0625 m2 (maximum: 240 individuals/0.0625 m2 at Platform Grace) and average 

coverage ranged from 19.2 to 60.4 percent (maximum: 100 percent at Platform 

Habitat). Mussels typically occurred in a depth range that extended from the 

intertidal to 12 to 24 m (40 to 80 ft). 

 Barnacles, represented by Balanus spp., Balanus nubilus, and, to a lesser extent by 

Tetraclita squamosa, ranked third in total density among platform-associated taxa. 

Average densities ranged from 2.5 to 42.0 individuals/0.0625 m2 (maximum: 

200 individuals/0.0625 m2 at Platform Irene). The predominant depth range for 

barnacles was within the upper portions of the platform leg (i.e., usually from the 

intertidal to approximately 18 m [60 ft]), although barnacles were found extending 

deeper at platforms Grace, Harvest, Hidalgo, Habitat, and Irene. 

 Worm tubes, including both calcareous and plain forms, jointly ranked fourth in 

total density among platform-associated taxa. Average densities for calcareous 

worm tubes ranged from 1.0 to 51.5 individuals/0.0625 m2 (maximum: 

100 individuals/0.0625 m2 at Platform Irene). The predominant depth range for 

worm tubes, whether calcareous or plain, was below approximately 46 m (150 ft). 

Maximum depth of occurrence for worm tubes was 213 m (700 ft). 

ES-20
 Two forms of encrusting sponge – yellow encrusting and tan encrusting – were 

present (along with all of the taxa noted above) on all platform legs sampled. Yellow 

encrusting sponge exhibited average cover ranging from 0.5 to 16.1 percent 

(maximum: 70 percent at Platform Harvest), while tan encrusting sponge exhibited 

average cover ranging from 4.0 to 32.4 percent (maximum: 60 percent at Platform 

Irene). 

Bare metal was also present on all ten platform legs, primarily at depth, with average 

cover ranging from 7.5 to 49.2 percent; this physical characteristic was noticeably reduced at 

Platform Irene, present in only a few photographs near the base of the platform. 

Other prominent platform-associated taxa included the anthozoan anemones Corynactis 

californica and Anthopleura elegantissima who ranked fifth and sixth in total density among 

density-dominant species, respectively. Corynactis californica exhibited a rather broad depth 

distribution, typically between approximately 15 and 61 m (50 and 200 ft), although Corynactis

was observed at deeper depths (e.g., >91 m [300 ft] at Platform Gail; >61 m [200 ft] at Platform 

Habitat). The rosy morph form of Anthopleura elegantissima exhibited a very restricted depth 

range, occurring primarily in the upper 1 to 14 m (3 to 45 ft) of each submerged platform leg 

(i.e., with the intertidal, barnacle, and Mytilus zones). 

Ophiuroids, as represented by Ophiothrix spiculata or unidentified ophiuroids, were also 

prevalent on the platforms and were ranked seventh in total density among the dominant 

species. Ophiuroid dominance at each platform varied, ranging in density-based ranking from 

second to tenth. Highest average densities of Ophiothrix spiculata or unidentified ophiuroids 

were observed at Platform Hidalgo, while lowest average densities were evident at platforms 

Irene, Habitat, and Gail. Ophiuroids exhibited a wide depth distribution and were found at 

nearly all depths of a platform, in similar fashion to Metridium senile. 

Comparison of Platforms and Natural Rock Outcrops 

Results of the quantitative slide analysis of photographs from Diablo and Nifty Rocks 

resulted in the identification of 44 taxa. There were several taxa found to be dominant on both 

natural outcrops and platforms (i.e., Ophiothrix spiculata, Mytilus californianus, Corynactis 

californica, and Metridium senile; filamentous red algae). However, twenty-four of the taxa 

identified at Diablo and Nifty Rocks were not observed on the platforms. In spite of the 

restricted scope of photographic sampling conducted at Diablo and Nifty Rocks, it is suggested 

that species diversity at the natural rock outcroppings was higher than that seen in comparable 

depth zones at the six platforms, particularly for algal species which, by comparison, were 

under-represented on the platforms. 

Previous regional characterizations of California’s hard bottom fauna offer insight into 

the community composition of hard bottom features found at depth (e.g., low to high relief rock 

outcrops, generally 1 to 3+ m above the seafloor, at various water depths). The 30 most 

frequently encountered megabenthic taxa occurring on hard substrate in the western Santa 

Barbara Channel and Santa Maria Basin were represented by five phyla – Porifera (sponges), 

Cnidaria (anthozoans), decapod crustaceans, brachiopods, and echinoderms (i.e., crinoids, 

holothuroids, echinoids/urchins, asteroids/sea stars, and ophiuroids). Thirteen of the 

ES-21
30 natural hard bottom megafauna taxa also occur on the platforms, however, nearly half of 

these taxa occurred only once (i.e., sole occurrence on a single platform). Most frequently 

encountered species include Metridium farcimen and a tan zoanthid. The zoanthid depth 

distribution was across the entire platform leg depth. M. farcimen depth distribution was more 

restricted. For a limited number of species which occur at both platforms and hard bottom 

features (e.g., Galathea californiensis), respective depth distributions were similar. Depth 

distribution for other species was confounding and no apparent trends were evident. 

Statistical Analysis of Photographic Data 

Platform Leg Comparisons 

 Results of the clustering analysis using the density data sets indicated greatest similarity 

between (1) adjacent legs on Platform Harvest; (2) adjacent legs on Platform Hidalgo; and 

(3) Platform Gail (Leg A1) and Platform Grace (Leg C4). While similarity between adjacent legs 

on the same platform might be expected, the high level of similarity between Grace and Gail 

was not. While Grace and Gail are both located in the eastern Santa Barbara Channel, there are 

significant water depth differences and corresponding differences in the total number of biotic 

zones between the two platforms. The process of combining data along a platform leg 

effectively eliminated any biotic zone bias that might be introduced and allowed for a direct 

comparison of flora and fauna between legs. In this instance, it appeared that the relative 

contribution of fauna from the lower zone of Gail had minor effect on clustering; the strong 

similarities evident were attributed to geographic proximity. Support for this hypothesis was 

also evident in subsequent groupings, where the Santa Barbara Channel platforms 

(Habitat-Grace-Gail) exhibited similarity with one another and the Santa Maria Basin platforms 

(Harvest-Hidalgo-Irene) exhibited similarity with one another. The inconsistent element in the 

clustering results rested with Platform Gail (Leg B1), which showed similarity with 

Harvest-Hidalgo-Irene. No obvious explanation was available to explain this clustering result. 

 Results of the clustering analysis using percent cover data were very similar to those 

shown by the count data and strongly supported similarities between adjacent legs. Greatest 

similarities, in descending order, were evident between adjacent legs on all primary platforms – 

Harvest, Hidalgo, Gail, and Grace. The secondary platforms grouped according to geographic 

location: Habitat grouped with Grace, while Irene grouped with the Hidalgo-Harvest grouping. 

Biotic Zone Comparisons 

 Results of clustering analysis using density data indicated strongest similarities between 

(1) Platform Irene (Leg A1) Mytilus and Corynactis zones; (2) Platform Harvest (Legs B1 and B2) 

Metridium/sea star zones; and (3) Platform Hidalgo (Leg B1) intertidal and Mytilus zones. The 

top down analysis of density clustering results produced three groupings which generally 

reflected community water depth. Results of clustering analysis using percent cover data, while 

producing associations which were not identical to those noted with the count data, did identify 

strong similarities between adjacent zones of the same platform leg or the same zones between 

adjacent legs. The top down analysis of percent cover clustering results produced four 

groupings. In general, with minor exception, similarity groupings (based on count or percent 

cover biotic zone data resulting from whole slide analysis) tended to occur between adjacent 

ES-22
zones of the same platform leg (e.g., intertidal and Mytilus) or the same zones between adjacent 

legs. These results suggested that there was (1) a strong similarity between biota of adjacent 

platform legs, and (2) a gradual shift in community structure with increasing depth along a 

platform leg. Further, the boundaries of each biotic zone are not tied strictly to water depth. 

PointCount’99® Analysis 

 The first clustering analysis of PointCount’99® data determined similarities between 

platform legs, with greatest similarities evident between (1) adjacent legs on Platform Harvest; 

and (2) adjacent legs on Platform Hidalgo. The second clustering determined the similarities 

between biotic zones, with greatest similarities evident between (1) Platform Irene Mytilus and 

Corynactis zones; (2) Platform Gail barnacle/scallop and Platform Grace barnacle/scallop zones; 

(3) Platform Harvest anemone/encruster and Platform Hidalgo sponges/encruster zones; and 

(4) Platform Hidalgo intertidal zones. 

 The top down analysis of the PointCount’99® biotic zone data sets resulted in the 

identification of four groupings. The first grouping, comprised of select intertidal and Mytilus 

communities from the six platforms, suggested a similarity between intertidal and Mytilus

zones, regardless of geographic location. The second grouping, comprised primarily of 

Corynactis and various encrusters, suggested similarity between the zones present in 

intermediate water depths of select platforms, most of which are characterized by the presence 

of encrusters, regardless of geographic location. The third grouping, consisting of Mytilus and 

barnacle zones along with other zones, suggested similarity of biotic zones across a depth range 

for the northern platforms, and indicated that several taxa (e.g., Metridium senile, Leucetta) that 

were widely distributed down a platform leg produced a biotic continuum which countered the 

concept of distinct biotic zones. The fourth grouping, comprised of remaining intertidal, 

Mytilus, barnacle/scallop, and vase sponge/encruster communities, also suggested the 

presence of a biotic continuum, with several species present (and often dominant) in adjacent 

biotic zones (e.g., Ophiothrix spiculata, Metridium senile, barnacles, Corynactis californica). 

PointCount’99® vs. QSA 

Eighty-one percent of the taxa identified during point count analyses (PointCount’99®) 

were also identified as percent cover dominants during whole or quantitative slide analysis 

(QSA). Overall, rankings of QSA percent cover dominants were very consistent with 

PointCount’99® results. Typically, the top dominants on each platform leg were noted 

accordingly, although shuffling of position between top dominants was evident between the 

two analytical approaches. Such reshuffling of dominant taxa was not unexpected, given the 

differences between comparison parameters (i.e., 50 random points vs. whole slide analysis). 

 At least one species of interest was potentially under represented in the point count 

approach – mussels. Mytilus spp. on Platform Gail averaged only 24.9 percent cover via the 

point count method, while QSA results averaged 60.4 percent, a level considered to be more 

representative. Under representation of mussels was also evident at platforms Grace and 

Hidalgo, and, to a lesser extent, at Platform Harvest. Mytilus coverage estimates at the 

remaining platform were comparable. Under representation was not evident with other 

dominant taxa. 

ES-23
Diablo and Nifty Rocks and Comparable Platform Zones 

 The last set of clustering analyses employed QSA data to determine the similarities 

between epibiota of natural rock outcrops and platform legs within similar water depths using 

density (i.e., count) and percent cover data sets. Results of clustering analysis using count data, 

comparing platform biota to natural outcrop communities in the 5 to 17 m depth range, 

indicated greatest similarities between (1) Platform Hidalgo and Platform Irene; (2) Platform 

Grace and Diablo Rock; and (3) Platform Harvest. Results of the clustering analysis using 

percent cover data revealed greatest similarities for (1) Platform Hidalgo and Platform Irene; 

(2) Platform Grace with the Hidalgo-Irene group; and (3) Platform Harvest with the 

Grace-Hidalgo-Irene group. Diablo Rock exhibited closest affinity to the 

Harvest-Grace-Hidalgo-Irene group, while Nifty Rock showed greatest similarity with Platform 

Grace. Aside from the Hidalgo-Irene grouping, none of the percent cover similarities were 

evident in the earlier count data comparisons. No readily discernable trends were evident. 

Depth Distribution of Platform-Associated Biota 

 In general, the biotic zones determined from videotape analysis were confirmed through 

the photographic analysis. Mussel zones were always present, although their vertical extent 

may have differed from those estimated from the videotapes alone. Mussel zones extended to 

depths of 16 m (52 ft), with only limited presence below that depth (maximum depth: 24 m; 

79 ft). Mytilus typically co-occurred with several taxa, including (1) algae, with filamentous and 

foliose red algae predominating, extending to depths of 17 to 20 m (55 to 65 ft); barnacles, with 

Balanus nubilus and Balanus spp. predominant; and (3) several anemone species, including 

Anthopleura elegantissima (rosy morph) and Metridium senile. Ophiuroids were also present 

within the mussel zone, but typically in the mid to lower portions of the Mytilus zone, perhaps 

to avoid stronger surge present closer to the surface. 

 Dominant species or taxa found at intermediate depths and beyond were generally, but 

not always, consistent with the biotic zone designations. These findings may be related to the 

broad categories used in the videotape analysis (e.g., encrusters), may reflect differences 

inherent in comparing data sets acquired at different spatial scales, or may be attributed to 

changes in community composition over time. Overall, it was evident that there was 

considerable overlap in the depth distributions of major taxa (i.e., density- and percent cover 

dominants). 

 Graphic representations of the generalized depth distribution of dominant species 

present at each platform are provided in Figures ES-2 through ES-4. These figures present 

generalized depth distribution patterns, based on random sampling between the intertidal and 

base of one or two platform legs. General depth distribution and patterns of occurrence for the 

most prevalent platform-associated species are depicted graphically in Figure ES-5. 

ES-24
Figure ES-2. Generalized depth distribution of dominant species present at platforms Gail and Grace. 

Depth (ft)

Metridium

exilis

Metridium

senile

Mytilus spp.

Ophiothrix spiculata Balanus spp.

Desmophyllum dianthus

Depth (m)

0

153045607691106121137152167182198213

225

Algae

, filamentous

red

Corynactis

californica

Gail

0

50

100150200250300350400450500550600650700739

0

50

100150200250300318

Depth (ft)

Grace

Mytilus

californianus

Corynactis

californica

Anthopleura

elegantissima (rm) Metridium senile Balanus spp.

Paracyathus

stearnsii

Ophio

Coenocyathus bowersi
Figure ES-3. Generalized depth distribution of dominant species present at platforms Harvest and Hidalgo. 

0

50

100150200250300350400450500550600

650

Corynactis californica

Anthopleura

elegantissima (rm)

Worm tubes

,

calcareous

Balanus spp. Leucetta Mytilus spp.

Ophiuroid

,

unidentified

Depth (ft)

Harvest

Depth (m)

675

Metridium

senile 0

153045607691106121137152167182

198

206

Hidalgo Anthopleura

elegantissima (rm)

Worm tubes

,

calcareous

Balanus nubilus

Metridium farcimen Metridium senile My

0

50

100150200250300350400

430

Depth (ft)

Leucetta losangelensis
Figure ES-4. Generalized depth distribution of dominant species present at platforms Habitat and Irene.

Habitat

Depth (m)

0

15

3045

60

76

88

0

50

100150200250

290

Anthopleura

elegantissima (rm) Staurocalyptus sp. Triopha catalinae

Paracyathus stearnsii Ophiothrix spiculata Balanus nubilus Metridium senile Mytilus spp. Corynactis californica

Depth (ft)

Ophiothrix spiculata Metridium senile Tetraclita squamosa Corynactis californica

Anthopleura

elegantissima (rm)

Mytilus

cali

Mytilus 

Irene

0

50

100150200

242

Depth (ft)

Sponge

, yellow

encrusting
ES-28
ES-29 

In general terms, the zonation patterns of all California platforms may include: 

 an upper zone (from the intertidal to 18 to 26 m [60 to 85 ft]), including the intertidal 

and mussel bed, and consisting of Mytilus spp., various algae (e.g., filamentous and 

foliose red algae, several green algal species such as Ulva), barnacles, several 

anemone species (e.g., Anthopleura elegantissima, Metridium senile), sponges, and 

ophiuroids; 

 a mid zone (from 19 to 26 m [65 to 85 ft] to about 76 m [250 ft]), including Corynactis 

californica, ophiuroids, barnacles, Metridium senile, Leucetta/Leucetta losangelensis, and 

worm tubes; and 

 a lower zone (below 76 m [250 ft]), including Metridium senile, M. farcimen, 

Paracyathus stearnsii, turf, and worm tubes. Platform- or platform group-specific taxa 

may also be present in the lower zone (e.g., Desmophyllum dianthus only at Platform 

Gail; red encruster only at platforms Harvest, Hidalgo, and Irene). 

Scraping Analysis – Taxonomic Identification

 A total of 23 scraping samples were collected from Platform Harvest – four samples 

from the barnacle zone and eight samples from the Mytilus zone of Leg B1; three samples from 

the barnacle zone and eight samples from the Mytilus zone of Leg B2. Depth of collection on 

Platform Harvest ranged from 3.4 to 24.1 m (11 to 79 ft). A total of 31 scraping samples were 

collected from Platform Gail – five samples from the intertidal zone, six samples from the 

barnacle/scallop zone, and six samples from the Mytilus zone of Leg A1; three samples from the 

intertidal zone, two samples from the barnacle/scallop zone, and nine samples from the Mytilus 

zone of Leg B1. Depth of collection on Platform Gail ranged from 0.3 to 24.1 m (1 to 79 ft). 

At Platform Harvest, a total of 130 taxa were identified. Dominant taxa included 

Ophiothrix spiculata, Rhodymenia californica, Mytilus spp., Membranoptera multiramosa, Caprella 

alaskana, Megabalanus californicus, Mytilus californianus, Halosydna brevisetosa, Elasmopus cf. 

holgurus, and Metridium senile. Several species, including Ophiothrix spiculata, Caprella alaskana, 

Elasmopus cf. holgurus, Pycnogonum stearnsi, and Hiatella arctica, were present in all 23 scraping 

samples. Other species, such as Rhodymenia californica, Mytilus spp., Membranoptera multiramosa, 

Megabalanus californicus, and Halosydna brevisetosa, were very abundant when they occurred, but 

were not always present. 

 At Platform Gail, a total of 90 taxa were identified. Dominant taxa included Pterosiphonia 

dendroidea, Anthopleura elegantissima, Metridium senile, Spirobranchus spinosus, Ophiothrix spiculata, 

Elasmopus holgurus, Diadumene cincta, Balanus trigonus, and Metridium exilis. Several species, 

including Elasmopus holgurus and Balanus trigonus, were present in all 31 scraping samples. 

Other species, such as Ophiothrix spiculata, Pterosiphonia dendroidea, Spirobranchus spinosus, 

Metridium exilis, Chama arcana, and Spirobranchus spinosus, were very abundant when present, 

but were not consistently present in all scraping samples. Mytilus spp., which was sparse on 

Leg A1, was a dominant species on Leg B1. 

 The complex, three-dimensional structure of the barnacle and Mytilus zones provides 

habitat and protection for a variety of interstitial fauna and epibionts, including caprellid and 

gammarid amphipods, crabs, pycnogonids, brittle stars, holothuroids, gastropods, bivalves, 

nudibranchs, chitons, polychaetes, anemones, hydroids, hydrozoans, nemerteans, sponges, 
ES-30 

bryozoans, tunicates, sipunculids, and flatworms. In total, 181 separate taxonomic entities were 

noted from the scraping samples collected from platforms Gail and Harvest (Table ES-5), 

including 123 monospecific taxa (i.e., 68% of the taxa were identified to species level). Several 

of the species identified in the scraping analysis were also noted as density- and/or percent 

cover-dominant taxa during the whole slide analysis (e.g., Mytilus, Balanus, Metridium, 

Anthopleura, Ophiothrix). Results of the scraping analysis also provided further taxonomic 

clarification for unidentified biota observed during photographic analysis. Ophiothrix spiculata 

and Ophiopterus papillosa were the only two ophiuroid species identified during scraping 

analysis from Platform Harvest. During the whole slide analysis, specimen size, photographic 

resolution, and/or a lack of specimens upon which a detailed analysis could be conducted 

resulted in the classification of unidentified ophiuroids in many of the photographs. Scraping 

analysis results allowed for a complete species-level determination; ophiuroids present in 

photographs from Platform Harvest were considered to be Ophiothrix spiculata, among the 

dominant taxa at all platforms. 

Scraping Data Analysis

Statistical Analysis 

 Correspondence analysis of the scraping data set from Platform Harvest revealed that 

the two zones, Mytilus and barnacle, were distinct in terms of their respective taxonomic 

compositions. Further, the taxonomic composition of the Mytilus zone was more variable than 

the barnacle zone. 

Wet Weight Determinations 

Wet weight determinations of scraping samples from Platform Harvest were variable. 

Total sample wet weights ranged between 149 and 5,059 g per quadrat (2.4 and 80.9 kg/m2) on 

Leg B1, but were noticeably higher on the adjacent leg, where they ranged between 2,281 and 

25,966 g per 0.0625 m2 quadrat (36.5 to 415.5 kg/m2). Average total sample wet weights per 

quadrat on Leg B1 and B2 were 2,129 and 9,180 g (34 and 147 kg/m2), respectively. 

 Mussel only biomass measurements (i.e., wet weight, shell included) exhibited similar 

variability, affecting the relative mussel biomass contribution to the community. Mussel wet 

weights on Leg B1 ranged from 0 to 4,025 g (0 to 64.4 kg/m2). In contrast, mussel only wet 

weights from the Leg B2 mussel zone were consistently high, ranging from 3,752 to 17,779 g per 

quadrat (60.0 to 284.5 kg/m2). These results were generally consistent with results of the whole 

slide analysis, where highest densities and percent cover estimates were evident above 6 to 8 m 

water depths. 

 Minimum and maximum average lengths, widths, and heights for Platform Harvest 

mussels were 3.81 and 9.90 cm, 2.25 and 4.48 cm, and 1.67 to 3.42 cm, respectively. Individual 

average weights were variable, ranging from 10.78 to 111.42 g. Smallest mussels were collected 

at water depths where the fewest mussels were available, while the larger mussel specimens 

were present in those portions of the platform leg where higher densities were evident. 
Table ES-5. Taxa identified during the analysis of scraping samples from the intertidal, barnacle, and m

platforms Gail and Harvest. Taxa common to both platforms denoted in bold. 

FLORA:  Algae: 

Acrosorium venulosum Antithamnion hubbsii Branchioglossum bipinnatifidum Callophyllis spp. Ceramium camouii Delesseriaceae, unidentified Heterosiphonia japonica? 1

Membranoptera multiramosa 2

Polysiphonia scopularum Pterosiphonia dendroidea 

 Pugetia fragillissima 

Pugetia spp. (juvenile) Rhodymenia californica Rhodymenia pacifica

FAUNA:  Crustaceans:  Barnacles (Cirripedia): 

Balanus nubilus Balanus spp. (juvenile) Balanus trigonus Megabalanus californicus Tetraclita rubescens

 Caprellid amphipods: 

Caprella alaskana Caprella equilibra Caprella ferrea Caprella verrucosa 

Gammarid amphipods: 

Aoroides spp. Dulichiella appendiculata Elasmopus cf. holgurus Elasmopus holgurus Ericthonius brasiliensis Gammaropsis thompsoni 

 Gammarid amphipods, continued: 

Janiralata occidentalis Jassa slatteryi Leucothoe alata Monocorophium spp.Parapleustes pugettensis Podocerus brasiliensis Quadrimaera reishi 

cf. Sinocorophium spp. 

Stenothoe estacola 

 Crabs (Brachyura, Cancridea): 

Cancer branneri Cancer jordani Cancer productus Cancer spp. (juvenile)Maera simile Pachycheles pubescens Pachycheles rudis Pachygrapsus crassipes Paraxanthias taylori Pilumnus spinohirsutus Podocerus brasiliensis Scyra acutifrons 

 Isopods (Isopoda): 

Janiropsis tridens 

 Sea spiders (Pycnogonida): 

Anoplodactylus nodosus Pycnogonida, unidentified (juvenile) Pycnogonum stearnsi

 Mysids (Mysidacea): 

Mysidacea, unidentified (fragment) 

Echinoderms:  Brittle stars (Ophiuroidea): 

Ophiactis simplex Ophiopteris papillosa Ophiothrix spiculata Ophiuroidea, unidentified (juvenile) 

 Holothuroids (Holothu

Holothuroidea, Holothuroidea, Parastichopus calPentamera lissopl

 Urchins (Echinoidea): 

Echinoidea, unidLytechinus pictus Strongylocentrotu

Mollusks:  Bivalves (Pelecypoda): 

Anomia peruviana Chama arcana Crassadoma gigaCrassostrea gigas Gregariella chenui Gregariella coarctaHiatella arctica Irus lamellifer Kellia suborbicuLithophaga plumModiolus capax Mya arenaria Musculus (=MuscMytilus california

Mytilus spp. Mytilus spp. (juvMytilus trossulus/Ostrea conchaphilPetricola spp. (juvPododesmus cepPseudochama exog

 Gastropods (Gastropod

Amphissa reticulaAmphissa versicol

Anisodoris nobilis Doridacea, unide

Iselica ovoidea 
Table ES-5. Taxa identified during the analysis of scraping samples from the intertidal, barnacle, and m

Platforms Gail and Harvest. Taxa common to both platforms denoted in bold (continued). 

 Gastropods (continued): 

Iselica spp. Seila montereyensisTritonia diomedea

Chitons (Polyplacaphores): 

Mopalia porifera

Polychaetes: 

Arabella iricolor Arabella semimaculata Brania spp. Cirratulus, unidentified Dodecaceria concharum Dodecaceria fewkesi Dodecaceria, unidentified Eudistylia polymorpha Halosydna brevisetosa Halosydna johnsoni Harmothoe ? hirsuta Harmothoe spp. 

Lepidonotus spiculus Myxicola spp.Naineris dendritica Nereis eakini Nereis mendocinana Nereis pelagica neonigripes Paleanotus bellis Pholoides asperus Phyllochaetopterus prolifica Phyllodoce medipapillata Phyllodoce spp.

Polydora spp. Proceraea cf. kiiensis 

Proceraea spp. Sabellidae, unidentified Serpula columbiana Spirobranchus spinosus Syllidae, unidentified Syllis gracilis 

Polychaetes (continued): 

Trypanosyllis spp. Typosyllis spp. 

Cnidarians:  Anthozoans (Actiniaria): 

Actiniidae, unidentified Anthopleura elegantissima (rosy morph) Anthopleura elegantissima Corynactis californica Diadumene cincta Metridium exilis Metridium senile

 Hydrozoans: 

Campanularia spp.

Campanulariidae, unidentified Eucopella everta Filellum serpens Halecium spp. 

Halecium tenellum Lafoea adnata Obelia geniculata Obelia nr. surcularis Obelia plicata Obelia spp. Plumularia alicia Plumularia alicia complex Plumularia nr. septata 

Plumularia spp. Sertularella tenella

Syncoryne eximia 

Minor Phyla:  Bryozoans (Ectoprocta or Bryozoa): 

Callopora spp. Celleporella spp. Celleporina spp. Costazia spp. Crisia spp. Cyclostomata, unidentified 

 Bryozoans, continued: 

Ectoprocta, unidFilicrisia spp. Scrupocellaria spTegella spp. 

 Flatworms (Platyhelme

Rhabdocoela, unStylochoplana lonStylochus spp. 

 Nemerteans (Nemertea

Amphiporus spp. Carinoma mutabilLineus rubescens Nemertea, unideParanemertes calif

Tetrastemma sig

 Sipunculids (Sipunculi

Phascolosoma a

 Sponges (Porifera): 

Haplosclerida nr. Porifera sp. A Porifera, unidenRhabdodermella n

 Tunicates (Urochordat

Aplidium spp. Aplousobranchi

unidentified 

Styela coriacea Styela truncata Tunicate, uniden

Total: 181 taxonomic ent

monospecific tax

Footnotes: 1 - HeterosiphonHeterosiphonia densiuscula – Membranoptera multimar

Membranoptera platylphylla Kylin, per Miller (2004). 
Growth Thickness Measurements 

 Growth thickness measurements were made periodically within the mussel zones at 

Platform Harvest (two legs) and Irene (single leg). Thickness measures ranged from 5.1 to 

30.5 cm (2 to 12 inches). Greatest thickness of the mussel zone occurred at the 14.3 to 16.5 m 

(47 to 54 ft) on the first leg of Platform Harvest (Leg B1), at 6.7 m (22 ft) on the second leg of 

Platform Harvest (Leg B2), and 0.3 to 2.7 m (1 to 9 ft) on Irene. 

 Differences in the depths of maximum thickness between Legs B1 and B2 may be 

attributed to the fact that Leg B2 is an inner leg, protected on three sides by adjacent legs, 

whereas Leg B1 is an outer leg. Sloughing of the mussel mat is a common occurrence on 

platforms, particularly following the passage of storms, as evidenced by the presence of a shell 

mound at the base (and downcurrent) of each platform. 

Platform vs. Natural Hard Bottom – Comparisons of Biota 

 A comparison of characteristic platform fauna (from the photographs; platform water 

depths ranged from 74 to 225 m) and the characteristic hard bottom fauna identified and 

enumerated in the western Santa Barbara Channel and Santa Maria Basin from previous studies 

(e.g., Steinhauer and Imamura, 1990; Blake and Lissner, 1993; Science Applications International 

Corporation and Marine Ecological Consultants, 1995) indicated that 13 of the 30 natural hard 

bottom megafauna taxa also occur on the platforms, however, nearly half of these taxa occurred 

only once (i.e., sole occurrence on a single platform). Most frequently encountered species 

include Metridium farcimen and a tan zoanthid. The zoanthid depth distribution was across the 

entire platform leg depth. M. farcimen depth distribution was more restricted. For a limited 

number of species which occur at both platforms and hard bottom features (e.g., Galathea 

californiensis), respective depth distributions are similar. Depth distribution for other species 

was confounding and no apparent trends were evident. 

ES-4 Summary 

 In summary, the major findings pertinent to invertebrate and algal communities 

inhabiting six of California’s platforms and two natural rock outcrops include the following: 

(1) Results of videotape, quantitative slide, and point contact analyses, in general, 

produced similar biotic zonation patterns at the platforms studied, although an 

alternate, three-zone approach to platform characterization may be viable. 

(2) A total of 173 species (or higher taxa) were identified during quantitative slide 

analysis of 821 photographs from six platforms and two rock outcrops, while a 

total of 55 species or higher taxa were identified during point count analysis of 

883 photographs from six platforms; invertebrate fauna dominated, with only a 

few algal species/species groups evident (filamentous and foliose red algae; other 

red and green algae). 

ES-33
(3) In general, the presence and relative ranking of percent cover dominants from the 

point count analysis were very consistent with the results of whole slide analysis. 

Random point count analysis provides a straightforward means of identifying 

percent cover dominants, whereas quantitative slide analysis (i.e., individual 

counts or percent cover) provides a more comprehensive characterization of all 

taxa present, within the limitations of photographic interpretation and 

identification. 

(4) A total of 130 species or higher taxa (primarily cryptic, interstitial forms typically 

not visible via photographic techniques) were identified during analysis of 

scraping samples from the mussel and barnacle zones of Platform Harvest; a total 

of 90 species or higher taxa were identified from scraping samples from the 

intertidal, barnacle, and mussel zones of Platform Gail. Findings highlight the 

complexity and three-dimensional structure of these zones. In total, 181 separate 

taxonomic entities were noted from scrapings at both platforms, of which 

123 (68%) were monospecific taxa. Only 41 taxa occurred at both platforms. 

 (5) A mussel zone was present at each platform, although the vertical extent and 

maximum depth of each mussel zone varied between platforms; considerable 

variability in mussel density and percent cover was evident. 

(6) Highest species- or taxa-specific density levels were typically encountered in the 

upper portions of each platform, normally within the upper 30 m (100 ft); within 

this depth range, the intertidal and mussel zones also contained several other 

numerically dominant species (e.g., anemones, ophiuroids, barnacles, algae). 

(7) Middle and lower portions of each platform showed considerable variability, but 

typically contained encrusters (e.g., sponges) and various cnidarian species (e.g.,

Metridium, Corynactis); some prominent species at depth were limited in their 

geographic distribution (e.g., Desmophyllum dianthus only at Platform Gail; red 

encruster only at platforms Harvest, Hidalgo, and Irene). On the deeper water 

platforms (i.e., Gail and Harvest), deepest zones at the bottom of each platform 

exhibited a strong affinity to basin fauna. 

(8) Upper portions of the platforms exhibited similar dominant taxa; taxa unique to 

each platform tended to occur at depth. Overall, comparisons of density- and 

percent cover-dominants from adjacent platform legs were very similar, although 

species-specific enumerations were variable. 

(9) Clustering analyses comparing density- and percent cover-dominants at the six 

platforms identified strong similarities between adjacent platform legs and 

relatively strong similarity between all platforms, with minor exceptions (i.e., few 

trends suggesting existence of a north-south gradient in species composition). 

(10) Correspondence analysis of the scraping data revealed that Mytilus and barnacle 

zones were distinct in terms of their respective taxonomic compositions; taxonomic 

composition of the Mytilus zone was more variable than the barnacle zone; and 

(11) Species diversity at the platforms was relatively high, although the number of 

species present in individual photographs was relatively low and species diversity 

at natural outcrops was higher (within comparable, shallow depth zones) than that 

observed at the platforms. 

ES-34
There are few substrates comparable to those afforded by existing platform structures. 

Naturally-occurring rock substrates that mimic the entire depth range (i.e., continuous 

substrate) found on platforms do not exist, while intermittent or discontinuous outcrop features 

exhibiting limited vertical extent are limited (e.g., shallow nearshore outcrops; shelf and slope 

hard bottom features with vertical relief of 1 to 3 m). Submerged platform surfaces, including 

platform legs, are optimal settling plates which provide habitat for a variety of attached and 

motile biota, particularly in the shallower portions of a platform where Mytilus, Metridium 

senile, barnacles, and associated fauna and flora predominate. Mid and lower platform zones 

exhibit decreasing species diversity with depth, yet frequently contain unique taxa which 

suggest subtle differences in platform community structure affected by platform location. 

ES-35
1.0 Introduction 

The U.S. Department of the Interior, Minerals Management Service (MMS) is mandated 

by the Outer Continental Shelf (OCS) Lands Act, as amended, to manage the development of 

OCS oil, gas, and mineral resources, while protecting the human, marine, and coastal 

environments. Thus, MMS oversees the orderly development of offshore resources in an 

environmentally sound manner. MMS also compiles, summarizes, and evaluates scientific and 

technical information pertinent to environmental resources and the potential effects of oil and 

gas operations on such resources as part of its mandate. Such information may be utilized in 

one or more ways. For example, it may provide the basis upon which impacts of proposed 

operations on the environment are determined (i.e., used in the preparation of environmental 

assessments or environmental impact statements pursuant to Federal environmental laws). 

In the Pacific OCS Region, a total of 24 oil and gas production facilities have been 

installed in Federal waters. All of these facilities have been located in the Southern California 

Planning Area, with all found either in the Santa Maria Basin, Santa Barbara Channel, or San 

Pedro Bay (Figure 1-1). Twenty-two of these facilities were installed to produce oil and gas; the 

remaining two facilities were installed for oil and/or gas processing. Only one of these facilities 

has been decommissioned and removed to date (i.e., Exxon’s Offshore Storage and Transfer 

[OS&T] unit in the Santa Ynez Unit, Santa Barbara Channel). 

All of California’s OCS platform facilities were installed during the 23-year period from 

1967 through 1989. While more than 1 billion barrels of oil and 1.3 trillion cubic feet of gas have 

been produced from these operations (through March 2003), production volumes from Federal 

waters offshore California are presently reflecting a general decrease over time. Given the 

projected life expectancy of production operations at each offshore facility (i.e., impending 

decommissioning and removal of several platforms in the next several years), the MMS has a 

vested regulatory mandate and scientific interest in properly characterizing the 

platform-associated communities present on California’s OCS. 

As with most biological systems, there are recognized data gaps in our knowledge of 

marine ecosystems. In particular, the faunal components found in association with offshore oil 

and gas platforms are only recently being studied, particularly on the California OCS. Of 

particular interest is a characterization of the epifaunal and epifloral communities found on 

these artificial structures. One important unknown aspect of platform-associated biology 

pertains to the relative contribution of these communities to the regional ecosystem. For 

example, how productive are these communities and what loss of biological production will 

occur when these platforms are removed? 

To address these information gaps as they pertain to platform-associated communities, 

the MMS developed two primary study objectives – to conduct field surveys of invertebrate and 

algal communities at selected oil and gas platforms and natural reefs in the Santa Barbara 

Channel and Santa Maria Basin, and to describe community structure by determining 

abundance, density, and distribution of these species. 

1
N

123o 122o 121o 120o 119o 118o 

San Luis Obispo

Santa Maria

Lompoc

Gaviota Santa

Barbara Carpinteria

Ventura

Oxnard

Port Hueneme

Los

Angeles

Santa 

Monica

Long 

Beach

Huntington Beach

Newport Beach

Laguna Bea

O

Figure 1-1. Southern California Planning Area, including currently designated fields or units (Adapted from: U.S. Departm

Minerals Management Service, 2001).

Cali

Legend:

= Southern California Planning Area= Designated Fields or Units

0 50 Nautical Miles

0 60 Kilometers

25

30

Santa Rosa 

Island

Santa Cruz

Island

San Miguel 

Island

Santa Barbara 

Island

Santa Catalina

Island

San Clemente

Island

San Nicolas 

Island

Begg Rock

Santa Barbara Channel

San Pedro

Bay

Santa

MariaBasin
Specific study objectives included: 

(1) Determine abundance, density, and depth distribution/vertical zonation 

characteristics of invertebrate and algal communities on selected platforms and 

natural reefs; 

(2) Quantify biomass production estimates of invertebrate and algal communities on 

platforms (and natural reefs, where practical); 

(3) Conduct the research using methods that are similar or complementary to those 

being used in related studies; and 

(4) Evaluate and discuss the relative importance of platform-associated invertebrate 

and algal communities to the ecology of the region. 

In June 1998, the MMS awarded a contract to Continental Shelf Associates, Inc. (CSA) of 

Jupiter, Florida and Monterey, California to conduct detailed field surveys at select platforms 

on the California OCS and to characterize the invertebrate and algal communities present. CSA 

was supported in this project by a highly qualified team of biologists, including 

 Robert P. Meek, Ph.D., Principal Investigator (ECOMAR, Inc., Goleta, CA); 

 Suzanne V. Benech, M.S. (Benech Biological and Associates, Ventura, CA); and 

 John C. Ljubenkov, M.S. (Dancing Coyote Ranch Taxonomy, Pauma Valley, CA). 

Additional technical oversight and guidance were provided by a Quality Review Board 

(QRB), including 

 John (Jack) M. Engle, Ph.D. (Marine Science Institute, University of California, Santa 

Barbara, Santa Barbara, CA); 

 Miriam Polne-Fuller, Ph.D. (Marine Science Institute, University of California, Santa 

Barbara Santa Barbara, CA); and 

 James P. Ray, Ph.D. (Oceanic Environmental Solutions, LLC, Spring, TX). 

To address these objectives, a series of questions were developed, followed by selection 

of appropriate sampling and data analysis methods. The primary questions to be addressed 

included: 

(1) What benthic biota live on platforms? 

(2) Do platform benthic biota differ between legs (using sampling results from 

adjacent platform legs)? 

(3) Do platform benthic biota differ between platforms? 

(4) Do platform benthic biota differ between depth zones? 

(5) Do platform benthic biota differ between oceanographic regions (Santa Maria 

Basin vs. eastern Santa Barbara Channel)? 

(6) Do platform benthic biota differ between platforms and naturally occurring hard 

bottom areas (e.g., pinnacles)? 

The following report summarizes the findings of this study effort. Section 2.0 outlines 

materials and methods employed to collect and analyze various data sets. Section 3.0 considers 

the characteristics of each of the sites sampled, with results and discussion centering on species 

3
diversity, dominant taxa, and depth distribution data derived from videotape and quantitative 

photographic analysis and discrete sampling. Section 4.0 provides a discussion of platform and 

reef/outrop community characteristics, compares biota between adjacent platform legs and 

between platforms, compares platform taxa to natural hard bottom communities, and discusses 

general trends evident in the composition and depth distribution of platform-associated 

invertebrate and algal communities. Sections 5.0 and 6.0 provide a list of preparers and 

literature cited, respectively. 

4
2.0 Materials and Methods 

2.1 Review of Platform Information 

As of December 2004, the MMS oversees activities on 79 active leases in Federal OCS 

waters offshore California, of which 43 are currently producing (i.e., oil and gas production 

and/or processing operations). Groupings of active leases form fields or units, 19 of which 

stretch from the Santa Maria Basin region (north of Pt. Conception, offshore southern central 

California) to San Pedro Bay, including portions of the western and eastern Santa Barbara 

Channel (Figures 2-1 and 2-2). Within this region, there are 23 platforms in Federal waters of 

the California OCS (Table 2-1). 

2.2 Platform Selection and Inspection Videotape Review 

 All platforms on the California OCS were considered as potential sampling sites during 

the platform selection process. Criteria for selection included a consideration of water depth 

and geographic location. In consideration of difference in mesoscale oceanographic conditions, 

the Santa Barbara Channel and Santa Maria Basin regions and the platforms found within these 

areas were identified as optimal candidates for study. Further, water depths in which these 

facilities are found range from relatively shallow to deep (i.e., shallowest at Platform Gina in 

29 m of water; deepest at Platform Harmony in 365 m of water). Eight platforms were 

identified as preferred sampling locations – Platforms Irene, Hidalgo, Harvest, and Hermosa in 

the Santa Maria Basin, Platform Hondo in the western Santa Barbara Channel, and Platforms 

Grace, Gail, and Habitat in the eastern Santa Barbara Channel. 

Among these eight facilities, four primary platforms were selected for sampling – Grace, 

Gail, Hidalgo, and Harvest; at each of these primary platforms, two outer legs were 

photographed and videotaped from the intertidal zone to the base of the platform. Four 

additional secondary platforms were also selected – Hondo, Hermosa, Habitat, and Irene; at 

these locations, only single outer legs were slated for photographic and videotape 

characterization from the intertidal zone to the platform base. Two of the secondary platforms – 

Hermosa and Hondo, located in deeper waters of the Santa Maria Basin and Santa Barbara 

Channel, were not sampled due to operational restrictions and/or weather constraints. 

Naturally occurring rocky outcrops, or pinnacles, were also sampled using similar quantitative 

photographic techniques. Sites selected for this aspect of the project included Diablo and Nifty 

Rocks, two outcrops located off the northern Channel Islands in the Santa Barbara Channel. A 

summary of sampling activities conducted at each platform and natural reef is provided in 

Table 2-2 1. 

 During the platform review and selection process, contact was made with individual 

operators regarding prior cleaning history and future activity (e.g., repair work, drilling 

operations, planned cleaning); platforms with recent cleaning activity were removed from 

 

1 Offshore operators utilize an alphanumeric system to label individual platform legs (i.e., A, B, C along one 

platform axis, 1, 2, 3, etc. along the adjacent axis). Numerical axes run east-west for Santa Barbara Channel 

platforms and north-south for Santa Maria Basin platforms. Individual leg designations and orientation for the six 

platforms are detailed in Section 3.2; see also Figures 3-1 through 3-3. 

5
N

Figure 2-1. Santa Maria Basin OCS operations (Adapted from: U.S. Department of the Interior,

Minerals Management Service, 2001).

Santa Maria

Orcutt

Lompoc

Santa Barbara

County

Point

Arguello

Point

Conception

LION ROCK

UNIT

POINT SAL

UNIT

PURISIMA

POINT UNIT

SANTA

MARIA UNIT

POINT

PEDERNALES

UNIT

Surf

TRANQUILLON

RIDGE UNIT

ROCKY

POINT UNIT

BONITO

UNIT

POINT

ARGUELLO

UNIT

HIDALGO

HARVEST

HERMOSA

SWORD

UNIT

State Waters

State

Waters San Luis Obispo

County

Vandenberg

Air Force

Base

IRENE

PACIFIC

OCEAN

0 3 STATUTE MILES

CALIFORNIA

6
CAVERN

UNIT

Santa Cruz Island

Figure 2-2. East Santa Barbara Channel OCS operations (Adapted from: U.S. Department of the Interior, Minerals Managem

POINHUE

GAIL

Anacapa Island

Santa Rosa

Island

HABITAT

C

FEDERAL ECOLOGICAL PRESERVE

BUFFER ZONE

State

Waters

SANTA CLARA

UNIT

PITAS POINT UNIT

HILLHOUSE

B A

HENRY

HOGAN

HOUCHIN

SANTA BARBARA

OIL AND GAS

SANCTUARY

CHANNEL ISLANDS NATIONAL

MARINE SANCTUARY BOUNDARY

GRACE GILDA

Ven

Cou

Santa Barbara

Carpinteria

Go Santa Barbara County leta

0 3 

HOLLY
Table 2-1. Summary of California OCS candidate platforms, designated units or fields, and 

platform water depth and installation date by geographic area (Adapted from: 

U.S. Department of the Interior, Minerals Management Service, 2005). 

Field or Unit Platform Operator Depth 

(m) 

Installation 

Date 

Southern Santa Maria Basin 

Point Pedernales Unit Irene Plains Exploration & Production Co. 74 Aug 1985 

Pt. Arguello Field/Unit Hidalgo Arguello, Inc. 131 July 1986 

 Harvest Arguello, Inc. 206 June 1985 

 Hermosa Arguello, Inc. 184 Oct 1985 

Santa Barbara Channel 

Santa Ynez Unit Hondo ExxonMobil Corporation 257 June 1976 

 Harmony ExxonMobil Corporation 365 June 1989 

 Heritage ExxonMobil Corporation 328 Oct 1989 

Pitas Point Unit Habitat Plains Exploration & Production Co. 88 Oct 1981 

Dos Cuadras Field Hillhouse Plains Exploration & Production Co. 58 Nov 1969 

 A Plains Exploration & Production Co. 57 Sept 1968 

 B Plains Exploration & Production Co. 58 Nov 1968 

 C Plains Exploration & Production Co. 59 Feb 1977 

Carpinteria Offshore 

Field Henry Plains Exploration & Production Co. 53 Aug 1979 

 Houchin Pacific Operators Offshore LLC 50 July 1968 

 Hogan Pacific Operators Offshore LLC 47 Sept 1967 

Santa Clara Field/Unit Grace Venoco, Inc. 97 July 1969 

 Gail Venoco, Inc. 225 Apr 1987 

 Gilda Plains Exploration & Production Co. 62 Jan 1981 

Point Hueneme Unit Gina Plains Exploration & Production Co. 29 Dec 1980 

San Pedro Bay 

Beta Field/Unit Edith Plains Exploration & Production Co. 49 Jan 1983 

 Elly Aera Energy LLC 78 Mar 1980 

 Ellen Aera Energy LLC 81 Jan 1980 

 Eureka Aera Energy LLC 213 July 1984 

8
Table 2-2. Summary of sampling conducted during the analysis of invertebrate and algal 

communities on offshore oil and gas platforms in southern California. 

Platform and 

Leg(s) Sampled 

Diver 

Video 

Diver 

Photos 

ROV 

Video 

ROV 

Photos Scraping Growth 

Primary Platforms (2 legs per platform) 

Gail – Legs A1, B1 + + + + + - 

Grace – Legs C1, C4 + + + + - - 

Harvest – Legs B1, B2 + + + + + + 

Hidalgo – Leg A1, B1 + + + + - - 

Secondary Platforms (1 leg per platform) 

Habitat – Leg A1 + + + + - - 

Irene – Leg A1 + + + + - + 

Offshore Rocks/Pinnacles 

Diablo Rock + + - - - - 

Nifty Rock + + - - - - 

Key: + = data collected; - = no sampling required; ROV = remotely operated vehicle. 

further consideration. The selection of candidate sites was based on recommendations and 

guidance offered by the MMS, the project team, and members of the Quality Review Board 

(QRB). 

 Sampling priorities and rationale for the six platforms and two pinnacles were as 

follows. Depending upon the number of platform legs to be sampled, platforms were either 

designated as primary (i.e., two legs to be sampled) or secondary (i.e., one leg to be sampled). 

Among the primary platforms targeted, Platforms Grace and Hidalgo are both located in 

relatively shallow water (i.e., 97 to 131 m), with one platform in the Santa Barbara Channel and 

the other in the Santa Maria Basin. 

 Platforms Gail and Harvest are located in intermediate to deep waters (i.e., 206 to 

225 m), with one platform in the Santa Barbara Channel and the other in the Santa Maria Basin. 

For the secondary platforms, Platforms Habitat and Irene are located in relatively shallow water 

depths (i.e., 74 to 88 m) either within the Santa Barbara Channel or Santa Maria Basin. 

 Also of interest to this study effort were the invertebrate and algal communities found in 

association with naturally occurring rock outcrops or pinnacles. Only a limited number of 

suitable candidate sites were identified, most of which occur off the northern Channel Islands. 

Diablo and Nifty Rocks were selected for sampling following discussions with the MMS and the 

QRB. Diablo Rock is located several kilometers to the west of Diablo Point, off the northern 

coastline of Santa Cruz Island (Figure 2-3). Water depths at the base of this feature are 

approximately 33 m. Similarly, Nifty Rock is located several kilometers east-southeast of Harris 

Point, off the northwestern point of San Miguel Island (Figure 2-4). Water depths at the foot of 

this rock outcrop are approximately 15 m. 

9
Diablo 

Rock

0

0 1 3 Miles

1 2 5 Kilometers

2

3 4

Santa Cruz Island

West Point

Black 

Point

Kinton 

Point

Morse Point

Gull Island

Bowen Point

Sandsto

Point

Coche Point

Figure 2-3. Location of Diablo Rock, Santa Cruz Island, California.

San Luis Obispo

Santa Maria

Lompoc

Gaviota Santa 

Barbara

VenturaPort 

Huenem

e 

Santa 

Monic

Santa 

Rosa 

Island

Santa 

Cruz 

Island

San Miguel 

Island

Santa 

Barbara 

Island

San

Cata

Isla

C

San 

Nicolas 

Island

Begg 

Rock

Location 

Area 

Shown
San Miguel Island

Location Ma

Nifty 

Rock

Harris Point

Prince 

Island

Bay Point

Cardwell 

Point

Crook

Point

Judith 

Rock

Point 

Bennett

Castle Rock

0

0 1 2 Miles

1 2 3 Kilometers

Figure 2-4. Location of Nifty Rock, San Miguel Island, California.

San Luis Obispo

Santa Maria

Lompoc

Gaviota

Santa 

Barbara

VenturaPort 

Huenem

e L

An

Santa 

Monica

Santa 

Rosa 

Island

Santa 

Cruz 

Island

San Miguel 

Island

Santa 

Barbara 

Island

Santa 

Catalina 

Island

San 

Clemen

Island

San 

Nicolas 

Island

Begg 

Rock

Area 

Shown
The scope of sampling conducted at each platform and rock outcrop varied. At all 

platforms and rock outcrops, sampling emphasized collection of 35-mm slide transparencies 

(i.e., photoquadrats) and high resolution color video, each of which was collected via diver (i.e., 

from the intertidal zone to 24 m subsurface) and ROV (from 24 m subsurface to the seafloor). 

Table 2-2 summarizes sampling conducted at platform and rock outcrop sites. In addition, 

“scraping” collections (i.e., removal of all epibiota within a prescribed area) and thickness/ 

depth measurements (i.e., measurement from the outer portion of the community inward to the 

platform leg) were also completed at several select platforms, as noted in Table 2-2. 

 After primary and secondary platforms were identified, biologists reviewed MMS 

inspection videotapes. The purpose of this videotape analysis was to establish preliminary 

biotic zonation patterns along the outer portions of the legs of each platform. Review of the 

tapes occurred at the MMS Pacific OCS Region office in Camarillo, CA. Depth and range 

characteristics of these biotic zones were used in determining where discrete samples 

(e.g., 35-mm slides, scrapings) were to be taken during subsequent field surveys. 

2.3 Field Surveys

 Field surveys were completed in several phases between 1998 and 2000. A preliminary 

survey was conducted in October 1998 to test the various diver and ROV systems. Full surveys 

at six platforms were slated for late 1999 through late 2000. All surveys were completed using 

the R/V Dawn, a 30-m research vessel operated by ECOMAR, Inc. of Goleta, CA. Precision 

navigation was provided by a Gorman differential global positioning system. Select surface 

operations were also videotaped using a Sony Hi-8 video camera. 

 The Dawn supported both scientific diver and ROV operations. Both divers and the 

ROV were employed to collect high resolution color video and 35-mm slide transparencies from 

one or two platform legs, depending upon whether the site was a primary or secondary 

platform. Divers also collected 1/16 m2 (0.0625 m2) scraping samples from select platform legs. 

Diver operations were restricted to water depths from the surface to 24 m subsurface. ROV 

operations extended from 24 m subsurface to the seafloor. Videotape and photographic data 

collection specifications, by platform, are provided in Table 2-2. 

 For ROV operations, a Phantom HD2 ROV was equipped with (1) a Kongsberg/Simrad 

Photosea PS1000A 35-mm camera; (2) a Benthos DSC4000 camera and lighting system; (3) a 

Sony high resolution (>450 lines of resolution/inch) Deep Ocean Engineering Color Smart 

Zoom video camera; (4) a Mesotech MS 900 sonar unit; and (5) a three-function manipulator 

arm. Aboard the Dawn, dual Super VHS videocassette recorders were employed as primary 

recording equipment, generating two original tapes. Frame number, time, and water depth 

were recorded on data sheets for each of the ROV slide transparencies collected. 

 For scientific diver operations, equipment included (1) a 35-mm Nikonos V camera with 

strobe; and (2) a hand-held Nikon Super Hi-8 video camera housed in an Amphibico housing. 

Divers utilized surface supplied air using a Heliox 18 bandmask. Diver videotape operations 

produced a single, Hi-8 videotape. During diving operations, two-way communication 

occurred between divers and the surface. All diver observations were recorded on data sheets. 

12
2.3.1 Operational Procedures 

 Detailed operational and sampling procedures are outlined in an updated version of the 

sampling plan (Appendix A). This appendix outlines the full suite of operational procedures 

used during the surveys, including vessel departure and logistics, as well as mooring systems 

and the mooring process. 

2.3.2 Platform Leg Selection 

 Mooring location was the primary determining factor as to which legs were sampled. 

Deviations in site-specific conditions also prompted adjustments to these preferred 

designations; recommendations for such adjustments were made in the field. Legs sampled at 

each platform are designated in Table 2-2. 

2.3.3 Sampling Procedures 

 Surveying and sampling occurred in two different modes. Diving operations were 

conducted from deepest to shallowest diving depths in compliance with proper diving 

protocols. ROV operations routinely occurred from the surface to the seafloor (i.e., surveying of 

the upper biotic zones downward). Diver operations were limited to the upper 24 m of the 

water column, below which ROV operations occurred. Multiple dives were common. When 

feasible, the extent and characteristics of the litterfall zone around each platform (i.e., at the base 

of the platform leg[s] sampled, downcurrent) were characterized via ROV. Protocols followed 

for diver mobilization and specifics of the diving equipment suite are outlined in Appendix A. 

Diver Video 

 The diver video system consisted of a hand-held Sony Hi-8 color camera and housing 

with a wide-angle lens. The system was pre-set at a focal length of approximately 1 m and 

moved slowly at a rate of 1.8 to 2.4 m/min. Two 250-watt underwater lights were used to color 

fill the frame, aiding in video detail and proper color rendition (i.e., an aid to post-survey video 

interpretation and biological identification). Periodically, annotation of the videotapes was 

augmented by placing a dive computer in the field of view displaying depth and dive duration. 

Diver Photography

 Photographic data (photoquadrats) were collected via diver (hand-held) 35-mm color 

camera and a 0.0625 m2 photoquadrat frame (i.e., image area 25 cm x 25 cm). Optimal 

photographic results were achieved through the use of a Nikonos V camera equipped with a 

28-mm Nikon lens and a dual strobe configuration. All photographs and settings were logged 

verbally by the diver and recorded by the tender and data recording personnel. Ten to 

15 photographs (slide transparencies) were taken per zone; photograph location was 

predetermined using the randomization protocol (Appendix B). It was expected that the zones 

found at each platform would conform to the zonation patterns defined during the inspection 

videotape analysis. 

13
Diver Sampling (Air Lift) System and Scraping Collections 

 The diver sampling system consisted of a 10-cm diameter flexible hose array, air 

compressor, sample accumulator drum, and screening system. The flexible hose array was 

connected at the surface to a high volume compressor and consisted of 30 m of hose attached to 

a down weight. At depth, the air lift system was also connected to a 10-cm diameter, 30-m long 

diver sampling hose that terminated on deck into a 4-L aluminum accumulator drum (i.e., to 

allow slow deceleration of the sample). Compressed air was forced down the air hose, creating 

a suction and entraining effect at the hose terminus underwater; entrained seawater (from 

depth) and air were transported to the surface. Specimens were carried up the sampling hose in 

the entrained seawater and entered the accumulator horizontally near the top of the drum. 

Seawater and entrained biota swirled and decelerated in a clockwise direction within the drum 

before exiting through an opening at the bottom of the drum. The accumulator drum was 

positioned over a sieve box (i.e., two nested screens) outfitted with removable, 1.0-mm and 

0.5-mm Nytex mesh screening to capture scraped material as it exited the bottom of the 

accumulator drum. 

 Divers employed a 0.0625 m2 quadrat (i.e., 25 cm x 25 cm) and a small pneumatic 

hammer and chisel to measure and dislodge the biological material within the quadrat frame. 

Scraped material was suctioned off the quadrat and conveyed to the surface via the lift system. 

The depth of the down weight and lift system were adjusted as needed, depending upon diver 

depth and position. 

 The lift system was activated prior to any scraping activity to assure that cryptic and 

motile interstitial fauna were collected. The lift system continued to operate for 20 to 30 seconds 

after scraping was completed to clear all specimens from the lift line (i.e., to assure that scraped 

specimens reached the surface). Field preparation of algal and invertebrate samples was via 

buffered formalin preservation (i.e., no freezing; 4 percent formalin solution for algae; 

10 percent formalin solution for invertebrates). Some pressing was completed for larger algal 

specimens. Invertebrates were relaxed prior to preservation using magnesium sulfate. 

Observations of sample content were made prior to fixation. When practical, large algal 

specimens were processed separately to facilitate pressing. Biotic zones sampled included the 

mussel (Mytilus) zone 2 and the barnacle/scallop zone. A minimum of eight scrapings per zone 

per platform leg was proposed; scrapings occurred at Platforms Gail and Harvest. 

ROV Video 

 The ROV video system was operated at vertical speeds of 1.8 to 2.4 m/min at a distance 

of 0.6 to 0.9 m, appropriate for general biological characterization. Zoom capabilities were 

employed, as needed, to investigate community components of interest. 

 

2 Mytilus refers to the Mytilus species complex, which contains Mytilus californianus, M. galloprovincialis, 

and M. trossulus. 

14
ROV Photography 

Photographs collected by the ROV were consistent with those collected by divers. 

Proper focal distance was assured through the use of an ROV-mounted laser sighting system 

maintained within the field of view of the video camera. The ROV was equipped with a 

Photosea PS 1000A 35-mm camera and 1500S strobe system for still photography; the camera 

was fitted with a 28-mm lens. Based on results from the preliminary survey, focal distance and 

aperture were preset (i.e., lens to subject distance of 40.6 cm; lens aperture at f 22). The camera 

was bulk loaded with 200 ASA color slide film. Use of the laser sighting system ensured precise 

and repeatable photographic distances between photographs both along the legs of a particular 

platform and between platforms. Consistent focal distance and image area also allowed for a 

standardized estimation of the relative size of biota and other features. 

The depth at which each photograph was collected was predetermined using a 

randomized sampling approach. This was accomplished by referencing the zonation patterns 

determined via inspection videotape review for each platform, eliminating 0.6 m at the edges of 

each zone (i.e., transition zone), and implementing a randomization protocol for the remaining 

region within each biotic zone. 

ROV and Diver Recording and Annotation 

 Dual recording systems were used to provide two original S-VHS tapes for each ROV 

excursion. The second recorder in the series was hooked to a TV monitor where recorded video 

quality was continuously monitored. Diver video was copied from Hi-8 to S-VHS; the S-VHS 

copy was utilized during biological interpretation. Photographs were taken in slide format (i.e., 

E6). Periodically, test strips were developed on board or at the end of each field day to ensure 

proper photograph collection (i.e., proper focal distance and aperture setting). All photographs 

were logged and annotated by both the tender and quality assurance/quality control (QA/QC) 

personnel. 

Sample Labeling 

 All samples were labeled with a unique station number and date (i.e., platform and leg 

designation, sample depth). Samples containing specimens (i.e., scrapings, voucher collections) 

were also prepared using internal labels containing the same station and date information. All 

samples (i.e., photographs, videotapes, vouchers) were logged upon collection. Sample 

collection and sample tracking forms were maintained per proper QA/QC protocols. 

2.4 Sample Analyses

2.4.1 Quantitative Slide and Videotape Analysis 

 Post-cruise analysis of data included videotape review and quantitative slide analysis 

(QSA). QSA (also called photographic analysis because digital slide images/photographs were 

also reviewed) encompassed two approaches to biotic characterization, including (1) complete 

identification of specimens within each slide (whole slide analysis); and (2) identification of 

biota present under 50 randomly placed points (random point or point count analysis). 

15
 For whole slide analyses, 15 or more photographic images per biotic zone were 

analyzed. During whole slide analysis, each 35-mm image was projected onto a large screen 

and the taxonomic identification and enumeration of biota present (i.e., abundance and percent 

cover) was completed. Species names and slide data (i.e., slide code, water depth, date and time 

of collection) were manually entered onto data sheets and subsequently transcribed into 

separate (i.e., platform leg-specific) MS Excel spreadsheets. Each spreadsheet contained a 

unique photographic code, date of collection, leg designation, and water depth. 

 Following completion of the whole slide analysis, all 35-mm slides were digitized to 

facilitate error checking and as a prelude to completion of point count analysis. During point 

count analysis, digital images were processed using PointCount’99® software. PointCount’99® 

software was originally designed for the U.S. EPA Coral Reef Monitoring Project by researchers 

at the University of Georgia (Dustan et al., 1999). Since its inception, it has been applied to a 

variety of hard bottom/live bottom photographic surveys as an analytical tool. In brief, the 

program allows for (1) application of a prescribed number of random points to each 

photographic image in a series; (2) assignment of a region- or area-specific species or group 

name (from a composite listing of potential species or groups); (3) tracking and compilation of 

species/groups encountered on each digital image; and (4) preparation of an output file for 

each platform leg. PointCount’99® was used to randomly generate a total of 50 points on each 

slide (i.e., digital image). Each digital image was organized into an appropriate group (i.e., by 

individual platform leg) prior to analysis, then assigned a unique file name (i.e., coded to 

platform, leg, and unique photograph number). During point count analysis, all photographic 

images were reviewed. 

 Approximately nine hundred individual photographic images were characterized 

during the two step analysis – the first during QSA (whole slide analysis) and subsequently 

during point count analysis. All identified biota entered into the spreadsheets were organized 

by platform leg. Zonation patterns and identification of mega-epibiota were also documented 

from a review of digital images and videotapes. 

2.4.2 Voucher Collections

 Voucher collections were sorted and identified to the lowest practical taxon. Voucher 

collections were intended to characterize the most prominent epifaunal species (i.e., major 

community formers). 

2.4.3 Scraping Collections 

 Based on the preliminary results of sampling within the mussel zone on Platform Grace, 

an optimal number of scrapings per zone was determined (i.e., eight scrapings per biotic zone). 

Scrapings from the mussel and barnacle/scallop zones of Platforms Gail and Harvest were 

analyzed. Total sample weight and mussel weight measurements were made on scraping 

samples. Individual mussels from Platform Harvest were measured and weighed. Whole 

scraping samples were subsequently sorted into major phylogenetic groups and forwarded to 

individual taxonomic experts for complete identification. Species identification data, relative 

abundance, wet weight determinations, and mussel measurements were entered into an MS 

Excel spreadsheet for subsequent analysis. 

16
2.4.4 Growth Thickness Measurements

 Growth thickness measurements were completed by divers during sampling operations 

at Platforms Harvest and Irene. A hand-held ruler was used at varying water depths and the 

thickness of the biota present (e.g., from the outer edge of the mussel bed to the platform leg) 

was measured and relayed to the data recorder. Thickness measurements made in the field 

were transferred to an MS Excel spreadsheet for tabularization and analysis. 

2.5 Data Analyses

 After all photographic and scraping analyses were completed, taxonomic data were 

reviewed and standardized. For each platform leg, both density (i.e., individual counts) and 

percent cover of the species or taxa present were estimated and separate spreadsheets created. 

Basic summary statistics were generated for each species or taxon present (i.e., sum of 

individual counts or percent cover; maximum; minimum; number of occurrences; average per 

occurrence). Species or taxa were subsequently sorted based on the sum of individual counts or 

(cumulative) percent cover. Spreadsheets were analyzed to determine if trends or unique 

characteristics were evident. Total numbers of species (or higher taxa) and dominants 

(abundance, percent cover) were determined for each platform leg sampled. Mussel bed 

thickness measurements were also tabularized for comparative purposes. 

 Six basic questions related to community composition, intra- and inter-platform 

variability, and zonation patterns were addressed in the statistical analysis of the data with the 

overall purpose to determine density, percent cover, and depth distribution/vertical zonation 

characteristics of invertebrate and algal communities on selected platforms: 

 What benthic biota live on platforms? 

 Do platform benthic biota differ between legs (primary platforms)? 

 Do platform benthic biota differ between platforms (all platforms sampled)? 

 Do platform benthic biota differ between depth zones? 

 Do platform benthic biota differ between oceanographic regions? 

 Do platform benthic biota differ between platforms and pinnacles? 

 The analytical approach employed was consistent with that used during the California 

Monitoring Program (CAMP; Hyland and Neff, 1988). Summary statistics (i.e., mean, standard 

deviation, minimum-maximum, frequency of occurrence) were computed to describe the biota 

residing at each platform. Separate cluster analyses (Bray Curtis similarity index) of the percent 

cover data and available count data were conducted. For analysis of entire platform legs, 

replicates on a leg were pooled. First, replicates within a depth zone were pooled and then a 

weighted average was computed based on the contribution of each depth zone on a particular 

leg. 

 To evaluate how benthic biota differ between zones, estimates of percent cover (and 

available count data) for individual biotic zones were used in a separate cluster analysis. The 

replicates within each biotic zone were pooled at individual platform legs, providing a means to 

evaluate the occurrence and similarities of the biotic zones. There was no weighting for the 

analysis of biotic zones. A reduced portion of the data set was also analyzed to compare 

17
platform legs to the pinnacles. Because there was no distinct vertical zonation evident at the 

pinnacles, the data were pooled over the pinnacle and individual platform legs for the 

applicable depth zones. Specifically, only the samples occurring within the 5 to 17 m depth 

range from the platforms were used in this portion of the data analysis because these 

correspond to the depth range of the biota sampled at the pinnacles. 

18
3.0 Results 

3.1 Inspection Videotape Review 

Biotic zonation patterns were determined based on a review of MMS inspection 

videotapes for each of the selected platforms (Table 3-1). MMS requires periodic observation, 

inspection, and characterization of a platform’s jackets (legs) as part of routine facility 

maintenance; visual inspections typically include the use of photographs and/or videotapes. 

The depth and range characteristics of each platform’s biotic zones, as established during 

inspection videotape review, were used in determining where discrete samples (e.g., 

photographs, scrapings) were to be taken during the field surveys. Figures 3-1 through 3-3 

show the zonation patterns evident from videotape analysis of platforms Gail and Grace, 

Harvest and Hidalgo, and Habitat and Irene, respectively. 

 A total of four to six distinct biotic zones (i.e., zonation patterns) were evident, 

depending on platform depth. As platform depth increased, the total number of biotic zones 

increased. Below the Mytilus zone, the expanse of each zone may also broaden. Platforms in 

shallower water (e.g., platforms Grace, Hidalgo, Habitat, and Irene) exhibited four or five zones, 

while the deeper platforms (e.g., platforms Gail and Harvest) provide additional vertical 

substrate for a sixth platform-associated community. 

Based on inspection videotape review, several observations of platform-associated 

community structure were noteworthy: 

 Mytilus was always present, therefore there was always a mussel zone whose 

vertical extent and lower boundary were quite variable; 

 Barnacles were typically present above and/or below the mussel zone; 

 Encrusters (e.g., sponges) were routinely present at depth, often in conjunction with 

various cnidarian species (e.g., Metridium, Corynactis, Paracyathus); and 

 Beneath the intertidal, barnacle, and mussel zones, considerable variability in faunal 

composition was suggested. 

In addition to identifying the extent and characteristics of each biotic zone during 

inspection videotape review, algal presence and extent (i.e., depth of occurrence) along the four 

outer legs of each platform was also determined. The approximate vertical extent of algal 

growth is depicted in Figures 3-1 through 3-3. Several platforms (i.e., Habitat, Hidalgo, Irene) 

had also been cleaned prior to filming of the inspection videotape. The time that had elapsed 

between cleaning and the current survey efforts was variable, ranging from several months to 

several years. 

3.2 Field Surveys 

A summary listing of platforms and rock outcrops sampled during the field surveys is 

provided in Table 3-2. Platform and rocky outcrop locations in the Santa Maria Basin and Santa 

Barbara Channel areas were provided previously (i.e., see Figures 2-1 through 2-4). 

19
Table 3-1. Characteristics of platform biotic zones as determined during inspection 

videotape analysis. 

Biotic Zone 1 Zone Depth 

(m [ft] subsurface) 

Vertical Extent 

(m [ft]) 

Primary Platforms – 

Platform Gail

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Mytilus 1.8 to 12.1 (6 to 40) 10.3 (34) 

 Barnacle/Scallop 12.1 to 48.8 (40 to 160) 36.7 (120) 

 Corynactis/Encruster 48.8 to 115.8 (160 to 380) 67.0 (220) 

 Vase sponge/Encruster 115.8 to 192.0 (380 to 630) 76.2 (250) 

 Encruster/Sea Star/Cup Coral 192.0 to 225.2 (630 to 739) 33.2 (109) 

Platform Grace 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Mytilus 1.8 to 13.7 (6 to 45) 11.9 (39) 

 Barnacle/Scallop 13.7 to 27.4 (45 to 90) 13.7 (45) 

 Anemone/Encruster 27.4 to 70.1 (90 to 230) 42.6 (140) 

 Encruster/Sea Star 70.1 to 96.9 (230 to 318) 26.8 (88) 

Platform Harvest 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Mytilus 1.8 to 25.9 (6 to 85) 24.1 (79) 

 Barnacle/Corynactis 25.9 to 50.3 (85 to 165) 24.4 (80) 

 Anemone/Encruster 50.3 to 105.2 (165 to 345) 54.9 (180) 

 Vase Sponge/Encruster 105.2 to 169.2 (345 to 555) 64.0 (210) 

 Metridium/Sea Star 169.2 to 205.7 (555 to 675) 36.6 (120) 

Platform Hidalgo 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Mytilus 1.8 to 19.8 (6 to 65) 18.0 (59) 

 Barnacle 19.8 to 32.0 (65 to 105) 12.1 (40) 

 Metridium/Encruster 32.0 to 109.7 (105 to 360) 77.7 (255) 

 Sponges/Encruster 109.7 to 132.3 (360 to 434) 22.5 (74) 

Secondary Platforms – 

Platform Habitat 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Mytilus 1.8 to 18.3 (6 to 60) 16.5 (54) 

 Corynactis 18.3 to 54.9 (60 to 180) 36.6 (120) 

 Metridium/Encruster 54.9 to 88.4 (180 to 290) 33.5 (110) 

Platform Irene 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Barnacle/Algae 2 1.8 to 10.7 (6 to 35) 8.8 (29) 

 Mytilus 10.7 to 25.9 (35 to 85) 15.2 (50) 

 Corynactis/Encruster 25.9 to 73.4 (85 to 242) 47.9 (157) 

 

1 Zonation patterns based on the results of inspection videotape review; zones verified via ROV 

observations. 

2 The barnacle/algae zone of Platform Irene represents an area recently cleaned; see Platform Irene 

analysis within this section. 

20
Figure 3-1. Zonation patterns evident from videotape analysis of (a) Platform Gail and (b) Platform Grace, as viewed from an outbo

Squares in key plan denote legs analyzed.

B

(+)15'

(-)100'(-)160'(-)230'

(-)40'

(-)305'(-)640'

SP1 SP12

1 2 3 4

A

4

3

21

PLATFORM

NORTH

(-)380'

(-)460'(-)545'(-)740'

SP11 SP10

Encruster/Sea Star/Cup CoralBottom/Shell DebrisVase Sponge/EncrusterCorynactis/EncrusterBarnacle/ScallopIntertidalMytilus

(a) Platform Gail 

(+)16'

(-)93'

(-)155'

(-)231'

(-)33'

(-)271'(-)318'

S2 S1

4 3 2 1

Bottom

Anemo

Mytilu

Encrus

IntertidBarna

(b) Platform Grace

KEY PLAN

Algal

Algal
Figure 3-2. Zonation patterns evident from videotape analysis of (a) Platform Harvest and (b) Platform Hidalgo, as viewed from an 

Squares in key plan denote legs analyzed.

Bottom/Shell DebrisAnemone/EncrusterMytilusVase Sponge/EncrusterIntertidalBarnacle/Corynactis

(-)45'

(-)120'

(-)195'

(+)20'

(-)275'(-)385'

1 2 3 4

(-)460'

(-)560'

(-)677'

5

Metridium/Sea Star

B

KEY PLAN

A

4

3

21

PLATFORM

NORTH

5

 (a) Platform Harvest 

(+)20'

(-)115'

(-)190'(-)270'

(-)45'

(-)350'

(-)434'

SP3 SP2

5 4 2 1

 (b) Platform Hidalgo

Algal Algal
Figure 3-3. Zonation patterns evident from videotape analysis of (a) Platform Habitat and (b) Platform Irene, as viewed from an out

Squares in key plan denote legs analyzed.

CorynactisMytilusMetridium/EncrusterIntertidal

(-)288'

(-)208'

(-)135'

(-)75'(-)25'

(+)15'

1 2 3 4

(a) Platform Habitat

Bottom/Shell Debris

(+)18'

(-)35'(-)95'

(-)240'

(-)0' LLW

(-)165'

1 2 3 4

(b) Platform Irene

Algal

Algal

KEY PLAN

PLATFORM

NORTH

4

3

21

A B
Table 3-2. Summary of platform legs and rocky outcrops sampled during the analysis 

of invertebrate and algal communities on offshore oil and gas platforms in 

southern California. 

Platform Location, Jacket Characteristics, 

and Water Depth 

Dates 

Sampled 

Leg(s) 

Sampled Orientation1

Primary Platforms 

A1 SW 

Gail 

Eastern Santa Barbara Channel; 

8 legs (2 x 4 design); 

deep (225 m; 739 ft) 

16 Oct 00; 

19 Oct 00 B1 NW 

C1 NW 

Grace 2

Eastern Santa Barbara Channel; 

12 legs (3 x 4 design); 

shallow (97 m; 318 ft) 

23-24 Oct 99 

C4 NE 

Harvest Southern Santa Maria Basin; B1 NE 

10 legs (2 x 5 design); 

deep (206 m; 675 ft) 

13-15 Nov 99

B2 NE 

A1 SE 

Hidalgo 

Southern Santa Maria Basin; 

8 legs (2 x 4 design); 

shallow (132 m; 434 ft) 

14-15 Nov 99

B1 SW 

Secondary Platforms 

Habitat 

Eastern Santa Barbara Channel; 

8 legs (2 x 4 design); 

shallow (88 m; 290 ft) 

12-14 Oct 99; 

24 Oct 99 A1 NE 

Irene 

Southern Santa Maria Basin; 

8 legs (2 x 4 design); 

shallow (73 m; 242 ft) 

3-5 Nov 00 A1 SW 

Offshore Rocks/Pinnacles 

Diablo Rock 3 Western Santa Barbara Channel; 

Shallow (33 m; 108 ft) 11-12 Oct 98 NA S 

Nifty Rock 4 Western Santa Barbara Channel; 

Shallow (15 m; 50 ft) 12 Oct 98 NA S 

1 Approximate orientation of the outer portion of the platform leg or rocky outcrop sampled. 

2 Platform Grace was sampled initially via ROV and diver during the Preliminary Survey (Legs C1 

and C4), 18-20 October 1998 to test the photographic, videotape, and sample lift systems; 

subsequent sampling of this platform was conducted in October 1999; this latter data set was used 

in quantitative slide analyses. 

3 Located in the Santa Barbara Channel region, several kilometers to the west of Diablo Point, off the 

northern coastline of Santa Cruz Island (northern Channel Islands). 

4 Located in the Santa Barbara Channel region, several kilometers east-southeast of Harris Point, off 

the northwestern point of San Miguel Island (northern Channel Islands). 

24
Given the proximity of certain platforms to one another and the weather considerations 

encountered, the following sampling sequence was realized: 

 Diablo and Nifty Rocks (Rock Outcrops/Pinnacles); 

 Eastern Santa Barbara Channel: platforms Gail, Grace, and Habitat; and 

 Southern Santa Maria Basin platforms: platforms Harvest, Hidalgo, and Irene. 

Note that legs that were actually sampled often differed slightly from those proposed for 

sampling (see Table 2-2) due to limitations imposed on the field survey crew (e.g., location of 

mooring buoy(s), predominant wind and swell direction). Field surveys were completed 

during a 25-month period between October 1998 and November 2000. A preliminary survey 

was completed in October 1998 to test the various diver and ROV systems and to complete 

sampling at the rock outcrop sites. Full surveys at six platforms were completed over a 

13-month period between October 1999 and November 2000, as detailed in Table 3-2. 

3.3 Platform Characterization – Photographic Interpretation 

 The following discussion provides a brief description of the physical characteristics of 

each of the sampled platforms and detailed descriptions of the communities present as 

determined from quantitative slide analysis (i.e., whole slide [or photograph] analysis).1 The 

species and taxa identified at each discrete photographic site (i.e., photoquadrats sampled along 

the legs of six platforms and at two rocky outcrops) are provided in Appendix C. 

 Based on the identification and enumeration of all flora and fauna present in each 

photoquadrat, 149 taxa (i.e., species level or higher) were identified on the six platforms. An 

additional 24 taxa were observed on the rock outcrops (see Section 3.4), for a total of 173 taxa at 

all sites sampled. The composite species list included representatives from five invertebrate 

phyla – mollusks (e.g., Mytilus, Triopha), cnidarians (e.g., Metridium, Corynactis, Anthopleura), 

crustaceans (e.g., Balanus, Pollicipes, Tetraclita), polychaetes (e.g., worm tubes, Protula), and 

echinoderms (e.g., Ophiothrix), plus numerous minor phyla (e.g., sponges, bryozoans, tunicates) 

and undifferentiated assemblages. Various algae (e.g., green, red filamentous, red foliose) were 

also identified. Random point count (PointCount’99®) analysis using digital images created 

from the original 35-mm transparencies resulted in the identification of 55 taxa total (see 

Section 3.5). 

 Photographic analysis of all species present (i.e., quantitative slide analysis) provided an 

estimate of both total density and percent cover for all specimens present on each photograph 

(image area: 0.0625 m2). Individual counts are important as a means of identifying numerical 

dominants, determining relative species densities, and as one basis for comparing platform legs. 

Estimates of percent cover are important for those species where individual counts are more 

difficult to acquire or where counts may not be truly representative (e.g., with colonial taxa or 

major “community formers”; see Lessios, 1996). Percent cover estimates may also be used in a 

comparison of platform legs. Both measures were considered in the following analysis. 

Photographic interpretation of both primary and secondary platforms was based on species 

 

1

 Data consist of 35-mm photographic slide transparencies and digital files created from each transparency; the 

terms slide and photograph are used interchangeably in the following discussion and may refer to one or both 

image forms. 

25
presence, specifically density and percent cover estimates for each 0.0625 m2 area 

photographed. 

3.3.1 Platform Gail 

Physical Characteristics 

Platform Gail, operated by Venoco, Inc., is located on Lease OCS-P 0205 (Sockeye Field, 

Santa Clara Unit), approximately 16 km (8.6 nautical miles [nmi]) from shore in the eastern 

Santa Barbara Channel. This 8-legged platform was installed on 5 April 1987 in a water depth 

of 225 m (739 ft). 

Community Description 

Legs A1 and B1 were sampled at Platform Gail from the intertidal zone to the base of 

each platform leg. Based on complete analysis of 196 photographs from both legs, 74 taxa were 

identified, of which 39 percent (29) were monospecific taxa (i.e., species level identification). 

Remaining taxa were identified primarily to genus level, with a few specimens enumerated at 

higher taxonomic levels. Only five floral taxa (i.e., filamentous red algae, including Polysiphonia, 

Neoptilota, Antithamnion; Codium; encrusting coralline algae; filamentous green algae; foliose red 

algae) were among the 74 total taxa observed. 

On Leg A1, the six most dominant taxa (based on total density, in descending order) 

included Corynactis californica, Metridium exilis, Metridium senile, filamentous red algae, 

Ophiothrix spiculata, and Mytilus spp. (Table 3-3). While Metridium senile had the highest 

frequency of occurrence (70 out of 98 photographs), Corynactis californica and M. exilis exhibited 

highest average density per occurrence at 449 and 147 individuals/0.0625 m2, respectively. In 

terms of percent cover, prevalent species on Leg A1 included (in descending order) Corynactis 

californica, Mytilus spp., Metridium senile, Anthopleura elegantissima (rosy morph), and Metridium 

exilis. Turf, a composite of smaller flora and fauna (including protozoa, hydrozoa, bryozoa, and 

algae) that co-occur with one another and coat the surface of the platform legs in an irregular 

manner, was also a prominent contributor to percent cover. While turf species were typically 

too small to distinguish individually at the scale of the photoquadrats, the presence of turf was 

readily identifiable in the photographs. Bare metal was also a prevalent feature on this leg at 

depths below 69 m (225 ft), extending to a point near the base of Leg A1 at 233 m (733 ft). 

 Based on videotape review, algal depth on Leg A1 extended from the upper portions of 

the intertidal zone to a maximum depth of approximately 8 to 11 m (25 to 30 ft). Results of 

whole slide analysis, however, indicated algal presence (dominated by filamentous red algae – 

Polysiphonia, Neoptilota, Antithamnion, etc.) extending to a depth of 17 m (55 ft). 

 On Leg B1, similar dominant species were evident as compared to Leg A1, with slight 

reordering among the top five taxa – Metridium exilis, Corynactis californica, Metridium senile, 

Mytilus spp., and filamentous red algae. Metridium exilis was the numerical dominant and a 

major contributor to percent cover, occurring in >60 percent of the photographs and prevalent 

in depths between 1 and 98 m (3 and 322 ft) on Leg B1 (Table 3-4; Photo 1). 

26
Table 3-3. Dominant taxa (or physical characteristics) on Leg A1 of Platform Gail identified during quan

analysis. 

Taxon Total Average per Occurrence Frequency (%) Minimum- Maximum Depth of Occ

(ft subsur

Density:Corynactis californica 15,263 448.9 34.7 2-693 34; 39; 53-216; 36Metridium exilis 4,554 146.9 31.6 3-570 4-12; 24; 30-45; 53-55; Metridium senile 4,227 60.4 71.4 1-213 4-9; 14-24; 30-34; 38-68; 87-89; 104Filamentous red algae 752 27.9 27.6 2-70 4-9; 14; 18-21; 30Ophiothrix spiculata 533 24.2 22.4 2-66 21; 31-34; 36-38; 131; 3Mytilus spp. 497 35.5 14.3 3-160 4-9 Desmophyllum dianthus 416 21.9 19.4 1-54 363; 410; 620-67Anthopleura elegantissima (rosy morph) 305 20.3 15.3 1-100 4; 6; 7-18; 28Balanus spp. 145 9.1 16.3 1-30 3-57 Ophiuroid, unidentified 113 7.5 15.3 1-34 36; 42-48; 61-63; 84-89; 137; Metridium farcimen 103 11.4 9.2 1-88 131; 162-168; 184-2Worm tubes, plain 62 8.9 7.1 2-23 302-367; 34Percent Cover:Corynactis californica 64.0 34.7 1-98 34; 39; 53-216; 36Mytilus spp. 60.4 14.3 5-90 4-9 Metridium senile 41.7 71.4 1-95 4-9; 14-24; 30-34; 38-68; 87-89; 104Bare Metal 33.3 38.8 2-66 225-73Anthopleura elegantissima (rosy morph) 26.4 15.3 0.5-100 4; 6; 7-18; 28Metridium exilis 23.0 31.6 1-80 4-12; 24; 30-45; 53-55; Zoanthid, colonial tan 10.0 2.0 5-15 620; 63Turf 6.0 35.7 0.4-25 39; 48; 55-61; 68-75; 91; 118-137; Hydroid, tan branching 5.8 6.1 5-10 4-6; 7; Sponge, tan encrusting 4.0 31.6 0.5-15 12; 24; 30-34; 36-38; 42; 63-70; 75

309; 397; 

Tunicate, encrusting tan 3.0 1.0 3 675 Sponge, orange encrusting 2.9 6.1 0.5-10 12; 21-24; 30Notes: Total = total number of individuals in all photographs. Minimum-maximum = minimum and maximum number o

minimum and maximum percent cover estimates for a 0.0625 m2 photoquadrat. Ninety-eight (98) photographs we

Taxonomic notes: Filamentous red algae include Polysiphonia, Neoptilota, Antithamnion, etc. 
Table 3-4. Dominant taxa (or physical characteristics) on Leg B1 of Platform Gail identified during quan

analysis. 

Taxon Total Average per Occurrence Frequency (%) Minimum- Maximum Depth of Occ

(ft subsur

Density:Metridium exilis 20,739 340.0 62.2 2-580 3-71; 74-231; 30Corynactis californica 3,035 159.7 19.4 1-630 57-59; 63-99; 127; 141; 15Metridium senile 1,669 38.8 43.9 1-169 3-5; 58-60; 261-294; 309-68Mytilus spp. 607 24.3 25.5 2-87 3-14; 18-28; 34-Filamentous red algae 277 11.1 25.5 1-30 6-9; 14-53; Desmophyllum dianthus 210 12.4 17.3 2-37 594-602; 63Ophiothrix spiculata 206 15.8 13.3 1-51 59-60; 63; 86-97; 123; 3Balanus spp. 180 9.5 19.4 1-25 3-9; 21; 30; 33-3Worm tubes, calcareous 158 11.3 14.3 1-26 231-420; Protula superba 155 11.9 13.3 1-28 261-420; Worm tubes, plain 124 5.6 22.4 1-27 308-420; 594; 615; 662-678; 68Amphipholis spp. 82 4.3 19.4 1-9 500-689; 70Percent Cover:Metridium exilis 62.0 62.2 1-95 3-71; 74-231; 30Bare Metal 49.2 42.9 2-85 8-9; 24; 27Metridium senile 31.8 43.9 1-84 3-5; 58-60; 261-294; 309-68Halichondria panicea 30.0 1.0 30 (max) 34 Corynactis californica 22.8 19.4 0.5-90 57-59; 63-99; 127; 141; 15Mytilus spp. 19.2 25.5 5-85 3-14; 18-28; 34-Sponge, tan encrusting 10.5 34.7 0.5-50 3-6; 28; 31-33; 38; 58-73; 9Leucetta 10.0 2.0 10 24; 60 Sponge, tan globose 10.0 1.0 10 36 Sponge, cup tan 9.9 6.1 0.5-46 78; 123; 143; 594Turf 8.4 46.9 0.5-30 97; 123; 168-460Zoanthid, tan (Palythoa) 6.8 5.1 2-15 518; 594; 680-Notes: Total = total number of individuals in all photographs. Minimum-maximum = minimum and maximum number o

minimum and maximum percent cover estimates for a 0.0625 m2 photoquadrat. Ninety-eight (98) photographs we

Taxonomic notes: Filamentous red algae include Polysiphonia, Neoptilota, Antithamnion, etc. 
Photo 1. View of (1) Metridium exilis, (2) Corynactis californica, and (3) tan and 

yellow encrusting sponges at -47 m (-153 ft), Leg B1, Platform Gail.

Photo 2. View of (1) Metridium senile, (2) Amphipholis spp., and (3) turf 

at -152 m (-500 ft), Leg B1, Platform Gail.

1

2

3

1

2

3

29
On Leg A1, M. exilis species was the second most abundance species, but more 

intermittently distributed and, when present, in lower average abundance (146.9 

individuals/0.0625 m2). On Leg B1, this species occurred from the shallowest stations to a 

depth of 70 m (231 ft), and again in a narrow band at approximately 93 to 98 m (305 to 322 ft). 

On Leg A1, M. exilis was present from the shallowest stations to a depth of 17 m (55 ft), then 

intermittently down to 41 m (134 ft) below the surface. This might be explained by fortuitous 

settling on newly cleaned areas in shallow water by a colony already established in deeper 

water. Maximum density for this species was 580 individuals, or 9,280 individuals/m2. M. 

exilis also exhibited the highest mean percent cover among taxa on Leg B1 (Table 3-4). 

A second cnidarian species, Metridium senile, occurred in nearly 60 percent of the 

photographs from Legs A1 and B1, ranging in depth from the shallow subtidal to the foot of the 

platform (Tables 3-3 and 3-4; Photo 2). Maximum density for M. senile in a single photograph 

was 213 individuals (3,408 individuals/m2). Of particular note, Metridium was a predominant 

faunal element in zones below 69 m (225 ft). In deeper portions of the legs, Desmophyllum was 

evident below 110 m (360 ft) on Leg A1, and prevalent below 183 m (600 ft) on both legs. 

 Review of inspection videotapes suggested that algal depth on Leg B1 extended from 

the upper portions of the intertidal zone to a maximum depth of approximately 8 to 9 m (25 to 

30 ft). Results of whole slide analysis, however, indicated algal presence (dominated by 

filamentous red algae – Polysiphonia, Neoptilota, Antithamnion, etc.) extending to a depth of 18 m 

(60 ft). 

A well-defined Mytilus zone was noted on Platform Gail, with frequent occurrence 

between 0.9 and 16 m (3 and 53 ft) (Tables 3-3 and 3-4; Photo 3). Maximum abundance of 

Mytilus was 160 individuals/0.0625 m2, or 2,758 individuals/m2, found at a depth of 1 m (4 ft) 

on Leg A1. M. exilis and filamentous red algae were also noticeable dominants within the 

Mytilus zone at Platform Gail. Dominant taxa on both legs, based on percent cover estimators, 

included Metridium (both M. exilis and M. senile), Corynactis californica (Photo 4), and Mytilus 

spp. (Tables 3-3 and 3-4). The high occurrence and significant percent cover contribution of 

M. exilis, C. californica, and M. senile were expected given their density dominance noted 

previously. 

While results of the inspection videotape review suggested the presence of a prominent 

barnacle/scallop zone on Platform Gail, a total of only eight Crassadoma gigantea were noted on 

both legs during photographic analysis. This may be attributed to one or more factors, 

including a dense overgrowth of the strawberry anemone, C. californica, which effectively covers 

and blocks the view of underlying scallops. C. californica was a dominant species, by density 

and percent cover, on both legs and prevalent in water depths where Crassadoma had previously 

been documented (i.e., 12 to 49 m; 40 to 160 ft). 

The relative densities (i.e., numbers of individuals/0.0625 m2) of the six numerical 

dominants present on Legs A1 and B1 are depicted in Figures 3-4 and 3-5. Platform Gail 

exhibited a well-defined Mytilus zone, a broadly distributed anthozoan community (Metridium

and others, termed the "anthozoan mix"), and several abundant species that were also present 

on most other platforms (e.g., filamentous red algae, O. spiculata, Balanus spp., C. californica). 

30
Photo 3. View of (1) Mytilus spp., (2) Metridium senile, and some (3) Metridium 

exilis at -1 m (-4 ft), Leg B1, Platform Gail.

Photo 4. View of (1) Corynactis californica, (2) tan encrusting sponge, and 

(3) Metridium farcimen at -51 m (-168 ft), Leg A1, Platform Gail.

1

3

2

1

2

3

31
Number of Individuals/0.0625 m2

0 20 40 60 80 100 120 140 160 180

Water Depth (ft)

0

20

40

60

80

720

Mytilus spp.

Number of Individuals/0.0625 m2

0 10 20 30 40 50 60 70

Water Depth (ft)

0

200

400

600

O. spiculata 

Number of Individuals/0.0625 m2

0 10 20 30 40 50 60

Water Depth (ft)

0

200

400

600

Desmophyllum

Number of Individuals/0.0625 m2

0 50 100 150 200 250

Water Deoth (ft)

0

200

400

600

M. senile 

Number of Individuals/0.0625 m2

0 100 200 300 400 500 600

Water Depth (ft)

0

200

400

600

M. exilis 

Number of Individuals/0.0625 m2

0 200 400 600 800

Water Depth (ft)

0

200

400

600

C. californica 

Figure 3-4. Density and depth distribution of the six numerically dominant taxa on Leg A1 of Platform 

Gail determined from quantitative slide analysis.

32
Number of Individuals/0.0625 m2

0 20 40 60 80 100

Water Depth (ft)

0

20

40

60

80

720

Mytilus spp. 

Number of Individuals/0.0625 m2

0 10 20 30 40

Water Depth (ft)

0

200

400

600

Desmophyllum

Number of Individuals/0.0625 m2

0 10 20 30 40 50 60

Water Depth (ft)

0

200

400

600

O. spiculata

Number of Individuals/0.0625 m2

0 20 40 60 80 100 120 140 160 180

Water Deoth (ft)

0

200

400

600

M. senile 

Number of Individuals/0.0625 m2

0 100 200 300 400 500 600 700

Water Depth (ft)

0

200

400

600

M. exilis 

Number of Individuals/0.0625 m2

0 100 200 300 400 500 600 700

Water Depth (ft)

0

200

400

600

C. californica 

Figure 3-5. Density and depth distribution of the six numerically dominant taxa on Leg B1 of Platform 

Gail determined from quantitative slide analysis.

33
In terms of unique characteristics, Platform Gail exhibited (1) an unusual trend, 

specifically notable in the species identified within the anthozoan mix – the presence of dense 

colonies of Metridium exilis; (2) a Desmophyllum zone evident along the lower portions of both 

Legs A1 and B1; and (3) Corynactis californica, usually a dominant species at depth, was 

supplanted by M. exilis on Leg B1. 

3.3.2 Platform Grace 

Physical Characteristics 

 Platform Grace, operated by Venoco, Inc., is located on Lease OCS-P 0217 (Santa Clara 

Field, Santa Clara Unit), approximately 17 km (9.2 nmi) from shore in the eastern Santa Barbara 

Channel. This 12-legged platform was installed on 30 July 1979 in a water depth of 97 m 

(318 ft). 

Community Description 

Legs C1 and C4 were sampled at Platform Grace from the intertidal zone to the base of 

each platform leg. Based on analysis of 150 photographs, 48 taxa were identified, of which 

46 percent (22) were monospecific taxa (i.e., species level identification). Remaining taxa were 

identified to genus level or higher. Only two floral taxa (i.e., filamentous red algae, including 

Polysiphonia, Neoptilota, Antithamnion; Ulva lactuca) were among the 48 total taxa observed. 

The six most dominant taxa present on Leg C1 (based on total density, in descending 

order) included Corynactis californica, Paracyathus stearnsii, Mytilus spp., Ophiothrix spiculata, 

Balanus spp., and the rosy morph form of Anthopleura elegantissima (Table 3-5). While 

O. spiculata was most frequently observed on Leg C1, occurring in 37 of 73 photographs, 

C. californica exhibited the highest mean densities (212 individuals/0.0625 m2), nearly two and 

half times more dense than the second most numerically dominant taxa – Mytilus spp. A 

well-defined Mytilus zone was evident between the intertidal and 6 m (19 ft). 

Dominant taxa present on Leg C1 in terms of percent cover included Mytilus spp., 

Corynactis californica, turf, Anthopleura elegantissima (rosy morph), an unidentified tan hydroid, 

filamentous red algae, and bryozoa turf. Several of these species exhibited both numerical 

dominance (i.e., higher densities) and higher percent cover contributions, suggesting that they 

were major community formers at Platform Grace. 

 Results of videotape analysis suggested that algae on Leg C1 of Platform Grace extended 

from the intertidal to a depth of 1 m (4 ft). Results of whole slide analysis, however, indicated 

algal presence (dominated by filamentous red algae – Polysiphonia, Neoptilota, Antithamnion, etc.) 

in a near continuous band to 11 m (35 ft), with limited occurrence down to 19 m (61 ft). 

34
Table 3-5. Dominant taxa (or physical characteristics) on Leg C1 of Platform Grace identified during qua

analysis. 

Taxon Total Average per Occurrence Frequency (%) Minimum- Maximum Depth of Occ

(ft subsur

Density:Corynactis californica 5,720 211.9 37.0 1-450 30; 35; 38-15Paracyathus stearnsii 2,085 71.9 39.7 1-201 111-30Mytilus spp. 1,357 79.8 23.3 13-190 3-8; 10-1Ophiothrix spiculata 987 26.7 50.7 1-180 3-4; 6; 8-16; 24-28; 31-61; 87-88; 93Balanus spp. 627 27.3 31.5 1-68 3-25 Anthopleura elegantissima (rosy morph) 441 25.9 20.5 1-62 8-35 Mytilus californianus 124 62.0 2.7 60-64 7-8 Worm tubes, calcareous 90 4.7 26.0 1-10 144; 150; 20Coenocyathus bowersi (c) 89 6.8 17.8 1-21 81; 119-2Turf 64 1.0 87.7 1 (max) 3-6; 8; 15-38; 58-Metridium senile 54 10.8 6.8 1-36 3-4; 8; 1Filamentous red algae 25 1.0 34.2 1 (max) 3-30; 34-35Percent Cover:Mytilus spp. 49.1 23.3 5-80 3-8; 10-1Corynactis californica 42.6 37.0 0.5-95 30; 35; 38-15Turf 37.4 87.7 1-97 3-6; 8; 15-38; 58-Anthopleura elegantissima (rosy morph) 30.8 20.5 0.5-90 8-35 Hydroid, tan 25.0 1.4 25-25 10 Filamentous red algae 21.2 34.2 0.5-50 3-30; 34-35Bryozoa turf 20.0 1.4 20-20 7 Sponge, gray encrusting 16.7 4.1 10-25 38; 81-8Hydroid, tan branching 15.5 5.5 2-30 7-8; 14Sponge, yellow encrusting 11.3 24.7 1-30 55-65; 73-Sponge, tan encrusting 9.8 27.4 1-50 15-24; 28-35; 52-55; 61; 84; 88Bare metal 7.5 2.7 5-10 256; 30Notes: Total = total number of individuals in all photographs. Minimum-maximum = minimum and maximum number o

or minimum and maximum percent cover estimates for a 0.0625 m2 photoquadrat. Balanus spp. and Balanus sp. co

presentation (see Appendix C). Seventy-three (73) photographs were analyzed from Leg C1. 

Taxonomic notes: Filamentous red algae include Polysiphonia, Neoptilota, Antithamnion, etc.; Coenocyathus bowersi is a coloni
The six most dominant taxa present on Leg C4 (based on total density, in descending 

order), included Corynactis californica, Mytilus spp., Ophiothrix spiculata, Metridium senile, Balanus

spp., and Paracyathus stearnsii (Table 3-6). Dominant species on Leg C4 were similar, with the 

exception of Metridium senile, to those documented from Leg C1. O. spiculata was most 

frequently observed on Leg C4, occurring in 33 of 77 photographs, while C. californica exhibited 

the highest mean densities (344 individuals/0.0625 m2). Mytilus occurred in two bands on 

Leg C4, with presence in depths of 1 to 4 and 10 to 12 m (3 to 14 and 33 to 39 ft). Dominant taxa 

present on Leg C4 in terms of percent cover included Corynactis californica, Mytilus spp., 

Metridium senile, a colonial tan zoanthid, turf, and an unidentified tan hydroid. Most of these 

species exhibited both numerical dominance and higher percent cover contributions, again 

suggesting that they were major community formers at Platform Grace. 

 Results of videotape analysis indicated that algae on Leg C4 of Platform Grace extended 

from the intertidal to a depth of approximately 12 m (40 ft). Results of whole slide analysis 

indicated algal presence slightly deeper. Dominated by filamentous red algae (e.g., Polysiphonia, 

Neoptilota, Antithamnion, etc.), algae occurred in a nearly continuous band between 1 and 15 m 

(4 and 49 ft). Corynactis californica was a prevalent species at Platform Grace, dominating on 

both legs in terms of total density and average density per occurrence, and was a major 

contributor to percent cover, exceeded only by turf on Leg C1. This species was dominant in 

water depths between 9 and 58 m (30 and 190 ft). Mytilus was also a prevalent species at 

Platform Grace, present within nearly all photographs between 0.9 and 12.2 m (3 and 40 ft). 

Highest numbers were evident between 0.9 and 2.7 m (3 and 9 ft), with densities tapering off 

with increasing depth. Maximum mussel abundance was 240 individuals/0.0625 m2, or 

3,840 individuals/m2, the highest recorded among the six platforms. Filamentous red algae and 

barnacles were also co-dominants within the mussel zone and regularly co-occurred in 

photographs with mussels (Table 3-5; Photo 5). 

Another dominant species at Grace, the ophiuroid Ophiothrix spiculata, was prevalent at 

depths between 0.9 and 78 m (3 and 256 ft), overlapping a portion of the mussel zone and 

extending across the barnacle/scallop and anemone/encruster zones. Highest ophiuroid 

abundance was 180 individuals/0.0625 m2, with highest concentrations evident between 0.9 and 

15.2 m (3 and 50 ft). O. spiculata co-occurred with another dominant, the strawberry anemone 

C. californica, below the mussel zone between 9.1 and 61 m (30 and 200 ft) (Photo 6). The 

solitary cup coral, Paracyathus stearnsii, and turf were also dominant numerically between 

approximately 30.5 and 91.4 m (100 and 300 ft). Considerable leg-to-leg differences were also 

evident for this hexacoral species, with Leg C4 consistently higher in Paracyathus abundance 

than Leg C1. Coenocyathus bowersi (hexacoral), another dominant, co-occurred with Paracyathus 

between 36 and 62 m (119 and 205 ft) water depths (Photo 7). 

Percent cover contributions on both legs were led by Corynactis and Mytilus, and 

Metridium. Additionally, two other cnidarian taxa (i.e., Coenocyathus and the tan colonial 

zoanthid) were noted as percent cover dominants within select depth ranges (Table 3-6). 

Reduced abundance and species diversity were evident with increasing depth at Platform 

Grace. Along the lower portions of the platform, below approximately 70 m (230 ft), Paracyathus

and turf predominate along with Ophiothrix (tapers off at 76 m [250 ft]) and occasional larger 

predatory starfish (e.g., Asterina, Photo 8). 

36
Table 3-6. Dominant taxa (or physical characteristics) on Leg C4 of Platform Grace identified during qua

analysis. 

Taxon Total Average per Occurrence Frequency (%) Minimum- Maximum Depth of Occ

(ft subsur

Density:Corynactis californica 7,917 344.2 29.9 10-500 39; 57-150Mytilus spp. 1,824 76.0 31.2 4-240 3-14; 33-Metridium senile 1,769 43.1 53.2 1-165 3-8; 28-61; 2Ophiothrix spiculata 1,548 46.9 42.9 2-180 6-67; 72-74; 87; 9Balanus spp. 548 24.9 28.6 1-100 3-26; 2Paracyathus stearnsii 214 26.8 10.4 1-57 133-19Anthopleura elegantissima (rosy morph) 191 13.6 18.2 2-30 3; 6-9; 11Metridium exilis 97 32.3 3.9 15-60 67; 72-7Metridium farcimen 71 6.5 14.3 1-18 130; 146-193; 202; Turf 46 1.0 59.7 1 (max) 3-12; 14-28; 39-42; 49; 61-85; 133Balanus nubilus 39 2.8 18.2 1-8 49; 61; 76-Filamentous red algae 24 1.0 31.2 1 (max) 4-26; 33; 39-Percent Cover:Corynactis californica 69.2 29.9 2-100 39; 57-150Mytilus spp. 52.6 31.2 5-85 3-14; 33-Zoanthid, colonial tan 37.6 9.1 3-90 197; 255; 277-Metridium senile 36.6 52.3 0.5-80 3-8; 28-61; 2Turf 25.6 59.7 1-90 3-12; 14-28; 39-42; 49; 61; 85; 133Hydroid, tan 18.2 14.3 5-60 29-39; 4Filamentous red algae 16.7 31.2 1-50 4-26; 33; 39-Cliona spp., yellow 10.0 2.6 10 28; 39 Anthozoa, unidentified 10.0 1.3 10 202 Anthopleura elegantissima (rosy morph) 8.7 18.2 1-20 3; 6-9; 11Bare Metal 8.4 6.5 2-15 3-4; 255; 27Sponge, tan encrusting 6.6 6.6 1-10 72-74; 133; 1Notes: Total = total number of individuals in all photographs. Minimum-maximum = minimum and maximum number o

or minimum and maximum percent cover estimates for a 0.0625 m2 photoquadrat. Balanus spp. and Balanus sp. co

presentation (see Appendix C). Seventy-seven (77) photographs were analyzed from Leg C4. 

Taxonomic notes: Filamentous red algae include Polysiphonia, Neoptilota, Antithamnion, etc. 
Photo 5. View of (1) Mytilus spp., (2) Balanus spp., and (3) filamentous red 

algae at -2 m (-8 ft), Leg C1, Platform Grace.

Photo 6. View of (1) Corynactis californica, (2) filamentous red algae, and 

(3) encrusting sponges at -19 m (-61 ft), Leg C1, Platform Grace.

1

2

3

1

2

2

3

38
Photo 7. View of (1) Paracyathus stearnsii, (2) Coenocyathus bowersi, and 

(3) Metridium farcimen at -53 m (-174 ft), Leg C1, Platform Grace. 

Photo 8. View of (1) Paracyathus stearnsii, (2) Ophiothrix spiculata, 

(3) Asterina miniata, and turf at -74 m (-242 ft), Leg C1, Platform Grace.

1

2

3

1

2

3

39
 A graphic presentation of relative density (i.e., numbers of individuals/0.0625 m2) of the 

six numerical dominants present on Legs B1 and B2 is provided in Figures 3-6 and 3-7. 

Platform Grace exhibited well-defined Mytilus and Corynactis zones, abundant ophiuroids, a 

prominent barnacle community, and a broadly distributed anthozoan community (Metridium, 

Corynactis, Anthopleura). Many of the dominant species were also present on most other 

platforms (e.g., filamentous red algae, Balanus spp.). In terms of unique characteristics, Platform 

Grace exhibited the following trends: (1) prominent Mytilus and Corynactis communities, with 

no apparent overlap between the two species; and (2) a prominent Paracyathus community 

beginning in the lower portions of the Corynactis community and extending to the base of the 

platform. 

3.3.3 Platform Harvest 

Physical Characteristics 

Platform Harvest, operated by Arguello, Inc., is located on Lease OCS-P 0315 (Arguello 

Field), approximately 10.8 km (5.8 nmi) from shore in the southern Santa Maria Basin. This 

10-legged platform was installed on 12 June 1985 in a water depth of 206 m (675 ft). 

Community Description 

Legs B1 and B2 were sampled at Platform Harvest from the intertidal zone to the base of 

each platform leg. Based on complete analysis of 178 photographs from both legs, 53 taxa were 

identified, of which 34 percent (18) were monospecific taxa (i.e., species level identification). 

Remaining taxa were identified primarily to genus level, with several specimens enumerated at 

higher taxonomic levels. Only three floral taxa (i.e., foliose red algae; Egregia; filamentous red 

algae, including Polysiphonia, Neoptilota, Antithamnion) were among the 53 total taxa observed. 

On Leg B1, the six most dominant taxa (based on total density, in descending order) 

included Metridium senile, an unidentified ophiuroid, Mytilus spp., Corynactis californica, 

Leucetta, and Balanus spp. (Table 3-7). Based on scraping analysis results (see Section 3.7), 

Ophiothrix spiculata and Ophiopterus papillosa were the only two ophiuroid species identified 

from Platform Harvest. Unidentified ophiuroids documented (via photographic analysis) at 

Platform Harvest were considered to be Ophiothrix spiculata, among the dominant taxa at all 

platforms. 

Metridium senile had the highest frequency of occurrence on Leg B1 (82 out of 

92 photographs), while Corynactis californica exhibited highest average density per occurrence at 

168 individuals/0.0625 m2. In terms of percent cover, prevalent species on Leg B1 included (in 

descending order) Corynactis californica, Metridium senile, Metridium farcimen, a red encruster, a 

lavender encruster, and turf. Mytilus spp. and foliose red algae were also prevalent. Bare metal 

was a prominent physical characteristic on this leg at depths below 38 m (125 ft). 

 Based on videotape review, algal depth on Leg B1 extended from the upper portions of 

the intertidal zone to a maximum depth of approximately 17 m (55 ft). Results of whole slide 

analysis, however, indicated algal presence (dominated by foliose red algae) extending to a 

depth of nearly 20 m (65 ft). 

40
Number of Individuals/0.0625 m2

0 20 40 60 80 100 120 140 160 180 200

Water Depth (ft)

0

20

40

60

80

100

280

300 Mytilus spp.

Number of Individuals/0.0625 m2

0 10 20 30 40 50 60 70

Water Depth (ft)

0

50

100

150

200

250

300

A. elegantissima (rosy morph)

Number of Individuals/0.0625 m2

0 20 40 60 80

Water Depth (ft)

0

50

100

150

200

250

300

Balanus spp.

Number of Individuals/0.0625 m2

0 20 40 60 80 100 120 140 160 180 200

Water Deoth (ft)

0

50

100

150

200

250

300

O. spiculata

Number of Individuals/0.0625 m2

0 50 100 150 200 250

Water Depth (ft)

0

50

100

150

200

250

300

P. stearnsii

Number of Individuals/0.0625 m2

0 100 200 300 400 500

Water Depth (ft)

0

50

100

150

200

250

300

C. californica

Figure 3-6. Density and depth distribution of the six numerically dominant taxa on Leg C1 of Platform 

Grace determined from quantitative slide analysis.

41
Number of Individuals/0.0625 m2

0 20 40 60 80 100 120 140 160 180 200 220 240 260

Water Depth (ft)

0

20

40

60

80

100

280

300 Mytilus spp.

Number of Individuals/0.0625 m2

0 20 40 60 80 100 120 140 160 180

Water Depth (ft)

0

50

100

150

200

250

300

M. senile

Number of Individuals/0.0625 m2

0 10 20 30 40 50 60

Water Depth (ft)

0

50

100

150

200

250

300

Balanus spp.

Number of Individuals/0.0625 m2

0 20 40 60 80 100 120 140 160 180 200

Water Deoth (ft)

0

50

100

150

200

250

300

O. spiculata

Number of Individuals/0.0625 m2

0 10 20 30 40 50 60

Water Depth (ft)

0

50

100

150

200

250

300

P. stearnsii

Number of Individuals/0.0625 m2

0 100 200 300 400 500 600

Water Depth (ft)

0

50

100

150

200

250

300

C. californica

Figure 3-7. Density and depth distribution of the six numerically dominant taxa on Leg C4 of Platform 

Grace determined from quantitative slide analysis.

42
Table 3-7. Dominant taxa (or physical characteristics) on Leg B1 of Platform Harvest identified during qu

analysis. 

Taxon Total Average per Occurrence Frequency (%) Minimum- Maximum Depth of Occurr

(ft subsurfac

Density:Metridium senile 3,168 38.6 89.1 1-90 3-6; 10; 16; 22; 28; 33-98; 10Ophiuroid, unidentified 782 23.0 37.0 1-120 29-31; 37-41; 48-135; 225-33Mytilus spp. 734 36.7 21.7 1-75 3-29; 33-35; 4Corynactis californica 672 168.0 4.3 12-360 102-103; 120; 1Leucetta losangelensis 354 13.1 29.3 2-40 4; 12; 31-41; 48-51; 65-144Balanus spp. 188 5.9 34.8 1-18 3-22; 26-33; 46; 124; 135-157; 17Anthopleura elegantissima (rosy morph) 124 7.8 17.4 1-24 3-26; 65 Worm tubes, calcareous 105 3.5 32.6 1-11 144; 154; 176-199; 225-243; 278-288; 314

597; 614-618 

Turf 72 1.0 78.3 1 (max) 3-41; 48-51; 65-68; 135-209; 243; 288-301Tunicate, encrusting translucent 50 7.1 7.6 1-15 314; 366-370; 395; 519Bare Metal 48 1.0 52.2 1 (max) 125; 137; 149-157; 176-225; 260-2Encruster, red 48 1.0 52.2 1 (max) 135-144; 176-292; 314-6Percent Cover:Corynactis californica 42.0 4.3 3-90 102-103; 120; 1Metridium senile 38.5 89.1 1-90 3-6; 10; 16; 22; 28; 33-98; 10Metridium farcimen 37.0 5.4 15-100 29-31; 659-66Encruster, red 35.4 52.2 2-75 135-144; 176-292; 314-6Encruster, lavender 27.7 3.3 3-65 278; 301; 533 Turf 21.3 78.3 1-75 3-41; 48-51; 65-68; 135-209; 243; 288-301Mytilus spp. 21.0 21.7 5-50 3-29; 33-35; 4Botrylloides spp. 20.0 1.1 20 65 Leucetta losangelensis 14.8 29.3 1-30 4; 12; 31-41; 48-51; 65-144Encruster - yellow 13.1 14.1 0.5-65 144-154; 209; 260-278; 292Foliose red algae 12.2 23.9 1-30 4-6; 10; 14-46; 58Bare Metal 11.5 52.2 1-50 125; 137; 149-157; 176-225; 260-2Notes: Total = total number of individuals in all photographs. Minimum-maximum = minimum and maximum number o

minimum and maximum percent cover estimates for a 0.0625 m2 photoquadrat. Ninety-two (92) photographs wer

Taxonomic notes: Foliose red algae possibly include Callophyllis. 
44 

On Leg B2, similar dominant species were evident as compared to Leg B1, with slight 

reordering among the top five taxa – Metridium senile, an unidentified ophiuroid (considered to 

be O. spiculata), Leucetta, Mytilus spp., Corynactis californica, and Balanus spp. Leucetta exhibited 

the highest total density on this leg, followed closely by ophiuroids, Mytilus, Corynactis, and 

Metridium senile. On Leg B2, Metridium senile was the most frequently encountered species, 

occurring in 87 percent of the photographs. While M. senile was present at nearly all depths on 

this leg (Table 3-8), its mean density was lower than that evident on Leg B1 (i.e., 30 versus 

39 individuals/0.0625 m2). Maximum density for this species was 90 individuals, or 

1,440 individuals/m2. 

Review of inspection videotapes suggested that algal depth on Leg B2 extended from 

the upper portions of the intertidal zone to a maximum depth of approximately 17 m (55 ft). 

Results of whole slide analysis indicated algal presence (dominated by foliose red algae) 

extending to this depth. Filamentous red algae were very limited on Leg B2, present only in the 

intertidal zone at depths of 0.6 to 1.2 and 1.8 to 2.1 m (2 to 4 and 6 to 7 ft). 

A relatively well-defined Mytilus zone was noted on Platform Harvest, with frequent 

occurrence between the intertidal and 11 m (3 to 35 ft), although depth of occurrence on Leg B2 

was limited to the upper 8 m (25 ft) (Tables 3-7 and 3-8; Photo 9). Maximum abundance of 

Mytilus was 110 individuals/0.0625 m2, or 1,760 individuals/m2, found at a depth of 0.6 m (2 ft) 

on Leg B2. Balanus, Anthopleura, and red algae were also noticeable dominants within the 

Mytilus zone at Platform Harvest. 

 Dominant taxa on both legs of Platform Harvest, based on percent cover estimators, 

included a red encruster, Metridium senile, turf, and Mytilus spp, among other taxa. (Tables 3-7

and 3-8). The high occurrence and significant percent cover contribution of M. senile and 

Mytilus were expected given their numerical dominance noted previously. The presence of 

“turf” is also noteworthy; turf was present in ~80 percent of the photographs at Platform 

Harvest and its contribution to total percent cover was generally high, averaging 19 to 

21 percent. A prominent sponge (Leucetta) was also a numerical and percent cover dominant on 

both legs of Platform Harvest. 

Maximum mussel abundance was only 110 individuals/0.0625 m2, or 1,760 individuals 

per m2. Turf, barnacles, and red algae were also dominant within the mussel zone and 

regularly co-occurred with mussels, while Metridium senile occurred intermittently within the 

mussel zone (Photo 9). The rosy morph form of Anthopleura elegantissima was also prominent in 

the upper 8 m (25 ft) of both legs. Depending on where along the platform it occurs, Metridium 

senile can also be found in association with ophiuroids, barnacles, and/or turf (Photos 10, 11, 

and 12). 

 A graphic presentation of relative density (i.e., numbers of individuals/0.0625 m2) of the 

six numerical dominants present on Legs B1 and B2 is provided in Figures 3-8 and 3-9. 

Platform Harvest exhibited a well-defined Mytilus zone, abundant ophiuroids, a prominent 

sponge (Leucetta), and a broadly distributed anthozoan community (Metridium, Corynactis, 

Anthopleura). Many of the dominant species were also present on most other platforms 

(e.g., filamentous red algae, Balanus spp.). 
Table 3-8. Dominant taxa (or physical characteristics) on Leg B2 of Platform Harvest identified during qu

analysis. 

Taxon Total Average per Occurrence Frequency (%) Minimum- Maximum Depth of Occu

(ft subsurfa

Density:Metridium senile 2,216 29.5 87.2 2-90 4-6; 10-61Ophiuroid, unidentified 1,566 44.7 40.7 1-180 4; 12; 27-47; 54-69; 88-129; 229Leucetta losangelensis 1,473 50.8 33.7 6-80 4; 10-150 Mytilus spp. 858 42.8 23.3 1-110 2-12; 18-2Corynactis californica 179 35.8 5.8 4-80 14; 30; 52; 95Balanus spp. 169 4.2 46.6 1-27 3-8; 12-18; 25; 30-69; 88; 95-145; 1Anthopleura elegantissima (rosy morph) 160 9.4 19.8 2-20 2-10; 24 Filamentous red algae 107 21.4 5.8 2-40 2-4; 6-7 Turf 71 1.0 82.6 1 (max) 2-25; 30-52; 64; 88; 122; 129-196; 2Worm tubes, calcareous 68 2.8 27.9 1-12 150-153; 229-241; 292-330Encruster, red 43 1.0 50.0 1 (max) 145-155; 199Pollicipes polymerus 36 9.0 4.7 5-20 2; 4; 6 Percent Cover:Encruster, red 49.6 50.0 3-90 145-155; 199Leucetta losangelensis 48.8 33.7 5-80 4; 10-150 Mytilus spp. 35.0 23.3 5-90 2-12; 18-2Sponge, tan encrusting 30.0 2.3 30 241-244 Metridium senile 29.5 87.2 2-90 4-6; 10-61Encruster - tan 26.3 4.7 5-50 7; 196-22Turf 19.3 82.6 0.5-70 2-25; 30-52; 64; 88; 122; 129-196; 2Sponge, yellow encrusting 16.1 9.3 2-80 3-6; 8; 158; 27Encruster - yellow 16.0 8.1 1-70 7; 150; 155; 266; 32Corynactis californica 11.0 5.8 1-20 14; 52; 30; 95Anthopleura elegantissima (rosy morph) 8.9 19.8 2-20 2-10; 24 Bare Metal 7.8 39.5 0.5-25 127; 153-155; 196-241; 259; 294-320Notes: Total = total number of individuals in all photographs. Minimum-maximum = minimum and maximum number o

minimum and maximum percent cover estimates for a 0.0625 m2 photoquadrat. Eighty-six (86) photographs were 

Taxonomic notes: Filamentous red algae may include Polysiphonia, Neoptilota, Antithamnion, etc. 
Photo 9. View of (1) Mytilus spp., (2) Metridium senile, (3) Balanus spp., and 

(4) filamentous red algae at -2 m (-6 ft), Leg B1, Platform Harvest.

Photo 10. View of (1) Metridium senile, (2) tan branching bryozoan colonies, (3) red 

encrusters, and (4) unidentified ophiuroids at -90 m (-294 ft), Leg B2, 

Platform Harvest. 

1

2

3

4

1

2

3

4

1

46
Photo 11. View of (1) Balanus nubilus, (2) Metridium senile, and (3) turf at 

-47 m (-153 ft), Leg B2, Platform Harvest. 

Photo 12. View of (1) Metridium senile, (2) turf, (3) bare metal, and (4) Galathea 

californiensis at -177 m (-580 ft), Leg B2, Platform Harvest.

1

2

3

1

2

3

2

4

47
Number of Individuals/0.0625 m2

0 20 40 60 80

Water Depth (ft)

0

20

40

60

80

600

620

640

660

Mytilus spp.

Number of Individuals/0.0625 m2

0 2 4 6 8 10 12 14 16 18 20

Water Depth (ft)

0

200

400

600 Balanus spp.

Number of Individuals/0.0625 m2

0 10 20 30 40 50

Water Depth (ft)

0

200

400

600 Leucetta

Number of Individuals/0.0625 m2

0 100 200 300 400

Water Deoth (ft)

0

200

400

600

C. californica

Number of Individuals/0.0625 m2

0 20 40 60 80 100 120 140

Water Depth (ft)

0

200

400

600 Ophiuroid, unidentified

Number of Individuals/0.0625 m2

0 20 40 60 80 100

Water Depth (ft)

0

200

400

600

M. senile

Figure 3-8. Density and depth distribution of the six numerically dominant taxa on Leg B1 of Platform

Harvest determined from quantitative slide analysis.

48
Number of Individuals/0.0625 m2

0 20 40 60 80 100 120

Water Depth (ft)

0

20

40

60

80

600

Mytilus spp.

Number of Individuals/0.0625 m2

0 5 10 15 20 25 30

Water Depth (ft)

0

100

200

300

400

500

600

Balanus spp.

Number of Individuals/0.0625 m2

0 20 40 60 80

Water Depth (ft)

0

100

200

300

400

500

600

Leucetta

Number of Individuals/0.0625 m2

0 20 40 60 80 100

Water Deoth (ft)

0

100

200

300

400

500

600

C. californica

Number of Individuals/0.0625 m2

0 20 40 60 80 100 120 140 160 180 200

Water Depth (ft)

0

100

200

300

400

500

600

Ophiuroid, unidentified

Number of Individuals/0.0625 m2

0 20 40 60 80 100

Water Depth (ft)

0

100

200

300

400

500

600

M. senile

Figure 3-9. Density and depth distribution of the six numerically dominant taxa on Leg B2 of Platform 

Harvest determined from quantitative slide analysis.

49
In terms of unique characteristics, Platform Harvest exhibited the following trends: (1) a 

broad barnacle zone (Balanus spp.) that extended along nearly two-thirds of the platform legs 

and exhibited a slight bimodal distribution (at 3.7 to 5.5 m [12 to 18 ft] and at approximately 

36.6 m [120 ft]); (2) foliose red algae occurring from the intertidal to 19.8 m (65 ft), primarily 

within the mussel bed, with limited presence and depth distribution of filamentous algae; and 

(3) red encrusters, representing a significant contributor to percent cover, found between 41.1 

and 203.9 m (135 ft and 669 ft), with maximum densities encountered at approximately 121.9 m 

(400 ft). 

3.3.4 Platform Hidalgo 

Physical Characteristics 

Platform Hidalgo, operated by Arguello, Inc., is located on Lease OCS-P 0450 (Arguello 

Field), approximately 9.5 km (5.1 nmi) from shore in the southern Santa Maria Basin. This 

8-legged platform was installed on 2 July 1986 in a water depth of 131 m (430 ft). 

Community Description 

Legs A1 and B1 were sampled at Platform Hidalgo. Based on analysis of 

141 photographs, a total of 54 taxa was identified, of which 39 percent (21) were monospecific 

taxa (i.e., species level identification). Remaining taxa were identified primarily to genus level, 

with several specimens enumerated at higher taxonomic levels. Only four floral taxa (i.e., 

foliose red algae; Egregia; filamentous red algae, including Polysiphonia, Neoptilota, Antithamnion: 

Rhodymenia) were among the 53 total taxa observed. 

On Leg A1, the six most dominant taxa (based on total density, in descending order) 

included Metridium senile, an unidentified ophiuroid, Mytilus spp., Corynactis californica, Balanus 

nubilus, and Metridium farcimen (Table 3-9). M. senile had the highest frequency of occurrence 

(58 out of 63 photographs), was nearly continuous in its distribution (from the intertidal to the 

base of the leg), and exhibited the highest average density (135 individuals/0.0625 m2). Among 

the other density-dominant taxa, ophiuroids were also prevalent along the entire length of 

Leg A1, while barnacles (Balanus nubilus) occurred within the upper 30 m (100 ft) of the leg. 

Corynactis californica was not well established on this leg, occurring intermittently between 

24 and 31 m (78 to 101 ft). In terms of percent cover, prevalent species on Leg A1 included (in 

descending order) Mytilus spp., Metridium senile, a yellow encruster, Leucetta losangelensis, 

Metridium farcimen, and a tan foliose sponge. Bare metal was evident at 44 m (145 ft), and was a 

prevalent feature on this leg at depths below 87 m (285 ft). Turf was also prominent on this leg. 

Based on videotape review, algal depth on Leg A1 extended from the upper portions of 

the intertidal zone to a maximum depth of approximately 18 m (60 ft). Results of whole slide 

analysis indicated algal presence (dominated by foliose red algae) extending to a depth of 16 m 

(52 ft). 

50
Table 3-9. Dominant taxa (or physical characteristics) on Leg A1 of Platform Hidalgo identified during q

analysis. 

Taxon Total Average per Occurrence Frequency (%) Minimum- Maximum Depth of Occ

(ft subsur

Density:Metridium senile 7,849 135.3 92.1 1-275 5-424 Ophiuroid, unidentified 3,842 78.4 77.8 1-430 5-318; 355; 4Mytilus spp. 1,190 85.0 22.2 5-194 3-29 Corynactis californica 139 27.8 7.9 9-75 78-82; 86; 9Balanus nubilus 92 3.4 42.9 1-13 5-15; 29-58; 72-88; 9Metridium farcimen 73 24.3 4.8 19-34 427-43Worm tubes, calcareous 47 2.9 25.4 1-8 256-285; 318-35Turf 34 1.0 54.0 1 (max) 3-8; 15-41; 145; 189; 2Eudistylia polymorpha 32 5.3 9.5 2-13 3-7 Leucetta losangelensis 30 1.0 47.6 1 (max) 3-7; 29-145; 1Tetraclita squamosa 23 23.0 1.6 23 (max) 6 Bare Metal 17 1.0 27.0 1 (max) 145; 243; 285-355; 39Percent Cover:Mytilus spp. 57.1 22.2 5-85 3-29 Metridium senile 46.7 92.1 3-90 5-424 Encruster - yellow 30.0 3.2 10-50 189; 25Leucetta losangelensis 25.3 47.6 5-60 3-7; 29-145; 1Metridium farcimen 21.7 4.8 10-35 427-43Sponge, tan foliose 20.0 1.6 20 418 Bare Metal 18.5 27.0 0.5-60 145; 243; 285-355; 39Turf 18.2 54.0 2-40 3-8; 15-41; 145; 189; 2Encruster - tan 17.3 23.8 1-60 85; 118-171; 243-285; 3Encruster, lavender 15.0 4.8 5-25 392; 401; Corynactis californica 9.0 7.9 2-25 78-82; 86; 9Sponge, tan encrusting 7.8 4.8 0.5-20 60; 222; 3Notes: Total = total number of individuals in all photographs. Minimum-maximum = minimum and maximum number o

minimum and maximum percent cover estimates for a 0.0625 m2 photoquadrat. Sixty-three (63) photographs were 

Taxonomic notes: Bryozoa, tan branching is a colonial (c) species; foliose red algae possibly include Gigartina and Crytopleu
On Leg B1, similar dominant species were evident as compared to Leg A1 (based on 

total density, in descending order), with slight reordering among the top six taxa – Metridium 

senile, Mytilus spp., an unidentified ophiuroid, the rosy morph form of Anthopleura elegantissima, 

Balanus spp., and Metridium farcimen (Table 3-10). Of particular note on this leg, the rosy 

morph form of Anthopleura elegantissima replaced Corynactis californica, the latter of which was 

not evident in any of the photographs from Leg B1. Metridium senile exhibited the highest total 

density and was a major contributor to percent cover, occurring in 82 percent of the 

photographs and prevalent in depths between 0 and 122 m (0 and 399 ft) on Leg B2 (Photo 13). 

When present in the 0 to 6 m (0 to 21 ft) depth range, Mytilus spp. exhibited the highest 

densities and percent cover contributions of the dominant taxa, often co-occurring with a 

variety of other taxa (Photo 14). 

Review of inspection videotapes suggested that algal depth on Leg B2 extended from 

the upper portions of the intertidal zone to a maximum depth of approximately 18 m (60 ft). 

Results of whole slide analysis indicated algal presence (dominated by foliose red algae) 

extending to a maximum depth of 25 m (81 ft). 

A well-defined Mytilus zone was noted on Platform Hidalgo, with frequent occurrence 

between the intertidal and 6 to 9 m (21 and 29 ft), depending upon the platform leg (Tables 3-9 

and 3-10). Maximum abundance of Mytilus was 220 individuals/0.0625 m2, or 3,520 

individuals/m2, found at a depth of 2 m (8 ft) on Leg B1. Metridium senile, ophiuroids, 

barnacles, and sponges were also noticeable dominants within the Mytilus zone at Platform 

Hidalgo. 

 Dominant taxa on both legs of Platform Hidalgo, based on percent cover estimators, 

included Mytilus spp., Metridium senile, Leucetta losangelensis, and turf (Photo 15; Tables 3-9 and 

3-10). The frequent occurrence and significant percent cover contribution of M. senile, Mytilus 

spp., and Leucetta losangelensis in the upper portions of the platform were expected given their 

numerical dominance noted previously. 

 Below the Mytilus zone, Metridium senile remained a predominant species, co-occurring 

with a variety of other species including various encrusters, calcareous worm tubes, and turf, all 

of which were noted numerical and/or percent cover dominants (Photo 16). The presence of 

“turf” is noteworthy; turf was present in 50 to 60 percent of the photographs at Platform 

Hidalgo; its contribution to total percent cover was variable and generally high, averaging 18 to 

30 percent. 

A graphic presentation of relative density (i.e., numbers of individuals/0.0625 m2) of the 

six numerical dominants present on Legs A1 and B1 is provided in Figures 3-10 and 3-11. 

Platform Hidalgo exhibited a relatively narrow, but well-defined Mytilus zone. The relative 

distribution of mussels over depth was generally similar between Legs A1 and B1. Highest 

numbers were evident between 0.6 and 2.4 m (2 and 8 ft), tapering off with depth. This 

platform also exhibited a broadly distributed anthozoan community (A. elegantissima [rosy 

morph] and Metridium senile), and several abundant species that were also present on most 

other platforms (e.g., ophiuroids, barnacles). In terms of unique characteristics, Platform 

Habitat exhibited an unusual trend, specifically notable in the limited presence of Corynactis 

californica on Leg A1 and the prevalence of Anthopleura elegantissima on Leg B1. 

52
Table 3-10. Dominant taxa (or physical characteristics) on Leg B1 of Platform Hidalgo identified during q

analysis. 

Taxon Total Average per Occurrence Frequency (%) Minimum- Maximum Depth of Occ

(ft subsur

Density:Metridium senile 5,048 78.9 82.1 1-245 0-399 Mytilus spp. 2,710 117.8 29.5 10-220 0-21 Ophiuroid, unidentified 2,659 59.1 57.7 1-260 3-5; 14-18; 27-50; 57; 73-151; 17Anthopleura elegantissima (rosy morph) 849 84.9 12.8 2-185 3; 7; 18-Balanus spp. 56 4.7 15.4 1-9 0-6; 8; 14; 1Metridium farcimen 55 27.5 2.6 13-42 430-43Turf 49 1.0 62.8 1 (max) 0-27; 40-45; 81Worm tubes, calcareous 49 2.6 24.4 1-5 215-299; 340; 38Ophiothrix spiculata 42 7.0 7.7 1-17 1; 6-7; 165; 2Tetraclita squamosa 38 5.4 9.0 2-9 3-7; 14-1Balanus nubilus 32 2.5 16.7 1-7 27-29; 40; 48-57; 73Leucetta losangelensis 32 1.0 41.0 1 (max) 7; 21; 29-151; Percent Cover:Mytilus spp. 54.2 29.5 3-80 0-21 Anthopleura elegantissima (rosy morph) 43.5 12.8 1-95 3; 7; 18-Bare Metal 39.0 10.3 2-65 27; 421-4Metridium senile 34.9 82.1 0.5-98 0-399 Leucetta losangelensis 30.5 41.0 2-80 7; 21; 29-151; Turf 30.1 62.8 0.5-80 0-27; 40-45; 81Encruster, red 22.4 21.8 5-70 165; 215-Metridium farcimen 17.5 2.6 15-20 430-43Encruster - blue 13.1 19.2 0.5-30 151; 215-279; Encruster - yellow 12.1 12.8 0.5-50 199; 232; 279-36Encruster - tan 10.4 7.7 0.5-30 165; 215; 255; 29Sponge, tan encrusting 10.0 1.3 10 54 Notes: Total = total number of individuals in all photographs. Minimum-maximum = minimum and maximum number o

minimum and maximum percent cover estimates for a 0.0625 m2 photoquadrat. Seventy-eight (78) photographs w
Photo 13. View of (1) Metridium senile, (2) Anthopleura elegantissima (rosy morph), 

and (3) Strongylocentrotus purpuratus at -14 m (-45 ft), Leg B1, Platform 

Hidalgo.

Photo 14. View of (1) Mytilus spp. and associated fauna at -2 m (-6 ft), Leg B1, 

Platform Hidalgo.

1

3

2

1

54
Photo 15. View of (1) unidentified ophiuroids, (2) Metridium senile, (3) Pisaster 

ochraceus, and (4) Leucetta losangelensis at -30 m (-99 ft), Leg A1, 

Platform Hidalgo.

Photo 16. View of (1) Metridium senile, (2) turf, (3) various encrusters, and 

(4) calcareous worm tubes at -122 m (-399 ft), Leg B1, Platform 

Hidalgo.

3

1

2

4

1

2

3

4

55
Number of Individuals/0.0625 m2

0 20 40 60 80 100 120 140 160 180 200 220

Water Depth (ft)

0

20

40

60

80

400

420 Mytilus spp.

Number of Individuals/0.0625 m2

0 10 20 30 40

Water Depth (ft)

0

100

200

300

400

M. farcimen

Number of Individuals/0.0625 m2

0 2 4 6 8 10 12 14

Water Depth (ft)

0

100

200

300

400

Balanus nubilus

Number of Individuals/0.0625 m2

0 20 40 60 80

Water Deoth (ft)

0

100

200

300

400

C. californica

Number of Individuals/0.0625 m2

0 100 200 300 400 500

Water Depth (ft)

0

100

200

300

400 Ophiuroid, unidentified

Number of Individuals/0.0625 m2

0 50 100 150 200 250 300

Water Depth (ft)

0

100

200

300

400 M. senile

Figure 3-10. Density and depth distribution of the six numerically dominant taxa on Leg A1 of Platform 

Hidalgo determined from quantitative slide analysis.

56
Number of Individuals/0.0625 m2

0 20 40 60 80 100 120 140 160 180 200 220 240

Water Depth (ft)

0

20

40

60

80

400

420

Mytilus spp.

Number of Individuals/0.0625 m2

0 10 20 30 40 50

Water Depth (ft)

0

100

200

300

400

M. farcimen

Number of Individuals/0.0625 m2

0 2 4 6 8 10

Water Depth (ft)

0

100

200

300

400

Balanus spp.

Number of Individuals/0.0625 m2

0 50 100 150 200

Water Deoth (ft)

0

100

200

300

400

A. elegantissima (rosy morph)

Number of Individuals/0.0625 m2

0 50 100 150 200 250 300

Water Depth (ft)

0

100

200

300

400 Ophiuroid, unidentified

Number of Individuals/0.0625 m2

0 50 100 150 200 250 300

Water Depth (ft)

0

100

200

300

400 M. senile

Figure 3-11. Density and depth distribution of the six numerically dominant taxa on Leg B1 of Platform 

Hidalgo determined from quantitative slide analysis.

57
In terms of unique characteristics, Platform Hidalgo exhibited the following trends: (1) a 

narrow barnacle zone (Balanus nubilus, Balanus spp.) within the upper 30 m (100 ft) of the 

platform; (2) a relative paucity of the strawberry anemone, Corynactis californica (present only 

intermittently in its depth range on Leg A1 and absent from Leg B1), and concurrent 

replacement of the strawberry anemone by Anthopleura elegantissima (rosy morph) on Leg B1; 

and (3) a robust zone of Metridium farcimen along the deepest portions of the platform. 

3.3.5 Platform Habitat 

Physical Characteristics 

Platform Habitat, operated by Plains Exploration & Production Company, is located on 

Lease OCS-P 0234 (Pitas Point Field, Pitas Point Unit), approximately 12.5 km (6.7 nmi) from 

shore in the eastern Santa Barbara Channel. This 8-legged platform was installed on 9 October 

1981 in a water depth of 88 m (290 ft). 

Community Description 

Leg A1 was sampled at Platform Habitat from the intertidal zone to the base of the 

platform leg. Based on complete analysis of 70 photographs, 43 taxa were identified, of which 

nearly 35 percent (15) were monospecific taxa (i.e., species level identification). Remaining taxa 

were identified primarily to genus level, with a few specimens enumerated at higher taxonomic 

levels. Only three floral taxa (i.e., filamentous red algae, including Polysiphonia, Neoptilota, 

Antithamnion; coralline algae (Corallina); foliose red algae) were among the 43 total taxa noted. 

 On Leg A1, the six most dominant taxa (based on total density, in descending order) 

included Corynactis californica, Mytilus spp., Metridium senile, Ophiothrix spiculata, Balanus 

nubilus, and the rosy morph form of Anthopleura elegantissima (Table 3-11). Ophiothrix spiculata

had the highest frequency of occurrence (40 out of 70 photographs), followed closely by Balanus 

nubilus and Corynactis californica. Corynactis californica exhibited the highest average density per 

occurrence at 448 individuals/0.0625 m2, with a dominant presence in the 17 to 66 m (56 to 

217 ft) depth range. The next highest average density was significantly lower, exhibited by 

Mytilus spp., at 33 individuals/0.0625 m2. In terms of percent cover, prevalent species on 

Leg A1 included (in descending order) Corynactis californica, Mytilus spp., an unidentified 

zoanthid anemone (Palythoa), Anthopleura elegantissima (rosy morph), filamentous red algae, and

Ophiothrix spiculata. 

Based on videotape review, algal depth on Leg A1 extended from the upper portions of 

the intertidal zone to a maximum depth of approximately 12 m (40 ft). Results of whole slide 

analysis, however, indicated algal presence (dominated by filamentous red algae – Polysiphonia, 

Neoptilota, Antithamnion, etc.) extending to a depth of 19 m (61 ft). 

 A discontinuous zone of Mytilus was noted on Platform Habitat, with mussels present 

between the intertidal zone and 6 m (20 ft) and between 9 and 16 m (30 and 52 ft) (Table 3-11). 

Maximum abundance of Mytilus was 80 individuals/0.0625 m2, or 1,280 individuals/m2, found 

at a depth of 3 m (9 ft). Metridium senile, Ophiothrix spiculata, Balanus nubilus, and Anthopleura 

elegantissima (rosy morph) were co-dominants within the Mytilus zone (Photos 17 and 18). 

58
Table 3-11. Dominant taxa on Leg A1 of Platform Habitat identified during quantitative slide analysis. 

Taxon Total Average per Occurrence Frequency (%) Minimum- Maximum Depth of Occ

(ft subsur

Density:Corynactis californica 14,799 448.5 47.1 12-700 8; 56-205; Mytilus spp. 847 32.6 37.1 3-80 4-19; 30-Metridium senile 594 22.8 37.1 1-60 4-19; 29-37; 48-52; Ophiothrix spiculata 575 14.4 57.1 1-73 4-7; 9; 13-19; 30-37; 46-56; Balanus nubilus 483 12.7 54.3 1-64 4-35; 60-81; 94-10Anthopleura elegantissima (rosy morph) 333 19.6 24.3 1-75 4-9; 18-3Paracyathus stearnsii 331 20.7 22.9 1-53 94-190; 205; 2Triopha catalinae 324.5 10.8 42.9 0.5-95 48-52; 60; 68-72; 78; 83-129; Metridium spp. 107 7.6 20.0 1-25 120; 178-190; 196; 21Corallina spp. 53 4.4 17.1 1-8 123-129; 15Staurocalyptus sp. 53 6.6 11.4 2-20 41; 46-52; 83; Turf 29 1.0 41.4 1 (max) 35; 60; 68-72; 80; 83-129; 1Percent Cover:Corynactis californica 73.5 47.1 1-100 8; 56-205; Mytilus spp. 40.6 37.1 4-100 4-19; 30-Zoanthid (Palythoa) 32.3 15.7 1-99 52; 134-152; 205; 2Anthopleura elegantissima (rosy morph) 23.0 24.3 1-95 4-9; 18-3Filamentous red algae 22.6 32.9 1-50 4-11; 18-19; 29-34; Metridium senile 11.5 37.1 0.5-30 4-19; 29-37; 48-52; Ophiothrix spiculata 10.8 57.1 1-60 4-7; 9; 13-19; 30-37; 46-56; Turf 10.5 41.4 0.5-95 35; 60; 68-72; 80; 83-129; 1Sponge, tan encrusting 7.9 20.0 1-40 4; 6-7; 9; 13-19; Paracyathus stearnsii 5.2 22.9 1-10 94-190; 205; 2Sponge, white encrusting 4.7 15.7 0.5-10 48-52; 76; 108; 123-13Ulva spp. 2.0 1.4 2 5 Notes: Total = total number of individuals in all photographs. Minimum-maximum = minimum and maximum number o

or minimum and maximum percent cover estimates for a 0.0625 m2 photoquadrat. Seventy (70) photographs were 

Taxonomic notes: Filamentous red algae include Polysiphonia, Neoptilota, Antithamnion, etc. 
Photo 17. View of (1) Mytilus spp., (2) Metridium senile, (3) Balanus spp., and 

(4) Ophiothrix spiculata at -4 m (-13 ft), Leg A1, Platform Habitat.

Photo 18. View of (1) Mytilus spp., (2) filamentous red algae, (3) Metridium senile, 

(4) Balanus spp., and (5) Anthopleura elegantissima (rosy morph) 

at -5 m (-18 ft), Leg A1, Platform Habitat.

1

2

3

4

1

2

3

4

5

60
Ophiothrix spiculata was also present in relatively high numbers in association with 

Corynactis californica and other encrusters (Photo 19). Below 15 m (50 ft), an unidentified 

zoanthid anemone (Palythoa) occurred intermittently to the base of the leg, often in a dense 

aggregation (Photo 20). 

 A graphic presentation of relative density (i.e., numbers of individuals/0.0625 m2) of the 

six numerical dominants present on Leg A1 is provided in Figure 3-12. In terms of unique 

characteristics, Platform Habitat exhibited the following: (1) an intermittent Mytilus zone; (2) a 

broadly distributed anthozoan community (i.e., Metridium, Corynactis, Anthopleura); and (3) 

dense aggregations of an unidentified zoanthid. 

3.3.6 Platform Irene 

Physical Characteristics 

Platform Irene, operated by Plains Exploration & Production Company, is located on 

Lease OCS-P 0441 (Pt. Pedernales Unit), approximately 7.5 km (4.0 nmi) from shore in the 

southern Santa Maria Basin. This 8-legged platform was installed on 7 August 1985 in a water 

depth of 74 m (242 ft). 

 

Community Description 

Leg A1 was sampled at Platform Irene from the intertidal zone to the base of the 

platform leg. Based on complete analysis of 64 photographs, 39 taxa were identified, of which 

nearly 41 percent (16) were monospecific taxa (i.e., species level identification). Remaining taxa 

were identified primarily to genus level, with a few specimens enumerated at higher taxonomic 

levels. Only four floral taxa (i.e., filamentous red algae, including Polysiphonia, Neoptilota, 

Antithamnion; foliose red algae; encrusting green alga; Ulva) were among the 39 total taxa noted. 

 Dominant taxa, based on total density, included Metridium senile, Mytilus californianus, 

Tetraclita squamosa, Balanus spp., Anthopleura elegantissima (rosy morph), and calcareous worm 

tubes (Table 3-12). Metridium senile had the highest frequency of occurrence (59 out of 

64 photographs), followed closely by Mytilus spp. and a yellow encrusting sponge. Metridium 

senile exhibited the highest average density per occurrence at 331 individuals/0.0625 m2, with a 

dominant presence in across most of the platform leg. The next highest average densities were 

significantly lower, exhibited by calcareous worm tubes, Mytilus californianus, and Tetraclita 

squamosa, at 52, 43, and 42 individuals/0.0625 m2, respectively. 

In terms of percent cover, prevalent species on Leg A1 included (in descending order) 

Metridium senile, a tan encrusting tunicate, Tetraclita squamosa, a tan encrusting sponge, Mytilus 

californianus, and calcareous worm tubes. Metridium senile represents the largest single contributor 

to total percent cover, ranging from three to 90 percent and averaging 66 percent. In the upper 

reaches of Leg A1, M. senile co-occurs with Mytilus and barnacles (e.g., Tetraclita), as shown in 

Photo 21. Further down Leg A1, at 9.4 m (31 ft), Metridium continues to share space with Mytilus

(Photo 22). As depth increases, M. senile co-occurs with encrusting sponges (Photo 23), or 

predatory starfish, calcareous worm tubes, and its congener, M. farcimen (Photo 24). 

61
Photo 19. View of (1) Corynactis californica, (2) Ophiothrix spiculata, and 

encrusters at -41 m (-134 ft), Leg A1, Platform Habitat.

Photo 20. View of (1) undescribed zoanthid anemones (Palythoa) at -82 m 

(-269 ft), Leg A1, Platform Habitat.

1

2

1

62
Number of Individuals/0.0625 m2

0 20 40 60 80 100

Water Depth (ft)

0

20

40

60

80

280 Mytilus spp.

Number of Individuals/0.0625 m2

0 20 40 60 80

Water Depth (ft)

0

50

100

150

200

250 A. elegantissima (rosy morph)

Number of Individuals/0.0625 m2

0 10 20 30 40 50 60 70

Water Depth (ft)

0

50

100

150

200

250 B. nubilus

Number of Individuals/0.0625 m2

0 20 40 60 80

Water Deoth (ft)

0

50

100

150

200

250

O. spiculata

Number of Individuals/0.0625 m2

0 10 20 30 40 50 60 70

Water Depth (ft)

0

50

100

150

200

250 M. senile

Number of Individuals/0.0625 m2

0 200 400 600 800

Water Depth (ft)

0

50

100

150

200

250 C. californica

Figure 3-12. Density and depth distribution of the six numerically dominant taxa on Leg A1 of Platform

Habitat determined from quantitative slide analysis.

63
Table 3-12. Dominant taxa on Leg A1 of Platform Irene identified during quantitative slide analysis. 

Taxon Total Average per Occurrence Frequency (%) Minimum- Maximum Depth of Occ

(ft subsur

Density:Metridium senile 19,522 330.9 92.2 15-510 2-4; 8-23Mytilus californianus 1,401 42.5 51.6 4-124 1-31; 48-Tetraclita squamosa 672 42.0 25.0 7-200 1-8; 24-2Balanus spp. 190 10.0 29.7 1-34 10-11; 14; 28; 40; 43-5Anthopleura elegantissima (rosy morph) 129 10.8 18.8 1-25 4; 11; 14; 23-Worm tubes, calcareous 103 51.5 3.1 3-100 43; 232 Corynactis californica 101 10.1 15.6 1-33 2-4; 6-8; Ophiothrix spiculata 36 4.0 14.1 2-7 10-13; 17; 23Mytilus spp. 23 3.8 9.4 2-6 38; 41; 62; 65Anthopleura spp. (whitish, no rose) 22 22.0 1.6 22 6 Sponge, yellow encrusting 19 1.0 29.7 1 (max) 28; 43; 58; 71-13Pisaster ochraceus 15 1.5 15.6 1-3 24-39; 179Percent Cover:Metridium senile 66.0 92.2 3-90 2-4; 8-23Tunicate, encrusting tan 50.0 1.6 50 39 Tetraclita squamosa 48.8 25.0 10-90 1-8; 24-2Sponge, tan encrusting 32.4 7.8 1-60 28; 38; 40; 4Mytilus californianus 29.5 51.6 2-85 1-31; 48-Worm tubes, calcareous 25.5 3.1 1-50 43; 232 Sponge, gray encrusting 17.5 37.5 2-50 13, 41; 48-173; Turf 10.2 7.8 1-25 1; 3-4; Alga, encrusting green 10.0 1.6 10 170 Anthopleura elegantissima (rosy morph) 3.9 18.8 0.5-10 4; 11; 14; 23-Sponge, yellow encrusting 3.3 29.7 0.1-15 28; 43; 58; 71-13Ulva spp. 3.0 1.6 3 3 Notes: Total = total number of individuals in all photographs. Minimum-maximum = minimum and maximum number o

or minimum and maximum percent cover estimates for a 0.0625 m2 photoquadrat. Fuzz (Appendix C) = Turf (Tab

photographs were analyzed from Leg A1. 

Taxonomic notes: Filamentous red algae include Polysiphonia, Neoptilota, Antithamnion, etc. 
Photo 21. View of (1) Mytilus californianus, (2) Metridium senile, (3) Tetraclita 

squamosa, and other barnacles at -1 m (-4 ft), Leg A1, Platform Irene.

Photo 22. View of (1) Mytilus californianus, (2) Metridium senile, (3) Anthopleura 

elegantissima (rosy morph), and (4) Pisaster ochraceus at -9 m (-31 ft), 

Leg A1, Platform Irene.

1

2

3

1

2

3

4

65
Photo 23. View of (1) Metridium senile and (2) encrusting sponges at -44 m 

(-145 ft), Leg A1, Platform Irene.

Photo 24. View of (1) Metridium farcimen (and possibly M. senile), (2) Asterina 

miniata, and (3) calcareous worm tubes at -71 m (-232 ft), Leg A1, 

Platform Irene.

1

2

1

2

3

66
Based on videotape review, algal depth on Leg A1 extended from the upper portions of 

the intertidal zone to a maximum depth of 23 m (75 ft). Results of whole slide analysis 

indicated algal presence (dominated by filamentous red algae – Polysiphonia, Neoptilota, 

Antithamnion, etc. and several green algal species) extending to a depth of only 12 m (41 ft). 

 A graphic presentation of relative density (i.e., numbers of individuals/0.0625 m2) of the 

six numerical dominants present on Leg A1 is provided in Figure 3-13. In terms of unique 

characteristics, Platform Irene exhibited the following: (1) a broadly distributed anthozoan 

community (i.e., Metridium, Corynactis, Anthopleura); and (2) a well-defined Mytilus californianus

zone extending to 16 m (51 ft), with co-dominants Tetraclita squamosa, Balanus spp., Anthopleura 

elegantissima, and Metridium senile. 

3.4 Diablo and Nifty Rocks – Photographic Interpretation 

3.4.1 Physical Characteristics 

Diablo Rock is located several kilometers to the west of Diablo Point, off the northern 

coastline of Santa Cruz Island, within the waters of the western Santa Barbara Channel (see 

Figure 2-3). Water depth at the base of this feature was approximately 33 m (108 ft). Similarly, 

Nifty Rock is located several kilometers east-southeast of Harris Point, off the northwestern 

point of San Miguel Island (see Figure 2-4). Water depth at the foot of this rock outcrop was 

approximately 15 m (50 ft). 

3.4.2 Community Description 

A total of 44 taxa was identified from the photographic analysis of 22 photographs 

acquired at Diablo and Nifty Rocks. Fourteen of the 44 taxa were monospecific (i.e., species 

level identification), with the remaining taxa identified to genus level or higher. Among the 

44 taxa, several algal taxa were observed in photographs from Diablo and Nifty Rocks, 

including filamentous red algae, Bossiella spp., Codium spp., an encrusting alga (Lithothamnion), 

two green clump algae (i.e., one Codium-like, the other non-Codium-like), and brown algae 

(clump and blades). The six most dominant taxa (based on total density, in descending order) 

at the rock outcrops included Corynactis californica, Chthalamus spp., Balanus spp., Anthopleura 

xanthogrammica, Ophiothrix spiculata, and Mytilus californianus (Table 3-13). Corynactis californica

had the highest frequency of occurrence (15 out of 22 photographs) and exhibited the highest 

average density per occurrence at 132 individuals/0.0625 m2. In terms of percent cover, 

prevalent species on Diablo and Nifty Rocks included (in descending order) an unidentified 

sponge, a composite of encrusters, Chthalamus spp., Corynactis californica, and filamentous red 

algae. 

 Two anemone species, Anthopleura xanthogrammica and A. elegantissima (rosy morph), 

were both prominent numerical dominants at Diablo and Nifty Rocks. In total, these two 

anemone species occurred in nearly one-third of the photographs analyzed. While A. 

xanthogrammica was completed absent at all of the platforms sampled, the rosy morph form of 

A. elegantissima was among the dominant species observed at all six platforms. Other 

dominants noted at Diablo and Nifty Rocks occurred with lower frequency, typically in 

sufficiently high numbers on those limited instances to be a density dominant. 

67
Number of Individuals/0.0625 m2

0 20 40 60 80 100 120 140

Water Depth (ft)

0

20

40

60

80

220

240

Mytilus californianus

Number of Individuals/0.0625 m2

0 20 40 60 80 100 120

Water Depth (ft)

0

50

100

150

200

Worm tubes, calcareous

Number of Individuals/0.0625 m2

0 5 10 15 20 25 30

Water Depth (ft)

0

50

100

150

200 A. elegantissima (rosy morph)

Number of Individuals/0.0625 m2

0 10 20 30 40

Water Deoth (ft)

0

50

100

150

200

Balanus spp.

Number of Individuals/0.0625 m2

0 50 100 150 200 250

Water Depth (ft)

0

50

100

150

200 T. squamosa

Number of Individuals/0.0625 m2

0 100 200 300 400 500 600

Water Depth (ft)

0

50

100

150

200

M. senile

Figure 3-13. Density and depth distribution of the six numerically dominant taxa on Leg A1 of Platform

Irene determined from quantitative slide analysis.

68
Table 3-13. Dominant taxa on natural substrate of Diablo and Nifty Rocks identified during quantitative 

Taxon Total Average per Occurrence Frequency (%) Minimum- Maximum Depth of Occ

(ft subsur

Density:Corynactis californica 1,982 132.1 68.2 2-375 25; 35; 45Chthalamus spp. 180 20.0 40.9 3-54 25; 35; 45Balanus spp. 67 22.3 13.6 2-60 25 Anthopleura xanthogrammica 60 12.0 22.7 1-25 15; 25; 3Ophiothrix spiculata 52 26.0 9.1 21-31 40; 48 Mytilus californianus 45 15.0 13.6 4-31 25 Anthopleura elegantissima (rosy morph) 37 18.5 9.1 7-30 25; 35 Metridium senile 33 33.0 4.5 33 (max) 15 Balanophyllia 31 31.0 4.4 31 (max) 55 Bossiella spp. 26 4.3 27.3 1-10 15; 25; 35Strongylocentrotus purpuratus 25 2.3 50.0 1-7 15-45; 5Dendrochirotida 24 8.0 13.6 4-15 40; 45-4Percent Cover:Sponge, unidentified 50.0 4.5 50 (max) 25 Encruster, all 34.0 13.6 2-50 25; 35 Chthalamus spp. 28.6 40.9 2-80 25; 35; 45Corynactis californica 26.4 68.2 0.5-75 25; 35; 45Filamentous red algae 21.8 77.3 1-75 25-55 Alga, encrusting (Lithothamnion) 21.5 63.6 0.5-60 25; 35; 40Balanus spp. 21.3 13.6 2-60 25 Foliose red algae 20.0 4.5 20 35 Turf 17.5 27.3 5-30 15-35; 45Alga, green clump (Codium-like) 12.5 9.1 5-20 50; 55 Ophiothrix spiculata 12.5 9.1 5-20 45 Bryozoa, Staghorn, yellow 9.1 22.7 0.5-20 35-50 Notes: Total = total number of individuals in all photographs. Minimum-maximum = minimum and maximum number o

or minimum and maximum percent cover estimates for a 0.0625 m2 photoquadrat. Twenty-two (22) photographs w

Diablo and Nifty Rocks. 

Taxonomic notes: Filamentous red algae include Polysiphonia, Neoptilota, Antithamnion, etc. 
 Of the density dominant taxa noted at the outcrops, four taxa were also prominent 

species on the platforms – Ophiothrix spiculata, Mytilus californianus, Corynactis californica, and 

Metridium senile. Depth of occurrence between outcrop-associated and platform-associated 

species was generally consistent, although deeper portions of Diablo Rock remained 

unsampled. At least one of the species common to both rock outcrops and platforms (e.g., 

Metridium senile) was present at depth on most platform legs (i.e., to the base of the platform 

legs). Other species appear to have a different depth range. For example, Corynactis californica

typically becomes a density and percent cover dominant at deeper depths on the platforms (e.g., 

minimum depth of 9 m [30 ft]; normally extending to approximately 61 m [200 ft]). Ophiothrix 

spiculata occurs along the upper and middle portions of a platform leg, often to depths of 70 m 

(230 ft) or more. 

 While filamentous red algae were noted at both outcrops and on the platforms, the 

predominance of Lithothamnion in the percent cover estimations was a unique characteristic of 

Diablo and Nifty Rocks. In terms of total species composition, the natural rock outcrops 

exhibited a higher algal diversity which included filamentous red algae (e.g., Polysiphonia, 

Neoptilota, Antithamnion), an encrusting alga (Lithothamnion), Bossiella spp., Codium, Codium-like 

green clump alga, foliose red algae, foliose brown algae, green foliose alga, and Ulva spp. 

documented on Diablo and Nifty Rocks. While filamentous red algae were consistently and 

frequently observed on the platforms, foliose red algae were only occasionally noted on the 

platforms and green algae were relatively rare. Increased algal diversity may be attributed to 

one or more factors, including (1) the presence of a more complex substrate at the outcroppings 

(e.g., discontinuous surfaces with numerous crevices; porous or semi-porous rock surfaces); 

(2) closer proximity to existing and well-established algae populations (e.g., within rocky 

intertidal and subtidal communities on the northern Channel Islands); and/or (3) different 

invertebrate fauna (e.g., different composition of herbivorous invertebrates). 

 It is also noteworthy that 44 taxa were identified from analysis of a limited number of 

photographs taken at Diablo and Nifty Rocks, as compared to the higher number of 

platform-associated photographs (e.g., typically 34 to 45 photographs in the Mytilus zone). This 

suggests that Diablo and Nifty rocks were characterized by higher species diversity than 

comparable depth zones on artificial structures such as platforms. 

The epibiotal variability of the Diablo and Nifty Rock area is evident in a review of the 

representative photography. Photo 25 is a view of yellow staghorn bryozoa, Strongylocentrotus 

purpuratus, S. franciscanus, Urticina sp., a solitary Anthopleura, and turf at 14 m (45 ft) at Diablo 

Rock. Photo 26 is a view of Paracyathus stearnsii, Balanophyllia elegans, turf, and an encrusting 

alga (Lithothamnion) at 17 m (55 ft) at Nifty Rock. Photo 27 shows Mytilus californianus, 

filamentous red algae, an encrusting alga (Lithothamnion), Anthopleura xanthogrammica, and 

A. elegantissima at 8 m (25 ft) at Diablo Rock. Photo 28 is a view of Corynactis californica, an 

encrusting alga (Lithothamnion), and Chthalamus spp. at 15 m (50 ft) at Diablo Rock. Photo 29 is 

a view of Anthopleura, filamentous red algae, and Strongylocentrotus purpuratus at 11 m (35 ft) at 

Diablo Rock. Photo 30 is a view of a Bossiella-type coralline alga at 14 m (45 ft) at Nifty Rock. 

70
Photo 25. View of (1) yellow staghorn bryozoa, (2) Strongylocentrotus 

purpuratus, (3) S. franciscanus, (4) Urticina spp., (5) a solitary 

Anthopleura spp., and (6) turf at -14 m (-45 ft), Diablo Rock.

Photo 26. View of (1) Paracyathus stearnsii, (2) Balanophyllia elegans, 

(3) an encrusting alga (Lithothamnion), and turf at -17 m (-55 ft), 

Nifty Rock.

1

2

3

4

5

6

1

2

3

71
Photo 27. View of (1) Mytilus californianus, (2) filamentous red algae, (3) an 

encrusting alga (Lithothamnion), (4) Anthopleura xanthogrammica, and 

(5) A. elegantissima at -8 m (-25 ft), Diablo Rock.

Photo 28. View of (1) Corynactis californica, (2) an encrusting alga (Lithothamnion), 

and (3) Chthalamus spp. at -15 m (-50 ft), Diablo Rock.

1

2

3

1

2

3

4

5

72
Photo 29. View of (1) Anthopleura elegantissima, (2) filamentous red algae, and 

(3) Strongylocentrotus purpuratus at -11 m (-35 ft), Diablo Rock.

Photo 30. View of (1) a Bossiella-type coralline alga at -14 m (-45 ft), Nifty Rock.

1

2

3

1

73
A graphic presentation of relative density (i.e., numbers of individuals/0.0625 m2) of the 

six numerical dominants present at Diablo and Nifty Rocks is provided in Figure 3-14. The rock 

outcrops exhibited a very limited Mytilus zone, a prominent and broadly distributed anthozoan 

community (i.e., Corynactis californica, Anthopleura xanthogrammica and A. elegantissima [rosy 

morph], and Metridium senile), and a few species that were also present on the platforms. While 

there were a few common dominant taxa found on both natural outcrops and platforms (i.e., 

Ophiothrix spiculata, Mytilus californianus, Corynactis californica, and Metridium senile; filamentous 

red algae), Diablo and Nifty Rocks appear overall to support a different community than those 

found in association with platforms. For example, although Mytilus was found in limited 

abundance at the outcrops, there was no well-defined mussel community present. This 

observation contrasts sharply with the prominent mussel zones evident on all of the offshore 

platforms. Further, with the exception of the anthozoan community, prominent 

platform-associated taxa were not as prevalent at the natural rock outcrops. 

3.5 Random Point Count Analysis 

 Random point count (PointCount’99®) analysis was completed using digital images 

created from the original 35-mm transparencies collected at each platform. Fifty-five taxa total 

were identified during the random point count analysis. The complete data set developed 

during this process is provided in Appendix E. 

Table 3-14 summarizes the top 12 dominant taxa on each platform leg identified during 

the random point count analysis. The mean value provided represents the average number of 

points occupied by a given taxon in those digital images in which that taxon was present; the 

higher the mean, the more prevalent a particular taxon was in digital images from a platform 

leg. Maximum and minimum occurrence and frequency of occurrence for each dominant taxon 

are also identified. In instances where the maximum was 50, that taxon occupied all 50 random 

points placed on a particular digital image. 

 The random point count results have been compared to density and/or percent cover 

dominants identified from whole slide analysis, the latter of which were presented in Tables 3-3

through 3-12. Results of the random point count analysis were in excellent agreement with the 

dominant taxa identified from the whole slide analysis (i.e., density and percent cover 

dominants). For eight of the 10 platform legs, the most dominant single taxon identified on 

each platform leg through random point count analysis was the same as that identified during 

whole slide analysis. The two exceptions, Platform Harvest, Leg B2 and Platform Hidalgo, 

Leg B1, showed PointCount’99® dominants that were highly ranked (i.e., second and fourth, by 

density, respectively) on the corresponding whole slide analysis dominant list. Overall, the vast 

majority of PointCount’99® dominants were also whole slide analysis dominants. Exceptions 

were typically associated with a low frequency of occurrence of a particular taxon (i.e., either 

the single or limited occurrence of a taxon on a digital image). 

74
Number of Individuals/0.0625 m2

0 20 40

Water Depth (ft)

0

20

40

60

Mytilus californianus

Number of Individuals/0.0625 m2

0 100 200 300 400

Water Depth (ft)

0

10

20

30

40

50

60

C. californica

Number of Individuals/0.0625 m2

0 10 20 30 40 50 60

Water Depth (ft)

0

10

20

30

40

50

60

Chthalamus sp.

Number of Individuals/0.0625 m2

0 10 20 30 40 50 60 70

Water Deoth (ft)

0

10

20

30

40

50

60

Balanus spp.

Number of Individuals/0.0625 m2

0 5 10 15 20 25 30

Water Depth (ft)

0

10

20

30

40

50

60

A. xanthogrammica

Number of Individuals/0.0625 m2

0 5 10 15 20 25 30 35

Water Depth (ft)

0

10

20

30

40

50

60

O. spiculata

Figure 3-14. Density and depth distribution of the six numerically dominant taxa at Diablo and Nifty 

Rocks determined from quantitative slide analysis.

75
Table 3-14. Dominant taxa on the six platforms as determined by PointCount’99® analysis. 

Platform and Leg Dominant Taxa Mean Minimum Maximum Freque

Platform Gail: 

Leg A1 - 111 images 

Corynactis californica Metridium senile Desmophyllum dianthus Anthopleura elegantissima (rosy morph) 

Red Algae Mytilus spp. Zoanthidea Metridium farcimen Turf Metridium exilis Ophiothrix spiculata Aglaophenia sp. 

31.21 18.88 15.29 14.85 14.62 12.43 11.71 10.20 

9.86 8.90 4.25 4.00 

1 1 1 1 2 1 3 1 1 1 1 4 

50 47 30 50 33 24 42 34 35 30 10 

4 

38/1167/1117/1113/1126/1114/11

7/115/11

83/1130/1188/11

1/11

Leg B1 - 110 images 

Metridium exilis Turf Corynactis californica Metridium senile Pleurobranchaea californica Desmophyllum dianthusRed Algae Metridium farcimen Mytilus spp. Porifera Ophiothrix spiculata Zoanthidea 

29.83 20.52 17.30 14.31 

9.00 8.82 8.30 8.00 7.47 5.16 3.75 3.75 

1 1 1 1 9 1 1 8 1 1 1 1 

48 46 48 34 

9 

27 25 

8 

22 16 

9 6 

63/1162/1123/1135/11

1/11

17/1120/11

1/11

17/1145/11

4/114/11

Platform Grace: 

Leg C1 – 94 images 

Corynactis californica Turf Anthopleura elegantissima (rosy morph)

Metridium farcimen Mytilus spp. Obelia sp. Red Algae Paracyathus stearnsii Ophiothrix spiculata 

Rockfish Metridium senile Ophionereis sp. 

23.69 18.32 17.30 13.50 12.37 11.83 

9.92 7.91 6.33 5.00 4.67 4.67 

1 1 1 

13 

1 1 1 1 1 5 1 1 

45 47 43 14 26 26 28 26 12 

5 

11 12 

42/981/920/9

2/94 

19/918/924/923/912/9

1/94 3/94 6/94 
Table 3-14. Dominant taxa on the six platforms as determined by PointCount’99® analysis (continued). 

Platform and Leg Dominant Taxa Mean Minimum Maximum Freque

Leg C4 – 94 images 

Corynactis californica Zoanthidea Metridium senile Metridium farcimen Mytilus spp. Turf Metridium exilis Red Algae Ophiothrix spiculata Green Algae Anthopleura elegantissima (rosy morph)

Obelia sp. 

39.14 21.17 20.55 18.89 15.00 10.99 

8.00 7.37 6.93 6.50 6.23 4.50 

5 4 1 1 1 1 4 1 1 4 1 1 

50 42 45 40 29 35 14 15 20 

9 

13 11 

37/9

6/94 

38/9

9/94 

25/972/9

3/94 

19/928/9

2/94 

13/9

4/94 

Platform Harvest: 

Leg B1 - 94 images 

Metridium senile Metridium farcimen Pisaster sp. Turf Corynactis californica Mytilus spp. Porifera Red Algae Macroalgae Anthopleura elegantissima (rosy morph)

Bryozoa erect Encruster 

23.65 22.67 20.00 19.75 16.00 12.50 

7.47 5.82 5.00 4.91 4.00 3.84 

1 5 

20 

1 1 1 1 1 2 1 4 1 

48 50 20 49 48 25 34 11 

8 

11 

4 

14 

79/9

3/94 1/94 

77/9

5/94 

18/943/917/9

2/94 

11/9

1/94 

25/9

Leg B2 - 90 images 

Turf Metridium senile Mytilus spp. Porifera Corynactis californica Red Algae Encruster Porifera, erect Anthopleura elegantissima (rosy morph)

Ophiothrix spiculata Obelia sp. Galathea californiensis 

17.81 17.09 11.67 10.73 

8.33 7.67 7.63 7.00 6.80 6.47 5.50 3.33 

1 1 2 1 1 1 1 7 1 1 3 1 

43 38 22 32 21 19 32 

7 

15 19 

8 6 

81/976/921/937/9

6/90 9/90 

54/9

1/90 

15/915/9

2/90 3/90 
Table 3-14. Dominant taxa on the six platforms as determined by PointCount’99® analysis (continued). 

Platform and Leg Dominant Taxa Mean Minimum Maximum Freque

Platform Hidalgo: 

Leg A1 - 64 images 

Metridium senile Mytilus spp. Turf Metridium farcimen Porifera Porifera, erect Corynactis californica Ophiothrix spiculata Pisaster sp. Encruster Red Algae Fan Worm 

23.85 18.23 13.57 10.33 

8.76 7.50 6.40 5.09 5.00 4.57 4.50 2.50 

1 4 1 4 1 5 2 1 2 1 3 1 

47 31 30 21 32 10 17 21 

8 

26 

6 4 

60/613/637/6

3/64 

46/6

2/64 5/64 

33/6

4/64 

35/6

2/64 2/64 

Leg B1 - 84 images 

Anthopleura elegantissima (rosy morph)

Mytilus spp. Metridium senile Turf Metridium farcimen Porifera Ophiothrix spiculata Encruster Porifera, erect Cancer sp. Florometra serratissima Pisaster sp. 

28.50 22.83 19.82 18.40 

8.50 7.93 6.11 5.97 5.50 5.00 5.00 4.50 

2 3 1 1 5 1 1 1 1 5 5 1 

45 36 47 50 12 23 19 32 10 

5 5 7 

8/84 

23/866/865/8

2/84 

44/828/838/8

2/84 1/84 1/84 4/84 

Platform Habitat: 

Leg A1 - 75 images 

Corynactis californica Zoanthidea Metridium farcimen Mytilus spp. Anthopleura elegantissima (rosy morph)

Metridium senile Turf Red Algae Rockfish Ophiothrix spiculata Coenocyathus bowersi Paracyathus stearnsii 

37.05 29.67 27.55 15.29 15.07 11.44 

7.90 6.81 4.00 3.83 3.36 3.33 

2 2 1 1 5 1 1 1 1 1 1 1 

50 50 50 35 49 39 47 24 

7 

12 

9 8 

37/7

6/75 

11/721/714/727/760/721/7

2/75 

18/711/7

9/75 
Table 3-14. Dominant taxa on the six platforms as determined by PointCount’99® analysis (continued). 

Platform and Leg Dominant Taxa Mean Minimum Maximum Freque

Platform Irene: 

Leg A1 - 67 images 

Metridium senile Metridium farcimen Mytilus spp. Porifera Turf Red Algae Balanus spp. Green Algae Pollicipes polymerus Pisaster sp. Anthopleura elegantissima (rosy morph)

Cancer sp. 

28.69 21.00 14.83 

9.03 7.33 5.91 5.12 4.00 3.50 3.11 2.50 2.25 

2 

21 

1 1 1 1 1 4 1 1 1 1 

50 21 28 24 27 24 14 

4 6 6 4 3 

59/6

1/67 

40/631/648/611/617/6

1/67 2/67 9/67 6/67 4/67 
3.6 Statistical Analysis of Photographic Data 

Photographic data (i.e., density and percent cover data sets from the whole slide analysis 

for all platform legs and Diablo and Nifty Rocks; PointCount’99® data for all platform legs) 

were analyzed using clustering analysis. Samples (i.e., photographs) were classified into 

separate zones based on the biotic zonation evident at each platform, as determined by 

inspection videotape analysis. Platform zonation patterns were previously depicted in 

Figures 3-1 through 3-3. 

For the six platforms sampled, biotic zones extended from the intertidal zone to the base 

of the platform. Platform biotic zones have been restated in Table 3-15, along with zone depths 

and unique zone codes as applied in the statistical analyses. For example, the intertidal zone on 

Leg A1 of Platform Gail was assigned the code GA-A1-6; the same biotic zone on Leg B1 of 

Platform Gail had the code GA-B1-6. 

 All taxa present on a platform leg were also combined to allow for leg to leg 

comparisons. This combination of taxa from different zones on the same platform leg was 

based on a weighted mean, with weighting based on the relative contribution of a zone on a 

particular leg. In this analysis, only platform and leg codes were used. For example, the data 

set containing taxa from Platform Gail, Legs A1 and B1 had the codes GA-A1 and GA-B1, 

respectively. 

3.6.1 Whole Slide Analysis Photographic Data 

 The first clustering analysis using whole slide data determined the similarities between 

platform legs, with separate analyses using density (i.e., count) and percent cover data. By 

combining all data from a single platform leg (i.e., eliminating biotic zones) into a single data 

set, 10 data sets in total were created. Figure 3-15 shows the clustering results for count data, by 

platform leg. The greatest similarity, at approximately 80 percent, was evident between 

(1) adjacent legs on Platform Harvest (HA-B1 and HA-B2); (2) adjacent legs on Platform 

Hidalgo (HI-A1 and HI-B1); and (3) Platform Gail, Leg A1 and Platform Grace, Leg C4. 

Similarity between adjacent legs on the same platform might be expected, however, the high 

level of similarity between Grace and Gail was unexpected and presents an interesting scenario. 

Both of these latter platforms are located in the eastern Santa Barbara Channel, within several 

miles of one another. However, Gail is located in considerably deeper water and exhibited six 

biotic zones whereas Grace is located in shallower water and showed only five biotic zones. 

 At the next similarity level, at approximately 60 percent, Platform Habitat, Leg A1 

exhibited an affinity with the Platform Gail, Leg A1-Platform Grace, Leg C4 grouping. At the 

50 percent similarity, this three-platform grouping showed affinity with Platform Grace, Leg 

C1. At the other end of Figure 3-15, the Harvest and Habitat groups showed similarity to one 

another at approximately 45 percent, then coupled with Platform Gail, Leg B1, and finally with 

Platform Irene, Leg A1. At the lowest similarity level, the Grace-Gail (Leg A1)-Habitat group 

was separate from the Harvest-Hidalgo-Irene-Gail (Leg B1) group. 

80
Table 3-15. Designations of zones used in the clustering analysis of photographic data. 

Biotic Zone Zone Depth 

(m [ft] subsurface) 

Site 

Code 

Leg 

Code 

Zone 

Code 

Platform Gail -- 

Intertidal 0 to 1.8 (0 to 6) 6 

Mytilus 1.8 to 12.1 (6 to 40) 7 

Barnacle/Scallop 12.1 to 48.8 (40 to 160) 8 

Corynactis/Encruster 48.4 to 115.8 (160 to 380) 9 

Vase sponge/ 

Encruster 115.8 to 192.0 (380 to 630) 10 

Encruster/Sea Star/ 

Cup Coral 192.0 to 225.2 (630 to 739) 

GA A1 and 

B1 

11 

Platform Grace -- 

Intertidal 0 to 1.8 (0 to 6) 1 

Mytilus 1.8 to 13.7 (6 to 45) 2 

Barnacle/Scallop 13.7 to 27.4 (45 to 90) 3 

Anemone/Encruster 27.4 to 70.1 (90 to 230) 4 

Encruster/Sea Star 70.1 to 96.9 (230 to 318) 

GR C1 and 

C4 

5 

Platform Harvest -- 

Intertidal 0 to 1.8 (0 to 6) 17 

Mytilus 1.8 to 25.9 (6 to 85) 18 

Barnacle/Corynactis 25.9 to 50.3 (85 to 165) 19 

Anemone/Encruster 50.3 to 105.2 (165 to 345) 20 

Vase Sponge/ 

Encruster 105.2 to 169.2 (345 to 555) 21 

Metridium/Sea Star 169.2 to 205.7 (555 to 675) 

HA B1 and 

B2 

22 

Platform Hidalgo -- 

Intertidal 0 to 1.8 (0 to 6) 12 

Mytilus 1.8 to 19.8 (6 to 65) 13 

Barnacle 19.8 to 32.0 (65 to 105) 14 

Metridium/Encruster 32.0 to 109.7 (105 to 360) 15 

Sponges/Encruster 109.7 to 132.3 (360 to 434) 

HI A1 and 

B1 

16 

Platform Habitat -- 

Intertidal 0 to 1.8 (0 to 6) 23 

Mytilus 1.8 to 18.3 (6 to 60) 24 

Corynactis 18.3 to 54.9 (60 to 180) 25 

Metridium/Encruster 54.9 to 88.4 (180 to 290) 

HH A1 

26 

Platform Irene -- 

Intertidal 0 to 1.8 (0 to 6) 27 

Barnacle/Algae 1.8 to 10.7 (6 to 35) 28 

Mytilus 10.7 to 25.9 (35 to 85) 29 

Corynactis/Encruster 25.9 to 73.4 (85 to 242) 

IR A1 

30 

81
100

80604020

0

Similarity

WSA Count Legs

Figure 3-15. Dendrogram of count data from the quantitative slide analysis, by platform leg.

GR-C1

HH-A1

GA-A1

GR-C4

IR-A1

GA-B1

HA-B1

HA-B2
Figure 3-16 shows the clustering results for percent cover data, by platform leg. The 

greatest similarity was evident between (1) adjacent legs on Platform Harvest (HA-B1 and 

HA-B2) at >80 percent similarity; (2) adjacent legs on Platform Hidalgo (HI-A1 and HI-B1) at 

>60 percent similarity; (3) adjacent legs on Platform Gail (GA-A1 and GA-B1) at 60 percent 

similarity; and (4) adjacent legs on Platform Grace (GR-C1 and GR-C4) at approximately 

60 percent similarity. Platform Habitat (HH-A1) subsequently grouped with Grace, while Irene 

(IR-A1) grouped with the Hidalgo-Gail-Harvest grouping. 

 The results of the clustering analysis for platform legs appeared to be most consistent 

with the percent cover data, where adjacent legs of the primary platforms showed a relatively 

high similarity with one another. For example, the grouping of adjacent legs at Platform 

Harvest and the grouping of adjacent legs at Platform Hidalgo were both evident in the count 

and percent cover comparisons (Figures 3-15 and 3-16). The Platform Gail grouping evident in 

percent cover was not present in the count comparisons. Results of clustering using the count 

data were more convoluted, with two platforms showing adjacent leg similarities and 

confounding results otherwise. No readily discernable trends (e.g., north-south; shallow-deep 

platforms) were evident beyond the similarity shown between adjacent platform legs. 

The second clustering of whole slide data determined the similarities between biotic 

zones, with separate analyses using density (i.e., count) and percent cover data. By maintaining 

separate biotic zones, 52 total data sets were created. Biotic zones were based on the zonation 

patterns identified during inspection videotape analysis. 

Figure 3-17 shows the clustering results for count data, by biotic zone. Greatest 

similarities (>90 percent) were evident for (1) Platform Irene, Leg A1, Mytilus and Corynactis

zones; (2) Platform Harvest, Legs B1 and B2, Metridium/sea star zones; and (3) Platform 

Hidalgo, Leg B1, intertidal and Mytilus zones. Unexpectedly high similarities were noted for 

(1) Platform Gail, Leg A1, barnacle/scallop and Platform Habitat, Leg A1, Corynactis zones; and 

(2) Platform Grace, Leg C4, encruster/sea star and Platform Harvest, Leg B1, vase 

sponge/encruster zones. 

 Analysis of the dendrograms in Figure 3-17 from lowest to highest similarity (i.e., top 

down) resulted in the identification of three groupings which generally reflected community 

water depth. Group A, comprised of 18 data sets, consisted exclusively of intertidal and Mytilus

communities of platforms Gail, Grace, Harvest, Hidalgo, and Habitat, with small contributions 

from barnacle/scallop and Corynactis assemblages from Platform Gail. The lone outlier from 

Group A was the two-zone grouping of the intertidal assemblages at Platform Irene. Group B, 

comprised of 25 data sets, consisted exclusively of Metridium/sea star, Metridium/encruster, 

anemone/encruster, and vase sponge/encruster zones of platforms Gail, Harvest, Hidalgo, and 

Habitat, plus several contributions from the barnacle zone of Platform Hidalgo. The last group, 

Group C, was comprised of nine data sets and consisted of barnacle/scallop, 

Corynactis/encruster, encruster/sea star, and anemone/encruster zones from platforms Gail, 

Grace, and Habitat. 

83
Figure 3-16. Dendrogram of percent cover data from the quantitative slide analysis, by platform leg.

100

80604020

Similarity

WSA Percent Legs

HH-A1

GR-C1

GR-C4

IR-A1

HA-B1

HA-B2

HI-A1

HI-B1
100

80604020

0

Similarity

WSA Count Zones

Figure 3-17. Dendrogram of count data from the quantitative slide analysis, by biotic zone for all platforms.

HH-A1-26

GA-A1-8

HH-A1-25

GR-C1-3

GR-C4-3

GA-A1-9

GR-C1-4

GR-C1-5

HA-B1-18

HA-B2-18

HA-B1-22

HA-B2-22

GR-C4-5

HA-B1-21

HA-B2-21

HA-B1-20

HA-B2-20

GA-B1-11

HI-B1-16

IR-A1-28

IR-A1-29

IR-A1-30

IR-A1-27

GA-A1-11

HI-A1-16

GA-A1-10

GA-B1-10

HA-B1-19

HA-B2-19

HI-B1-15

HI-B1-14

HI-A1-14

HI-A1-15

GA-B1-7

GA-B1-8

GA-B1-9

GA-A1-7

GA-A1-6

GA-B1-6

HH-A1-23

GR-C1-1

GR-C4-1

GR-C4-4
 Figure 3-18 shows the clustering results for percent cover data, by biotic zone. While 

similarity levels were not as high as noted with the count data, greatest similarities were 

evident between adjacent zones of the same platform leg or the same zones between adjacent 

legs. In general, with minor exception, similarity groupings (based on count or percent cover 

biotic zone data resulting from whole slide analysis) tended to occur between adjacent zones of 

the same platform leg (e.g., intertidal and Mytilus) or the same zones between adjacent legs. 

 A top down analysis of the dendrograms in Figure 3-18 resulted in the identification of 

four groupings. Group A, comprised of seven data sets, consisted of intertidal and Mytilus

communities from platforms Gail and Habitat. Group B, comprised of 15 data sets, consisted of 

intertidal and Mytilus communities from platforms Grace, Harvest, and Hidalgo, with small, 

anomalous contributions from sponge/encruster and encruster/sea star zones of platforms 

Hidalgo and Grace. Group C, comprised of 22 data sets, consisted barnacle, 

barnacle/Corynactis, barnacle/algae, Corynactis/encruster, Metridium/sea star, and 

Metridium/encruster communities from platforms Gail, Harvest, and Hidalgo, with minor 

contributions from vase sponge/encruster and vase sponge/sea star/cup coral assemblages 

from platforms Harvest and Gail, respectively. Group D, comprised of seven data sets, 

consisted of barnacle/scallop and anemone/encruster communities from platforms Grace and 

Gail, with minor contribution from Corynactis and Metridium/encruster assemblages from 

Platform Habitat. One lone outlier, the intertidal zone from Platform Irene, was not grouped 

with any of the communities noted above. 

3.6.2 PointCount’99® Photographic Data 

 The first clustering of PointCount’99® data determined the similarities between 

platform legs. As was the case with the whole slide data, combining all data from a single 

platform leg (i.e., eliminating biotic zones) resulted in the creation of 10 PointCount’99® data 

sets. 

Figure 3-19 shows the clustering results for PointCount’99® data, by platform leg. The 

greatest similarity, at approximately 80 to 85 percent, was evident between (1) adjacent legs on 

Platform Harvest (HA-B1 and HA-B2); and (2) adjacent legs on Platform Hidalgo (HI-A1 and 

HI-B1). These groupings were identical to those exhibited in the first clustering analysis of 

whole slide data (i.e., count data set). 

 The next groupings evident, at 75 percent similarity, were (1) Platform Grace, Leg C4 

and Platform Habitat, Leg A1; and (2) the Platform Harvest (Legs B1 and B2) and Platform 

Hidalgo (Legs A1 and B1) groupings noted previously. The Harvest-Hidalgo grouping was 

also evident in the first clustering analysis of whole slide data, while the Grace-Hidalgo 

grouping was not reflected in the earlier clustering analysis. The Harvest-Hidalgo grouping 

suggests a strong similarity between these two southern Santa Maria Basin platforms. No other 

groupings suggest a geographic-based similarity. For example, the Harvest-Hidalgo grouping 

was most similar to Platform Gail (Leg A1), from the eastern Santa Barbara Channel, and 

Platform Irene (Leg A1), in the southern Santa Maria Basin. 

86
Figure 3-18. Dendrogram of percent cover data from the quantitative slide analysis, by biotic zone for all platforms.

100

80604020

0

Similarity

WSA Percent Zones

IR-A1-27

GR-C4-4

GA-A1-8

GR-C4-3

GR-C1-3

HH-A1-25

GR-C1-4

HH-A1-26

HA-B1-19

HI-A1-14

HI-B1-14

IR-A1-28

GA-A1-10

IR-A1-29

IR-A1-30

GA-B1-9

GA-B1-11

GA-A1-11

GA-B1-10

GA-A1-9

HI-A1-16

HA-B2-21

HA-B1-21

HA-B1-22

HA-B2-22

HA-B1-20

HA-B2-20

HI-A1-15

HA-B2-19

HI-B1-15

GR-C1-1

GR-C1-2

GR-C4-1

GR-C4-2

GR-C4-5

HA-B1-18

HA-B2-18

HI-B1-13

HI-A1-12

HI-A1-13

HI-B1-12

HI-B1-16

GR-C1-5

HAB117
100

806040

Similarity

Point Count Legs

Figure 3-19. Dendrogram of PointCount data, by platform leg.

Grace-C4

Habitat-A1

Irene-A1

Gail-A1

Harvest-B1

Harvest-B2

Hidalgo-A1

Hidalgo-B1
 The second clustering of PointCount’99® data determined the similarities between biotic 

zones. By maintaining separate biotic zones, 52 total data sets were created. Figure 3-20 shows 

the clustering results for PointCount’99® data, by biotic zone. Greatest similarities 

(>90 percent) were evident for (1) Platform Irene, Leg A1, Mytilus and Corynactis zones; 

(2) Platform Gail, Leg A1, barnacle/scallop and Platform Grace, Leg C4, barnacle/scallop zones; 

(3) Platform Harvest, Leg B2, anemone/encruster and Platform Hidalgo, Leg A1, 

sponges/encruster zones; and (4) Platform Hidalgo, Legs A1 and B1, intertidal zones. The Irene 

Mytilus and Corynactis grouping was also evident in the first clustering of whole slide data, 

however, the remaining groupings were not evident in the earlier clustering analysis. Strongest 

similarities were evident between similar zones (e.g., intertidal, Metridium/encruster), 

regardless of platform geographic location or water depth. 

 A top down analysis of the dendrograms in Figure 3-20 resulted in the identification of 

four groupings. Group A, comprised of 14 data sets, consisted of intertidal and Mytilus

communities from platforms Gail, Grace, Harvest, Hidalgo, Habitat, and Irene. Group B, 

comprised of 14 data sets, consisted of (1) Corynactis/encruster, encruster/sea star/cup coral, 

and vase sponge/encruster communities of Platform Gail; (2) Mytilus and encruster/sea star 

communities of Platform Grace; anemone/encruster, vase sponge/encruster, and 

Metridium/sea star communities of Platform Harvest; and (3) sponges/encruster communities 

of Platform Hidalgo. Group C, comprised of 14 data sets, consisted of (1) Mytilus, 

barnacle/Corynactis, and Metridium/sea star communities of Platform Harvest; (2) Mytilus, 

barnacle, and Metridium/encruster communities of Platform Hidalgo; and (3) barnacle/algae, 

Mytilus, and Corynactis/encruster communities of Platform Irene. Group D, comprised of 

10 data sets, consisted of (1) intertidal, Mytilus, barnacle/scallop, and vase sponge/encruster 

communities of Platform Gail; (2) barnacle/scallop and anemone/encruster communities of 

Platform Grace; and (3) Corynactis and Metridium/encruster communities of Platform Hidalgo. 

3.6.3 Diablo and Nifty Rocks and Comparable Platform Zones 

 The last set of clustering analyses employed whole slide data to determine the 

similarities between epibiota of natural rock outcrops and platform legs within similar water 

depths using density (i.e., count) and percent cover data. The 10 whole slide count and percent 

cover data sets (as described previously in Section 3.6.1) were pared down to include only those 

photographs acquired between 5 and 17 m (15 and 55 ft), the depth range within which 

photographs had been collected at the natural outcrops. Clustering analyses were then 

conducted, with separate results generated for counts and percent cover. 

 Figure 3-21 shows the clustering results for count data, comparing comparable platform 

biota (in the 5 to 17 m depth range) to natural outcrop communities. The greatest similarity, at 

approximately 60 percent, was evident between (1) Platform Hidalgo, Leg A1 and Platform 

Irene, Leg A1; (2) Platform Grace, Leg C1 and Diablo Rock; and (3) Platform Harvest, Legs B1 

and B2. At the next similarity level, at approximately 40 percent, three groupings were evident: 

(1) Nifty Rock with the Hidalgo-Irene group; (2) Hidalgo, Leg B1 with the Harvest B1-B2 group; 

and (3) Platform Gail, Legs A1 and B1. Results of this analysis indicate that natural outcrop 

communities have a moderate similarity to select platform communities – Diablo Rock with 

Platform Grace and Nifty Rock with the Hidalgo-Irene group. 

89
Figure 3-20. Dendrogram of PointCount data, by biotic zone for all platforms.

100

80604020

0

Similarity

Point Count Zones

Gail-B1-6

Gail-B1-7

Gail-B1-8

Grace-C4-4

Gail-A1-8

Grace-C4-3

Grace-C1-3

Habitat-A1-25

Grace-C1-4

Habitat-A1-26

Hidalgo-A1-13

Gail-A1-10

Hidalgo-A1-14

Hidalgo-B1-14

Harvest-B1-19

Irene-A1-29

Irene-A1-30

Harvest-B1-18

Harvest-B2-18

Harvest-B2-19

Hidalgo-A1-15

Hidalgo-B1-15

Harvest-B2-22

Irene-A1-28

Gail-B1-9

Gail-B1-11

Harvest-B2-21

Grace-C1-5

Hidalgo-B1-16

Gail-A1-11

Gail-A1-9

Grace-C4-5

Gail-B1-10

Harvest-B1-22

Harvest-B2-20

Hidalgo-A1-16

Harvest-B1-20

Harvest-B1-21

Gail-A1-6

Grace-C1-1

Grace-C4-1

Irene-A1-27

Hidalgo-A1-12

Hidalgo-B1-12
100

80604020

0

Similarity

WSA Count Diablo & Nifty Rocks

Figure 3-21. Dendrogram of count data from the quantitative slide analysis – platform legs versus natural outcrops.

HA-B2

HA-B1

IR-A1

HI-A1

HI-B1

Nifty

GA-B1

GA-A1

GR-C1

Diablo
Figure 3-22 shows the clustering results for percent cover data, comparing comparable 

platform biotal cover (in the 5 to 17 m depth range) to natural outcrop communities. Greatest 

similarities were evident for (1) Platform Hidalgo, Leg A1 and Platform Irene, Leg A1; (2) 

Platform Grace, Leg C4 with the Hidalgo-Irene group; and (3) Platform Harvest, Leg B2 with 

the Grace-Hidalgo-Irene group. Diablo Rock exhibited closest affinity to the Harvest-GraceHidalgo-Irene group, while Nifty Rock showed greatest similarity with Platform Grace, Leg C1. 

Aside from the Hidalgo-Irene grouping, none of the percent cover similarities were evident in 

the earlier count data comparisons. No readily discernable trends were evident. 

3.7 Scraping Analysis 

The scraping analysis encompassed complete taxonomic identification of all species 

present within each 0.0625 m2 quadrat collected from Legs B1 and B2 of Platform Harvest and 

Legs A1 and B1 of Platform Gail. A total of 23 scraping samples were collected from Harvest 

and 31 scraping samples from Gail. 

 On Platform Harvest, the depth of collection ranged from 3.4 to 24.1 m (11 to 79 ft), with 

samples acquired from the mussel and upper barnacle zones. A total of 12 scraping samples 

were acquired from Harvest Leg B1, including four barnacle zone samples and eight Mytilus

zone samples. A total of 11 scraping samples were collected from Harvest Leg B2, including 

three barnacle zone samples and eight Mytilus zone samples. 

 On Platform Gail, the depth of collection ranged from 0.3 to 24.1 m (1 to 79 ft), with 

sampling in the intertidal, barnacle/scallop, and Mytilus zones. A total of 17 scraping samples 

were acquired from Gail Leg A1, including five intertidal zone samples, six barnacle/scallop 

zone samples, and six Mytilus zone samples. A total of 14 scraping samples were collected from 

Gail Leg B1, including three intertidal zone samples, two barnacle/scallop zone samples, and 

nine Mytilus zone samples. 

Species identification was completed for all species present in scraping samples from 

both platforms, from the larger megaepifauna to the cryptic interstitial biota beyond the view of 

35-mm photographic equipment (i.e., diver and ROV photography). Some overlap was 

expected between species identified in the photographs and those identified from scrapings, 

noting that scraping sample collections were restricted to diving depths, from within the 

intertidal, barnacle or barnacle/scallop, and Mytilus zones. For example, Ophiothrix spiculata 

and Ophiopterus papillosa were the only two ophiuroid species identified during scraping 

analysis from Platform Harvest. During the photographic analysis, specimen size, 

photographic resolution, and lack of specimens resulted in the classification of unidentified 

ophiuroids in many of the photographs. Scraping analysis results allowed for a complete 

species-level determination; ophiuroids present in photographs from Platform Harvest were 

considered to be Ophiothrix spiculata, among the dominant taxa at all platforms. Scraping 

material acquired from Platform Harvest was also weighed and measured, providing the basis 

for wet weight and length-width-height determinations (see Section 3.9). 

92
100

80604020

0

Similarity

WSA Percent Diablo & Nifty Rocks

Figure 3-22. Dendrogram of percent cover data from the quantitative slide analysis – platform legs versus natural outcrop

HI-B1

HA-B1

HI-A1

IR-A1

Diablo

HA-B2

GR-C4

Nifty

HH-A1

GR-C1
 The species identified at each discrete scraping location on both platforms (i.e., leg 

designation, water depth) are outlined in detail in Appendix D. Tables 3-16 and 3-17 list the 

most common taxa identified from the scraping analysis (i.e., taxa that occurred in a quarter or 

more of the scraping samples). Due to extremely high numbers of individuals and the presence 

of colonial species, the completion of total counts (i.e., total numbers of individuals) was not 

practical and a qualitative determination of species presence was made. Qualitative estimates 

were categorized as abundant, moderately abundant, and limited or sparse (see Tables 3-16 and 

3-17, and Appendix D). 

At Platform Harvest, a total of 130 taxa were identified, the majority of which were 

identified to species level. Dominant taxa were identified based on their frequency of 

occurrence and their mean relative abundance. Dominant taxa in scrapings from Platform 

Harvest, based on mean relative abundance, included Ophiothrix spiculata, Rhodymenia 

californica, Mytilus spp., Membranoptera multiramosa, Caprella alaskana, Megabalanus californicus, 

Mytilus californianus, Halosydna brevisetosa, Elasmopus cf. holgurus, and Metridium senile. The 

presence of these dominant taxa in either the Balanus or Mytilus zones, or both, is readily visible 

in Table 3-16. 

Several species, including Ophiothrix spiculata, Caprella alaskana, Elasmopus cf. holgurus, 

Pycnogonum stearnsi, and Hiatella arctica, were present in all 23 scraping samples. Other species, 

such as Rhodymenia californica, Mytilus spp., Membranoptera multiramosa, Megabalanus californicus, 

and Halosydna brevisetosa, were very abundant when they occurred, but were not always present 

(Table 3-16). 

At Platform Gail, a total of 90 taxa were identified, the majority of which were identified 

to species level. Dominant taxa in scrapings from Platform Gail (based on frequency of 

occurrence and mean relative abundance) included Pterosiphonia dendroidea, Anthopleura 

elegantissima, Metridium senile, Spirobranchus spinosus, Ophiothrix spiculata, Elasmopus holgurus, 

Diadumene cincta, Balanus trigonus, and Metridium exilis. As was noted for Platform Harvest, the 

presence of these dominant taxa in either the barnacle/scallop, intertidal, or Mytilus zones of 

Platform Gail is readily apparent in Table 3-17. Several species, including Elasmopus holgurus

and Balanus trigonus, were present in all 31 scraping samples. Other species, such as Ophiothrix 

spiculata, Pterosiphonia dendroidea, Metridium exilis, Chama arcana, and Spirobranchus spinosus, 

were very abundant when present, but were not consistently present in all scraping samples. 

Mytilus spp., which was sparse on Leg A1, was a dominant species on Leg B1 (Table 3-17). 

3.8 Statistical Analysis of Scraping Data 

Results of the analysis of scraping samples from Legs B1 and B2 of Platform Harvest 

were analyzed with correspondence analysis. As was the case with the photographic data, taxa 

for the analysis were selected in consultation with the taxonomists who oversaw the analysis. 

Taxa that were thought to be uniquely identified were retained in the statistical analysis. 

Samples were classified into either a Mytilus zone or a barnacle zone. A phylogenetic listing of 

the taxa included in the analysis is presented in Table 3-18. The data matrix for the analysis 

was the occurrence of a taxon in a particular scraping sample (i.e., presence/absence). 

94
Table 3-16. Summary of the most common taxa identified, their relative abundance, frequency of occurren

relative abundance per occurrence, as determined from scraping samples collected at Platform 

Relative Abundance 

Taxon Leg B1 Zone Leg B2 Zone 

Balanus Mytilus Balanus Mytilus 

Fre

O

Ophiothrix spiculata 1 1 1 1 1 2 1 1 1 3 1 1 1 1 1 1 1 1 1 1 1 1 1 Rhodymenia californica 2 1 2 2 1 1 1 1 1 1 1 1 Mytilus spp. 2 1 Membranoptera multiramosa 1 2 2 1 2 Caprella alaskana 2 2 3 2 1 1 2 2 2 1 2 2 2 2 2 1 1 1 1 1 1 1 2 Megabalanus californicus 3 3 2 1 1 1 2 3 1 1 3 3 2 1 1 2 1 1 1 1 1 Mytilus californianus 1 3 3 3 3 2 3 3 3 3 1 1 1 1 1 1 1 1 Halosydna brevisetosa 3 2 2 2 2 2 2 1 3 3 2 3 1 1 2 1 1 1 3 Elasmopus cf. holgurus 2 1 2 1 2 2 2 2 2 2 2 2 2 3 2 2 2 2 2 2 2 2 3 Metridium senile 1 1 1 1 1 2 3 3 3 2 2 2 3 2 3 1 2 1 1 3 3 3 Pugetia fragillissima 2 2 Rhodymenia pacifica 2 2 Anthopleura elegantissima 2 Phyllochaetopterus prolifica 3 1 1 3 2 3 2 1 1 2 3 2 3 1 3 3 2 3 3 Syllis gracilis 3 3 1 1 3 2 2 3 3 3 1 1 1 2 1 3 3 3 3 3 Jassa slatteryi 3 2 2 2 2 2 2 3 3 2 2 2 2 2 2 2 2 2 3 3 3 Maera simile 2 2 2 2 3 2 2 2 3 3 3 2 2 2 2 2 2 2 2 3 3 3 Pycnogonum stearnsi 2 3 3 3 2 2 2 2 3 2 3 2 2 3 2 3 2 2 2 2 2 3 3 Celleporina spp. 2 3 Typosyllis spp. 3 3 3 3 3 1 3 3 2 3 1 3 Caprella equilibra 3 2 3 2 3 Cirratulus, unidentified 2 3 3 Corynactis californica 2 3 3 Tetraclita rubescens 2 3 3 Porifera sp. A 1 1 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 3 Caprella verrucosa 3 2 3 2 3 2 2 3 3 3 3 2 3 3 3 3 Balanus nubilus 3 3 3 2 3 3 3 3 3 3 3 2 2 2 3 3 2 3 3 Polydora spp. 3 3 3 2 
Table 3-16. Summary of the most common taxa identified, their relative abundance, frequency of occurren

relative abundance per occurrence, as determined from scraping samples collected at Platform 

Relative Abundance 

Taxon Leg B1 Zone Leg B2 Zone 

Balanus Mytilus Balanus Mytilus 

Fre

O

Podocerus brasiliensis 3 3 2 3 3 2 3 3 3 3 3 2 3 3 3 2 3 3 Stenothoe estacola 3 3 3 3 2 3 3 3 3 3 3 2 2 2 3 3 3 3 3 Hiatella arctica 3 3 3 3 3 1 3 3 3 3 3 3 3 3 3 1 3 3 3 3 3 3 3 Erichthonius brasiliensis 3 3 3 2 3 3 Anthopleura elegantissima (rosy morph) 2 3 3 3 3 3 3 Pododesmus cepio 3 3 2 3 2 3 3 3 3 3 3 3 3 3 3 Pseudochama exogyra 3 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Obelia geniculata 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Halosydna johnsoni 2 3 3 3 3 3 3 3 3 Filicrisia spp. 3 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Balanus trigonus 3 3 2 3 3 3 3 3 3 3 3 Phyllodoce medipapillata 2 3 3 3 3 3 3 3 3 3 3 Phascolosoma agassizi 2 3 3 3 3 3 3 3 3 3 3 3 3 Key: 1 = abundant; 2 = moderately abundant; 3 = limited, sparse Note: Twenty-three (23) scraping samples collected from Platform Harvest. Frequency of occurrence based on presenc

samples. 
Table 3-17. Summary of the most common taxa identified, their relative abundance, frequency of occurrence, an

abundance per occurrence, as determined from scraping samples collected at Platform Gail. 

Relative Abundance 

Taxon Leg A1 Zone Leg B1 Zone 

Barnacle/Scallop Intertidal Mytilus B/S Inter Mytilus 

Pterosiphonia dendroidea 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Anthopleura elegantissima 1 Metridium senile 1 1 2 1 1 1 1 1 1 1 1 Spirobranchus spinosus 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 1 1 1 Ophiothrix spiculata 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 Elasmopus holgurus 2 1 1 1 1 1 1 2 2 1 1 1 1 2 1 1 1 3 1 1 1 1 1 1 1 1 1 1 Diadumene cincta 1 1 1 Balanus trigonus 1 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 3 1 2 1 1 2 1 1 Metridium exilis 1 2 3 1 1 1 1 2 1 1 2 1 2 1 1 1 1 1 1 1 1 1 Tetraclita rubescens 1 2 2 2 2 2 1 1 1 Chama arcana 3 1 2 3 1 2 1 2 2 1 1 1 1 1 1 1 1 1 2 3 1 2 1 Ophiactis simplex 2 2 2 2 1 2 2 2 2 2 2 2 1 1 2 2 2 2 2 2 1 Haplosclerida nr. Haliclona 

spp. 

1 1 1 2 1 2 2 3 1 2 2 2 2 2 3 3 2 2 2 2 

Phyllodoce medipapillata 1 1 2 2 2 2 1 2 2 2 2 2 2 2 2 2 2 2 2 Caprella equilibra 1 2 2 1 3 3 2 1 2 2 2 2 2 2 2 1 1 2 2 Nereis mendocinana 2 2 1 2 2 2 2 2 2 2 2 2 2 2 2 2 Lithophaga plumula 1 2 3 3 3 2 2 2 2 2 3 1 1 2 1 Antithamnion hubbsii 2 2 2 2 2 2 2 2 2 2 Pododesmus cepio 3 1 1 3 1 2 3 Polysiphonia scopulorum var. villosum 2 2 2 2 2 2 Crassadoma gigantea 2 Obelia nr. surcularis 2 Strongylocentrotus purpuratus 2 Hiatella arctica 2 2 3 1 2 1 2 3 2 2 2 2 2 1 1 3 2 2 Mytilus spp. 3 3 3 1 3 3 3 3 3 3 1 1 1 2 1 2 1 2 1 
Table 3-17. Summary of the most common taxa identified, their relative abundance, frequency of occurrence, an

abundance per occurrence, as determined from scraping samples collected at Platform Gail (continue

Relative Abundance 

Taxon Leg A1 Zone Leg B1 Zone 

Barnacle/Scallop Intertidal Mytilus B/S Inter Mytilus 

Megabalanus californicus 2 2 3 3 1 2 3 2 2 2 2 3 3 3 3 2 1 1 1 3 3 1 3 Jassa slatteryi 3 3 2 3 2 2 1 2 2 1 2 3 2 Aplidium spp. 3 3 3 1 1 3 2 2 Gammaropsis thompsoni 2 2 3 3 2 2 2 3 3 2 2 3 2 2 2 3 Ericthonius brasiliensis 2 3 2 3 2 Leucothoe alata 2 2 2 2 2 3 3 3 3 3 2 3 3 3 3 2 2 3 Kellia suborbicularis 3 3 3 2 3 2 3 2 3 Balanus nubilus 2 2 3 3 1 3 3 3 3 Monocorophium spp. 3 2 3 3 3 2 3 3 3 2 2 3 3 Halosydna brevisetosa 2 3 3 2 2 3 3 2 2 3 2 3 2 3 3 3 3 2 2 3 Ostrea conchaphila 3 2 3 2 3 Dulichiella appendiculata 2 3 3 3 Phascolosoma agassizi 3 3 3 3 3 3 3 2 3 3 1 Pachygrapsus crassipes 3 3 3 3 3 3 2 2 3 3 3 Parapleustes pugettensis 2 3 3 3 3 Phyllochaetopterus prolifica 3 2 3 3 3 3 3 3 3 3 3 3 3 3 

Key: 1 = abundant; 2 = moderately abundant; 3 = limited, sparse; B/S = barnacle/scallop; Inter = intertidal; FO = frequency o

Note: Thirty-one (31) scraping samples collected from Platform Gail. Frequency of occurrence based on presence in 31 scrapin
Table 3-18. Summary species list for scraping samples used in the correspondence analysis. 

Flora: Algae: 

Membranoptera multiramosa 

 Pugetia fragillissima 

Rhodymenia californica Rhodymenia pacifica

Fauna: Crustaceans:  Barnacles (Cirripedia): 

Balanus nubilus Balanus trigonus Megabalanus californicus Tetraclita rubescens

 Caprellid amphipods: 

Caprella alaskana Caprella equilibra Caprella ferrea Caprella verrucosa 

Gammarid amphipods: 

Aoroides spp. Elasmopus cf. holgurus 

 Erichthonius brasiliensis  Janiralata occidentalis 

Jassa slatteryi 

 Podocerus brasiliensis  Stenothoe estacola  Crabs (Brachyura, Cancridea): 

Cancer branneri Cancer jordani Cancer productus Maera simile Pachycheles pubescens Pachycheles rudis 

Crabs, continued:  Paraxanthias taylori 

Scyra acutifrons 

Sea spiders (Pycnogonida): 

Anoplodactylus nodosus Pycnogonum stearnsi 

Echinoderms:  Brittle Stars (Ophiuroidea): 

Ophiopteris papillosa Ophiothrix spiculata 

 Holothuroids (Holothuroidea): 

Parastichopus californicus 

 Pentamera lissoplaca Mollusks:  Gastropods (Gastropoda): 

Amphissa versicolor Anisodoris nobilis 

 Iselica ovoidea 

Tritonia diomedea

 Bivalves (Pelecypoda): 

Anomia peruviana 

 Chama arcana 

Crassadoma gigantea Gregariella chenui Hiatella arctica Irus lamellifer Kellia suborbicularis Lithophaga plumula Modiolus capax Mya arenaria

 Bivalves, continued 

Mytilus californMytilus spp.

Mytilus trossuluPododesmus cepPseudochama ex

 Chitons (Polyplacaph

Mopalia porifera 

Polychaetes: 

Arabella semimaBrania spp. Cirratulus, unid

Dodecaceria fewDodecaceria, unEudistylia polymHalosydna breviHalosydna johnsLepidonotus spicMyxicola spp.Nereis eakini Nereis pelagica nPaleanotus bellis Pholoides asperuPhyllochaetopterPhyllodoce mediPolydora spp. Proceraea cf. kiieSabellidae, uniSerpula columbiSpirobranchus sSyllis gracilis Typosyllis spp. 
Table 3-18. Summary species list for scraping samples used in the correspondence analysis (continued). 

Cnidarians:  Anthozoans (Actiniaria): 

Anthopleura elegantissima Anthopleura elegantissima (rosy morph)

 Corynactis californica  Metridium senile  Hydrozoans: 

Campanularia spp. Eucopella everta 

 Filellum serpens 

Halecium spp. 

Halecium tenellum 

 Lafoea adnata 

Obelia geniculata Obelia spp. 

Plumularia alicia Plumularia alicia complex

Plumularia nr. septata 

Plumularia spp. Sertularella tenellaSyncoryne eximia 

Minor Phyla:  Bryozoans (Bryozoa): 

Callopora spp. Celleporella spp. Celleporina spp. Costazia spp. Crisia spp. Filicrisia spp. Scrupocellaria spp. 

Tegella sp. 

 Flatworms (Platyhelmenthes): 

Stylochoplana longipenis 

Stylochus spp. 

Nemerteans (Nemertea): 

Amphiporus spp. Carinoma mutabilis Paranemertes californica 

 Tetrastemma signifer  Sipunculids (Sipunculida): 

Phascolosoma agassizi

Sponges (Porifera): 

 Porifera sp. A 

Rhabdodermella nuttingi 

 Tunicates (Urochordata, Ascidiacea): 

Styela coriacea 

 Styela truncata 
Much of the variability in the data set was not accounted for in the first several 

correspondence dimensions. The first dimension only explained 12.0 percent of the variability 

in the data set, and the second dimension only explained 11.2 percent, for a total of 23.2 percent 

of the total variability in the data set. Despite the low level of explained variability, the first two 

correspondence dimensions did reveal an interesting trend in the data. A plot of the two zones, 

Mytilus and barnacle, reveals that the two zones were distinct in terms of their respective 

taxonomic compositions and the taxonomic composition of the Mytilus zone was more variable 

among the scraping samples that was the taxonomic compositions of the barnacle zone samples 

(Figure 3-23). 

Numerous taxa occurred exclusively in the Mytilus zone, but only in a few of the 

scraping samples. Mytilus californianus occurred in most of the scraping samples collected in the 

Mytilus zone, but also in a number of samples collected in the barnacle zone, suggesting that a 

gradual transition exists between these zones. Taxa that occurred exclusively in this zone and 

more frequently were Phascolosoma agassizi, Halecium spp. Callopora spp., Anthopleura 

elegantissima (rosy morph), Celleporella spp., and Filellum serpens. The barnacles Balanus nubilus

and B. trigonus occurred frequently but not exclusively in the samples collected in the barnacle 

zone. Several species occurred exclusively in the barnacle zone: Aoroides spp., Brania spp., 

Cancer branneri, Cancer jordani, Ericthonius brasiliensis, Gregariella chenui, Myxicola spp., Pholoides 

asperus, and Typosyllis spp. 

3.9 Wet Weight Determinations 

Wet weight determinations were based on 0.0625 m2 scraping samples collected from 

Legs B1 and B2 on Platform Harvest. Whole samples were wet weighed, and Mytilus removed 

for separate wet weight determinations. Wet weight determinations are provided in Table 3-19. 

 On Leg B1, total sample wet weights were quite variable, ranging from 149 to 5,059 g, 

with a mean value of 2,129 g per quadrat, or approximately 34 kg/m2. Mussel biomass 

measurements were similarly variable, ranging from 0 to 4,025 g. As a result, the contribution 

of mussel biomass to total wet weight was extremely variable, ranging from 0 percent to 

80 percent, with an average of 12.8 percent for the 12 samples measured from Leg B1. 

 On Leg B2, total sample wet weights were less variable than on the adjacent platform 

leg. Biomass measurements ranged from 2,281 to 25,966 g, with an average of 9,180 g, or 

approximately 147 kg/m2. Similarly, mussel biomass measurements were consistently high, 

ranging from 3,752 to 17,779 g in the mussel zone; mussel biomass in the upper portions of the 

barnacle zone were very low (i.e., 1 to 7 g per sample). The relative contribution of mussel 

biomass to total sample wet weight were consistently high (64 percent to 81 percent) for 

samples taken from the mussel zone. However, mussel contributions were extremely limited 

(<1 percent) in the barnacle zone of Leg B2. In terms of depth distribution, the highest biomass 

values for mussels were evident between 3.4 and 5.8 m (11 and 19 ft), tapering off below 6.1 m 

(20 ft). 

101
Correspondence Dimension 

1

-2 -1 0 

Correspondence Dimension 2

-1

012

B

B

M BMB

M

MM

M M

M B

BB

M

M

M

M M M

M

M

Zones are plotted

Figure 3-23. Correspondence analysis results, as determined through the comparison of mussel and barnacle zones for e

platforms and Diablo and Nifty Rocks.
Table 3-19. Summary of weight measurements for scraping samples from Platform 

Harvest. 

Station/ 

Quadrat 

Total 

Weight (g) 

Mussel 

Weight (g) 

Non-Mussel 

Weight (g) 

Percent Mussel 

Weight 

HA-B1-B-47 909.00 0.00 909.00 0.00 

HA-B1-B-54 651.00 0.00 651.00 0.00 

HA-B1-B-78 1,171.00 0.00 1,171.00 0.00 

HA-B1-B-79 1,335.00 0.00 1,335.00 0.00 

HA-B1-M-18 5,059.00 4,025.00 1,034.00 79.56 

HA-B1-M-20 149.10 1.65 147.45 1.11 

HA-B1-M-24 2,916.00 589.00 2,327.00 20.20 

HA-B1-M-25 3,456.00 535.00 2,921.00 15.48 

HA-B1-M-28 3,615.00 266.00 3,349.00 7.36 

HA-B1-M-30 1,139.00 0.00 1,139.00 0.00 

HA-B1-M-32 3,493.00 906.00 2,587.00 25.94 

HA-B1-M-40 1,790.00 82.00 1,708.00 4.58 

HA-B2-B-47 2,828.10 7.10 2,821.00 0.25 

HA-B2-B-50 2,281.00 2.00 2,279.00 0.09 

HA-B2-B-60 2,944.80 0.80 2,944.00 0.03 

HA-B2-M-11 15,309.00 11,958.00 3,351.00 78.11 

HA-B2-M-13 14,430.00 11,658.00 2,772.00 80.79 

HA-B2-M-14 5,883.16 3,752.39 2,130.77 63.78 

HA-B2-M-15 17,661.00 11,936.00 5,725.00 67.58 

HA-B2-M-17 7,305.00 5,843.00 1,462.00 79.99 

HA-B2-M-19 20,213.00 14,933.00 5,280.00 73.88 

HA-B2-M-21 5,690.00 4,941.00 749.00 86.84 

HA-B2-M-22 5,440.00 4,062.00 1,378.00 74.67 

 

Total – 

Both Legs: 125,668.16 75,497.94 50,170.22 -- 

Mean: 5,463.83 3,282.52 2,181.31 33.05 

Maximum: 20,213.00 14,933.00 5,725.00 86.84 

Minimum: 149.10 0.00 147.45 0.00 

 

Total – 

Leg B1: 25,683.10 6,404.65 19,278.45 -- 

Mean: 2,140.26 533.72 1,606.54 12.85 

Maximum: 5,059.00 4,025.00 3,349.00 79.56 

Minimum: 149.10 0.00 147.45 0.00 

 

Total – 

Leg B2: 99,985.06 69,093.29 30,891.77 -- 

Mean: 9,089.55 6,281.21 2,808.34 55.09 

Maximum: 20,213.00 14,933.00 5,725.00 86.84 

Minimum: 2,281.00 0.80 749.00 0.03 

103
 Comparison of mussel weights to mussel presence in the photographs from Platform 

Harvest were confounding. While considerable variability in wet weights was evident both 

within and between platform legs, no significant differences in mussel presence were evident 

between Legs B1 and B2, based on photographic analyses. 

Biomass values for the mussel and barnacle zones were extremely variable based on wet 

weight measurements from Platform Harvest. Total wet weight from a 0.0625 m2 quadrat 

approached 26 kg (57 lb), equivalent to approximately 416 kg/m2 (915 lb/m2). Mussel 

contributions to total sample biomass were also quite variable. However, in the mussel zone, 

such contributions can reach 80 percent of total sample biomass. Under these circumstances, 

mussel biomass may typically be in the 10-12 kg (22-26 lb) range and occasionally higher (i.e., 

up to approximately 18 kg [40 lb]) for a 0.0625 m2 sample whose total wet weight was in the 

12-25 kg (26-55 lb) range. In such samples, total mussel biomass is estimated at 160-192 kg/m2

(352-422 lb/m2). 

3.10 Individual Mussel Measurements 

 A total of 932 mussels were measured (i.e., length, width, and height) and weighed from 

13 scraping samples collected from the mussel zone of Legs B1 and B2 of Platform Harvest. As 

noted previously, each scraping sample was retrieved from an area measuring 0.0625 m2. 

Detailed results of individual mussel measurements are presented in Appendix D. Summary 

information from each sample is provided in Table 3-20. 

 The number of mussels present in each scraping sample was extremely variable, ranging 

from four mussels collected at 6 m (20 ft) below the surface on Leg B1 to 167 mussels collected at 

5 m (15 ft) subsurface on Leg B2. Mussel size characteristics were also quite variable. Minimum 

and maximum average lengths, widths, and heights were 3.81 and 9.90 cm, 2.25 and 4.48 cm, 

and 1.67 to 3.42 cm, respectively. Individual average weights were also variable, ranging from 

10.78 to 111.42 g. The smallest mussels were collected at water depths where the fewest mussels 

were available (i.e., 6 to 8 m; 20 to 25 ft) on Leg B1, while the larger mussel specimens were 

present in the 3 to 8 m (10 to 22 ft) depths of Leg B2. 

3.11 Growth Thickness Measurements 

Growth thickness measurements were made periodically within the mussel zones at 

platforms Harvest (Legs B1 and B2) and Irene (Leg A1). Thickness measures (Table 3-21) 

ranged from 5.1 to 30.5 cm (2 to 12 inches). Greatest thickness of the mussel zone occurred at 

the 14.3 to 16.5 m (47 to 54 ft) on Harvest Leg B1, at 6.7 m (22 ft) on Harvest Leg B2, and 0.3 to 

2.7 m (1 to 9 ft) on Irene Leg A1. 

104
Table 3-20. Summary of mussel measurements of scraping samples collected from 

Platform Harvest. 

Station/ 

Quadrat 

Number of 

Mussels 

Average 

Length (cm) 

Average 

Width (cm) 

Average 

Height (cm) 

Average 

Weight (g) 

HA-B1-M-18 63 7.23 3.68 2.69 55.51 

HA-B1-M-20 4 4.13 2.25 1.58 10.78 

HA-B1-M-24 26 3.81 2.25 1.67 19.17 

HA-B1-M-25 22 4.92 2.67 1.80 21.78 

HA-B1-M-32 20 5.42 2.94 1.96 25.36 

HA-B2-M-11 149 8.67 4.02 2.93 78.94 

HA-B2-M-13 102 9.90 4.48 3.42 111.42 

HA-B2-M-14 50 8.55 4.12 2.99 108.12 

HA-B2-M-15 167 7.53 3.69 2.67 61.40 

HA-B2-M-17 87 6.80 3.40 2.46 50.44 

HA-B2-M-19 130 7.05 3.93 2.51 59.54 

HA-B2-M-21 63 8.44 3.98 2.95 68.32 

HA-B2-M-22 49 8.48 4.06 3.04 72.27 

105
Table 3-21. Summary of growth thickness measurements.

Water Depth 

[m] (ft) 

Growth Thickness 

[cm] (inches) 

Platform Harvest, Leg B1: 

5.5 (18) 12.7 to 17.8 (5 to 7) 

6.1 (20) 7.6 (3) 

7.3 (24) 5.1 to 10.2 (2 to 4) 

7.6 (25) 7.6 to 10.2 (3 to 4) 

8.5 (28) 7.6 (3) 

9.1 (30) 7.6 to 10.2 (3 to 4) 

9.8 (32) 7.6 to 10.2 (3 to 4) 

12.2 (40) 10.2 to 15.2 (4 to 6) 

14.3 (47) 15.2 to 20.3 (6 to 8) 

16.5 (54) 15.2 to 20.3 (6 to 8) 

19.8 (65) 7.6 to 10.2 (3 to 4) 

22.6 (74) 15.2 (6) 

24.1 (79) 15.2 (6) 

Platform Harvest, Leg B2: 

3.4 (11) 20.3 to 25.4 (8 to 10) 

4.3 (14) 15.2 (6) 

4.6 (15) 25.4 (10) 

5.2 (17) 15.2 (6) 

5.8 (19) 20.3 (8) 

6.4 (21) 25.4 (10) 

6.7 (22) 30.5 (12) 

14.3 (47) 7.6 to 10.2 (3 to 4) 

15.2 (50) 7.6 (3) 

16.5 (54) 7.6 (3) 

18.3 (60) 7.6 to 10.2 (3 to 4) 

Platform Irene, Leg A1: 

0.3 to 2.7 (1 to 9) 15.2 to 20.3 (6 to 8) 

2.7 to 3.0 (9 to 10) 15.2 (6) 

3.4 to 4.0 (11 to 13) 12.7 (5) 

4.3 to 4.6 (14 to 15) 10.2 to 12.7 (4 to 5) 

5.2 (17) 10.2 (4) 

106
4.0 Discussion 

4.1 Overview and Historical Perspective 

Until recently, no comprehensive survey-based characterization of invertebrate or algal 

communities associated with California’s offshore platforms has been completed. Historically, 

available information has been acquired as a result of species- or group-specific analyses, or as 

part of studies designed to determine the effects of drilling discharges on platform-associated 

fauna. Research on Mytilus, a recognized dominant invertebrate in California platform 

communities, has historically centered on its intertidal occurrence. Subtidal mussel 

communities have not been as thoroughly characterized as those that occur intertidally. Mussel 

beds, whether intertidal or subtidal, have been characterized as highly productive and complex 

communities that support a significant proportion of total productivity within nearshore 

benthic communities (see reviews by Gosling, 1992; Seed and Suchanek, 1992; and Helmuth, 

1998). 

Only a limited number of researchers have characterized the faunal communities found 

in association with California’s offshore platforms. MBC Applied Environmental Sciences 

(1987) summarized the available information on the ecology of oil and gas platforms. While 

their efforts concentrated primarily on fishes found in association with platforms, these 

investigators also synthesized and summarized available data on platform-associated 

invertebrate communities. MBC determined that platform epibiota were comprised primarily 

of mollusks, barnacles, and polychaetes, with bay mussels (Mytilus edulis) and California 

mussels (Mytilus californianus) being dominant. Platform communities have been characterized 

by the predominant presence of filter feeding fauna. Platform communities also exhibit 

definitive successional stages following periods of disturbance, whether through natural 

sloughing (e.g., removal of portions of the mussel bed community as a result of wave or storm 

surge) or man-induced disturbance (e.g., platform leg cleaning operations, mussel harvesting). 

MBC Applied Environmental Sciences (1987) suggested that the fauna associated with a 

particular platform may be influenced by various factors, including (but not limited to) 

platform location (i.e., water depth, distance from shore, proximity to hard bottom features, and 

seafloor characteristics), length of time in place and season of installation, and local 

hydrography. 

Page et al. (1999) examined the abundance and distribution of three species of 

commercially important cancrid crabs (i.e., rock crab, Cancer antennarius; yellow crab, 

C. anthonyi; and red crab, C. productus), and the majid crab Loxorhynchus grandis (sheep crab) in 

order to determine whether crabs occurred in higher densities beneath a platform compared to 

adjacent soft bottom. They also characterized the spatial and temporal patterns of crab 

recruitment to a platform (Platform Holly, 66 m water depth in the Santa Barbara Channel) and 

evaluated the data within the context of four hypothesized abundance and distribution 

scenarios. Page et al. (1999) noted that the invertebrate community on platform conductor pipes 

varied in thickness with depth and time. Thickness was greatest over time at a depth of 12 m 

and least at depths of 18 and 24 m. Rates of faunal litterfall to the benthos varied significantly 

over time ranging from 0.08 ± 0.03 to 2.6 ± 0.81 kg (wet weight) per trap per week. Rates of 

annual litterfall were significantly higher during two periods (i.e., October to March; August to 

107
September) than during other times (April to June). Mytilus galloprovincialis formed the majority 

(approximately 93%) of this material. Rock, yellow, and red crabs (C. antennarius, C. anthonyi, 

and C. productus) and the sheep crab (Loxorhynchus grandis) were caught in traps beneath 

Platform Holly. Of the four crab species studied, only C. antennarius recruited onto the platform 

structure. Recruitment was seasonal as crabs ≤10mm carapace width were most abundant 

during late spring and summer. In the recruitment cages, there were no differences in the 

densities of crabs among depth at 12, 18, and 24 m. Of the four crab species, only C. antennarius

were observed in visual surveys on the platform. There was no effect of time or depth on 

density which ranged from 0-4 crabs/m2. When data from mussel community samples and 

visual surveys were combined, crab density increased dramatically at 12 m (as compared to 

observations 18 or 24 m) during late spring and early summer as a result of recruitment. 

Trapping data suggests that adult C. antennarius were less abundant on the structure than on 

the bottom. Two of the four crab species (C. antennarius, C. anthonyi) occurred in higher 

densities at the platform compared to the surrounding soft bottom. Page et al. (1999) suggest 

that the platform structure and its associated invertebrate community may provide crabs with 

food, recruitment habitat, preferred habitat of adults, and/or increased shelter from predation. 

Both Cancer species may be attracted to the platform by food provided by the mussel 

community found from the surface to depth of less than 12 to 15 m and through faunal litterfall. 

The platform provides recruitment habitat only for C. antennarius. Recruitment contributed to 

elevated densities of small individuals of this species during the later winter and early spring 

months. Similar results were shown in Winn (1985). 

 Several other researchers affiliated with the Marine Science Institute at the University of 

California, Santa Barbara are currently studying various aspects of platform-associated 

communities. Bram et al. (2002) characterized the early development of subtidal invertebrate 

assemblages on Platform Houchin in the Santa Barbara Channel. The study design was based 

on the seasonal sampling of settling plates conducted over a two-year period. Plates were 

placed at 2-m increments (between 2 and ~18 m subsurface). Bram et al. (2002) determined that 

there was a strong seasonal component to settling at Platform Houchin, that competition for 

open space was hearty (i.e., limited open space available after four months; no open space 

available after 24 months), and that tunicates and bryozoans were dominant at all depths 

sampled during the first few months. Barnacles became more dominant at select depths within 

approximately one year. Between Year 1 and Year 2, researchers noted an increase in the 

coverage of barnacles and sponges, with a corresponding decrease in tunicates. The mussel 

community showed similar levels of coverage each year. 

Culver et al. (2002) determined the spatial distribution patterns of platform-associated 

invertebrates on a series of platforms in the Santa Maria Basin and Santa Barbara Channel. 

Platforms included Gail, Grace, Gilda, Gina, Hogan, Holly, and Houchin. Using photoquadrats 

at 6, 12, 18, and 24 m water depths, researchers sampled on conductor pipes and outside legs of 

these platforms. Preliminary comparisons at the 12 m sampling depth suggested that each 

platform contains unique fauna. Clustering analyses also suggested that there was some degree 

of similarity between platforms (i.e., groupings of Grace and Gilda; Gail and Gina; Hogan, 

Houchin, and Holly). Culver et al. (2002) also noted that the southeastern platforms (Gail, 

Grace, etc.) showed increases in mussel growth in summer, with similar growth patterns 

evident for all platforms during winter and fall. Species distribution and abundance were 

variable between the platforms, with recruitment of select taxa also variable. 

108
 There is increasing evidence that oil and gas platforms off California provide important 

habitat for a variety of fish species, several of which are of economic importance. Further, the 

potential conversion of California oil and gas platforms (i.e., those which have reached the end 

of their productive life) to artificial reefs has prompted debate, discussion, and a series of 

questions amongst resource managers, commercial and recreational fishing interests, scientists, 

and the general public. The U.S. Department of the Interior (USDOI) funded a series of studies 

beginning in the early 1990s to characterize fish assemblages at platforms and 

naturally-occurring rock outcrops. In recent years, researchers at the University of California, 

Santa Barbara (UCSB) have undertaken a variety of studies (with funding from USDOI and the 

California Reef Enhancement Program) to further characterize platform- and natural 

outcrop-associated fish species. While a thorough summarization of these efforts lies beyond 

the scope of the present analysis, several study results are relevant: 

 Love et al. (1999, 2003) – Nine platforms in the Santa Barbara Channel and Santa 

Maria Basin were sampled annually between 1995 and 2000, with several other 

platforms surveyed a single time. With exception of the shallow-water Platform 

Gina, three distinct fish assemblages were found in association with offshore 

platforms – midwater, bottom, and shell mound. The middle of the water column 

acts as a nursery ground for juvenile rockfishes, as well as blacksmith, painted 

greenling, and several other fish species. The base (bottom) of several platforms 

provide habitat to rockfishes, primarily adults of a variety of species, as well as 

lingcod and combfishes. The shell mound found at and near the base of each 

platform provides habitat to rockfish, including juveniles of the species found at the 

platform base and an assortment of lingcod, painted greenling, gobies, several 

flatfish species, and combfishes. Platforms usually harbor higher number of 

young-of-the-year rockfishes than natural outcrops and may be functionally more 

important as nurseries. In some locations, platforms may provide much or all of the 

adult fishes of some heavily fished species and thus contribute disproportionately to 

those species' larval production. Several platforms may be important to regional 

rockfish production. 

 UCSB Coastal Marine Institute (2004) – Page and colleagues at UCSB are conducting 

a study to characterize ecological performance and to determine the trophic links of 

fishes and their prey at both platforms and natural reefs. Monthly sampling has 

occurred at Naples and Mohawk reefs and platforms Holly and Houchin in the 

Santa Barbara Channel. Of primary interest are the potential food items of painted 

greenling, including small amphipod crustaceans. 

The importance of several platforms to regional rockfish production, coupled with the pending 

characterization of the trophic links between platform-associated fishes and their prey, might 

suggest that platform-associated invertebrate and algal communities may play a role in 

supporting fish populations at a local or regional level. 

4.2 Study Limitations 

A number of study limitations were evident following completion of the photographic 

data analysis. While a standardized approach to ROV and diver photography was 

accomplished (i.e., production of standard, repetitive image size), inherent limitations to 

109
photographic interpretation were noted. Specifically, there were limits evident in the 

taxonomists’ ability to completely identify specimens in the photographs. Factors which 

limited a complete identification of specimens in the photographs include: 

 Specimen size – under ideal conditions, a nominal specimen size of 3 cm (1 inch) was 

noted. Digitizing the 35-mm transparencies provided some degree of increased 

resolution in many instances. 

 Shadow – in some instances, the presence of shadow precluded complete 

identification of all specimens in a particular photograph. The presence of shadow 

also highlights the fact that, in many cases, there was a complex, three-dimensional 

structure to platform-associated communities. In these instances, the underlying 

species may or may not be visible for identification. A good example of this 

phenomenon was noted in the barnacle/scallop zone of Platform Gail, where a total 

of only eight Crassadoma gigantea were noted on both legs during photographic 

analysis. Low scallop density may be attributed to the dense overgrowth of the 

strawberry anemone, C. californica, which effectively covers and blocks the view of 

underlying scallops. C. californica was a dominant species, by density and percent 

cover, on both legs and prevalent in water depths where Crassadoma had previously 

been documented (i.e., 12 to 49 m; 40 to 160 ft). 

 Taxonomic limitations - some difficulty was encountered completing a species 

identification based solely on photographic data. The absence of a specimen in hand 

occasionally precluded a species level determination, although the project 

taxonomists attempted to identify each specimen to the lowest practical taxon. 

While some of these limitations were rectified with completion of the scraping data analysis, it 

is noted that only limited scraping data were available (i.e., scrapings collected only from the 

barnacle and Mytilus zones of platforms Harvest and Gail). Invertebrate phylogenetic 

standardizations conform to the most recent guidelines prepared by the Southern California 

Association of Marine Invertebrate Taxonomists (2001). 

Cleaning of the platform jacket and cross members may also have an effect on 

invertebrate and algal community characterization results. Discussions with platform operators 

indicates that cleaning operations are typically restricted to the upper 8 m (25 ft) of the platform, 

effectively between the intertidal zone and the Mytilus or barnacle zones. Cleaning operations 

are routinely completed on an irregular basis, typically annually, weather permitting. Most 

cleaning operations occur in spring or summer (R. Hamson, Veneco, Inc., pers. comm., 2005). In 

addition, mussel harvesting may also occur in conjunction with cleaning or as a separate 

activity on select platforms (e.g., Platform Grace). Finally, natural sloughing of biota within the 

upper portions of the platform jacket may also occur during storm periods or as a result of 

heavy swells, creating open space for planktonic colonizers. Litterfall contributes biomass and 

hard substrate to the shell mound community at the base and down current of the platform. 

4.3 Comparisons Between Adjacent Platform Legs 

 Comparisons of taxa between adjacent platform legs utilized the whole slide analysis 

(QSA) and, to a lesser extent, the PointCount’99® results. The primary basis for comparison 

was the density-dominant data set because it represents the most comprehensive and thorough 

110
analysis. The discussion was further supplemented by percent cover-dominant data, as 

appropriate. Because the PointCount’99® results were found to be very consistent with results 

of the whole slide analysis, they were not considered in detail in the following comparisons, 

although comparisons between percent cover estimates (i.e., PointCount’99® vs. QSA) have 

been detailed in Section 4.4.4. 

4.3.1 Platform Gail 

Legs A1 and B1 were sampled at Platform Gail. Based on complete analysis of 

196 photographs from both legs, 74 total taxa were identified, of which 41 percent (30) were 

monospecific taxa (i.e., species level identification). Remaining taxa were identified primarily to 

genus level, with a few specimens enumerated at higher taxonomic levels. Only five floral taxa 

(i.e., filamentous red algae, including Polysiphonia, Neoptilota, Antithamnion; Codium; encrusting 

coralline algae; filamentous green algae; foliose red algae) were among the 74 total taxa 

observed. One undifferentiated assemblage (turf) and one physical characteristic (bare metal) 

were also observed at Platform Gail. There were also indications that the upper portions (i.e., 

within the upper 8 m) of both legs of Platform Gail had been recently cleaned. 

Based on density determinations, 29 total taxa, plus turf and bare metal, were found to 

be common to both legs, while 20 taxa were unique to Leg B1 and 25 taxa were unique to Leg B2 

(Table 4-1). Dominant taxa common to both legs included Balanus spp., Corynactis californica, 

Desmophyllum, filamentous red algae, Metridium exilis, Metridium senile, Mytilus spp., 

unidentified ophiuroids, Ophiothrix spiculata, calcareous worm tubes, and plain worm tubes. 

Among the taxa unique to Leg B1, dominant species included Anthopleura elegantissima (rosy 

morph) and Metridium farcimen. Amphipholis and Protula superba were determined to be unique 

to Leg B2. 

 The top three density-dominant taxa common to both legs on Platform Gail (i.e., 

Corynactis californica, Metridium exilis, and Metridium senile) exhibited considerable between-leg 

variation in terms of total counts, average density per occurrence, and frequency of occurrence 

(see Tables 3-3 and 3-4). Corynactis exhibited the highest and second highest densities on Legs 

A1 and B1, respectively, occurring in 35 percent and 19 percent of the samples and averaging 

449 and 160 individuals/0.0625 m2. On Leg A1, Corynactis totaled 15,263 individuals, while on 

Leg B1 its total numbers decreased to 3,305 individuals, indicative of its reduced frequency of 

occurrence and, when present, its lower density. 

Metridium exilis exhibited the highest and second highest densities on Legs B1 and A1, 

respectively, occurring in 62 percent and 32 percent of the samples and averaging 340 and 

147 individuals/0.0625 m2. On Leg B1, M. exilis totaled 20,739 individuals, while on Leg A1 its 

total numbers decreased to 4,554 individuals. 

Metridium senile exhibited the third highest total densities on both legs, occurring in 

70 percent and 44 percent of the samples and averaging 60 and 39 individuals/0.0625 m2 on 

Legs A1 and B1, respectively. Total numbers of M. senile ranged between 4,227 and 

1,669 individuals. 

 

111
Table 4-1. Comparison of taxa between Legs A1 and B1 of Platform Gail based on the results of quantita

Common to Both Legs Unique to Leg A1

Balanus nubilus Ophiuroid, unidentified * Aeolidoidea 

Balanus spp. * Ophiothrix spiculata * Amphianthus californica 

Bare Metal * Paracyathus stearnsii Anthopleura elegantissima (rm) * Tun

Corynactis californica * Sebastes spp. Bryozoa, white branching Zoa

Crassadoma gigantea Sponge, cup tan * Cancer antennarius 

Doridacea Sponge, green encrusting Chama arcana 

Desmophyllum dianthus* Sponge, orange encrusting * Codium U

Encruster – orange Sponge, purple encrusting Coenocyathus bowersi 

Encruster – white Sponge, tan encrusting * Dermasterias imbricata 

Encruster – yellow Sponge, white encrusting Encrusting coralline A

Filamentous red algae * Sponge, yellow encrusting Eudistylia polymorpha A

Galathea californiensis Turf * Florometra serratissima 

Hydroid, tan branching * Urochordata (Cystodytes, Aplidium, Styela) Hemigrapsus nudus Aste

Metridium exilis * Worm tubes, calcareous * Hydroid, pink Bry

Metridium senile * Worm tubes, plain * Metridium farcimen * C

Mytilus spp. * Orthasterias koehleri 

Fila

Gor

Ha

O

Pleu

Pyc

Sp

T

Zo

Zoa

 Comparison of co-occurring dominant taxa (or physical characteristics) on adjacent legs of Platform Gail 

 Leg A1 Leg B1 

Taxon Total Average per Occurrence Frequency (%) Total Average per Occurrence Frequency (%) 

Density:

Corynactis californica 15,263 448.9 34.7 3,035 159.7 19.4 Metridium exilis 4,554 146.9 31.6 20,739 340.0 62.2 Metridium senile 4,227 60.4 71.4 1,669 38.8 43.9 Filamentous red algae 752 27.9 27.6 277 11.1 25.5 Ophiothrix spiculata 533 24.2 22.4 206 15.8 13.3 Mytilus spp. 497 35.5 14.3 607 24.3 25.5 Desmophyllum dianthus 416 21.9 19.4 210 12.4 17.3 Balanus spp. 145 9.1 16.3 180 9.5 19.4 Worm tubes, plain 62 8.9 7.1 124 5.6 22.4 

Percent Cover:

Corynactis californica 64.0 34.7 22.8 19.4

Mytilus spp. 60.4 14.3 19.2 25.5 

Metridium senile 41.7 71.4 31.8 43.9

Bare Metal 33.3 38.8 49.2 42.9Metridium exilis 23.0 31.6 62.0 62.2Turf 6.0 35.7 8.4 46.9Sponge, tan encrusting 4.0 31.6 10.5 34.7

* - indicaphysical or both p
Depth of distribution among the dominant taxa was also variable between the two 

platform legs. Corynactis present on Leg A1 was evident across a wide depth range between 

10 and 125 m (34 and 410 ft), with highest concentrations in 16 to 66 m (53 to 216 ft) water 

depths. On Leg B1, this species was more restricted in its depth distribution, present between 

17 and 98 m (57 and 322 ft), with highest concentrations in the 19 to 26 m (63 to 86 ft) depth 

range. By comparison, Metridium exilis on Leg B1 was evident across a wide depth range 

between 10 and 125 m (3 and 322 ft), with a single occurrence at 158 m (518 ft) and variable but 

relatively high concentrations throughout its depth range. On Leg A1, this species was more 

restricted in its depth distribution and intermittently present between 1 and 41 m (4 and 134 ft). 

Mytilus spp. was limited in its presence on Leg A1, occurring only between the 1 and 

3 m (4 and 9 ft) water depths. By contrast, its distribution on Leg B1 extended between 1 and 

16 m (3 and 53 ft). When present, mussel densities were very low when compared to other 

platforms. Low densities and limited depth distribution of Mytilus on both legs was attributed 

to prior leg cleaning activity. Another dominant taxon, Desmophyllum (Desmophyllum dianthus), 

was present only on Platform Gail. While ranked among the top 12 density-dominants on both 

legs, its distribution on Leg A1 extended between 111 and 223 m (363 and 733 ft), while it 

occurred between 181 and 224 m (594 and 734 ft) on Leg B1. 

 Percent cover estimates of the dominant taxa (or physical characteristics) on Platform 

Gail also exhibited considerable variability between adjacent legs. Percent cover dominants and 

respective average cover on Leg A1 included Corynactis californica (64 percent), Mytilus spp. 

(60 percent), Metridium senile (42 percent), bare metal (33 percent), Anthopleura elegantissima

(rosy morph; 26 percent), and Metridium exilis (23 percent). On Leg B1, percent cover dominants 

and respective average cover included Metridium exilis (62 percent), bare metal (49 percent), 

Metridium senile (32 percent), Halichondria panacea (30 percent), Corynactis californica (23 percent), 

and Mytilus spp. (20 percent). 

4.3.2 Platform Grace 

 Legs C1 and C4 were sampled at Platform Grace. Based on analysis of 150 photographs, 

61 total taxa were identified, of which 36 percent (22) were monospecific taxa (i.e., species level 

identification). Remaining taxa were identified to genus level or higher. Only two floral taxa 

(i.e., filamentous red algae, including Polysiphonia, Neoptilota, Antithamnion; Ulva lactuca) were 

among the 61 total taxa observed. Two undifferentiated assemblages (turf, bryozoa turf) and 

two physical characteristics (bare metal, line) were also observed at Platform Grace. While 

mussel harvesting had occurred recently at Platform Grace, cleaned areas were avoided during 

photographic sampling. 

Based on density determinations, 29 total taxa, plus turf and bare metal, were noted as 

being common to both legs, while 22 taxa, plus bryozoa turf, were unique to Leg C1 and 10 taxa 

were unique to Leg C4 (Table 4-2). Dominant taxa common to both legs included Anthopleura 

elegantissima (rosy morph), Balanus nubilus, Balanus spp., Coenocyathus bowersii, Corynactis 

californica, filamentous red algae, Metridium farcimen, Metridium senile, Mytilus spp., Ophiothrix 

spiculata, Paracyathus stearnsii, turf, and calcareous worm tubes. Among the taxa unique to 

Leg C1, dominant species consisted solely of Mytilus californianus, while Metridium exilis was 

unique to Leg C4. 

113
Table 4-2. Comparison of taxa between Legs C1 and C4 of Platform Grace based on the results of quantit

Common to Both Legs Unique to Leg C1

Anthopleura elegantissima (rm) * Hydroid, tan branching * Anemone, pink 

Balanus nubilus * Metridium farcimen * Anemone, unidentified Mytilu

Balanus spp. * Metridium senile * Anisodoris nobilis 

Bare Metal * Mytilus spp. * Anthopleura xanthogrammica Oxy

Bryozoa, tan branching Ophiothrix spiculata * Asterina miniata = Patiria Parastic

Coenocyathus bowersi * Ophiuroid, unidentified Bryozoa turf * Polyc

Corynactis californica * Paracyathus stearnsii * Bryozoa, white branching Sponge, 

Crassadoma gigantea Sebastes sp. Dialula sandiegensis Sponge, o

Encruster – blue Sponge, tan encrusting * Dorid, yellow (?Doriopsilla) Sponge, p

Encruster – pink Sponge, white encrusting Hydroid, pink 

Encruster – white Sponge, yellow encrusting * Hydroid, white clump Tunicat

Encruster – yellow Strongylocentrotus purpuratus Leucilla nuttingi 

Filamentous red algae * Stylasterias forreri

Foliose red algae Turf * 

Hermissenda crassicornis Worm tubes, calcareous * 

Hydroid, tan *

Uniq

Aeolid

Anthozo

Cliona 

Met

Spo

Spon

Spong

U

Zoanth

Comparison of co-occurring dominant taxa (or physical characteristics) on adjacent legs of Platform Grace 

Leg C1 Leg C4 

Taxon Total Average per Occurrence Frequency (%) Total Average per Occurrence Frequency (%) 

Density:Corynactis californica 5,720 211.9 37.0 7,917 344.2 29.9 Paracyathus stearnsii 2,085 71.9 39.7 214 26.8 10.4 Mytilus spp. 1,357 79.8 23.3 1,824 76.0 31.2 Ophiothrix spiculata 987 26.7 50.7 1,548 46.9 42.9 Balanus spp. 627 27.3 31.5 548 24.9 28.6 Anthopleura elegantissima (rm) 441 25.9 20.5 191 13.6 18.2 

Turf 64 1.0 87.7 46 1.0 59.7 Metridium senile 54 10.8 6.8 1,769 43.1 53.2 Filamentous red algae 25 1.0 34.2 24 1.0 31.2 Percent Cover:Mytilus spp. 49.1 23.3 52.6 31.2 Corynactis californica 42.6 37.0 69.2 29.9 Turf 37.4 87.7 25.6 59.7 Anthopleura elegantissima (rosy morph) 30.8 20.5 8.7 18.2 Hydroid, tan 25.0 1.4 18.2 14.3 Filamentous red algae 21.2 34.2 16.7 31.2 Sponge, tan encrusting 9.8 27.4 6.6 6.6 Bare metal 7.5 2.7 8.4 6.5 

* - indicates dphysical charaboth platform 
The top three density-dominant taxa on each leg of Platform Grace (i.e., Corynactis 

californica, Paracyathus stearnsii, and Mytilus spp. on Leg C1; Corynactis californica, Mytilus spp., 

and Ophiothrix spiculata on Leg C4) exhibited moderate between-leg variation in terms of total 

counts, average density per occurrence, and frequency of occurrence (see Tables 3-5 and 3-6). 

Corynactis exhibited the highest densities on Legs C1 and C4, occurring in 37 percent and 

30 percent of the samples and averaging 212 and 344 individuals/0.0625 m2, respectively. On 

Leg C1, Corynactis totaled 5,720 individuals, while on Leg C4 its total numbers increased to 

7,917 individuals, in spite of its reduced frequency (i.e., higher density when present). Mytilus 

spp. exhibited the third and second highest densities on Legs C1 and C4, respectively, occurring 

in 23 percent and 31 percent of the samples and averaging 80 and 76 individuals/0.0625 m2. On 

Leg C1, Mytilus spp. totaled 1,357 individuals, while on Leg C4 its total numbers increased to 

1,824 individuals. Paracyathus stearnsii exhibited the second highest total density on Leg C1, 

occurring in 40 percent of the samples and averaging 72 individuals/0.0625 m2. On Leg C4, this 

species was ranked sixth in terms of density, occurring in only 10 percent of the samples and, 

when present, averaging only 27 individuals/0.0625 m2. Ophiothrix spiculata exhibited the third 

highest total density on Leg C4, occurring in 43 percent of the samples and averaging 

47 individuals/0.0625 m2. On Leg C1, this species was ranked fourth in terms of density, 

occurring in 51 percent of the samples and averaging 27 individuals/0.0625 m2. 

Depth of distribution among the dominant taxa was also variable between the two 

platform legs. Corynactis present on Leg C1 was evident across a limited depth range between 

9 and 52 m (30 and 172 ft), with highest concentrations in 12 to 27 m (38 to 88 ft) water depths. 

On Leg C4, this species was similarly distributed, present between 12 and 58 m (39 and 191 ft), 

with highest concentrations in the 19 to 45 m (61 to 146 ft) depth range. By comparison, Mytilus 

spp. on Leg C1 was evident across a limited depth range between 1 and 6 m (3 and 19 ft); on 

Leg C4, this taxon was present in two bands, at 1 to 4 m (3 to 14 ft) and 10 to 12 m (33 to 39 ft). 

Paracyathus stearnsii was present on Leg C1 between 34 and 94 m (111 and 308 ft) water depths. 

By contrast, its distribution on Leg C4 was more restricted, extending only between 41 and 60 m 

(133 and 197 ft). Ophiothrix spiculata exhibited an interesting distribution on Platform Grace. On 

Leg C1, this ophiuroid species was present in lower average densities (27 individuals/ 

0.0625 m2) across a wider depth distribution between 1 and 78 m (3 and 256 ft); on Leg C4, this 

species occurred in higher densities (47 individuals/0.0625 m2) in a more restricted depth 

distribution between 2 and 45 m (6 and 146 ft). 

Metridium exilis, a dominant on Platform Gail, was present as a density dominant but 

unique only to Leg C4 of Platform Grace. This species exhibited a very limited distribution, 

occurring between 20 and 23 m (67 and 74 ft); when present, however, it occurred in relatively 

high densities averaging 32 individuals/0.0625 m2. 

Mytilus californianus, only documented at platforms Grace and Habitat and Diablo and 

Nifty Rocks, was present as a density dominant but unique only to Leg C1 of Platform Grace. 

This species exhibited very restricted depth distribution, occurring only at approximately 2 m 

(i.e., between 7 and 8 ft); when present, this mussel species occurred in relatively high densities 

averaging 62 individuals/0.0625 m2. 

Percent cover estimates of the dominant taxa on Platform Grace exhibited moderate 

variability between adjacent legs. Percent cover dominants and respective average cover on 

115
Leg C1 included Mytilus spp. (49 percent), Corynactis californica (43 percent), turf (37 percent), 

Anthopleura elegantissima (rosy morph; 31 percent), a tan hydroid (25 percent) and filamentous 

red algae (20 percent). On Leg C4, percent cover dominants and respective average cover 

included Corynactis californica (69 percent), Mytilus spp. (53 percent), Metridium senile

(39 percent), turf (26 percent), and filamentous red algae (17 percent).

4.3.3 Platform Harvest 

Legs B1 and B2 were sampled at Platform Harvest. Based on complete analysis of 

178 photographs from both legs, 53 total taxa were identified, of which 34 percent (18) were 

monospecific taxa (i.e., species level identification). Remaining taxa were identified primarily to 

genus level, with several specimens enumerated at higher taxonomic levels. Only three floral 

taxa (i.e., foliose red algae; Egregia; filamentous red algae, including Polysiphonia, Neoptilota, 

Antithamnion) were among the 53 total taxa observed. One undifferentiated assemblage (turf) 

and two physical characteristics (bare metal, line) were also observed at Platform Harvest. 

There was no indication that recent cleaning activity had occurred at this platform. 

Based on density determinations, 30 total taxa, plus turf and bare metal, were found to 

be common to both legs, while 13 taxa were unique to Leg B1 and 10 taxa, plus an egg case, 

were unique to Leg B2 (Table 4-3). Dominant taxa common to both legs included Anthopleura 

elegantissima (rosy morph), Balanus spp., Corynactis californica, a red encruster, Leucetta, 

Metridium senile, Mytilus spp., an unidentified ophiuroid, Pollicipes polymerus, an encrusting 

translucent tunicate, and calcareous worm tubes. Turf was also a predominant biological 

component present on both platform legs. No taxa unique to Leg B1 were dominant species, 

while only filamentous red algae were dominant and unique to Leg B2. 

The top three density-dominant taxa common to both legs on Platform Harvest (i.e., 

Metridium senile, an unidentified ophiuroid [probably Ophiothrix spiculata], and Mytilus spp. on 

Leg B1; Metridium senile, an unidentified ophiuroid, and Leucetta on Leg B2) exhibited moderate 

between-leg variation in terms of total counts, average density per occurrence, and frequency of 

occurrence (see Tables 3-7 and 3-8). Highest average densities were exhibited by Corynactis on 

Leg B1 (168 individuals/0.0625 m2), however, this species was only present in 4 percent of the 

samples; its densities dropped significantly on the adjacent Leg B2 to 36 individuals/0.0625 m2. 

Aside from Corynactis, Metridium senile exhibited the highest densities on both legs, occurring in 

89 percent and 87 percent of the samples and averaging 39 and 30 individuals/0.0625 m2 on 

Legs B1 and B2, respectively. On Leg B1, Metridium senile totaled 3,168 individuals, while on 

Leg B2 its total numbers decreased to 2,216 individuals, in conjunction with its reduced 

frequency. The unidentified ophiuroid, thought to be Ophiothrix spiculata based on scraping 

analysis results, occurred in 37 and 41 percent of the samples and averaged 23 and 

45 individuals/0.0625 m2 on Legs B1 and B2, respectively. Mytilus spp. exhibited the third and 

fourth highest densities on Legs B1 and B2, respectively, occurring in 22 percent and 24 percent 

of the samples and averaging 37 and 41 individuals/0.0625 m2. On Leg B1, Mytilus spp. totaled 

734 individuals, while on Leg B2 its total numbers increased to 858 individuals. Leucetta was 

also a dominant taxon, occurring in 20 percent of the samples on Leg B1 and 24 percent of the 

samples on Leg B2. 

116
Table 4-3. Comparison of taxa between Legs B1 and B2 of Platform Harvest based on the results of quan

Common to Both Legs Unique to Leg B1 U

Aeolidia papillosa Galathea californiensis Barnacle, unidentified 

Anthopleura elegantissima (rm) * Leucetta Botrylloides spp. * 

Balanus nubilus Leucetta losangelensis * Crassadoma gigantea C

Balanus spp. * Leucilla nuttingi Egregia spp. 

Bare Metal * Metridium senile * Encruster, lavender * 

Bivalve, nestling Mytilus spp. * Hermissenda crassicornis Eu

Bryozoa, tan branching Ophiuroid, unidentified * Line Fila

Bryozoa, white branching Plumularia spp. Metridium farcimen * Gast

Corynactis californica * Pollicipes polymerus * Metridium spp. 

Encruster – tan Sebastes spp. Pisaster ochraceus P

Encruster – white Sponge, tan encrusting Spionidae Spon

Encruster – yellow * Sponge, yellow encrusting Stylasterias forreri

Encruster, green Tunicate, encrusting translucent * Zoanthid, colonial tan 

Encruster, pink Turf * Zoanthid, solitary tan

Encruster, red * Worm tubes, calcareous * 

Foliose red algae * Worm tubes, plain 

 Comparison of co-occurring dominant taxa (or physical characteristics) on adjacent legs of Platform Harvest 

 Leg B1 Leg B2 

Taxon Total Average per Occurrence Frequency (%) Total Average per Occurrence Frequency (%) 

Density:

Metridium senile 3,168 38.6 89.1 2,216 29.5 87.2 Ophiuroid, unidentified 782 23.0 37.0 1,566 44.7 40.7 Mytilus spp. 734 36.7 21.7 858 42.8 23.3 Corynactis californica 672 168.0 4.3 179 35.8 5.8 Leucetta losangelensis 354 13.1 29.3 1,473 50.8 33.7 Balanus spp. 188 5.9 34.8 169 4.2 46.6 Anthopleura elegantissima (rm) 124 7.8 17.4 160 9.4 19.8 Worm tubes, calcareous 105 3.5 32.6 68 2.8 27.9 Turf 72 1.0 78.3 71 1.0 82.6 Encruster, red 48 1.0 52.2 43 1.0 50.0 

Percent Cover:

Corynactis californica 42.0 4.3 11.0 5.8 

Metridium senile 38.5 89.1 29.5 87.2 Encruster, red 35.4 52.2 49.6 50.0 Turf 21.3 78.3 19.3 82.6 Mytilus spp. 21.0 21.7 35.0 23.3 Leucetta losangelensis 14.8 29.3 48.8 33.7 Encruster - yellow 13.1 14.1 16.0 8.1 Bare Metal 11.5 52.2 7.8 39.5 

* - indicphysicaboth pla
Depth of distribution among the dominant taxa was also variable between the two 

platform legs. Metridium senile present on Leg B1 was evident across a broad depth range 

between 1 and 204 m (3 and 669 ft), with highest concentrations in 15 to 34 m (48 to 110 ft) water 

depths. On Leg B2, this species was similarly distributed, present between 1 and 187 m (4 and 

612 ft), with highest concentrations in the 5 to 14 m (18 to 47 ft) depth range. By comparison, 

Mytilus spp. on Leg B1 was evident across a depth range between 1 and 14 m (3 and 46 ft); on 

Leg B2, this taxon exhibited a more restricted depth distribution, extending between 1 and 8 m 

(2 to 25 ft). The unidentified ophiuroid was present intermittently on Leg B1 between 9 and 

191 m (29 and 625 ft) water depths. By contrast, its distribution on Leg B2 was also intermittent 

but more restricted, extending only between 1 and 119 m (4 and 390 ft). 

A red encruster, a dominant on Platform Harvest, was present as a density and percent 

cover dominant on both legs. This species, unique to Platform Harvest and secondary 

platforms Hidalgo and Irene, exhibited a very broad depth distribution, occurring between 

41 and 204 m (135 and 669 ft) on Leg B1 and between 44 and 187 m (145 and 612 ft) on Leg B2. 

When present, the red encruster covered an average of 35 to 50 percent of each photograph. 

Similarly, the sponge Leucetta losangelensis was also a percent cover dominant, with average 

coverage estimated at 15 and 47 percent for Legs B1 and B2, respectively. 

Percent cover estimates of the other dominant taxa on Platform Harvest exhibited 

considerable variability between adjacent legs. Percent cover dominants and respective average 

cover on Leg B1 (exclusive of the red encruster) included Metridium senile (39 percent), 

Metridium farcimen (37 percent), turf (21 percent), and Mytilus spp. (11 percent). Although very 

limited in its presence on Leg B1, Corynactis californica was a percent cover dominant, occupying 

an average of 42 percent of the photographic image in water depths between 31 and 38 m 

(102 and 126 ft). On Leg B2, percent cover dominants and respective average cover (exclusive of 

the red encruster and Leucetta losangelensis) included Mytilus spp. (35 percent), Metridium senile

(30 percent), and turf (19 percent). Other encrusters exhibited limited occurrence and variable 

percent cover contribution. 

4.3.4 Platform Hidalgo 

Legs A1 and B1 were sampled at Platform Hidalgo. Based on analysis of 141 

photographs, 53 total taxa were identified, of which 37 percent (21) were monospecific taxa (i.e., 

species level identification). Only four floral taxa (i.e., foliose red algae; Egregia; filamentous red 

algae, including Polysiphonia, Neoptilota, Antithamnion: Rhodymenia) were among the 53 total taxa 

observed. One undifferentiated assemblage (turf) and two physical characteristics (bare metal, 

fishing line) were also observed. There was no indication that recent cleaning activity had 

occurred at Platform Hidalgo. 

Based on density determinations, 26 taxa, plus turf and bare metal, were found to be 

common to both legs, while 10 taxa, plus an egg case, were unique to Leg A1 and 17 taxa were 

unique to Leg B1 (Table 4-4). Dominant taxa common to both legs included Balanus nubilus, 

Balanus spp., Eudistylia polymorpha, Leucetta losangelensis, Metridium farcimen, Metridium senile, 

Mytilus spp., an unidentified ophiuroid, Tetraclita squamosa, and calcareous worm tubes. Turf 

was also a predominant biological component present on both platform legs, while bare metal 

was a prominent physical characteristic on both legs. 

118
Table 4-4. Comparison of taxa between Legs A1 and B1 of Platform Hidalgo based on the results of quan

Common to Both Legs Unique to Leg A1 Un

Balanus nubilus * Mytilus spp. * Alga, encrusting green Anthopleu

Balanus spp. * Ophiuroid, unidentified * Amaroucium Asterin

Bare Metal * Pisaster giganteus Archidoris montereyensis Bi

Bryozoa, tan branching Pisaster ochraceus Astrangia spp. 

Bryozoa, white branching Pollicipes polymerus Corynactis californica * En

Encruster – tan * Sponge, tan encrusting * Egg case E

Encruster – white Sponge, yellow encrusting Encruster, lavender * E

Encruster – yellow * Strongylocentrotus purpuratus Oxylebius pictus E

Eudistylia polymorpha * Stylasterias forreri Pisaster brevispinis E

Foliose red algae Tetraclita squamosa * Sebastes spp. 

Leucetta losangelensis * Turf * Sponge, tan foliose * M

Leucilla nuttingi Worm tubes, calcareous * Oph

Metridium farcimen * Worm tubes, plain Or

Metridium senile * Zoanthid , solitary tan P

P

Tunicate, 

Zoan

 Comparison of co-occurring dominant taxa (or physical characteristics) on adjacent legs of Platform Hidalgo. 

 Leg A1 Leg B1 

Taxon Total Average per Occurrence Frequency (%) Total Average per Occurrence Frequency (%) 

Density:

Metridium senile 7,849 135.3 92.1 5,048 78.9 82.1 Ophiuroid, unidentified 3,842 78.4 77.8 2,659 59.1 57.7 Mytilus spp. 1,190 85.0 22.2 2,710 117.8 29.5 Balanus nubilus 92 3.4 42.9 32 2.5 16.7 Metridium farcimen 73 24.3 4.8 55 27.5 2.6 Worm tubes, calcareous 47 2.9 25.4 49 2.6 24.4 Turf 34 1.0 54.0 49 1.0 62.8 Leucetta losangelensis 30 1.0 47.6 32 1.0 41.0 

Percent Cover:

Mytilus spp. 57.1 22.2 54.2 29.5 Metridium senile 46.7 92.1 34.9 82.1 Encruster - yellow 30.0 3.2 12.1 12.8 Leucetta losangelensis 25.3 47.6 30.5 41.0 Metridium farcimen 21.7 4.8 17.5 2.6 Bare Metal 18.5 27.0 39.0 10.3 Turf 18.2 54.0 30.1 62.8 Encruster - tan 17.3 23.8 10.4 7.7 Sponge, tan encrusting 7.8 4.8 10.0 1.3 

* - indicates physical chaboth platfor
Several taxa were found on one leg of Platform Hidalgo but not on the other. Dominant 

taxa unique to Leg A1 included Corynactis californica. Anthopleura elegantissima (rosy morph) 

and Ophiothrix spiculata were identified as dominant taxa unique to Leg B1. 

 The top three density-dominant taxa common to both legs on Platform Hidalgo (i.e., 

Metridium senile, an unidentified ophiuroid, and Mytilus spp. on Leg A1; Metridium senile, 

Mytilus spp., and an unidentified ophiuroid on Leg B1) exhibited moderate between-leg 

variation in terms of total counts, average density per occurrence, and frequency of occurrence 

(see Tables 3-9 and 3-10). Metridium senile exhibited the highest density on Leg A1 and third 

highest density on Leg B1, occurring in 92 percent and 82 percent of the samples and averaging 

135 and 79 individuals/0.0625 m2 on Legs A1 and B1, respectively. On Leg A1, Metridium senile

totaled 7,849 individuals, while on Leg B1 its total numbers decreased to 5,048 individuals, in 

conjunction with its reduced frequency. The unidentified ophiuroid occurred in 78 and 

58 percent of the samples and averaged 78 and 59 individuals/0.0625 m2 on Legs A1 and B1, 

respectively. Mytilus spp. exhibited the third and second highest total densities on Legs A1 and 

B1, respectively, occurring in 22 percent and 28 percent of the samples and averaging 85 and 

118 individuals/0.0625 m2, respectively. On Leg A1, Mytilus spp. totaled 1,190 individuals, 

while on Leg B1 its total numbers increased to 2,710 individuals. 

Depth of distribution among the dominant taxa was also variable between the two 

platform legs. Metridium senile present on Leg A1 was evident across a broad depth range 

between 2 and 129 m (5 and 424 ft), with highest concentrations in 7 to 30 m (24 to 99 ft) water 

depths. On Leg B1, this species was similarly distributed, present between 0 and 122 m (0 and 

399 ft), with highest concentrations in the 15 to 29 m (48 to 96 ft) depth range. By comparison, 

Mytilus spp. on Leg A1 was evident across a depth range between 1 and 9 m (3 and 29 ft); on 

Leg B1, this taxon exhibited a more restricted depth distribution, extending between 1 and 6 m 

(2 to 21 ft). The unidentified ophiuroid was present intermittently on Leg A1 between 2 and 

131 m (5 and 430 ft) water depths. Its distribution on Leg B1 was also intermittent, extending 

between 1 and 128 m (4 and 421 ft). 

Percent cover estimates of the dominant taxa on Platform Hidalgo exhibited moderate 

variability between adjacent legs. Percent cover dominants and respective average cover on 

Leg A1 included Mytilus spp. (57 percent), Metridium senile (46 percent), a yellow encruster 

(30 percent), and Leucetta losangelensis (25 percent). Turf and bare metal exhibited average cover 

of 18 percent each. Corynactis californica was a percent cover dominant on Leg A1, but only 

occupied an average of 9 percent of the photographic images in water depths between 24 and 

31 m (78 and 101 ft). On Leg B1, percent cover dominants and respective average cover 

included Mytilus spp. (54 percent), Anthopleura elegantissima (rosy morph; 44 percent), Metridium 

senile (35 percent), Leucetta losangelensis (30 percent), and turf (30 percent). Bare metal averaged 

39 percent coverage on Leg B1. Other encrusters exhibited limited occurrence and variable 

percent cover contribution. 

4.3.5 Summary of Comparisons for Adjacent Platform Legs 

Among the four primary platforms sampled, there were varying numbers of common 

and unique dominant and subdominant taxa present on adjacent legs. When the top 

12 density-dominant taxa were considered, relatively high numbers of co-occurring dominants 

120
were evident at platforms Harvest and Gail, followed by Hidalgo and Grace. In all cases, the 

numbers of dominant taxa unique to a particular platform leg ranged from zero to two, 

suggesting a relatively strong similarity in community composition between adjacent platform 

legs. Two taxa, Metridium senile and Mytilus spp., were noted numerical dominants on all of 

the primary platform legs. Other dominant taxa which were consistently common to adjacent 

platform legs included Balanus spp., Ophiothrix spiculata or unidentified ophiuroids, and 

calcareous worm tubes. Turf, representing an aggregation of smaller flora and fauna (including 

protozoa, hydrozoa, bryozoa, and algae) that co-occur with one another, was included among 

the density co-dominants on three of the four primary platforms, while bare metal co-occurred 

on all adjacent legs and was a dominant feature on platforms Harvest and Hidalgo. 

 In terms of percent cover, there were interesting differences evident between adjacent 

platform legs. On Platform Gail, Corynactis californica, Metridium exilis, and Mytilus spp. 

contributions to percent cover were significantly different between the legs sampled, while 

contributions from bare metal and Metridium senile increased accordingly. On Platform Grace, 

percent cover estimates of dominant taxa exhibited moderate variability between adjacent legs. 

Percent cover contributions from Mytilus spp. and filamentous red algae were comparable 

between the two legs sampled, while those from Corynactis californica and turf were 

considerably different. On Platform Harvest, percent cover dominants Metridium senile and turf 

generally exhibited similar contributions between legs, while significant variability was evident 

between legs for the red encruster, Mytilus spp., Corynactis californica, and Leucetta losangelensis. 

On Platform Hidalgo, moderate variability in percent cover dominants was evident between 

adjacent legs. Contributions from Mytilus spp., Metridium farcimen, and Leucetta losangelensis

were similar between legs, while those from Corynactis californica, Metridium senile, and 

Anthopleura elegantissima (rosy morph) were noticeably different. 

There were several other interesting observations which resulted from a comparison of 

adjacent legs. Corynactis californica and Anthopleura elegantissima (rosy morph) were present on 

the adjacent legs of several primary platforms, however, Corynactis was noticeably and 

completely absent from Leg B1 of Platform Hidalgo and A. elegantissima (rosy morph) was 

absent from Leg A1 of Platform Hidalgo and Leg B1 of Platform Gail. 

4.4 Comparisons Between Platforms 

4.4.1 Rank Order of Dominant Taxa 

The rank order of dominant taxa identified at each platform provides a mechanism to 

compare taxa between platforms. Results presented previously in Section 3 outlined dominant 

taxa (and physical characteristics, as appropriate) on the basis of density and percent cover (see 

Tables 3-3 through 3-12). These data have been used in the development of the following text 

and associated tables. 

Table 4-5 identifies the ranking of dominant taxa (or physical characteristics) present on 

each platform leg, based on total individual counts (i.e., density). This table also indicates 

species presence as a sub-dominant (i.e., present, but not one of the top 12 taxa) or absence (i.e., 

not present), and denotes the relative frequency of occurrence of each taxa (i.e., as a dominant 

or sub-dominant). 

121
Table 4-5. Summary of rankings for each of the top 12 taxa (based on density) identified during quantita

by platform leg. Physical characteristics have also been included, as appropriate. 

Taxon Gail A1 Gail B1 Grace C1 Grace C4 Harvest B1 Harvest B2 Hidalgo A1 Hidalgo B1 Habitat A1 

Metridium senile 3 3 11 3 1 1 1 1 3 Mytilus spp. 6 4 3 2 3 4 3 2 2 Balanus spp. 9 8 5 5 6 6 SD 5 SD Worm tubes, calcareous SD 9 8 SD 8 10 7 8 SD Turf SD SD 10 10 9 9 8 7 12 Sponge, yellow encrusting SD SD SD SD SD SD SD SD SD Bare Metal SD SD SD SD 11 SD 12 SD SD Corynactis californica 1 2 1 1 4 5 4 NP 1 Balanus nubilus SD SD SD 11 SD SD 5 11 5 Ophiuroid, unidentified 10 SD SD SD 2 2 2 3 NP Anthopleura elegantissima (rosy morph) 8 NP 6 7 7 7 NP 4 6 Ophiothrix spiculata 5 7 4 4 NP NP NP 9 4 Metridium farcimen 11 NP SD 9 SD NP 6 6 NP Filamentous red algae 4 5 12 12 NP 8 NP NP SD Leucetta/Leucetta losangelensis NP SD NP SD 5 3 10 12 NP Paracyathus stearnsii SD SD 2 6 NP SD NP NP 7 Worm tubes, plain 12 11 NP NP SD SD SD SD NP Pollicipes polymerus NP NP NP NP SD 12 SD SD NP Eudistylia polymorpha SD NP NP NP NP SD 9 SD NP Encruster, red NP NP NP NP 12 11 NP SD NP Pisaster ochraceus NP NP NP NP SD NP SD SD NP Metridium exilis 2 1 NP 8 NP NP NP NP NP Mytilus californianus NP NP 7 NP NP NP NP NP SD Tetraclita squamosa NP NP NP NP NP NP 11 10 NP Coenocyathus bowersi (c) SD NP 9 SD NP NP NP NP NP 
Table 4-5. Summary of rankings for each of the top 12 taxa (based on density) identified during quantita

by platform leg. Physical characteristics have also been included, as appropriate (continued). 

Taxon Gail A1 Gail B1 Grace C1 Grace C4 Harvest B1 Harvest B2 Hidalgo A1 Hidalgo B1 Habitat A1 

Metridium spp. NP NP NP NP SD NP NP SD 9 Tunicate, encrusting translucent NP NP NP NP 10 SD NP SD NP Desmophyllum dianthus 7 6 NP NP NP NP NP NP NP Protula superba NP 10 NP NP NP NP NP SD NP Triopha catalinae NP NP NP NP NP NP NP NP 8 Anthopleura spp. (whitish, no rose) NP NP NP NP NP NP NP NP NP Corallina spp. NP NP NP NP NP NP NP NP 10 Staurocalyptus sp. NP NP NP NP NP NP NP NP 11 Amphipholis spp. NP 12 NP NP NP NP NP NP NP Notes: NP = not present; SD = sub-dominant. 
Thirty-four numerically dominant species, taxa, undifferentiated assemblages, or 

physical characteristics were present on one or more of the six platforms evaluated. Two taxa, 

Metridium senile and Mytilus spp., were identified as numerical dominants on all ten platform 

legs evaluated. Three other taxa and one undifferentiated assemblage – Balanus spp., calcareous 

worm tubes, a yellow encrusting sponge, and turf – were either dominants or present (as 

sub-dominants) on all ten platform legs. 

Turf, representing an undifferentiated aggregation of smaller flora and fauna (including 

protozoa, hydrozoa, bryozoa, and algae) that co-occur with one another, was included among 

the density dominants in spite of the fact that it was only assigned a numerical (i.e., density) 

value of one, indicative of its prevalence on many of the platforms. A similar approach was 

used with filamentous red algae, bare metal, red encruster, and the sponge Leucetta losangelensis. 

These taxa (or physical characteristics) were more appropriately characterized in terms of their 

relative contributions to percent cover, as discussed below. 

 One physical characteristic, bare metal, was also present on all ten platform legs 

evaluated. While bare metal estimates were not determined on Platform Irene, this 

characteristic was evident near the base of the platform. Bare metal was a prominent feature on 

single legs of platforms Harvest and Hidalgo (i.e., with a ranking of 11 and 12 on Legs B1 and 

A1, respectively; Table 4-5), and was a sub-dominant on all remaining platform legs. 

Corynactis californica was present on nine of the ten legs as a dominant taxon, noticeably 

absent from Leg B1 of Platform Hidalgo. Balanus nubilus was either a dominant species or was 

present on nine of the platform legs sampled, being absent only from Platform Irene. It is 

noteworthy that in most instances where Balanus nubilus was a sub-dominant, barnacles (i.e., 

Balanus spp.) were present at a dominant component of the fauna. Other taxa present on a 

majority of the platform legs included unidentified ophiuroids, Anthopleura elegantissima (rosy 

morph) Ophiothrix spiculata, Metridium farcimen, filamentous red algae, Leucetta/Leucetta 

losangelensis, Paracyathus stearnsii, and plain worm tubes. 

Seventeen of the 34 taxa or physical characteristics identified in Table 4-5 occurred on 

60 percent or more of the platform legs. Remaining taxa occurred on one or more of the six 

platforms, with considerable variability evident. For example, Metridium exilis and 

Desmophyllum dianthus at Platform Gail were among this platform’s numerical dominants. 

Metridium exilis only occurred elsewhere on a single platform leg – Platform Grace, Leg C4. 

Desmophyllum dianthus, the sixth or seventh most abundant species (by density) at Platform 

Gail, was not encountered at any of the other platforms sampled. Similarly, three species – 

coralline alga (Corallina spp.), Staurocalyptus sp., and Triopha catalinae – were present only at 

Platform Habitat. 

Other dominant or sub-dominant taxa that occurred exclusively at a limited number of 

platforms included: 

 Pollicipes polymerus – present only at platforms Harvest, Hidalgo, and Irene 

 Red encruster – present only at platforms Harvest, Hidalgo, and Irene 

 Pisaster ochraceus – present only at platforms Harvest, Hidalgo, and Irene 

 Mytilus californianus – present only at platforms Grace, Habitat, and Irene 

124
 Tetraclita squamosa – present only at platforms Hidalgo and Irene 

 Coenocyathus bowersi – present only at platforms Gail and Grace 

 Protula superba – present only at platforms Gail and Hidalgo 

 Coralline alga (Corallina spp.), Staurocalyptus sp., and Triopha catalinae – present only 

at Platform Habitat 

 Amphipholis spp. – present only at Platform Grace 

Species presence or absence may be influenced by platform location for several taxa. 

Several species were absent from platforms in the eastern Santa Barbara Channel (i.e., Grace, 

Gail), but nearly always present on those in the Santa Maria Basin (i.e., Harvest, Hidalgo, Irene), 

including the gooseneck barnacle Pollicipes polymerus, a red encruster, and the starfish Pisaster 

ochraceus. By comparison, several species were present on platforms in the eastern Santa 

Barbara Channel but were absent from the Santa Maria Basin, including Coenocyathus bowersi

and Amphipholis spp. In other cases, several species exhibited limited distribution, with no 

apparent geographic affinities (e.g., Protula superba). 

It is unclear as to why these species have not successfully colonized all platforms. 

Possible reasons for this phenomenon include the community composition of Santa Barbara 

Channel or Santa Maria Basin platforms (i.e., existing species’ ability to preclude larval 

settlement), low larval planktonic concentrations of select species in certain areas, or an inability 

to survive following settlement (i.e., predation pressure), or a combination of these factors. 

Table 4-6 identifies the ranking of dominant taxa, undifferentiated assemblages, and 

physical characteristics present on each platform leg, based on percent cover estimates. This 

table also indicates presence as a sub-dominant (i.e., present, but not one of the top 12 taxa) or 

absence (i.e., not present), and denotes the relative frequency of occurrence of each taxa (i.e., as 

a dominant or sub-dominant). In some cases, a percent cover estimate for a particular taxon 

could not easily be determined; those instances have been noted in Table 4-6 and have been 

accounted for in the frequency total based on individual counts summarized in Table 4-5. 

Forty-three dominant species, taxa, or physical characteristics resulted from the percent 

cover analysis. Five taxa, one undifferentiated assemblage, and one physical characteristic were 

present on all ten platform legs, based on percent cover estimates. Mytilus spp., Metridium 

senile, and turf were ranked as the top three contributors to percent cover at the six platforms 

characterized. Mytilus spp., with an average ranking of 2.78, was a major contributor to percent 

cover on nine of the ten legs evaluated. While percent cover estimates for Mytilus spp. were not 

determined on Platform Irene, Mytilus californianus was recognized as a dominant contributor to 

percent cover on Irene, indicating that mussels were percent cover dominants on all platform 

legs. Metridium senile and turf were percent cover dominants on all ten platform legs, averaging 

a rank of 3.33 and 7.00, respectively. 

Calcareous worm tubes, tan encrusting sponge, and yellow encrusting sponge were also 

dominants or sub-dominants on all ten platform legs evaluated. Percent cover estimates for 

calcareous worm tubes were available only for one platform (Irene), although this taxon was 

present as a numerical dominant or sub-dominant on all of the remaining platforms (Table 4-5). 

125
Table 4-6. Summary of rankings for each of the top 12 taxa (based on percent cover) identified during qu

analysis, by platform leg. Physical characteristics have also been included, as appropriate. 

Taxon Gail A1 Gail B1 Grace C1 Grace C4 Harvest B1 Harvest B2 Hidalgo A1 Hidalgo B1 Habitat A1 Iren

A1 

Mytilus spp. 2 6 1 2 7 3 1 1 2 ND Metridium senile 3 3 SD 4 2 5 2 4 6 1 Turf 8 11 3 5 6 7 8 6 8 8 Bare Metal 4 2 12 11 12 12 7 3 SD ND Sponge, tan encrusting 10 7 11 12 SD 4 12 12 9 4 Sponge, yellow encrusting 12 SD 10 SD SD 8 SD SD SD 11 Worm tubes, calcareous ND ND ND ND ND ND ND ND ND 6 Corynactis californica 1 5 2 1 1 10 11 NP 1 ND Encruster, yellow SD SD SD SD 10 9 3 10 SD NP Anthopleura elegantissima (rosy morph) 5 NP 4 10 SD 11 NP 2 4 10 Metridium farcimen ND NP ND ND 3 NP 5 8 NP ND Filamentous red algae ND ND 6 7 NP ND NP NP 5 ND Ophiothrix spiculata ND ND ND ND NP NP NP ND 7 ND Foliose red algae NP SD SD SD 11 SD SD SD NP NP Leucetta/Leucetta losangelensis NP 8-t NP SD 9 2 4 5 NP NP Encruster, tan NP SD NP NP SD 6 9 11 SD NP Hydroid, tan branching 9 SD 9 SD NP NP NP NP NP SD Paracyathus stearnsii ND ND ND ND NP ND NP NP 10 NP Sponge, white encrusting SD SD SD SD NP SD NP NP 11 NP Encruster, red NP NP NP NP 4 1 NP 7 NP SD Bryozoa, tan branching (c) NP NP NP NP SD SD 11 SD NP NP Tetraclita squamosa NP NP NP NP NP NP ND ND NP 3 Metridium exilis 6 1 NP ND NP NP NP NP NP NP Mytilus californianus NP NP ND NP NP NP NP NP SD 5 Zoanthid, colonial tan 7 NP NP 3 SD NP NP NP NP NP 
Table 4-6. Summary of rankings for each of the top 12 taxa (based on percent cover) identified during qu

analysis, by platform leg. Physical characteristics have also been included, as appropriate (con

Taxon Gail A1 Gail B1 Grace C1 Grace C4 Harvest B1 Harvest B2 Hidalgo A1 Hidalgo B1 Habitat A1 Iren

A1 

Sponge, cup tan SD 10 NP SD NP NP NP NP NP NP Zoanthid, tan (Palythoa) NP 12 NP NP NP NP ND ND NP NP Sponge, orange encrusting 12 SD SD NP NP NP NP NP NP NP Zoanthid (Palythoa) NP SD NP NP NP NP NP NP 3 NP Hydroid, tan NP NP 5 6 NP NP NP NP NP NP Sponge, tan foliose NP NP NP SD NP NP 6 NP NP NP Tunicate, encrusting tan 11 NP NP NP NP NP NP NP NP 2 Sponge, gray encrusting NP NP 8 NP NP NP NP NP NP 7 Encruster, lavender NP NP NP NP 5 NP 10 NP NP NP Encruster, blue NP NP SD NP NP NP NP 9 NP NP Alga, encrusting green NP NP NP NP NP NP SD NP NP 9 Ulva spp. NP NP NP ND NP NP NP NP 12 12 Halichondria panicea NP 4 NP NP NP NP NP NP NP NP Bryozoa turf NP NP 7 NP NP NP NP NP NP NP Cliona spp., yellow NP NP NP 8-t NP NP NP NP NP NP Botrylloides spp. NP NP NP NP 8 NP NP NP NP NP Sponge, tan globose NP 8-t NP NP NP NP NP NP NP NP Anthozoa, unidentified NP NP NP 8-t NP NP NP NP NP NP Notes: NP = not present; ND = not determined but present, based on density estimates (Table 4-5); SD = sub-dominan

-t = average percent cover estimates for two taxa were identical; respective rankings reflect this fact. 
Bare metal was also a percent cover dominant or sub-dominant as a physical 

characteristic on nine of the ten platform legs evaluated. Bare metal was present to a very 

limited extent, and subsequently was not assessed, on Leg A1 of Platform Irene. 

 Corynactis californica was a percent cover dominant or sub-dominant on eight legs and 

present (but coverage not determined) on another leg, for a total of nine platform legs. 

Corynactis was absent on Platform Hidalgo, Leg B1, and not determined on Platform Irene. 

Anthopleura elegantissima (rosy morph) was present as a dominant or sub-dominant on eight 

legs; this species was absent on Platform Gail, Leg B1 and Platform Hidalgo, Leg A1. Other taxa 

which were contributors to percent cover on a majority of the platform legs included a yellow 

encruster, Metridium farcimen, Ophiothrix spiculata, filamentous red algae, foliose red algae, 

Leucetta/Leucetta losangelensis, a tan encruster, a tan branching hydroid, Paracyathus stearnsii, 

and a white encrusting sponge (Table 4-6). 

 The remaining taxa identified in Table 4-6 contributed to percent cover in varying 

degrees at one or more of the six platforms, with considerable variability evident as was noted 

previously during the discussion of density dominant taxa. Similar trends regarding 

geographic distribution were noted in the percent cover estimates, although the species 

identified differed slightly: 

 Red encruster – present only at platforms Harvest, Hidalgo, and Irene 

 Bryozoa, tan branching – present only at platforms Harvest and Hidalgo 

 Tetraclita squamosa – present only at platforms Hidalgo and Irene 

 Metridium exilis – present only at platforms Gail and Grace 

 Colonial tan zoanthid – present only (on single legs) at platforms Gail, Grace, and 

Harvest 

 Cup tan sponge – present only at platforms Gail and Grace 

 Orange encrusting sponge – present only at platforms Gail and Grace 

 Gray encrusting sponge – present only at platforms Grace and Irene 

 Lavender encruster – present only at platforms Harvest and Hidalgo 

As noted previously, platform location may influence presence or absence for several 

taxa identified during either density or percent cover analyses. When considering percent cover 

results, several species absent from platforms in the eastern Santa Barbara Channel were 

present in the Santa Maria Basin – red encruster, tan branching bryozoa, Tetraclita squamosa, and 

lavender encruster. Several species present on platforms in the eastern Santa Barbara Channel 

were absent from the Santa Maria Basin – Metridium exilis, cup tan sponge, and orange 

encrusting sponge. Several species exhibited limited distribution with no apparent geographic 

affinities (e.g., gray encrusting sponge, colonial tan zoanthid). Insufficient information exists as 

why some species have successfully colonized all platforms while others have not. 

 Combining dominant taxa from both density and percent cover determinations into a 

composite listing produced 60 taxa, undifferentiated assemblages (i.e., turf, bryozoa turf), and 

physical characteristics (e.g., bare metal), as outlined in Table 4-7. Table entries are grouped by 

frequency of occurrence, then in ascending order (i.e., highest average rank first). 

128
Table 4-7. Comparison of average rankings – density vs. percent cover – for the dominant taxa, all platform

Taxon Density Percent Cover Frequency (%) Taxon Density 

Metridium senile 2.90 3.33 100 Zoanthid, colonial tan ND Mytilus spp. 3.80 2.78 100 Tetraclita squamosa 8.00 Balanus spp. 6.00 ND 100 Coenocyathus bowersi 9.00 Worm tubes, calcareous 8.00 6.00 100 Metridium spp. 9.00 Turf 9.29 7.00 100 Tunicate, encrusting translucent 10.00 Sponge, tan encrusting ND 9.00 100 Sponge, cup tan ND Bare Metal 11.50 7.88 100 Zoanthid, tan (Palythoa) ND Sponge, yellow encrusting 11.00 10.25 100 Sponge, orange encrusting ND Corynactis californica 2.89 4.00 90 Desmophyllum dianthus 6.50 Ophiuroid, unidentified 3.80 ND 90 Protula superba 10.00 Balanus nubilus 8.00 ND 90 Zoanthid (Palythoa) ND Encruster, yellow ND 8.00 90 Hydroid, tan ND Anthopleura elegantissima (rm) 6.25 6.57 80 Sponge, tan foliose ND Ophiothrix spiculata 5.86 7.00 70 Tunicate, tan encrusting ND Metridium farcimen 8.00 5.33 70 Sponge, gray encrusting ND Filamentous red algae 8.20 6.00 70 Encruster, lavender ND Foliose red algae ND 11.00 70 Encruster, blue ND Leucetta/Leucetta losangelensis 7.50 5.60 60 Alga, encrusting green ND Encruster, tan ND 8.67 60 Ulva spp. ND Hydroid, tan branching ND 9.00 60 Halichondria panicea ND Paracyathus stearnsii 5.00 10.00 60 Bryozoa turf ND Sponge, white encrusting ND 11.00 60 Cliona spp., yellow ND Worm tubes, plain 11.50 ND 60 Triopha catalinae 8.00 Pollicipes polymerus 12.00 ND 50 Botrylloides spp. ND Eudistylia polymorpha 9.00 ND 40 Sponge, tan globose ND Encruster, red 11.50 4.00 40 Anthozoa, unidentified ND Pisaster ochraceus 12.00 ND 40 Anthopleura spp. (whitish, no rose) 10.00 Bryozoa, tan branching ND 11.00 40 Corallina spp. 10.00 Metridium exilis 3.67 3.50 30 Staurocalyptus sp. 11.00 Mytilus californianus 4.50 5.00 30 Amphipholis spp. 12.00 Note: ND = not determined; rm = rosy morph. 
For many of the taxa, the average density and average percent cover rank 

determinations were comparable, particularly for the most frequently observed species (e.g., 

Metridium senile – 2.90 vs. 3.33; Mytilus spp. – 3.80 vs. 2.78; calcareous worm tubes – 8.00 vs. 6.00; 

Corynactis californica – 2.89 vs. 4.00; Anthopleura elegantissima [rosy morph] – 6.25 vs. 6.57). Other 

dominant taxa present at all six platforms included Balanus spp. and a tan encrusting sponge, 

although these determinations resulted from either individual counts or percent cover 

estimations only. Comparability of average rankings underscores the fact that these species 

were not only present at all of the platforms, but present as dominant taxa in terms of 

individual counts and/or percent cover. 

 Individual counts and percent cover estimators are viable mechanisms, both separately 

and jointly, in determining relative importance of a species to platform community structure. 

Sixteen taxa and undifferentiated assemblages, and a single physical characteristic, were 

characterized in terms of both counts and percent cover and included the vast majority of 

dominant taxa. For most entities (i.e., turf, bare metal, colonial and/or encrusting species, algal 

species), the relative contribution to community structure is best evaluated on the basis of 

percent cover determinations. Percent cover estimations do not suffer from the inherent 

limitations associated with enumerating colonial or algal taxa (e.g., proper determination of the 

number of individuals in a colony is problematic). Further, the mechanism used in the present 

analysis to determine individual counts (i.e., assignment of the number “1”) underestimates the 

relative contribution of these forms. Individual counts (i.e., density) are appropriate for readily 

identifiable individuals and as one means of estimating the relative contribution of a given 

taxon to platform community structure. 

Additional observations noted in the comparison of average rankings for dominant 

platform taxa. Forty percent of the dominant taxa occurred on 50 percent or more of the 

platform legs. For species with lower frequencies of occurrence, platform location may be an 

important factor (i.e., indicative of taxa unique to either eastern Santa Barbara Channel or Santa 

Maria Basin platforms. 

4.4.2 Density Comparisons 

Among the numerically dominant (i.e., density-dominant) taxa, cnidarians (i.e., 

Metridium senile, Anthopleura elegantissima [rosy morph], Corynactis californica), mussels (i.e., 

Mytilus californianus; Mytilus spp. complex), barnacles (i.e., Balanus nubilus, Balanus spp., 

Tetraclita squamosa), worm tubes (calcareous and plain), and ophiuroids (Ophiothrix spiculata; 

ophiuroids, unidentified) represented the most prominent and consistent community-formers 

present on the platforms studied. Minimum, maximum, and average density determinations 

for several of these density-dominant taxa are provided in Table 4-8 and discussed below. 

Metridium senile was the highest ranked species observed overall – the numerical 

(density) dominant of platforms Harvest, Hidalgo, and Irene, and ranking within the top four at 

platforms Gail, Grace, and Habitat. Its lowest ranking occurred on Leg C1 of Platform Grace 

(see Table 4-5). Maximum densities of M. senile ranged from 60 to 510 individuals/0.0625 m2, 

with highest density seen at Platform Irene (Table 4-8). Average density was highest at 

Platform Irene and lowest at Platform Habitat. This species exhibited a wide depth distribution 

and was found at nearly all depths of a platform. 

130
Table 4-8. Minimum, maximum, and average densities 1 of select dominant taxa (based on numerical abun

Gail Grace Harvest Hidalgo Habi

Species or 

Taxon Average Min- Max Average Min- Max Average Min- Max Average Min- Max Average 

Metridium senile 38.8-60.4 1-213 10.8-43.1 1-165 29.5-38.6 1-90 78.9-135.3 1-275 22.8 Mytilus spp./ Mytilus californianus 24.3-35.5 2-160 76.0-79.8 4-240 36.7-40.9 1-110 85.0-117.8 5-220 32.6 Balanus spp./ Balanus nubilus/ Tetraclita squamosa 

9.1-9.5 1-30 24.9-27.3 1-100 4.2-5.9 1-27 2.5-5.4 1-25 12.7 

Worm tubes, plain and calcareous 5.6-11.3 1-27 1.0-4.7 1-10 2.8-3.5 1-12 2.6-2.9 1-8 1.0 Corynactis californica 159.7-448.9 1-693 211.9-344.2 1-500 35.8-168.0 4-360 27.8 9-75 448.5 Anthopleura elegantissima 

(rosy morph) 20.3 1-100 13.6-25.9 1-62 7.8-9.4 1-24 84.9 2-185 19.6 

Ophiothrix spiculata/ Ophiuroid, unidentified 15.8-24.2 1-66 26.7-46.9 1-180 23.0-44.7 1-180 57.7-78.4 1-430 14.4 Metridium farcimen 11.4 1-88 1.0-6.5 1-18 4.4 3-8 24.3-27.5 19-42 - Filamentous red algae 11.1-27.9 1-70 1.0 1 21.4 2-40 - - 1.0 Leucetta/Leucetta losangelensis 1.0 2 1 1.0 1 13.1-50.8 1-80 1.0 1 - Paracyathus stearnsii 4.0-9.0 1-12 26.8-71.9 1-201 1.0 1 - - 20.7 Red encruster - - - - 1.0 1 1.0 1 - Metridium exilis 146.9-340.0 2-580 32.3 15-60 - - - - - 

1 Minimum, maximum, and average number of individuals/0.0625 m2, as presented in Tables 3-3 through 3-12 and Appendix C. A

for taxa from the primary platforms (Gail, Grace, Harvest, Hidalgo) are provided as a range, reflecting averages representative of 

for Mytilus spp./Mytilus californianus at Platform Gail, average density values of 35.5 and 24.3 individuals/0.0625 m2 were calcul

respectively. Solitary average density values are for taxa from secondary platforms or for dominant species/taxa which only occ

primary platform. 

2 The occurrence of several colonial or algal taxa were either counted or denoted using the number “1” to indicate their presence (

losangelensis, red encruster); please refer to Table 4-9 for a summary of percent cover for these taxa.
Mytilus spp. was the second highest ranked species observed and the most prominent 

taxon between the intertidal and the upper few tens of meters of a platform leg. Mytilus spp. or 

Mytilus californianus consistently ranked in the top six density dominants, and usually was the 

second or third most abundant taxa (by density) at the platforms sampled. At Platform Grace, 

where it exhibited the highest density levels among the platforms, maximum densities reached 

240 individuals/0.0625 m2, or approximately 3,840 individuals/m2. At the other platforms, 

maximum mussel densities ranged from 80 to 220 individuals/0.0625 m2 (Table 4-8). This 

species exhibited highest average density at Platform Hidalgo and lowest average density at 

Platform Gail. 

The vertical extent of the mussel zone was limited and variable between the platforms 

sampled. The deepest mussel occurrence was noted at platforms Irene and Habitat, where 

Mytilus was noted to approximately 24 m (79 and 78 ft, respectively). The shallowest 

distribution of mussels (i.e., shallowest lower end of the mussel zone) was encountered at 

Platform Hidalgo, where Mytilus was present to only 9 m (29 ft). The lower extent of the mussel 

zone at the remaining platforms ranged from 11 to 14 m (35 to 46 ft). In spite of its relatively 

narrow depth of occurrence and variable vertical extent, mussels were consistently found 

among the numerically dominant taxa at all platforms. Further, mussel beds also provide a 

complex, three-dimensional environment for a myriad of interstitial fauna and epibionts (e.g., 

caprellid and gammarid amphipods, crabs, pycnogonids, brittle stars, holothuroids, gastropods, 

bivalves, nudibranchs, chitons, polychaetes, anemones, hydroids, hydrozoans, nemerteans, 

sponges, bryozoans, tunicates, sipunculids, and flatworms). This complex interstitial and 

epibiont space provides habitat, food, and protection for many species. 

Barnacles, represented by Balanus spp., Balanus nubilus, and, to a lesser extent by 

Tetraclita squamosa, ranked third in total density among platform-associated taxa. The 

maximum barnacle density of 200 individuals/0.0625 m2 was observed at Platform Irene, while 

lowest maximum density of 23 individuals/0.0625 m2 was evident at Platform Hidalgo 

(Table 4-8). Maximum barnacle densities noted at platforms Grace and Habitat were 100 and 

64 individuals/0.0625 m2, respectively. Highest average density of barnacles was observed at 

Platform Irene, while lowest average densities were evident at Platform Hidalgo. The 

predominant depth range for barnacles was within the upper portions of the platform leg (i.e., 

usually from the intertidal to approximately 18 m [60 ft]), although barnacles were found 

extending down a platform’s leg at Grace, Harvest, Hidalgo, Habitat, and Irene. 

Worm tubes, including both calcareous and plain forms, jointly ranked fourth in total 

density among platform-associated taxa. The maximum worm tube density of 100 

individuals/0.0625 m2 was observed at Platform Irene, while lowest maximum density of 

1 individual/0.0625 m2 was evident at Platform Habitat (Table 4-8). Highest average density of 

worm tubes was observed at Platform Irene, while lowest average densities were evident at 

Platform Habitat. The predominant depth range for worm tubes, whether calcareous or plain, 

was below approximately 46 m (150 ft), with specimens evident in photographs at 100 m (328 ft) 

or more. Maximum depth of occurrence for worm tubes was 213 m (700 ft). 

The anthozoan anemones Corynactis californica and Anthopleura elegantissima ranked 

seventh and tenth in total density among density-dominant species, respectively (see Tables 4-5

and 4-8). Maximum density of Corynactis californica ranged from a minimum of 33 individuals 

132
to a maximum of 700 individuals/0.0625 m2, with highest densities noted at platforms Habitat, 

Grace, and Gail (where this species ranked first or second in total density). Highest average 

densities of Corynactis were observed at platforms Gail and Habitat, while lowest average 

densities were evident at platforms Irene, Hidalgo, and Harvest, perhaps highlighting a 

difference between Santa Barbara Channel and Santa Maria Basin platforms. This species has a 

rather broad depth distribution, typically between approximately 15 and 61 m (50 and 200 ft), 

although Corynactis was observed at deeper depths (e.g., >91 m [300 ft] at Platform Gail; >61 m 

[200 ft] at Platform Habitat). 

Maximum density of the rosy morph form of Anthopleura elegantissima ranged from 24 to 

185 individuals/0.0625 m2, with highest densities evident at Platform Hidalgo (where it ranked 

fourth and fifth in total density; see Table 4-5). Highest average densities of Anthopleura were 

observed at Platform Hidalgo, while lowest average densities were evident at platforms 

Harvest and Irene. In contrast to Metridium senile, Anthopleura elegantissima (rosy morph) 

exhibited a very restricted depth range, occurring primarily in the upper 1 to 14 m (3 to 45 ft) of 

each submerged platform leg (i.e., with the intertidal, barnacle, and Mytilus zones). 

Ophiuroids, as represented by Ophiothrix spiculata or unidentified ophiuroids, were also 

prevalent on the platforms and were ranked seventh in total density among the dominant 

species. Ophiuroid dominance at each platform varied, ranging in density-based ranking from 

second to tenth (see Table 4-5). Ophiuroids had the second highest total abundance among taxa 

on both legs of Platform Harvest and a single leg of Platform Hidalgo. Maximum densities of 

ophiuroids ranged from 7 to 430 individuals/0.0625 m2. Highest ophiuroid densities were 

noted at Platform Hidalgo, with significantly lower maximum densities at platforms Harvest 

and Grace; lowest maximum ophiuroid densities were evident at platforms Irene, Gail, and 

Habitat. Highest average densities of Ophiothrix spiculata or unidentified ophiuroids were 

observed at Platform Hidalgo, while lowest average densities were evident at platforms Irene, 

Habitat, and Gail. Ophiuroids exhibited a wide depth distribution and were found at nearly all 

depths of a platform, in similar fashion to Metridium senile. 

Several other density-dominant taxa were identified including: 

 Metridium farcimen – sixth highest density at Platform Hidalgo (maximum density: 

42 individuals/0.0625 m2), also relatively high total density-dominant at platforms 

Grace and Gail, with minor contributions at Platform Harvest; 

 Filamentous red algae – fourth and fifth highest total density at Platform Gail, eighth 

highest total density on a single leg at Platform Harvest, and twelfth highest total 

density at Platform Grace; 

 Leucetta/Leucetta losangelensis – third and fifth highest total density at Platform 

Harvest, and tenth and twelfth highest total density at Platform Hidalgo; 

 Paracyathus stearnsii – second and sixth highest total density at Platform Grace 

(maximum density: 201 individuals/0.0625 m2), and seventh highest total density at 

Platform Habitat. 

 Red encruster – eleventh and twelfth highest total density at Platform Harvest, and a 

sub-dominant taxa at platforms Hidalgo and Irene. 

133
 Metridium exilis – highest and second highest total density at Platform Gail, and the 

eighth highest density-dominant at Platform Grace; this species was not encountered 

at any of the remaining platforms. 

Several of these colonial or algal taxa were either counted or their presence noted (by assigning 

the number “1”), including filamentous red algae, Leucetta/Leucetta losangelensis, and red 

encruster. In spite of their low totals when counted, these taxa occurred in a relatively high 

number of photographs and, thus, were recognized as density-dominants. A more 

representative evaluation of their contribution to platform-associated communities is found in 

the following discussion of percent cover. 

4.4.3 Percent Cover Comparisons 

 Several of the density-dominant taxa were also noted as significant fauna elements when 

percent cover was determined. The major taxa, undifferentiated assemblages, or physical 

characteristics evaluated for percent cover (i.e., coverage-dominant) included cnidarians (i.e., 

Metridium senile, Anthopleura elegantissima [rosy morph], Corynactis californica; Metridium 

farcimen), mussels (i.e., Mytilus californianus; Mytilus spp. complex), turf, calcareous worm tubes, 

sponges (tan encrusting, yellow encrusting, Leucetta/Leucetta losangelensis), bare metal, 

encrusters (yellow), ophiuroids (Ophiothrix spiculata), and algae (filamentous red algae, foliose 

red algae). These taxa represented the most prominent and consistent community-formers 

present on the platforms studied. Minimum, maximum, and average percent cover 

determinations for several of the dominant taxa are provided in Table 4-9. 

 At Platform Gail, major contributors to percent cover included Corynactis californica, 

Mytilus spp., Metridium senile, and bare metal, with minor contributions from Anthopleura 

elegantissima (rosy morph), tan encrusting sponge, and turf. At Platform Grace, major 

contributors included Corynactis californica, Mytilus spp., turf, Metridium senile, Anthopleura 

elegantissima (rosy morph), with contributions from filamentous red algae, yellow and tan 

encrusting sponges, and bare metal. 

 At Platform Harvest, major contributors to percent cover included red encruster, 

Leucetta/Leucetta losangelensis, Corynactis californica, Metridium senile, Mytilus spp., a tan 

encrusting sponge, and Metridium farcimen, with contributions from turf, a yellow encrusting 

sponge, and a yellow encruster. At Platform Hidalgo, major contributors included Mytilus spp., 

Metridium senile, Anthopleura elegantissima (rosy morph), and bare metal; lower contributions to 

percent cover were attributed to Leucetta losangelensis, turf, and a yellow encruster. 

 At Platform Habitat, major contributors to percent cover included Corynactis californica, 

Mytilus spp., Anthopleura elegantissima (rosy morph), and filamentous red algae, with minor 

contributions from Ophiothrix spiculata, Metridium senile, and turf. At Platform Irene, major 

contributors included Metridium senile, a tan encrusting sponge, Mytilus californianus/Mytilus

spp., and calcareous worm tubes, with minor contributions from turf, Anthopleura elegantissima

(rosy morph), a yellow encrusting sponge, and a red encruster. 

134
Table 4-9. Minimum, maximum, and average coverage 1 of select dominant taxa (based on percent cover) by 

Gail Grace Harvest Hidalgo Habitat 

Species or 

Taxon Average Min- Max Average Min- Max Average Min- Max Average Min- Max Average M

M

Metridium senile 31.8-41.7 1-95 3.7-36.6 0.5-80 29.5-38.5 1-90 34.9-46.7 0.5-98 11.5 0.Mytilus spp./Mytilus californianus 19.2-60.4 5-90 49.1-52.6 5-85 21.0-35.0 5-90 54.2-57.1 3-85 40.6 4Sponge, yellow encrusting 1.2-3.5 0.5-20 3.5-11.3 0.5-30 5.3-16.1 1-70 0.5-3.0 0.5-3 0.6 0Sponge, tan encrusting 4.0-10.5 0.5-50 6.6-9.8 1-50 7.5-30.0 5-30 7.8-10.0 0.5-20 7.9 1Turf 6.0-8.4 0.4-30 25.6-37.4 1-97 19.3-21.3 0.5-75 18.2-30.1 0.5-80 10.5 0.Bare Metal 33.3-49.2 2-85 7.5-8.4 2-15 7.8-11.5 0.5-50 18.5-39.0 0.5-65 1.0 Corynactis californica 22.8-64.0 0.5-98 42.6-69.2 0.5-100 11.0-42.0 1-90 9.0 2-25 73.5 1-Anthopleura elegantissima (rosy morph)

26.4 0.5-100 8.7-30.8 0.5-90 6.3-8.9 1-20 43.5 1-95 23.0 1

Filamentous red algae ND ND 16.7-21.2 0.5-50 ND ND NP NP 22.6 1Foliose red algae 1.7 1-2 1.2-3.0 0.5-5 5.6-12.2 0.5-30 1.4-2.2 0.5-10 NP NLeucetta/Leucetta losangelensis 10.0 10 6.2 1-20 14.8-48.8 1-80 25.3-30.5 2-80 NP NRed encruster NP NP NP NP 35.4-49.6 2-90 22.4 5-70 NP NMetridium exilis 23.0-62.0 1-95 ND ND NP NP NP NP NP NEncruster, yellow 0.5-0.75 0.5-1 0.8-1.8 0.5-3 13.1-16.0 0.5-70 12.1-30.0 0.5-50 0.5 Metridium farcimen ND ND ND ND 37.0 15-100 17.5-21.7 10-35 NP NOphiothrix spiculata ND ND ND ND ND ND ND ND 10.8 1Worm tubes, calcareous ND ND ND ND ND ND ND ND ND N

1 Minimum, maximum, and average percent cover/0.0625 m2, as presented in Tables 3-3 through 3-12 and Appendix C. Avera

values of taxa from the primary platforms (Gail, Grace, Harvest, Hidalgo) are provided as a range, reflecting averages repres

For example, for Mytilus spp./Mytilus californianus at Platform Gail, average percent cover values of 60.4 and 19.2 percent/0.

for Leg A1 and B1, respectively. Solitary average percent cover values are for taxa from the secondary platforms or for domiwhich only occurred on one leg of a primary platform. 

Notes: ND = present but not determined; NP = not present. 
 Percent cover contributions were frequently variable between platform legs and 

between platforms. Average percent cover estimates, by taxa, ranged from less than one 

percent to >60 percent. Several species exhibited minimum-maximum coverage estimates 

which ranged from 0.5 to 90 or 100 percent, including the major community formers (e.g., 

Mytilus, Corynactis, and, to a lesser extent, Anthopleura) (Table 4-9). Other species did not 

exhibit high percent cover estimates, but were important community formers along the 

mid- and lower portions of the platform (e.g., Leucetta, tan encrusting sponge), underscoring the 

importance of species presence at depth and species-specific depth distribution in the 

characterization of platform-associated communities. 

 

4.4.4 Comparison of Percent Cover Data: PointCount’99® vs. QSA 

 Eighty-one percent of the taxa identified during point count analyses (PointCount’99®) 

were also identified as percent cover dominants during whole or quantitative slide analysis 

(QSA). Table 4-10 lists the 12 dominant taxa and associated characteristics, as determined from 

point count analyses; data include minimum and maximum percent cover, average percent 

cover, and frequency of occurrence. Similarly, this table also provides data for percent cover 

dominants determined during QSA (i.e., as derived from Tables 3-3 through 3-12), as well as 

whether those taxa identified during point contact analyses were also QSA percent cover 

dominants. 

Taxa presented and ranked in Table 4-10 were based on average percent cover, in 

descending order. For example, Corynactis californica exhibited the highest average percent 

cover on Platform Gail, Leg A1 in terms of both point count and QSA rankings. Overall, 

rankings of QSA percent cover dominants were very consistent with PointCount’99® results. 

Strong similarities and a few inconsistencies were evident in a comparison of minimum and 

maximum values, average percent cover estimates, and frequency determinations, as presented 

in Table 4-10. Typically, the top dominants on each platform leg were noted accordingly, 

although shuffling of position between top dominants was evident. Such reshuffling of 

dominant taxa was not unexpected, given the differences between comparison parameters (i.e., 

50 random points vs. whole slide analysis). 

At least one species of interest was potentially under represented in the point count 

approach – mussels. Mytilus spp. on Platform Gail ranked sixth in the point count results with 

an average of 24.9 percent cover; QSA results were considered more representative, ranking 

Mytilus spp. second overall with an average of 60.4 percent cover. Under representation was 

also evident at Platform Grace (Legs C1 and C4) and Hidalgo (Legs A1 and B1), and, to a lesser 

extent, at Platform Harvest (Leg B2). At the other platforms, Mytilus coverage estimates were 

comparable between the two data sets. Under representation was not evident with other 

dominant taxa. For example, Metridium senile and Anthopleura elegantissima (rosy morph) 

coverage was, in general, comparable between point count and QSA determinations. 

In several instances, bare metal was noted as a dominant contributor to percent cover 

during QSA. Because this physical characteristic was not documented during PointCount’99® 

analyses, no direct comparisons between point count and QSA data sets were available for this 

characteristic. 

136
Table 4-10. Comparison of dominant taxa on the six platforms – PointCount’99® vs. QSA – based on perce

PointCount’99® QSA 

Platform 

and Leg Taxa Average Percent 

Cover 

MinimumMaximum Frequency (%) D-R Average Percent Cover Minim

Maxim

Platform Gail: 

Leg A1 

Corynactis californica 

Metridium senile 

Desmophyllum dianthus Anthopleura elegantissima (rm) Red Algae Mytilus spp. Zoanthidea 

Metridium farcimen 

Turf Metridium exilis Ophiothrix spiculata Aglaophenia sp. 

62.4 37.6 30.6 29.7 29.2 24.9 23.4 20.4 19.7 17.8 

8.5 8.0 

2-100 

2-94 2-60 

2-100 

4-66 2-48 6-84 2-68 2-70 2-60 2-20 

8 

34.2 60.4 15.3 11.7 23.4 12.6 

6.3 4.5 

74.8 27.0 79.3 

0.9 

Y (1) Y (3) 

Y (D) 

Y (5) 

Y (D) 

Y (2) Y (7) 

Y (D) 

Y (8) Y (6) 

Y (D) 

N 

64.0 41.7 

ND 

26.4 

ND 

60.4 10.0 

ND 

6.0 

23.0 

ND 

NP 

1-98 1-95 

ND 

0.5-10

ND 

5-90 5-15 

ND 

0.4-2

1-80 

ND 

NP 

Leg B1 

Metridium exilis 

Turf Corynactis californica 

Metridium senile 

Pleurobranchaea californica Desmophyllum dianthusRed Al

gae 

Metridium farcimen 

Mytilus spp. Porifera Ophiothrix spiculata Zoanthidea 

59.7 41.0 34.6 28.6 18.0 17.6 16.6 16.0 14.9 10.3 

7.5 7.5 

2-96 2-92 2-96 2-68 

18 

2-54 2-50 

16 

2-44 2-32 2-18 2-12 

57.3 56.4 20.9 31.8 

0.9 

15.5 18.2 

0.9 

15.5 40.9 

3.6 3.6 

Y (1) 

Y (11) 

Y (5) Y (3) 

N 

Y (D) Y (D) 

N 

Y (6) Y (7) 

Y (D) 

Y (12) 

62.0 

8.4 

22.8 31.8 

ND ND 

1.7 

ND 

19.2 10.5 

ND 

6.8 

1-95 

0.5-30.5-9

1-84 

ND ND 

1-2 

ND 

5-85 

0.5-4

ND 

2-15 

Platform Grace: 

Leg C1 

Corynactis californica Turf Anthopleura elegantissima (rm)

Metridium farcimen 

Mytilus spp. Obelia sp. Red Al

gae 

Paracyathus stearnsii Ophiothrix spiculata Rockfish 

Metridium senile 

Ophionereis sp. 

47.4 36.6 34.6 27.0 24.7 23.7 19.4 15.8 12.7 10.0 

9.3 9.3 

2-90 2-94 2-86 

26-28 

2-52 2-52 2-56 2-56 2-24 

10 

2-22 2-24 

44.7 86.2 21.3 

2.1 

20.2 19.1 25.5 24.5 12.8 

1.1 3.2 6.4 

Y (2) Y (3) Y (4) 

N 

Y (1) 

Y (D) 

Y (6) 

Y (D) Y (D) 

N 

Y (14) 

N 

42.6 37.4 30.8 

ND 

49.1 

1.0 

21.2 

ND ND ND 

3.7 

ND 

0.5-9

1-97 

0.5-9

ND 

5-80 

1 

0.5-5

ND ND ND 

0.5-1

ND 
Table 4-10. Comparison of dominant taxa on the six platforms – PointCount’99® vs. QSA – based on perce

(continued). 

PointCount’99® QSA 

Platform 

and Leg Taxa Average Percent 

Cover 

MinimumMaximum Frequency (%) D-R Average Percent Cover Minim

Maxim

Leg C4 

Corynactis californica Zoanthidea 

Metridium senile 

Metridium farcimen Mytilus spp. Turf 

Metridium exilis 

Red Al

gae 

Ophiothrix spiculata Green Al

gae 

Anthopleura elegantissima (rm)Obelia sp. 

78.3 42.3 41.1 37.8 30.0 22.0 16.0 14.7 13.9 13.0 12.5 

9.0 

10-100 

8-84 2-90 2-80 2-58 2-70 8-28 2-30 2-40 8-18 2-26 2-22 

39.4 

6.4 

40.4 

9.6 

26.6 76.6 

3.2 

20.2 29.8 

2.1 

13.8 

4.3 

Y (1) Y (4) Y (3) 

Y (D) 

Y (2) Y (5) 

Y (D) 

Y (7) 

Y (D) 

N 

Y (10) 

N 

69.2 37.6 36.6 

ND 

52.6 25.6 

ND 

16.7 

ND ND 

8.7 

ND 

2-100 

3-90 

0.5-8

ND 

5-85 1-90 

ND 

1-50 

ND ND 

1-20 

ND 

Platform Harvest:

Leg B1 

Metridium senile Metridium farcimen Pisaster sp. Turf Corynactis californica Mytilus spp. Porifera Red Al

gae 

Macroalgae Anthopleura elegantissima (rm)

Bryozoa, erect Encruster 

47.3 45.3 40.0 39.5 32.0 25.0 14.9 11.6 10.0 

9.8 8.0 7.7 

2-96 

10-100 

40 

2-98 2-96 2-50 2-68 2-22 4-16 2-22 

8 

2-28 

84.0 

3.2 1.1 

81.9 

5.3 

19.1 45.7 18.1 

2.1 

11.7 

1.1 

26.6 

Y (2) Y (3) 

N 

Y (6) Y (1) Y (7) Y (9) 

Y (11) 

N 

Y (17) 

Y (D) 

Y (4) 

38.5 37.0 

ND 

21.3 42.0 21.0 

7.5 

12.2 

ND 

6.2 0.5 

35.4 

1-90 

15-10

ND 

1-75 3-90 5-50 5-10 1-30 

ND 

1-20 

0.5 

2-75 

Leg B2 

Turf 

Metridium senile 

Mytilus spp. Porifera Corynactis californica Red Al

gae 

Encruster Porifera, erect Anthopleura elegantissima (rm)

Ophiothrix spiculata Obelia sp. Galathea californiensis 

35.6 34.2 23.3 21.5 16.7 15.3 15.3 14.0 13.6 12.9 11.0 

6.7 

2-96 2-76 4-44 2-64 2-42 2-38 2-64 

14 

2-30 2-38 6-16 2-12 

90.0 84.4 23.3 41.4 

6.7 

10.0 60.0 

1.1 

16.7 16.7 

2.2 3.3 

Y (7) Y (5) Y (3) Y (4) 

Y (10) Y (14) 

Y (1) Y (2) 

Y (11) 

Y (D) 

N N 

19.3 29.5 35.0 30.0 11.0 

5.6 

49.6 48.8 

8.9 

ND ND ND 

0.5-7

2-90 5-90 

30 

1-20 

0.5-2

3-90 5-80 2-20 

ND ND ND 
Table 4-10. Comparison of dominant taxa on the six platforms – PointCount’99® vs. QSA – based on perce

(continued). 

PointCount’99® QSA 

Platform 

and Leg Taxa Average Percent 

Cover 

MinimumMaximum Frequency (%) D-R Average Percent Cover Minim

Maxim

Platform Hidalgo:

Leg A1 

Metridium senile 

Mytilus spp. Turf 

Metridium farcimen 

Porifera Porifera, erect Corynactis californica Ophiothrix spiculata Pisaster sp. Encruster Red Al

gae 

Fan Worm 

47.7 36.5 27.1 20.7 17.5 15.0 12.8 10.2 10.0 

9.1 9.0 5.0 

2-94 8-62 2-60 8-42 2-64 

10-20 

4-34 2-42 4-16 2-52 6-12 

2-8 

93.8 20.3 57.8 

4.7 

71.9 

3.1 7.8 

51.6 

6.3 

54.7 

3.1 3.1 

Y (2) Y (1) Y (8) Y (5) 

Y (D) 

Y (4) 

Y (11) 

Y (D) Y (D) 

Y (3) 

Y (15) 

N 

46.7 57.1 18.2 21.7 27.8 25.3 

9.0 

ND ND 

16.2 

2.2 

ND 

3-90 5-85 2-40 

10-35 

0.5-2

5-60 2-25 

ND ND 

1-60 

0.5-1

ND 

Leg B1 

Anthopleura elegantissima (rm)Mytilus spp. Metridium senile Turf 

Metridium farcimen 

Porifera Ophiothrix spiculata Encruster Porifera, erect Cancer sp. Florometra serratissima Pisaster spp. 

51.6 45.7 39.6 36.8 17.0 15.9 12.2 11.9 11.0 10.0 10.0 

9.0 

4-90 6-72 2-94 

2-100 10-24 

2-46 2-38 2-64 2-20 

10 10 

2-14 

9.5 

27.4 78.6 77.4 

2.4 

52.4 33.3 45.2 

2.4 1.2 1.2 4.8 

Y (2) Y (1) Y (4) Y (6) Y (8) Y (5) 

Y (D) 

Y (7) 

N N N 

Y (D) 

43.5 54.2 34.9 30.1 17.5 30.5 

ND 

22.4 

ND ND ND ND 

1-95 3-80 

0.5-90.5-8

15-20 

2-80 

ND 

5-70 

ND ND ND ND 

Platform Habitat:

Leg A1 

Corynactis californica Zoanthidea Metridium farcimen Mytilus spp. Anthopleura elegantissima (rm)

Metridium senile Turf Red Algae Rockfish Ophiothrix spiculata Coenocyathus bowersi Paracyathus stearnsii 

74.1 59.3 55.1 30.6 30.1 22.9 15.8 13.6 

8.0 7.7 6.7 6.7 

4-100 4-100 2-100 

2-70 

10-98 

2-78 2-94 2-48 2-14 2-24 2-18 2-16 

49.3 

8.0 

14.7 28.0 18.7 36.0 80.0 28.0 

2.7 

24.0 14.7 12.0 

Y (1) Y (3) 

Y (D) 

Y (2) Y (4) Y (7) Y (8) Y (5) 

N 

Y (6) 

N 

Y (10) 

73.5 32.3 

ND 

40.6 23.0 11.5 10.5 22.6 

ND 

10.8 

ND 

5.2 

1-100 

1-99 

ND 

4-100 

1-95 

0.5-30.5-9

1-50 

ND 

1-60 

ND 

1-10 
Table 4-10. Comparison of dominant taxa on the six platforms – PointCount’99® vs. QSA – based on perce

(continued). 

PointCount’99® QSA 

Platform 

and Leg Taxa Average Percent 

Cover 

MinimumMaximum Frequency (%) D-R Average Percent Cover Minim

Maxim

Platform Irene: 

Leg A1 

Metridium senile Metridium farcimen 

Mytilus spp. Porifera Turf Red Al

gae 

Balanus spp. Green Algae Pollicipes polymerus Pisaster sp. Anthopleura elegantissima (rm)

Cancer sp. 

57.4 42.0 29.7 18.1 14.7 11.8 10.2 

8.0 7.0 6.2 5.0 4.5 

4-100 

42 

2-56 2-48 2-54 2-48 2-28 

8 

2-12 2-12 

2-8 2-6 

88.1 

1.5 

59.7 46.3 71.6 16.4 25.4 

1.5 3.0 

13.4 

9.0 6.0 

Y (1) 

Y (D) 

Y (5) Y (4) Y (8) 

Y (D) Y (D) 

Y (9) 

Y (D) Y (D) 

Y (10) 

Y (D) 

66.0 

ND 

29.5 32.4 10.2 

ND ND 

10.0 

ND ND 

3.9 

ND 

3-90 

ND 

2-85 1-60 1-25 

ND ND 

10 

ND ND 

0.5-1

ND 

Notes: D-R = Dominant-Rank; indicates whether the taxon was a percent cover dominant or subdominant identified during QSA (Y 

what rank; QSA percent cover rankings noted in parentheses. In cases where a taxon was not determined (ND) during QSA pQSA density data were reviewed and applied, as appropriate (e.g., QSA frequency of occurrence column); ranking entries maof the taxon as a density dominant or subdominant (D). 

Taxonomic notes: 

− Anthopleura elegantissima (rm) = Anthopleura elegantissima (rosy morph)− Zoanthidea noted during PointCount’99® analyses identified as Zoanthid, colonial tan (Platform Gail, Legs A1 and B1; Platform Gra

Habitat, Leg A1) or Zoanthid (Palythoa) (Platform Habitat, Leg A1) during QSA.

− Red algae noted during PointCount’99® analyses identified as Filamentous or Foliose red algae during QSA (present on all except Pl− Porifera noted during PointCount’99® analyses identified as sponge, tan encrusting (Platform Gail, Leg B1; Platform Harvest, Leg B1

encrusting and sponge, tan foliose (combined) (Platform Hidalgo, Leg A1) during QSA. Porifera noted during PointCount’99® an

Leucetta losangelensis during QSA (Platform Hidalgo, Leg B1).

− Porifera, erect noted during PointCount’99® analyses identified as Leucetta/Leucetta losangelensis during QSA (Platform Harvest, Leg − Ophionereis sp. noted during PointCount’99® analyses identified as Ophiuroid, unidentified during QSA (Platform Grace, Leg C1).− Rockfish noted during PointCount’99® analyses identified as Sebastes spp. during QSA (Platform Grace, Leg C1).− Green algae noted during PointCount’99® analyses identified as Ulva lactuca during QSA (Platform Grace, Leg C4).− Bryozoa, erect noted during PointCount’99® analyses identified as Bryozoa, tan branching during QSA (Platform Harvest, Leg B1).− Encruster noted during PointCount’99® analyses identified as Encruster, red during QSA (Platform Harvest, Leg B1; Platform Hidal

noted during PointCount’99® analyses identified as Encruster – tan and Encruster – lavender (combined) during QSA (Platform H

− Pisaster sp./spp. noted during PointCount’99® analyses identified as Pisaster ochraceus, P. brevispinus, and P. giganteus (Platform Hida

and P. ochraceus (Platform Hidalgo, Leg B1), or P. ochraceus (Platform Harvest, Leg B1) during QSA.

− Metridium farcimen noted during PointCount’99® analyses identified as Metridium sp. during QSA (only at Platform Habitat, Leg A− Cancer sp. noted during PointCount’99® analyses identified as Cancer antennarius and Cancer sp. (combined) during QSA (Platform 
During point count analyses, several taxa were identified using a different set of 

descriptors. Undifferentiated groups which were noted during point counts were lumped into 

larger categories (e.g., sponges, encrusters, red algae). Comparisons of point count findings to 

QSA results prompted a series of clarifying notes relevant to phylogenetic classification and 

species distribution by platform, as footnoted in Table 4-10. These notes rectify several minor 

inconsistencies in terminology. For example, Zoanthidae noted during point count analyses 

were identified as either Zoanthid, colonial tan (Platform Gail, Legs A1 and B1; Platform Grace, 

Leg C4; Platform Habitat, Leg A1) or Zoanthid (Palythoa) (Platform Habitat, Leg A1) during 

QSA. 

Several taxa were not determined during QSA percent cover analyses but were 

identified during point count analyses. In many cases, percent cover determinations for these 

taxa were not practical (e.g., barnacles – Balanus nubilus and Balanus spp.; Metridium farcimen; 

Desmophyllum dianthus; Ophiothrix spiculata; Paracyathus stearnsii; Pisaster sp./spp.); however, 

individual count data for these taxa were available and frequency of occurrence data were 

integrated into Table 4-10. 

In one instance, a taxon was identified during the point count analyses which had not 

been noted during QSA (e.g., Aglaophenia sp.). In several other instances, taxa identified during 

point count were not among the taxa identified during QSA (e.g., Obelia sp. on Platform Grace, 

Leg C4; Platform Harvest, Leg B2; fan worm on Platform Hidalgo, Leg A1). Because point 

count analyses utilized digital images (while QSA relied upon the projection of 35-mm slide 

transparencies), additional flexibility was available to the taxonomists to further identify 

specimens. For example, an image area containing a specimen of interest could be digitally 

magnified, allowing for closer examination of key taxonomic characteristics. Image 

comparisons could also be made to assist in species identifications. In those cases where new 

taxa were identified (i.e., taxa not observed during QSA), their frequency of occurrence was 

extremely low. 

Overall, the presence and relative ranking of percent cover dominants from the 

PointCount’99® analysis were very consistent with the results of whole slide analysis. While 

random point count provides a straightforward means of identifying percent cover dominants 

within a photographic image, whole slide analysis, based either on individual counts or percent 

cover estimates, provides a more comprehensive characterization of all taxa present, within the 

limitations of photographic interpretation and identification. 

4.4.5 Clustering Analyses 

Quantitative (Whole) Slide Analysis

Platform Leg Comparisons

 The initial clustering analysis combined all whole slide data from each single platform 

leg, effectively eliminating all biotic zones, to create ten separate single data sets. This process 

was repeated for both density (i.e., count) and percent cover data. 

141
 Results of the clustering analysis using the density data sets (see Figure 3-15) indicated 

greatest similarity (~80 percent) between (1) adjacent legs on Platform Harvest; (2) adjacent legs 

on Platform Hidalgo; and (3) Platform Gail (Leg A1) and Platform Grace (Leg C4). At the next 

similarity level, Platform Habitat (Leg A1) exhibited an affinity with the Platform Gail (Leg A1)-

Platform Grace (Leg C4) grouping. This three-platform grouping next showed affinity with 

Platform Grace (Leg C1). Platform Harvest and Habitat groups also showed similarity to one 

another, then coupled with Platform Gail (Leg B1), and finally with Platform Irene, Leg A1. At 

the lowest similarity level, the Grace-Gail (Leg A1)-Habitat group was separate from the 

Harvest-Hidalgo-Irene-Gail (Leg B1) group. 

 While similarity between adjacent legs on the same platform might be expected, the high 

level of similarity between Grace and Gail was not. While Grace and Gail are both located in 

the eastern Santa Barbara Channel, there are significant water depth differences and 

corresponding differences in the total number of biotic zones between the two platforms. The 

process of combining data along a platform leg effectively eliminates any biotic zone bias that 

might be introduced and allows for a direct comparison of flora and fauna between legs. In this 

instance, it appeared that the relative contribution of fauna from the lower zone of Gail had 

minor effect on clustering; the strong similarities evident were attributed to geographic 

proximity. Support for this hypothesis was also evident in subsequent groupings, where the 

Santa Barbara Channel platforms (Habitat-Grace-Gail) exhibited similarity with one another 

and the Santa Maria Basin platforms (Harvest-Hidalgo-Irene) grouped in similar fashion. The 

inconsistent element in the clustering results rested with Platform Gail (Leg B1), which showed 

similarity with Harvest-Hidalgo-Irene. No obvious explanation was available to explain this 

clustering result. 

 Results of the clustering analysis using percent cover data (see Figure 3-16) were very 

similar to those shown by the count data and strongly supported similarities between adjacent 

legs. Greatest similarities, in descending order, were evident between adjacent legs on all 

primary platforms – Harvest, Hidalgo, Gail, and Grace. The secondary platforms grouped 

according to geographic location: Habitat grouped with Grace, while Irene grouped with the 

Hidalgo-Harvest grouping. 

Biotic Zone Comparisons

The second clustering of whole slide data determined the similarities between biotic 

zones, with separate analyses using density (i.e., count) and percent cover data. By maintaining 

separate biotic zones, 52 total data sets were compared. 

Results of clustering analysis using density data (see Figure 3-17) indicated strongest 

similarities between (1) Platform Irene (Leg A1) Mytilus and Corynactis zones; (2) Platform 

Harvest (Legs B1 and B2) Metridium/sea star zones; and (3) Platform Hidalgo (Leg B1) intertidal 

and Mytilus zones. Unexpectedly high similarities were noted for (1) Platform Gail (Leg A1) 

barnacle/scallop and Platform Habitat (Leg A1) Corynactis zones; and (2) Platform Grace 

(Leg C4) encruster/sea star and Platform Harvest (Leg B1) vase sponge/encruster zones. The 

Gail-Habitat anomaly was explained through a review of the dominant taxa present in each 

respective zone. The barnacle/scallop zones of Platform Gail, while relatively devoid of 

scallops, contained numerous barnacles, ophiuroids (including Ophiothrix spiculata), and 

142
anemones (Corynactis californica, Metridium senile, and M. exilis). Corynactis californica, Ophiothrix 

spiculata, and barnacles were also dominants in the Corynactis zone of Platform Habitat. 

 The top down analysis of density clustering results produced three groupings which 

generally reflected community water depth. Group A, comprised of 18 data sets, consisted 

exclusively of intertidal and Mytilus communities of platforms Gail, Grace, Harvest, Hidalgo, 

and Habitat, with small contributions from barnacle/scallop and Corynactis assemblages from 

Platform Gail. The intertidal assemblages at Platform Irene were outliers, perhaps a result of 

the low species diversity evident at this platform. Group B, comprised of 25 data sets, consisted 

exclusively of Metridium/sea star, Metridium/encruster, anemone/encruster, and vase 

sponge/encruster zones of platforms Gail, Harvest, Hidalgo, and Habitat, plus several 

contributions from the barnacle zone of Platform Hidalgo. The last group, Group C, was 

comprised of nine data sets and consisted of barnacle/scallop, Corynactis/encruster, 

encruster/sea star, and anemone/encruster zones from platforms Gail, Grace, and Habitat. 

Results of clustering analysis using percent cover data (see Figure 3-18), while 

producing associations which were not identical to those noted with the count data, did identify 

strong similarities between adjacent zones of the same platform leg or the same zones between 

adjacent legs. In general, with minor exception, similarity groupings (based on count or percent 

cover biotic zone data resulting from whole slide analysis) tended to occur between adjacent 

zones of the same platform leg (e.g., intertidal and Mytilus) or the same zones between adjacent 

legs. These results suggested that there was (1) a strong similarity between biota of adjacent 

platform legs, and (2) a gradual shift in community structure with increasing depth along a 

platform leg. Further, the boundaries of each biotic zone were not tied strictly to water depth. 

 The top down analysis of percent cover clustering results produced four groupings. 

Group A, comprised of seven data sets, consisted of intertidal and Mytilus communities from 

platforms Gail and Habitat. Group B, comprised of 15 data sets, consisted of intertidal and 

Mytilus communities from platforms Grace, Harvest, and Hidalgo, with small, anomalous 

contributions from sponge/encruster and encruster/sea star zones of platforms Hidalgo and 

Grace. Group C, comprised of 22 data sets, consisted barnacle, barnacle/Corynactis, 

barnacle/algae, Corynactis/encruster, Metridium/sea star, and Metridium/encruster 

communities from platforms Gail, Harvest, and Hidalgo, with minor contributions from vase 

sponge/encruster and vase sponge/sea star/cup coral assemblages from platforms Harvest and 

Gail, respectively. Group D, comprised of seven data sets, consisted of barnacle/scallop and 

anemone/encruster communities from platforms Grace and Gail, with minor contribution from 

Corynactis and Metridium/encruster assemblages from Platform Habitat. One lone outlier, the 

intertidal zone from Platform Irene, was not grouped with any of the communities noted above. 

These results highlight the similarities evident between intertidal and Mytilus zones of all 

platforms, with no strong indication of differences attributed to geographic location. 

PointCount’99® Analysis

 The first clustering analysis of PointCount’99® data determined similarities between 

platform legs (see Figure 3-19). Greatest similarities were evident between (1) adjacent legs on 

Platform Harvest; and (2) adjacent legs on Platform Hidalgo. Subsequent groupings included 

(1) Platform Grace (Leg C4) and Platform Habitat (Leg A1); and (2) Platform Harvest (Legs B1 

143
and B2) and Platform Hidalgo (Legs A1 and B1). These groupings were identical to those 

exhibited in the first clustering analysis of whole slide data (i.e., count data set), with the 

exception of the Grace-Hidalgo grouping. While the Harvest-Hidalgo grouping suggests a 

strong similarity between these two southern Santa Maria Basin platforms, no other groupings 

suggested a geographic-based similarity. 

 The second clustering of PointCount’99® data determined the similarities between biotic 

zones (see Figure 3-20). Greatest similarities were evident between (1) Platform Irene (Leg A1) 

Mytilus and Corynactis zones; (2) Platform Gail (Leg A1) barnacle/scallop and Platform Grace 

(Leg C4) barnacle/scallop zones; (3) Platform Harvest (Leg B2) anemone/encruster and 

Platform Hidalgo (Leg A1) sponges/encruster zones; and (4) Platform Hidalgo (Legs A1 and 

B1) intertidal zones. The Irene Mytilus and Corynactis grouping was also evident in the first 

clustering of whole slide data, however, the remaining groupings were not evident in the earlier 

clustering analysis. Strongest similarities were evident between similar zones (e.g., intertidal, 

Metridium/encruster), regardless of platform geographic location or water depth. 

 The top down analysis of the PointCount’99® biotic zone data sets resulted in the 

identification of four groupings. Group A, comprised of 14 data sets, consisted of select 

intertidal and Mytilus communities from platforms Gail, Grace, Harvest, Hidalgo, Habitat, and 

Irene. This grouping suggests a similarity between intertidal and Mytilus zones, exclusive of 

Groups C and D (below), regardless of geographic location. Group B, comprised of 14 data sets, 

consisted of (1) Corynactis/encruster, encruster/sea star/cup coral, and vase sponge/encruster 

communities of Platform Gail; (2) Mytilus and encruster/sea star communities of Platform 

Grace; (3) anemone/encruster, vase sponge/encruster, and Metridium/sea star communities of 

Platform Harvest; and (4) sponges/encruster communities of Platform Hidalgo. This grouping 

suggested similarity between the zones present in intermediate water depths of select 

platforms, most of which were characterized by the presence of encrusters, regardless of 

geographic location. Group C, comprised of 14 data sets, consisted of (1) Mytilus, 

barnacle/Corynactis, and Metridium/sea star communities of Platform Harvest; (2) Mytilus, 

barnacle, and Metridium/encruster communities of Platform Hidalgo; and (3) barnacle/algae, 

Mytilus, and Corynactis/encruster communities of Platform Irene. This grouping suggested 

similarity of biotic zones across a depth range for the northern platforms, and indicated that 

several taxa (e.g., Metridium senile, Leucetta) that were widely distributed down a platform leg 

produced a biotic continuum which countered the concept of distinct biotic zones. Group D, 

comprised of 10 data sets, consisted of (1) intertidal, Mytilus, barnacle/scallop, and vase 

sponge/encruster communities of Platform Gail; (2) barnacle/scallop and anemone/encruster 

communities of Platform Grace; and (3) Corynactis and Metridium/encruster communities of 

Platform Hidalgo. This grouping also suggested the presence of a biotic continuum, with 

several species present (and often dominant) in adjacent biotic zones (e.g., Ophiothrix spiculata, 

Metridium senile, barnacles, Corynactis californica). 

Diablo and Nifty Rocks and Comparable Platform Zones

 The last set of clustering analyses employed whole slide data to determine the 

similarities between epibiota of natural rock outcrops and platform legs within similar water 

depths using density (i.e., count) and percent cover data sets (see Figures 3-21 and 3-22). 

144
 Results of clustering analysis using count data, comparing platform biota to natural 

outcrop communities in the 5 to 17 m depth range, indicated greatest similarities between 

(1) Platform Hidalgo (Leg A1) and Platform Irene (Leg A1); (2) Platform Grace (Leg C1) and 

Diablo Rock; and (3) Platform Harvest (Legs B1 and B2). At the next similarity level, three 

groupings were evident, including: (1) Nifty Rock with the Hidalgo-Irene group; (2) Hidalgo 

(Leg B1) with the Harvest (Leg B1-Leg B2) grouping; and (3) Platform Gail (Legs A1 and B1). 

Results of the clustering analysis using density data indicated that (1) natural outcrop 

communities have a moderate affinity with select platform communities – Diablo Rock with 

Platform Grace and Nifty Rock with the Hidalgo-Irene group; (2) there were strong similarities 

between adjacent platform legs; and (3) similarities between biota within the upper depth zones 

(Mytilus, barnacle/scallop, barnacle/algae) of two of the northern platforms (Hidalgo and 

Irene). 

 Results of the clustering analysis using percent cover data revealed greatest similarities 

for (1) Platform Hidalgo (Leg A1) and Platform Irene (Leg A1); (2) Platform Grace (Leg C4) with 

the Hidalgo-Irene group; and (3) Platform Harvest (Leg B2) with the Grace-Hidalgo-Irene 

group. Diablo Rock exhibited closest affinity to the Harvest-Grace-Hidalgo-Irene group, while 

Nifty Rock showed greatest similarity with Platform Grace (Leg C1). Aside from the 

Hidalgo-Irene grouping, none of the percent cover similarities were evident in the earlier count 

data comparisons. No readily discernable trends were evident. 

4.5 Depth Distribution of Platform-Associated Biota 

A total of four to six biotic zones were identified for each platform, depending upon 

water depth, as outlined in Section 3.1. The review of inspection videotapes provided a 

continuous broad view and characterization of the invertebrate and algal communities present 

on platform legs, from the intertidal to the base of each platform. In contrast, the results of the 

quantitative slide analysis, where 15 or more 35-mm slide transparencies from each biotic zone 

were evaluated, provided identification and enumeration of all recognizable species present 

(i.e., numbers of individuals and percent cover per 0.0625 m2). 

Density- and coverage-dominant taxa identified at each platform were tabularized in 

Tables 3-3 through 3-12 and summarized in the accompanying text of Section 3.3. Table 4-11

provides a narrative summary of the depth distributions of density- and percent-cover 

dominants at each platform. For primary platforms, depth information for the species present 

on adjacent legs has been combined, reflecting a composite characterization of depth 

distribution. For secondary platforms, depth-related species data from a single leg has been 

summarized. 

In general, the biotic zones determined from videotape analysis were confirmed through 

the photographic analysis. Mussel zones were always present, although their vertical extent 

may have differed from those estimated from the videotapes alone. This was not necessarily 

unexpected given the fact that the videotapes were representative of all platform legs, while the 

present analysis considered only one or two legs; reviewers normally identified maximum 

depth of occurrence for the mussel zone. Further, considerable time may have separated the 

collection of videotape information from the collection of photographic data during the current 

analysis. 

145
Table 4-11. Comparison of biotic zones and species/taxon presence by depth at six platforms. 

Biotic Zone 

Designation 

Zone Depth 

[ft (m) subsurface] Prominent Taxa 

Platform Gail, Legs A1 and B1  Intertidal 0 to 6 

(0 to 1.8 m) 

This zone was comprised predominantly of barnacles (Balanus spp.), algae (fi

(Mytilus spp.), anemones (Anthopleura elegantissima [rosy morph]; Metridium e

branching hydroids 

 Mytilus 6 to 40 

(1.8 to 12.1 m) 

Mytilus spp. occurred from 3 to 53 ft; mussels co-occurred with algae (filamen(Ophiothrix spiculata and unidentified ophiuroids), and Metridium senile

 Barnacle/Scallop 40 to 160 

(12.1 to 48.8 m) 

Balanus spp. occurred from 3 to 57 ft; Crassadoma was found in low abundanc

24, 53, 74, 127, and 173 ft; ophiuroids (Ophiothrix spiculata, unidentified ophiu

(Corynactis californica, Metridium senile, and M. exilis) were numerical dominan

tan encrusting sponge and a yellow encrusting sponge were contributors to p

Corynactis/Encruster 160 to 380 

(48.8 to 115.8 m) 

Corynactis californica occurred from 144 to 199 ft; Metridium exilis was present 

between 36 and 322 ft; turf was also present, contributing to percent cover 

 Vase sponge/ 

Encruster 

380 to 630 

(115.8 to 192.0 m) 

No vase sponges (e.g., Staurocalyptus, Leucilla) were present in this depth rang

by Metridium senile, Ophiothrix spiculata, limited presence of Corynactis californ

 Encruster/Sea Star/  Cup Coral 

630 to 739 

(192.0 to 225.2 m) 

Paracyathus stearnsii occurred from 173 to 184 ft, 261 to 315 ft, and 415 ft; this zMetridium senile, Desmophyllum, and plain worm tubes, as well as turf 

Platform Grace, Legs C1 and C4  Intertidal 0 to 6 

(0 to 1.8 m) 

This zone was comprised primarily of barnacles (Balanus spp.), algae (filamen

(Mytilus spp.), and anemones (Anthopleura elegantissima [rosy morph]; Metridi

 Mytilus 6 to 45 

(1.8 to 13.7 m) 

Mytilus spp. was predominant in this zone betweem 3 and 40 ft, with limited californianus; mussels co-occurred with the anemone Anthopleura elegantissima 

(Ophiothrix spiculata), and Metridium senile

 Barnacle/Scallop 45 to 90 

(13.7 to 27.4 m) 

Balanus nubilus was present at 49, 61, and 76-133 ft; Crassadoma gigantea exhibbetween 69 and 146 ft; Corynactis californica occurred in dense aggregations thdepths of 50 to 150 ft 

 Anemone/Encruster 90 to 230 

(27.4 to 70.1 m) 

Metridium senile was very limited in its presence in this zone, however, M. far

between 150 and 200 ft and beyond; this depth zone was dominated by Coeno

californica, and Metridium farcimen

 Encruster/Sea Star 230 to 318 

(70.1 to 96.9 m) 

Asterina was present from 238 to 308 ft), although not a dominant; this depth Metridium farcimen and Paracyathus stearnsii; a tan zoanthid was also present a

dominant 
Table 4-11. Comparison of biotic zones and species/taxon presence by depth at six platforms (continued). 

Biotic Zone 

Designation 

Zone Depth 

[ft (m) subsurface] Prominent Taxa 

Platform Harvest, Legs B1 and B2  Intertidal 0 to 6 

(0 to 1.8 m) 

This zone was comprised primarily of barnacles (Balanus spp.), algae (filamen

anemones (Anthopleura elegantissima [rosy morph]; Metridium senile), and a lim

(Mytilus spp.) and sponges (Leucetta) 

 Mytilus 6 to 85 

(1.8 to 25.9 m) 

Mytilus spp. occurred from 2 to 46 ft; barnacles (Balanus spp.), unidentified op

as Ophiothrix spiculata from scraping results), and Leucetta were also dominan

 Barnacle/Corynactis 85 to 165 

(25.9 to 50.3 m) 

Balanus spp. exhibited relatively high abundance from 100 to 157 ft; Corynactiintermittently between 101 and 146 ft but was rarely a numerical or percent c

was also densely populated by Metridium senile, some Leucetta, and, along it l

 Anemone/Encruster 165 to 345 

(50.3 to 105.2 m) 

Metridium senile occurred along almost the entire length of the platform as bopercent cover dominant; a red encruster was prevalent between below 176 ft; tubes, and bare metal were also common in this zone 

 Vase Sponge/ 

Encruster 

345 to 555 

(105.2 to 169.2 m) 

Staurocalyptus was not present; Leucilla was present intermittently between 90 

occupied primarily by Metridium senile, calcareous worm tubes, a red encrustand bare metal 

 Metridium/Sea Star 555 to 675 

(169.2 to 205.7 m) 

Metridium senile occurred along almost the entire length of the platform and wdepth range; a red encruster was also prevalent, co-occurring with calcareoubare metal; no sea stars were evident within this depth range 

Platform Hidalgo, Legs A1 and B1  Intertidal 0 to 6 

(0 to 1.8 m) 

This zone was comprised primarily of barnacles (Balanus spp.; Balanus nubilu

anemones (Metridium senile; a few Anthopleura elegantissima [rosy morph]), mu

sponges (Leucetta losangelensis), and a feather duster worm Eudistylia polymorp

 Mytilus 6 to 65 

(1.8 to 19.8 m) 

Mytilus spp. occurred from 2 to 29 ft; barnacles (primarily Balanus nubilus), an

Anthopleura elegantissima [rosy morph]), ophiuroids, and Leucetta were also do

 Barnacle 65 to 105 

(19.8 to 32.0 m) 

Balanus nubilus occurred as a dominant species from 5 to 101 ft; this zone was Corynactis californica (on Leg A1 only) and sponges (Leucetta)

 Metridium/Encruster 105 to 360 

(32.0 to 109.7 m) 

Metridium senile occurred from 103 to 165 ft and from 340 to 424 ft; this zone wophiuroids, with frequent presence of calcareous worm tubes, turf, and, in thzone, Leucetta

 Sponges/Encruster 360 to 434 

(109.7 to 132. 3 m) 

Leucetta did not occur below 222 ft; calcareous worm tubes, Metridium senile, M

unidentified ophiuroids were dominants in this depth range; M. farcimen occu

platform, from 427 to 431 ft; tan and lavender encrusters and turf were also p

zone 
Table 4-11. Comparison of biotic zones and species/taxon presence by depth at six platforms (continued). 

Biotic Zone 

Designation 

Zone Depth 

[ft (m) subsurface] Prominent Taxa 

Platform Habitat, Leg A1  Intertidal 0 to 6 

(0 to 1.8 m) 

This zone was comprised primarily of mussels (Mytilus spp.), anemones (Met

elegantissima [rosy morph]), barnacles (Balanus nubilus), and ophiuroids (Ophi

 Mytilus 6 to 60 

(1.8 to 18.3 m) 

Mytilus occurred from 4 to 52 ft (and at 77 to 78 ft); this zone was dominated 

dominants Metridium senile, Anthopleura elegantissima, Balanus nubilus, and Op

species of interest in the lower portions of this zone included the dorid nudib

and the sponge Staurocalyptus

 Corynactis 60 to 180 

(18.3 to 54.9 m) 

Corynactis occurred between 50 and 205 ft in relative high densities; other speincluded Balanus nubilus, Ophiothrix spiculata, Paracyathus stearnsii, Triopha cat

Staurocalyptus

 Metridium/Encruster 180 to 290 

(54.9 to 88.4 m) 

Metridium spp. occurred at 178 to 190 ft, 196 ft, 213 to 259 ft, and 269 to 283 ft; occurred in this depth range included Triopha, Parayathus stearnsii, and Coryn

Platform Irene, Leg A1 Intertidal 0 to 6 

(0 to 1.8 m) 

This zone was comprised primarily of mussels (Mytilus californianus), anemon

Anthopleura elegantissima [rosy morph], one occurrence of Anthopluera sp. [wh

(Tetraclita squamosa), and Corynactis californica

 Barnacle/Algae 6 to 35 

(1.8 to 10.7 m) 

Balanus occurred from 5 to 101 ft; Anthopleura elegantissima (rosy morph), Oph

Metridium senile were also dominants within this depth range 

 Mytilus 35 to 85 

(10.7 to 25.9 m) 

Mytilus spp. occurred intermittently from 38 to 79 ft, while Mytilus californian

and from 48 to 51 ft; Metridium senile and Balanus spp. were numerical domin

Pisaster ochraceus was also present between 24 and 39 ft 

 Corynactis/Encruster 85 to 242 

(25.9 to 73.4 m) 

Corynactis californica only occurred between 2 and 10 ft; this zone was domina

Balanus spp., and a yellow encrusting sponge were dominants in this depth ra
Mussel zones extended to depths of 16 m (52 ft), with only limited presence below that 

depth (maximum depth: 24 m; 79 ft). Mytilus typically co-occurred with several taxa, including 

(1) algae, with filamentous and foliose red algae predominating, extending to depths of 17 to 

20 m (55 to 65 ft); barnacles, with Balanus nubilus and Balanus spp. predominant; and (3) several 

anemone species, including Anthopleura elegantissima (rosy morph) and Metridium senile. 

Ophiuroids were also present within the mussel zone, but typically in the mid to lower portions 

of the Mytilus zone, perhaps to avoid stronger surge present closer to the surface. 

Dominant species or taxa found at intermediate depths and beyond were generally, but 

not always, consistent with the biotic zone designations. These findings may be related to the 

broad categories used in the videotape analysis (e.g., encrusters), may reflect differences 

inherent in comparing data sets acquired at different spatial scales, or may be attributed to 

changes in community composition over time. Overall, it was evident that there was 

considerable overlap in the depth distributions of major taxa (i.e., density- and percent cover 

dominants). 

 In general, there was an intermediate (mid) zone, located below the mussel zone at 

water depths ranging from 19 to 26 m [65 to 85 ft] to about 76 m [250 ft]). Prominent taxa in this 

mid zone included Corynactis californica, ophiuroids, barnacles, Metridium senile, Leucetta, and 

worm tubes. It has been suggested that the presence of a dense Corynactis californica zone below 

the Mytilus zone is important to the health of the mussel bed, as the anemone’s nematocysts 

provide a barrier to starfish species that prey on mussels (J. Ljubenkov, pers. comm., 2005). 

Other species (e.g., Metridium senile) also occur above and below this mid zone, while barnacles 

and worm tubes also occur above and below this zone, respectively. 

Below the mid zone, a lower zone was present (below 76 m [250 ft]). Prominent taxa in 

the lower zone were more variable among the platforms and included Metridium senile, 

M. farcimen, Paracyathus stearnsii, red encruster, turf, worm tubes, and Desmophyllum dianthus

(below 168 m [550 ft]). While M. senile was present at all of the platforms, its depth distribution 

was variable; on occasion, this species was present for the intertidal to the base of the platform 

(e.g., at platforms Harvest and Irene), while on other platforms its depth distribution was more 

intermittent (e.g., at platforms Grace, Habitat, and Hidalgo). Similarly, turf was present on all 

platforms as a dominant or sub-dominant taxa but its depth distribution was variable. Other 

taxa within the lower zone were restricted in their geographic distribution (i.e., between 

platforms). 

Paracyathus stearnsii was not present at platforms Hidalgo or Irene, and only occurred on 

one leg of Platform Harvest, yet was a dominant at the remaining (Santa Barbara Channel) 

platforms within the lower zone. The red encruster was a major contributor to percent cover in 

the lower zones on two legs of Platform Harvest, a single leg of Platform Hidalgo, and a single 

leg of Platform Irene, yet was totally absent from all of the remaining platforms. Desmophyllum 

dianthus was present in the lower zone only at Platform Gail. 

 Graphic representations of the generalized depth distribution of dominant species 

present at each platform are provided in Figures 4-1 through 4-3. These figures present 

generalized depth distribution patterns, based on random sampling between the shallow 

intertidal and base of one or two platform legs. 

149
Figure 4-1. Generalized depth distribution of dominant species present at platforms Gail and Grace. 

Depth (ft)

Metridium

exilis

Metridium

senile

Mytilus spp.

Ophiothrix spiculata Balanus spp.

Desmophyllum dianthus

Depth (m)

0

153045607691106121137152167182198213

225

Algae

, filamentous

red

Corynactis

californica

Gail

0

50

100150200250300350400450500550600650700739

0

50

100150200250300318

Depth (ft)

Grace

Mytilus

californianus

Corynactis

californica

Anthopleura

elegantissima (rm) Metridium senile Balanus spp.

Paracyathus

stearnsii

Ophio

Coenocyathus bowersi
Figure 4-2. Generalized depth distribution of dominant species present at platforms Harvest and Hidalgo. 

0

50

100150200250300350400450500550600

650

Corynactis californica

Anthopleura

elegantissima (rm)

Worm tubes

,

calcareous

Balanus spp. Leucetta Mytilus spp.

Ophiuroid

,

unidentified

Depth (ft)

Harvest

Depth (m)

675

Metridium

senile 0

153045607691106121137152167182

198

206

Hidalgo Anthopleura

elegantissima (rm)

Worm tubes

,

calcareous

Balanus nubilus

Metridium farcimen Metridium senile My

0

50

100150200250300350400

430

Depth (ft)

Leucetta losangelensis
Figure 4-3. Generalized depth distribution of dominant species present at platforms Habitat and Irene.

Habitat

Depth (m)

0

15

3045

60

76

88

0

50

100150200250

290

Anthopleura

elegantissima (rm) Staurocalyptus Triopha catalinae

Paracyathus stearnsii Ophiothrix spiculata Balanus nubilus Metridium senile Mytilus spp. Corynactis californica

Depth (ft)

Ophiothrix spiculata Metridium senile Tetraclita squamosa Corynactis californica

Anthopleura

elegantissima (rm)

Mytilus

cali

Mytilus 

Irene

0

50

100150200

242

Depth (ft)

Sponge

, yellow

encrusting
153 

Species presence by depth, as depicted in Figures 4-1 through 4-3, was derived from 

Appendix C and Tables 3-3 through 3-12. While the terminal points of each bar in the figures 

correctly note minimum and maximum depths of occurrence, a species presence across the 

entire depth range may be suggested but was not confirmed. 

In general terms, the zonation patterns of all California platforms may be outlined as 

follows: 

 an upper zone (from the intertidal to 18 to 26 m [60 to 85 ft]), including the intertidal 

and mussel bed, and consisting of Mytilus spp., various algae (e.g., filamentous and 

foliose red algae, several green algal species such as Ulva), barnacles, several 

anemone species (e.g., Anthopleura elegantissima, Metridium senile), sponges, and 

ophiuroids; 

 a mid zone (from 19 to 26 m [65 to 85 ft] to about 76 m [250 ft]), including Corynactis 

californica, ophiuroids, barnacles, Metridium senile, Leucetta/Leucetta losangelensis, and 

worm tubes; and 

 a lower zone (below 76 m [250 ft]), including Metridium senile, M. farcimen, 

Paracyathus stearnsii, turf, and worm tubes. Platform- or platform group-specific taxa 

may also be present in the lower zone (e.g., Desmophyllum dianthus only at Platform 

Gail; red encruster only at platforms Harvest, Hidalgo, and Irene). 

4.6 Scraping Analysis 

 The scraping analysis encompassed complete taxonomic identification and 

determination of relative abundance of all species present within each 0.0625 m2 quadrat 

collected from Platform Harvest (Legs B1 and B2) and Platform Gail (Legs A1 and B1). In 

addition, mussel samples (whole community and mussels only) were weighed, and individual 

mussels weighed and measured. 

A total of 23 scraping samples were collected from Platform Harvest, consisting of four 

samples from the barnacle zone and eight samples from the Mytilus zone of Leg B1, and three 

samples from the barnacle zone and eight samples from the Mytilus zone of Leg B2. Depth of 

collection on Platform Harvest ranged from 3.4 to 24.1 m (11 to 79 ft). A total of 31 scraping 

samples were collected from Platform Gail, consisting of five samples from the intertidal zone, 

six samples from the barnacle/scallop zone, and six samples from the Mytilus zone of Leg A1, 

and three samples from the intertidal zone, two samples from the barnacle/scallop zone, and 

nine samples from the Mytilus zone of Leg B1. Depth of collection ranged on Platform Gail 

ranged from 0.3 to 24.1 m (1 to 79 ft). 

At Platform Harvest, 130 total taxa were identified. Dominant taxa included ophiuroids 

(Ophiothrix spiculata), algae (Rhodymenia californica, Membranoptera multiramosa), mollusks 

(Mytilus spp., Mytilus californianus, Hiatella arctica), caprellid and gammarid amphipods (Caprella 

alaskana, Elasmopus cf. holgurus), barnacles (Megabalanus californicus, Balanus nubilus), 

polychaetes (Halosydna brevisetosa, Syllis gracilis), and anthozoans (Metridium senile), among 

others. Several species, including Ophiothrix spiculata, Caprella alaskana, Elasmopus cf. holgurus, 

Pycnogonum stearnsi, and Hiatella arctica, were present in all 23 scraping samples. Other species, 

such as Rhodymenia californica, Mytilus spp., Membranoptera multiramosa, Megabalanus californicus, 
and Halosydna brevisetosa, were very abundant when they occurred, but were not always 

present. 

At Platform Gail, 90 total taxa were identified. Dominant taxa included algae 

(Pterosiphonia dendroidea), anthozoans (Anthopleura elegantissima, Metridium senile, Metridium 

exilis, Diadumene cincta), caprellid amphipods (Caprella equilibra), polychaetes (Spirobranchus 

spinosus, Elasmopus holgurus), ophiuroids (Ophiothrix spiculata), mollusks (Chama arcana), 

sponges (Haplosclerida), and barnacles (Balanus trigonus). Several species, including Elasmopus 

holgurus and Balanus trigonus, were present in all 31 scraping samples. Other species, such as 

Ophiothrix spiculata, Pterosiphonia dendroidea, Spirobranchus spinosus, Metridium exilis, Chama 

arcana, and Spirobranchus spinosus, were very abundant when present, but were not consistently 

present in all scraping samples. Mytilus spp., which was sparse on Leg A1, was a dominant 

species on Leg B1. 

 The complex, three-dimensional structure of the barnacle and Mytilus zones provide 

habitat and protection for a variety of interstitial fauna and epibionts, including caprellid and 

gammarid amphipods, crabs, pycnogonids, brittle stars, holothuroids, gastropods, bivalves, 

nudibranchs, chitons, polychaetes, anemones, hydroids, hydrozoans, nemerteans, sponges, 

bryozoans, tunicates, sipunculids, and flatworms. In total, 181 separate taxonomic entities were 

noted from scrapings at both platforms, of which 123 (68%) were monospecific taxa (i.e., 

identification to species level). Of this total, only 22 percent (41) of the taxa co-occurred within 

the sampled portions of both platforms Gail and Harvest. Co-occurring taxa represented all of 

the major phylogenetic groups (Table 4-12). 

 Several of the species identified in the scraping analysis were also noted as 

density- and/or percent cover-dominant taxa during QSA (e.g., Mytilus, Balanus, Metridium, 

Anthopleura, Ophiothrix). The majority of the taxa observed in the scraping samples, however, 

were either cryptic or juvenile forms not readily identifiable during the analysis of photographs. 

 Mussel bed thickness is a major factor affecting species diversity within the Mytilus

zone. According to Seed and Suchanek (1992), increases in mussel bed thickness dramatically 

change the microhabitats present under, between, and around the mussels. While the bottom 

layer of mussels act as the primary point of attachment to the substrate (i.e., platform legs), 

subsequent mussel layers serve to strengthen the mussel bed through interconnecting byssal 

threads, creating a complex of interstitial spaces. These complex interstitial and epibiont spaces 

provide habitat, food, and protection for many cryptic species. Of particular note were the 

abundant crustaceans (including barnacles, caprellid and gammarid amphipods, crabs, isopods, 

sea spiders, and mysids), polychaetes, and mollusks, most of which were not visible in the 

photographic analysis. Potential contributors to undifferentiated assemblages (e.g., turf) may 

also be present in the scraping results, including various species of bryozoans, hydrozoans, 

algae, and hydroids. 

154
Table 4-12. Taxa identified during the analysis of scraping samples from the intertidal, barnacle, and m

platforms Gail and Harvest. Taxa common to both platforms denoted in bold. 

FLORA:  Algae: 

Acrosorium venulosum Antithamnion hubbsii Branchioglossum bipinnatifidum Callophyllis spp. Ceramium camouii Delesseriaceae, unidentified Heterosiphonia japonica? 1

Membranoptera multiramosa 2

Polysiphonia scopularum Pterosiphonia dendroidea 

 Pugetia fragillissima 

Pugetia spp. (juvenile) Rhodymenia californica Rhodymenia pacifica

FAUNA:  Crustaceans:  Barnacles (Cirripedia): 

Balanus nubilus Balanus spp. (juvenile) Balanus trigonus Megabalanus californicus Tetraclita rubescens

 Caprellid amphipods: 

Caprella alaskana Caprella equilibra Caprella ferrea Caprella verrucosa 

Gammarid amphipods: 

Aoroides spp. Dulichiella appendiculata Elasmopus cf. holgurus Elasmopus holgurus Ericthonius brasiliensis Gammaropsis thompsoni 

 Gammarid amphipods, continued: 

Janiralata occidentalis Jassa slatteryi Leucothoe alata Monocorophium spp.Parapleustes pugettensis Podocerus brasiliensis Quadrimaera reishi 

cf. Sinocorophium spp. 

Stenothoe estacola 

 Crabs (Brachyura, Cancridea): 

Cancer branneri Cancer jordani Cancer productus Cancer spp. (juvenile)Maera simile Pachycheles pubescens Pachycheles rudis Pachygrapsus crassipes Paraxanthias taylori Pilumnus spinohirsutus Podocerus brasiliensis Scyra acutifrons 

 Isopods (Isopoda): 

Janiropsis tridens 

 Sea spiders (Pycnogonida): 

Anoplodactylus nodosus Pycnogonida, unidentified (juvenile) Pycnogonum stearnsi

 Mysids (Mysidacea): 

Mysidacea, unidentified (fragment) 

Echinoderms:  Brittle stars (Ophiuroidea): 

Ophiactis simplex Ophiopteris papillosa Ophiothrix spiculata Ophiuroidea, unidentified (juvenile) 

 Holothuroids (Holothu

Holothuroidea, Holothuroidea, Parastichopus calPentamera lissopl

 Urchins (Echinoidea): 

Echinoidea, unidLytechinus pictus Strongylocentrotu

Mollusks:  Bivalves (Pelecypoda): 

Anomia peruviana Chama arcana Crassadoma gigaCrassostrea gigas Gregariella chenui Gregariella coarctaHiatella arctica Irus lamellifer Kellia suborbicuLithophaga plumModiolus capax Mya arenaria Musculus (=MuscMytilus california

Mytilus spp. Mytilus spp. (juvMytilus trossulus/Ostrea conchaphilPetricola spp. (juvPododesmus cepPseudochama exog

 Gastropods (Gastropod

Amphissa reticulaAmphissa versicol

Anisodoris nobilis Doridacea, unide

Iselica ovoidea 
Table 4-12. Taxa identified during the analysis of scraping samples from the intertidal, barnacle, and m

platforms Gail and Harvest. Taxa common to both platforms denoted in bold (continued). 

 Gastropods (continued): 

Iselica spp. Seila montereyensisTritonia diomedea

Chitons (Polyplacaphores): 

Mopalia porifera

Polychaetes: 

Arabella iricolor Arabella semimaculata Brania spp. Cirratulus, unidentified Dodecaceria concharum Dodecaceria fewkesi Dodecaceria, unidentified Eudistylia polymorpha Halosydna brevisetosa Halosydna johnsoni Harmothoe ? hirsuta Harmothoe spp. 

Lepidonotus spiculus Myxicola spp.Naineris dendritica Nereis eakini Nereis mendocinana Nereis pelagica neonigripes Paleanotus bellis Pholoides asperus Phyllochaetopterus prolifica Phyllodoce medipapillata Phyllodoce spp.

Polydora spp. Proceraea cf. kiiensis 

Proceraea spp. Sabellidae, unidentified Serpula columbiana Spirobranchus spinosus Syllidae, unidentified Syllis gracilis 

Polychaetes (continued): 

Trypanosyllis spp. Typosyllis spp. 

Cnidarians:  Anthozoans (Actiniaria): 

Actiniidae, unidentified Anthopleura elegantissima (rosy morph) Anthopleura elegantissima Corynactis californica Diadumene cincta Metridium exilis Metridium senile

 Hydrozoans: 

Campanularia spp.

Campanulariidae, unidentified Eucopella everta Filellum serpens Halecium spp. 

Halecium tenellum Lafoea adnata Obelia geniculata Obelia nr. surcularis Obelia plicata Obelia spp. Plumularia alicia Plumularia alicia complex Plumularia nr. septata 

Plumularia spp. Sertularella tenella

Syncoryne eximia 

Minor Phyla:  Bryozoans (Ectoprocta or Bryozoa): 

Callopora spp. Celleporella spp. Celleporina spp. Costazia spp. Crisia spp. Cyclostomata, unidentified 

 Bryozoans, continued: 

Ectoprocta, unidFilicrisia spp. Scrupocellaria spTegella spp. 

 Flatworms (Platyhelme

Rhabdocoela, unStylochoplana lonStylochus spp. 

 Nemerteans (Nemertea

Amphiporus spp. Carinoma mutabilLineus rubescens Nemertea, unideParanemertes calif

Tetrastemma sig

 Sipunculids (Sipunculi

Phascolosoma a

 Sponges (Porifera): 

Haplosclerida nr. Porifera sp. A Porifera, unidenRhabdodermella n

 Tunicates (Urochordat

Aplidium spp. Aplousobranchi

unidentified 

Styela coriacea Styela truncata Tunicate, uniden

Total: 181 taxonomic ent

monospecific tax

Footnotes: 1 - HeterosiphonHeterosiphonia densiuscula – Membranoptera multimar

Membranoptera platylphylla 

Kylin, per Miller (2004). 
157 

Results of the scraping analysis also provided further taxonomic clarification for 

unidentified biota observed during photographic analysis. Ophiothrix spiculata and Ophiopterus 

papillosa were the only two ophiuroid species identified during scraping analysis from Platform 

Harvest. During the QSA, specimen size, photographic resolution, and/or a lack of specimens 

upon which a detailed analysis could be conducted resulted in the classification of unidentified 

ophiuroids in many of the photographs. Scraping analysis results allowed for a complete 

species-level determination; ophiuroids present in photographs from Platform Harvest were 

considered to be Ophiothrix spiculata, among the dominant taxa at all platforms. 

The vast majority of algal taxa from the scraping samples were rhodophytes (red algae). 

During photographic analyses, red algae (i.e., both filamentous and foliose forms) were 

prominent, depth-dependent groups observed on nearly all of the platforms. Scraping results 

from Platform Gail indicate that filamentous red algal species include Antithamnion hubbsii, 

Polysiphonia scopularum, and Pterosiphonia dendroidea. Foliose red algal taxa from Platform Gail 

include Callophyllis spp., while foliose forms from Platform Harvest include Rhodymenia 

californica, and R. pacifica. 

 Correspondence analysis of the scraping data set from Platform Harvest revealed that 

the two zones, Mytilus and barnacle, were distinct in terms of their respective taxonomic 

compositions. Further, the taxonomic composition of the Mytilus zone was more variable than 

the barnacle zone. 

 Numerous taxa occurred exclusively in the Mytilus zone, but only in a few of the 

scraping samples. While Mytilus californianus occurred in most of the scraping samples 

collected in the Mytilus zone, it was also present in a number of samples collected in the 

barnacle zone, suggesting that there was a gradual transition between these zones. Taxa that 

occurred exclusively in this zone and more frequently were Phascolosoma agassizi, Halecium spp. 

Callopora spp., Anthopleura elegantissima (rosy morph), Celleporella spp., and Filellum serpens. The 

barnacles Balanus nubilus and B. trigonus occur frequently but not exclusively in the samples 

collected in the barnacle zone. Several species occurred exclusively in the barnacle zone: 

Aoroides spp., Brania spp., Cancer branneri, Cancer jordani, Ericthonius brasiliensis, Gregariella 

chenui, Myxicola spp., Pholoides asperus, and Typosyllis spp. 

Wet weight determinations of scraping samples from Platform Harvest were variable. 

Total sample wet weights on Leg B1 ranged from 149 to 5,059 g per quadrat (2.4 to 80.9 kg/m2), 

with a mean value of 2,129 g (34 kg/m2). Total sample weights on adjacent Leg B2 were 

noticeably higher, ranging from 2,281 to 25,966 g per quadrat (36.5 to 415.5 kg/m2); the average 

total sample wet weight on this leg was 9,180 g (147 kg/m2). 

 Mussel only biomass measurements (i.e., wet weight, shell included) exhibited similar 

variability, affecting the relative mussel contribution (biomass) to the community. Mussel wet 

weights on Leg B1 ranged from 0 to 4,025 g (0 to 64.4 kg/m2). The contribution of mussel 

biomass to total wet weight was extremely variable, ranging from 0 to 80 percent, with an 

average of 12.8 percent for the 12 samples measured from Leg B1. In contrast, mussel only wet 

weights from the Leg B2 mussel zone were consistently high, ranging from 3,752 to 17,779 g 

(60.0 to 284.5 kg/m2). The relative contribution of mussel biomass to total sample wet weight 

on Leg B2 was consistently high (64 percent to 81 percent) for samples taken from the mussel 
zone. However, as expected, mussel wet weight contributions were extremely limited 

(<1 percent) in the barnacle zone of Leg B2. 

 Highest biomass values for mussels were observed between 3.4 and 5.8 m (11 and 19 ft), 

tapering off below 6.1 m (20 ft). This observation was generally consistent with results of the 

whole slide analysis, where highest numbers of mussels on Leg B1 were encountered between 

1.8 and 3.0 m (6 and 10 ft), tapering off below 3.7 m (12 ft). On Leg B2, highest densities were 

seen between 2.1 and 7.3 m (7 and 24 ft), tapering off below 7.9 m (26 ft). 

 A total of 932 mussels were measured and weighed from 13 samples collected from the 

mussel zone of Legs B1 and B2 of Platform Harvest. The number of mussels present in each 

sample was extremely variable, ranging from four mussels collected at 6 m (20 ft) below the 

surface on Leg B1 to 167 mussels collected at 5 m (15 ft) on Leg B2. From the whole slide 

analysis, the maximum number of mussels observed on Leg B2 within a single photograph was 

110 individuals at 0.6 m (2 ft) water depth, underscoring one of the inherent limitations in using 

photographic analysis to count individuals present in a complex, three-dimensional 

community. 

 Mussel size characteristics were also quite variable. Minimum and maximum average 

lengths, widths, and heights were 3.81 and 9.90 cm, 2.25 and 4.48 cm, and 1.67 to 3.42 cm, 

respectively. Individual average weights were also variable, ranging from 10.78 to 111.42 g. 

The smallest mussels were collected at water depths where the fewest mussels were available 

(i.e., 6 to 8 m; 20 to 25 ft) on Leg B1, while the larger mussel specimens were present in the 3 to 

8 m (10 to 22 ft) depths of Leg B2. 

4.7 Growth Thickness Measurements 

Growth thickness measurements were made periodically within the mussel zones at 

Platform Harvest (Legs B1 and B2) and Irene (Leg A1). Thickness measures ranged from 5.1 to 

30.5 cm (2 to 12 inches). Greatest thickness of the mussel zone occurred at the 14.3 to 16.5 m 

(47 to 54 ft) on Harvest Leg B1, at 6.7 m (22 ft) on Harvest Leg B2, and 0.3 to 2.7 m (1 to 9 ft) on 

Irene Leg A1 (Figure 4-4). 

 The vertical extent of the mussel zone at Platform Harvest extended from the intertidal 

to 24 m (79 ft) on Leg B1 and to more than 16 m (60 ft) on Leg B2. The mussel bed thickness 

measurements at Platform Harvest occurred during the scraping collections, the latter of which 

were conducted separately from photographic (i.e., diver and ROV) data acquisition. As a 

result, the maximum depth of occurrence of mussels on Platform Harvest was different between 

the two data sets (i.e., maximum depth of occurrence in photographs: 14 m, 46 ft; maximum 

depth of occurrence in growth thickness/scraping data: 24 m, 79 ft). The maximum mussel 

thickness on Leg B1 was eight inches (20.3 cm), and typically in the three to four inch (7.6 to 

10.2 cm) range; maximum thickness occurred at 14.3 to 16.5 m (47 to 54 ft) water depths. The 

maximum mussel thickness on Leg B2 was 12 inches (30.5 cm), and typically in the 6 to 10 inch 

(15.2 to 25.4 cm) range; maximum thickness occurred at 6.7 m (22 ft) water depths. 

158
Harvest Leg B1

Thickness (inches)

024 6 8 10

0

20

40

60

80

Figure 4-4. Mussel thickness at platforms Harvest and Irene. 

Harvest Leg B2

Thickness (inches)

0246 8 10 12 14

0

10

20

30

40

50

60

Irene Leg A1

Thickness (inches)

024 6 8 10

D th (ft)

0

5

10

15

20

Mussel Thickness

159
Differences in the depths of maximum thickness between Legs B1 and B2 may be 

attributed to the fact that Leg B2 is an inner leg, protected on three sides by adjacent legs, 

whereas Leg B1 is an outer leg. Sloughing of the mussel mat is a common occurrence on 

platforms, particularly following the passage of storms, as evidenced by the presence of a shell 

mound at the base (and downcurrent) of each platform. 

 The vertical extent of the mussel zone at Platform Irene, based on photographic data, 

extended from the intertidal to 9 m (31 ft), with a small aggregation at 15 to 16 m (48 to 51 ft). 

At greater depths, there was no multi-layer mussel mat, only mussel clumps. At 

approximately 6 m (20 ft), mussel mat thickness dropped to a single layer. The maximum 

mussel thickness on Leg A1 was eight inches (20.3 cm), and typically in the five- to six-inch 

(12.7- to 15.2-cm) range; maximum thickness occurred in the upper portions of the platform leg, 

in a depth range of 0.3 to 2.7 m (1 to 9 ft). This mussel distribution was different from that 

evident at Platform Harvest, where mussel thickness in the intertidal region was lower than that 

found at depth. 

4.8 Platform vs. Natural Hard Bottom – Comparisons of Biota 

Previous regional characterizations of California’s hard bottom fauna offer insight into 

the community composition of hard bottom features found at depth (e.g., low to high relief rock 

outcrops, generally 1 to 3+ m above the seafloor, at various water depths). Several previous 

studies and study summaries (e.g., Steinhauer and Imamura, 1990; Blake and Lissner, 1993; 

Science Applications International Corporation and Marine Ecological Consultants, 1995) have 

identified characteristic hard substrate taxa. The 30 most frequently encountered megabenthic 

taxa occurring on hard substrate in the western Santa Barbara Channel and Santa Maria Basin 

were represented by five phyla – Porifera (sponges), Cnidaria (anthozoans), decapod 

crustaceans, brachiopods, and echinoderms (i.e., crinoids, holothuroids, echinoids/urchins, 

asteroids/sea stars, and ophiuroids). Blake and Lissner (1993) noted that the spatial 

distribution of hard bottom communities reflected varying degrees of zonation pattern by 

depth. They noted that within OCS waters (i.e., ranging from 100 to 500 m water depths), 

almost half of the dominant or characteristic megafauna were eurybenthic. 

A comparison of characteristic platform fauna (from the photographs; platform water 

depths ranged from 74 to 225 m) and the characteristic hard bottom fauna identified and 

enumerated in the western Santa Barbara Channel and Santa Maria Basin has been provided in 

Table 4-13. Thirteen of the 30 natural hard bottom megafauna taxa also occur on the platforms, 

however, nearly half of these taxa occurred only once (i.e., sole occurrence on a single platform). 

Most frequently encountered species include Metridium farcimen and a tan zoanthid. The 

zoanthid depth distribution was across the entire platform leg depth. M. farcimen depth 

distribution was more restricted. For a limited number of species which occur at both platforms 

and hard bottom features (e.g., Galathea californiensis), respective depth distributions were 

similar. Depth distribution for other species was confounding and no apparent trends were 

evident. 

160
Table 4-13. Presence and depth of occurrence of species found both on platforms and natural hard bottom 

Characteristic megabenthic invertebrate taxa from hard bottom features (as reported by Blake are within the western Santa Barbara Channel and Santa Maria Basin. 

Platforms Natura

Taxon Presence (No. of 

Platforms) 

Depth of Occurrence 

[m (ft)] 

Shallow 

(100-200 m) 

M

(

Crustaceans 

 Galathea californiensis 2 140-223 (459-733) + 

Echinoderms 

 Allocentrotus fragilis 1 207 (680) +  Florometra serratissima 1 94-111 (309-363) +  Ophiocantha diplasia 1 140-208 (459-684) +  Parastichopus californicus 2 37; 44; 60; 71 (120; 144; 196; 232) +  Stylasterias forreri 4 76; 78; 94; 126; 128; 204; 210; 217; 223 (248, 249; 257; 310; 412; 421; 669; 713; 734) + 

Cnidarians 

 Amphianthus californicus 1 193 (633) +  Desmophyllum dianthus 1 111; 125; 181-224 (363; 410; 594-734) +  Metridium farcimen 5 9; 40-78; 83-84; 130-131; 201-224 (29-31; 130-255; 271-277; 427-431; 659-669) +  Paracyathus stearnsii 4 2; 29-96; 126 (6; 94-315; 413) x 

Tan zoanthid 5 60; 78; 84-87; 91; 102, 119, 129, 189; 193; 208; 215; 223 (197; 255; 277-285; 299; 335; 392; 424; 620; 633; 684; 704; 732) + 

Porifera 

 Encrusting sponge1 6 2, 12-76 (7-8, 41-250) +  Vase sponge2 4 12-74 (41-243) + 1 Encrusting sponges are diverse; several species were noted on the platforms (e.g., Cliona, Leucetta, Polyclinum). Data refle

distribution of Leucetta and Leucetta losangelensis on the six platforms. 

2 Vase sponges include Staurocalyptus and Leucilla; data reflect presence and distribution for Staurocalyptus and Leucilla. 

Key: + = present; x = most prominent depth; - = not present. 
4.9 Summary 

Four to six biotic zones per platform were determined from videotape analysis. The 

total number of biotic zones present was related to platform water depth – platforms in 

shallower water exhibited four or five zones, whereas platforms in deeper water were 

characterized by the presence of six biotic zones. Zones, typically named for the predominant 

species or taxon present (e.g., mussel or Mytilus zone), were generally supported by the results 

of the field surveys and subsequent photographic analyses, although there were noticeable 

differences in several instances. 

Complete taxonomic identification and enumeration of species present on each of six 

platforms was completed through analysis of 799 35-mm slide transparencies collected via ROV 

and scuba diver. Both density estimates and percent cover estimates were developed during 

this phase of quantitative slide analysis. For the primary platforms (i.e., platforms Gail, Grace, 

Harvest, and Hidalgo), where two legs were sampled, 665 images were reviewed. For the 

secondary platforms (i.e., platforms Habitat and Irene), where a single leg was evaluated, 

134 photographs were reviewed. At Diablo and Nifty Rocks, 22 photographs acquired within 

scuba diving depths (i.e., from 5 to 17 m [15 to 55 ft]) were also analyzed. In total, 821 35-mm 

slides were reviewed during quantitative slide analysis. 

Based on quantitative slide analysis of six platforms and Diablo and Nifty Rocks, 

173 total taxa were observed (Table 4-14). Phylogenetic groups represented included algae 

(predominantly red filamentous and foliose forms), crustaceans (e.g., barnacles, decapod and 

galatheid crabs), echinoderms (e.g., ophiuroids, sea stars, holothuroids), mollusks (e.g., 

bivalves, gastropods, nudibranchs), polychaetes, cnidarians (e.g., anthozoans, hexacorals, 

hydrozoans, hydroids, zoanthids), and minor phyla (e.g., sponges, bryozoans, tunicates). 

The total number of taxa identified at the six platforms ranged between 39 and 74, 

including between 15 and 30 monospecific identifications (i.e., to species level). Platform Gail 

exhibited the highest number of taxa, while Platform Irene exhibited the fewest. Summary 

findings of total taxa identified, numbers of monospecific taxa, and the percentage of the total 

which were monospecific, as determined from QSA, are detailed below: 

Platform Total Taxa Monospecific Percent of Total Monospecific

 Gail 74 30 41 

 Grace 61 22 36 

 Harvest 53 18 34 

 Hidalgo 53 21 37 

 Habitat 42 15 36 

 Irene 39 16 41 

Overall, QSA resulted in the photographic identification 34 to 41 percent of the platform taxa 

present to species level. Total number of taxa was highest among the primary platforms, where 

two platform legs were evaluated, suggesting that further sampling at either primary or 

secondary platforms would have resulted in the identification of additional taxa. 

162
Table 4-14. Taxa identified during the photographic analysis of six California platforms and Diablo and N

Dominant species or taxa, as determined via ranking of the top 12 taxa by density or percent co

type; dominant species shown separately for platforms (P), rock outcrops (R), or both (P+R). 

FLORA: Algae: 

Alga, brown, blade Alga, brown, clump Alga, coralline, encrusting Alga, encrusting (Lithothamnion) (R) 

Alga, green clump Alga, green clump (Codium-like) (R) Alga, green encrusting (P) Alga, green filamentous Algae, red filamentous (P+R) Algae, red foliose (P) Bossiella spp. (R)Codium spp. Corallina spp. (P) 

Egregia spp. Rhodymenia ?lobata Rhodymenia spp. 

Ulva lactuca (P) 

Note: Algae broadly characterized due to limitations of 

photographic resolution and interpretation. 

FAUNA: Crustaceans:  Barnacles (Cirripedia): 

Balanus nubilus (P)Balanus spp. (P+R)

Barnacle, unidentifiedChthalamus spp. (R) 

Pollicipes polymerus (P)Tetraclita squamosa (P)

 Decapod crabs (Decapoda): 

Cancer antennarius Cancer spp.Hemigrapsus nudus 

 Galatheid crabs (Galatheidae): 

Galathea californiensis

Echinoderms:  Sea stars (Asteroidea): 

Asterina miniata (=Patiria) 

Dermasterias imbricate Henricia leviuscula Henricia sanguinolenta Orthasterias koehleri Pisaster brevispinusPisaster giganteus Pisaster ochraceus (P)

Poraniopsis inflata Pycnopodia helianthoides Stylasterias forreri 

 Urchins (Echinoidea): 

Allocentrotus fragilis Lytechinus pictusStrongylocentrotus franciscanus

Strongylocentrotus purpuratus (R)

 Brittle stars (Ophiuroidea): 

Amphipholis spp. (P)Ophiocantha diplasia Ophiothrix spiculata (P+R)

Ophiuroid, unidentified (P) 

 Holothuroids (Holothuroidea): 

Dendrochirotida, unidentified (R) 

Parastichopus californicus 

 Crinoids (Crinoidea); 

Florometra serratissima 

Mollusks: 

Bivalves (Pelecypoda): 

Anomiidae, unidentified Bivalve, nestling, unidentified Chama arcana Crassadoma gigantea Mytilidae, unidentified Mytilus californianus (P+R)

Mytilus spp. (P) 

 Gastropods (Gastropoda

Aeolid (SF AeolidAeolidia papillosa? Aeolidioidea, unAnisodoris nobilisArchidoris monterCalliostoma spp.Cypraea spadicea Dialula sandiegensDorid, white, uniDorid, yellow, un

Doridacea, unideFlabellina iodineaGastropoda, unidHermissenda crass

Pleurobranchaea ca

Serpulorbis spp.

Triopha catalina

 Chitons (Polyplacophora

Chiton, unidentif

Polychaetes:

Eudistylia polymSabellidae/Serpu

(feather dus

Protula superba Salmacina spp. 

Serpulidae, unideSpionidae, unideSpirobranchus sppTube worm, douTube worm, singWorm tubes, calcWorm tubes, pla
Table 4-14. Taxa identified during the photographic analysis of six California platforms and Diablo and N

Dominant species or taxa, as determined via ranking of the top 12 taxa by density or percent co

type; dominant species shown separately for platforms (P), rock outcrops (R), or both (P+R) (c

Cnidarians:  Anthozoans (Actiniaria): 

Actiniaria, brown Actiniaria, pink Amphianthus californicus Anemone, pink Anemone, unidentified Anthopleura elegantissima 

(rosy morph) (P+R)

Anthopleura spp. Anthopleura spp. (whitish, no rose) (P) Anthopleura xanthogrammica (R)

Anthozoa, unidentified Astrangia spp. Balanophyllia elegans (R)Coenocyathus bowersi (P)

Corynactis californica (P+R)

Cup coral, white, unidentified Desmophyllum dianthus (P) Epiactis prolifera? Gorgonian, unidentified Metridium exilis (P)

Metridium farcimen (P)

Metridium senile (P+R)

Metridium spp. (P) Metridium spp., dark or Feather Duster Palythoa (tan zoanthid) (P) Palythoa (tan) Paracyathus stearnsii (P)Urticina spp. Zoanthid (Palythoa) (P) 

Zoanthid, colonial tan (P) Zoanthid, solitary tan 

Hydrozoans: 

Hydrozoa, colony Hydrozoa, tan clump Plumularia spp. (P) Eudendrium spp.? Hydroid, pink Hydroid, tan (P) Hydroid, tan branching (P) 

Hydroid, white 

Minor Phyla:  Sponges (Porifera): 

Cliona spp., yellow 

Halichondria panicea (P)

Leucetta losangelensis (P)

Leucilla nuttingiLeucetta spp. (P) Sponge, gray encrusting (P) Sponge, green encrusting (P) Sponge, orange encrusting (P) Sponge, orange round Sponge, purple encrusting Sponge, tan cup (P) Sponge, tan encrusting (P) Sponge, tan foliose encrusting Sponge, tan globose 

Sponge, unidentified (R) Sponge, white encrusting (P) Sponge, white finger Sponge, yellow encrusting (P) Staurocalyptus spp. (P)

 Bryozoans (Bryozoa): 

Bryozoa, staghorn, yellow (R) Bryozoa, tan branching (P) Bryozoa, white branching Bugula spp. Crisia/Filicrisia spp. Hippodiplosia spp 

Tunicates (Urochordata, A

Amaroucium spp.Aplidium spp. Botrylloides spp. Halocynthia igabojStyela spp. Tunicate, encrusTunicate, encrusTunicate, globulaTunicate, solitaryUrochordata, uni

Fishes (Osteichthyes): 

Oxylebius pictus Sebastes spp. 

Undifferentiated Assembl

Algae/hydrozoa Bryozoa turf (P) Encruster, blue (Encruster, gray Encruster, green Encruster, lavendEncruster, orange Encruster, pink Encruster, red (PEncruster, tan (PEncruster, white Encruster, yellow Turf (P+R) 

Physical Characteristics: 

Bare metal (P) Line (P) 

Total: 173 taxa, including u

assemblages and encharacteristics 
The rocky outcrops areas of Diablo and Nifty Rocks also exhibited 44 taxa during 

quantitative slide analysis, of which 14 were monospecific (i.e., 32 percent monospecific). 

Twenty-four of the taxa identified at Diablo and Nifty Rocks were not observed on the 

platforms. In spite of the restricted scope of photographic sampling conducted at Diablo and 

Nifty Rocks, it is suggested that species diversity at the natural rock outcroppings was higher 

than that seen in comparable depth zones at the six platforms, particularly for algal species 

which, by comparison, were under-represented on the platforms. 

 Point count analysis was also conducted on digital versions of the 35-mm slide set. 

Using PointCount’99® software, all images from the six platforms were evaluated and taxa 

present on 50 random points per image were identified to the lowest practical taxon. A total of 

883 digital images were reviewed during point count analysis. Fifty-five taxa total were 

identified during the random point count analysis. Results of the point count analysis, 

expressed as percent cover estimates, were very consistent with percent cover data developed 

from the quantitative slide analysis, particularly for the dominant taxa. As expected, rare fauna 

were less frequently identified during random point count analysis than during whole slide 

analysis. Point count provides a straightforward means of identifying percent cover dominants 

within a photographic image, whereas whole slide analysis, based either on individual counts 

or percent cover estimates, provides a more comprehensive characterization of taxa present. 

 Seven taxa were present on all ten legs of the six platforms characterized. Taxa present 

and their density and/or percent cover contributions at all platforms included: 

 Metridium senile – with average densities ranging from 10.8 to 330.9 individuals/ 

 0.0625 m2 (maximum: 510 individuals/0.0625 m2 at Platform Irene) and average 

coverage ranging from 3.7 to 66.0 percent (maximum: 98 percent at Platform Irene) 

 Mytilus spp. – with average densities ranging from 24.3 to 117.8 individuals/ 

 0.0625 m2 (maximum: 240 individuals/0.0625 m2 at Platform Grace) and average 

coverage ranging from 19.2 to 60.4 percent (maximum: 100 percent at Platform 

Habitat) 

 Balanus spp. – with average densities ranging from 2.5 to 42.0 individuals/0.0625 m2

(maximum: 200 individuals/0.0625 m2 at Platform Irene) 

 Calcareous worm tubes – with average densities ranging from 1.0 to 

51.5 individuals/0.0625 m2 (maximum: 100 individuals/0.0625 m2 at Platform Irene) 

 Yellow encrusting sponge – with average coverage ranging from 0.5 to 16.1 percent 

(maximum: 70 percent at Platform Harvest) 

 Tan encrusting sponge – with average coverage ranging from 4.0 to 32.4 percent 

(maximum: 60 percent at Platform Irene) 

 Turf – with average coverage ranging from 6.0 to 37.4 percent (maximum: 97 percent 

at Platform Grace). 

Bare metal was also present on all ten platform legs, primarily at depth, with average 

cover ranging from 7.5 to 49.2 percent; this physical characteristic was noticeably reduced at 

Platform Irene, present in only a few photographs near the base of the platform. As a result, no 

percent cover estimates for bare metal were made at this platform. 

165
Other prominent taxa included Corynactis californica, Anthopleura elegantissima (rosy 

morph), Ophiothrix spiculata/unidentified ophiuroid, Metridium farcimen, filamentous and 

foliose red algae, and Leucetta/Leucetta losangelensis. 

Few trends suggested the existence of a north-south gradient in species composition, 

although a limited number of species were unique to southern or northern platforms. Eight 

taxa occurred exclusively at the southern platforms – Gail and Grace – including the 

nudibranchs Anisodoris nobilis and Dialula sandiegensis, Metridium exilis, the brittlestar 

Amphipholis, the hexacoral Desmophyllum dianthus, yellow Cliona and Polyclinum planum 

sponges, the hydroid Obelia spp., and Styela spp. Five taxa occurred exclusively at Habitat – 

the bryozoans Bugula and Crisia/Filicrisia, coralline alga (Corallina), the sponge Staurocalyptus, 

and the nudibranch Triopha catalinae. Nine taxa occurred exclusively at platforms in the 

southern Santa Maria Basin (Hidalgo, Harvest), including the nudibranchs Aeolidia papillosa and 

Archidoris montereyensis; the tunicates Amaroucium and Botrylloides spp.; the gastropod 

Calliostoma spp.; algae Egregia and Rhodymenia; the hydroid Eudendrium spp.; and sea star 

Pisaster brevispinis. Two taxa occurred exclusively at Platform Irene, including the urchin 

Lytechinus pictus, and the anemone Epiactis prolifera. Three taxa occurred at all of the northern 

platforms – the starfish Pisaster ochraceus; the gooseneck barnacle Pollicipes polymerus; and a red 

encruster. 

In general, the biotic zones determined from videotape analysis were confirmed through 

the photographic analysis. Mussel zones were always present, although their vertical extent 

may have differed from those estimated from the videotape analysis. Dominant species or taxa 

found at intermediate depths and beyond were generally, but not always, consistent with the 

biotic zone designations. These findings may be related to the broad categories used in the 

videotape analysis (e.g., encrusters), may reflect differences inherent in comparing data sets 

acquired at different spatial scales, or may be attributed to changes in community composition 

over time. Overall, it was evident that there was considerable overlap in the depth distributions 

of major taxa (i.e., density- and percent cover-dominants). 

 Based on an overview of the photographic data, several broad characterizations were 

evident for the dominant taxa: 

 Mytilus spp. and, to a lesser extent, Mytilus californianus were the predominant 

mussels on all platforms sampled, primarily because they have adapted to rough, 

open ocean conditions and exposure to powerful waves and currents. Occasionally, 

other Mytilidae were also noted. Based on photographic observations, an upper and 

a lower Mytilus community was evident. This zonation pattern was created by the 

presence of a prominent, umbrella-like upper portion of the mussel mass; below that 

mussel counts decreased rapidly due to the presence of a dense epifauna cover that 

hid the underlying mussel mat. The shape of the whole mussel mass was roughly 

spindle-like. 

 Anemones and other anthozoan communities were an important faunal component 

of platform-associated communities, with depth-related distributions as follows: 

o Anthopleura elegantissima (rosy morph) and A. xanthogrammica in the shallower 

portions of the platform, typically within the mussel and/or barnacle zones; 

166
o Metridium senile, Paracyathus stearnsii, Coenocyathus bowersi, and Corynactis 

californica from the bottom of the mussel zone to the mid-depth portions of each 

platform; 

o Metridium farcimen and Desmophyllum dianthus, as well as various encrusters, in 

the lower portions of the deeper platforms (i.e., Gail, Harvest); and 

o Unique taxa at select platforms, including Metridium exilis at platforms Gail and 

Grace. 

In terms of anthozoan patterns discerned during this analysis, there were no obvious 

and distinct patterns evident. However, several casual observations were 

noteworthy. The mussel zone species assemblage and the mid zone species 

assemblage had major overlap (M. senile, M. exilis, Coenocyathus bowersi, Corynactis 

californica). In addition, the mussel zone had several co-occurring species including 

Anthopleura elegantissima (rosy morph) and Urticina, while the lower zones had 

M. farcimen and Paracyathus stearnsii. 

 Algal species, as expected, were limited in their distribution to the shallower depths 

of the platforms. Identifiable algae that were present were dominated by 

filamentous and foliose red algal species, with minor contributions from green and 

coralline forms. A lower algal diversity was evident at the platforms when 

compared to natural rock outcrops. 

 Barnacles were prominent and numerically dominant, typically within the upper 

portions of a platform. Several taxa were observed on the platforms, however, 

Balanus species (Balanus spp., Balanus nubilus) were prevalent. 

 Ophiuroids, particularly Ophiothrix spiculata, were routine co-dominants (by density) 

in the upper portions of a platform, however, their depth of distribution extended 

into deeper water. 

The general depth distribution and patterns of occurrence for the platform-associated 

dominant species is depicted graphically in Figure 4-5. Common observations included: 

 Mytilus – comprised of Mytilus spp. and M. californianus, mussels were always 

present and were routinely density– and percent cover-dominants, typically 

occurring in a depth range that extended from the intertidal to 12 to 24 m (40 to 

80 ft), co-occurring with barnacles, other anthozoans, ophiuroids, sponges, and red 

algae; 

 Metridium senile – a major contributor to total density and percent cover, with an 

extensive depth distribution, routinely beyond that exhibited by ophiuroids; this 

species, like Mytilus, Balanus, calcareous worm tubes, turf, and a yellow encrusting 

sponge, was present on all platform legs sampled; 

 Balanoids – a prominent and numerically dominant group including Balanus nubilus, 

Balanus spp., and, to a lesser extent, Tetraclita squamosa, that typically occurred 

within the upper portions of a platform (i.e., from the intertidal to a depth of 15 to 

30 m [50 to 100 ft]), but was observed extending to depths of 60 m or more; this 

group frequently co-occurred with mussels, ophiuroids, and anemones in the 

Mytilus zone; 

167
Figure 4-5. Generalized depth distribution of select biota - all platforms.

50

150

250

350

450

550

650

Balanus spp.

Algae

Mytilus spp.

Desmophyllum dianthus

Tetraclita

squamosa

Ophiuroids

Metridium

senile

Metridium farcimen

Anthopleura

elegantissima (rm)

Metridium

exilis

Coenocyathus bowersi

Paracyathus stearnsii

Worm Tubes

Leucetta/Leucetta losangelensis

Red

encruster

0

30

60

91

121

152

182

213

228

Depth (m)

0

100

200

300

400

500

600

700

750

Depth (ft)

15

45

76

106

137

167

198

Corynactis

californica

Taxon

168
 Ophiuroids – a significant contributor (in terms of total density) with an extensive 

depth distribution, most often represented by unidentified ophiuroids and 

Ophiothrix spiculata; this group frequently co-occurred with mussels, barnacles, and 

anemones in the Mytilus zone, and with other anemones and encrusting forms at 

greater depths; 

 Sponges – as a group, sponges were always present on the platforms, however, their 

identifiability was low; the most prominent sponge species encountered included a 

yellow encrusting species, a tan encrusting species, the calcareous sponge 

Leucetta/Leucetta losangelensis, and the hexactinellid sponge Staurocalyptus; 

 Filamentous red algae – this group was nearly always found within the mussel zone, 

often to depths of 15 m (50 ft) or more and present on five of the six platforms; 

filamentous red algae included Polysiphonia, Neoptilota, and Antithamnion, among 

other species; 

 Anthopleura elegantissima (rosy morph) and A. xanthogrammica – primarily intertidal 

and shallow subtidal, usually with the upper 15 m (50 ft) of a platform leg, routinely 

in association with mussels, other anthozoan species, barnacles, ophiuroids, and red 

algae; 

 Calcareous worm tubes – common co-dominants occurring in the mid- to lower 

portions of a platform leg, generally between 46 and 76 m (150 and 250 ft) subsurface 

to near the platform base; maximum depth of occurrence for worm tubes was 213 m 

(700 ft). 

 Corynactis californica – variable in density, this species was present on all of the 

platform legs (except Platform Hidalgo, Leg B1), usually below the mussel zone; this 

species depth distribution extended to approximately 122 m (400 ft);

 Paracyathus stearnsii – depth distribution primarily between 30 and 122 m (100 and 

400 ft);

 Desmophyllum dianthus – only found on Platform Gail (both legs), at depths 

comparable to below basin sill;

 Red encruster – only found on platforms Harvest, Hidalgo, and Irene, at depth; and

 Encrusters – as a group, they were always present, but exhibit very low 

identifiability.

Mussel beds provide three dimensional, interstitial space for a complex community. 

Scraping results from the barnacle and mussel zones of Platform Harvest and Gail contained a 

total of 130 and 90 taxa, respectively, of which only 22 percent (41) of the taxa co-occurred. 

Scraping samples from Harvest were dominated Ophiothrix spiculata, Rhodymenia californica, 

Mytilus spp., Membranoptera multiramosa, Caprella alaskana, Megabalanus californicus, Mytilus 

californianus, Halosydna brevisetosa, Elasmopus cf. holgurus, and Metridium senile. Dominant taxa 

in the scraping samples from Gail included Pterosiphonia dendroidea, Anthopleura elegantissima, 

Metridium senile, Spirobranchus spinosus, Ophiothrix spiculata, Elasmopus holgurus, Diadumene 

cincta, Balanus trigonus, and Metridium exilis. Ophiuroids and barnacles were prominent taxa in 

both photographic and scraping samples. 

Correspondence analysis of the scraping data set from Platform Harvest revealed that 

the two zones, Mytilus and barnacle, were distinct in terms of their respective taxonomic 

169
compositions. Further, the taxonomic composition of the Mytilus zone was more variable than 

the barnacle zone. 

Wet weight determinations of scraping samples from Platform Harvest were variable. 

Total sample wet weights ranged between 149 and 5,059 g per quadrat (2.4 and 80.9 kg/m2) on 

Leg B1, but were noticeably higher on the adjacent leg, where they ranged between 2,281 and 

25,966 g per 0.0625 m2 quadrat (36.5 to 415.5 kg/m2). Average total sample wet weights per 

quadrat on Leg B1 and B2 were 2,129 and 9,180 g (34 and 147 kg/m2), respectively. 

 Mussel only biomass measurements (i.e., wet weight, shell included) exhibited similar 

variability, affecting the relative mussel biomass contribution to the community. Mussel wet 

weights on Leg B1 ranged from 0 to 4,025 g (0 to 64.4 kg/m2). In contrast, mussel only wet 

weights from the Leg B2 mussel zone were consistently high, ranging from 3,752 to 17,779 g per 

quadrat (60.0 to 284.5 kg/m2). These results were generally consistent with results of the whole 

slide analysis, where highest densities and percent cover estimates were evident above 6 to 8 m 

water depths. 

 Minimum and maximum average lengths, widths, and heights for Platform Harvest 

mussels (932 count) were 3.81 and 9.90 cm, 2.25 and 4.48 cm, and 1.67 to 3.42 cm, respectively. 

Individual average weights were variable, ranging from 10.78 to 111.42 g. Smallest mussels 

were collected at water depths where the fewest mussels were available, while the larger mussel 

specimens were present in those portions of the platform leg where higher densities were 

evident. 

 Measurements of mussel bed thickness were completed at two platforms. The vertical 

extent of the mussel zone at each platform was variable. Maximum mussel thicknesses ranged 

from 8 to 12 inches (20.3 to 30.5 cm) at Platform Harvest, and 8 inches at Platform Irene; the 

depth of occurrence for maximum mussel bed thickness varied between the legs sampled. 

Differences in the depths of maximum thickness may be attributed to protection afforded by 

adjacent platform legs. 

 A review and comparison of the summary taxa listing from the photographic analysis 

and scraping identifications offered several interesting points of note. For the photographic 

analysis completed on six platforms and Diablo and Nifty Rocks, 173 total taxa were observed. 

Among these taxa there was a noted predominance of several phylogenetic groups, including 

cnidarians (e.g., anemones, hexacorals, hydrozoans, hydroids, and zoanthids), sponges (i.e., 

encrusting and upright forms), and echinoderms (e.g., ophiuroids, sea stars, urchins, a 

holothuroid, and a crinoid), as well as ubiquitous mussels. Photographic analysis also revealed 

a relatively low number of algal species, most of which were rhodophytes (red algae – Class 

Rhodophyceae). 

For the scrapings analysis, no sea stars or urchins were observed, but a significant 

contribution from caprellid and gammarid amphipods, more bivalve species, several additional 

algal species, and a significant increase in the number of polychaete taxa and minor phyla (e.g., 

nemerteans, bryozoans, sipunculids, and flatworms) were noted. These findings highlighted 

the complex nature and three-dimensional structure of the mussel and barnacle zones, and 

underscored one of the limitations inherent in photographic interpretation. This three170
dimensional structure provides an intricate network of interstitial space and affords habitat and 

protection for a variety of cryptic species. 

 Comparison of photographic and scraping samples taxa only resulted in limited species 

overlap. While several species were present in both photographic and scraping data, the 

scraping material was predominantly composed of smaller, more cryptic species (e.g., caprellid 

amphipods, gammarid amphipods, polychaetes, hydrozoans, bryozoans, nemerteans). 

Scrapings analysis and results allowed for a more detailed description of the platformassociated community at Platform Harvest and Gail. 

In general terms, the zonation patterns of all California platforms may be outlined as 

follows: 

 an upper zone (from the intertidal to 18 to 26 m [60 to 85 ft]), including the 

intertidal and mussel bed, and consisting of Mytilus spp., various algae (e.g., 

filamentous and foliose red algae, several green algal species such as Ulva), 

barnacles, several anemone species (e.g., Anthopleura elegantissima, Metridium 

senile), sponges, and ophiuroids; 

 a mid zone (from 19 to 26 m [65 to 85 ft] to about 76 m [250 ft]), including 

Corynactis californica, ophiuroids, barnacles, Metridium senile, Leucetta/Leucetta 

losangelensis, and worm tubes; and 

 a lower zone (below 76 m [250 ft]), including Metridium senile, M. farcimen, 

Paracyathus stearnsii, turf, and worm tubes. Platform- or platform group-specific 

taxa may also be present in the lower zone (e.g., Desmophyllum dianthus only at 

Platform Gail; red encruster only at platforms Harvest, Hidalgo, and Irene). 

 In summary, the major findings pertinent to invertebrate and algal communities 

inhabiting six of California’s platforms and two natural rock outcrops include the following: 

(1) Results of videotape, quantitative slide, and point contact analyses, in general, 

produced similar biotic zonation patterns at the platforms studied, although an 

alternate, three-zone approach to platform characterization may be viable. 

(2) A total of 173 species (or higher taxa) were identified during quantitative slide 

analysis of 821 photographs from six platforms and two rock outcrops, while a 

total of 55 species or higher taxa were identified during point count analysis of 

883 photographs from six platforms; invertebrate fauna dominated, with only a 

few algal species/species groups evident (filamentous and foliose red algae; other 

red and green algae). 

(3) In general, the presence and relative ranking of percent cover dominants from the 

point count analysis were very consistent with the results of whole slide analysis. 

Random point count analysis provides a straightforward means of identifying 

percent cover dominants, whereas quantitative slide analysis (i.e., individual 

counts or percent cover) provides a more comprehensive characterization of all 

taxa present, within the limitations of photographic interpretation and 

identification. 

171
(4) A total of 130 species or higher taxa (primarily cryptic, interstitial forms typically 

not visible via photographic techniques) were identified during analysis of 

scraping samples from the mussel and barnacle zones of Platform Harvest; a total 

of 90 species or higher taxa were identified from scraping samples from the 

intertidal, barnacle, and mussel zones of Platform Gail. Findings highlight the 

complexity and three-dimensional structure of these zones. In total, 181 separate 

taxonomic entities were noted from scrapings at both platforms, of which 

123 (68%) were monospecific taxa. Only 41 taxa occurred at both platforms. 

(5) A mussel zone was present at each platform, although the vertical extent and 

maximum depth of each mussel zone varied between platforms; considerable 

variability in mussel density and percent cover was evident. 

(6) Highest species- or taxa-specific density levels were typically encountered in the 

upper portions of each platform, normally within the upper 30 m (100 ft); within 

this depth range, the intertidal and mussel zones also contained several other 

numerically dominant species (e.g., anemones, ophiuroids, barnacles, algae). 

(7) Middle and lower portions of each platform showed considerable variability, but 

typically contained encrusters (e.g., sponges) and various cnidarian species (e.g.,

Metridium, Corynactis); some prominent species at depth were limited in their 

geographic distribution (e.g., Desmophyllum dianthus only at Platform Gail; red 

encruster only at platforms Harvest, Hidalgo, and Irene). On the deeper water 

platforms (i.e., Gail and Harvest), deepest zones at the bottom of each platform 

exhibited a strong affinity to basin fauna. 

(8) Upper portions of the platforms exhibited similar dominant taxa; taxa unique to 

each platform tended to occur at depth. Overall, comparisons of density- and 

percent cover-dominants from adjacent platform legs were very similar, although 

species-specific enumerations were variable. 

(9) Clustering analyses comparing density- and percent cover-dominants at the six 

platforms identified strong similarities between adjacent platform legs and 

relatively strong similarity between all platforms, with minor exceptions (i.e., few 

trends suggesting existence of a north-south gradient in species composition). 

(10) Correspondence analysis of the scraping data revealed that Mytilus and barnacle 

zones were distinct in terms of their respective taxonomic compositions; taxonomic 

composition of the Mytilus zone was more variable than the barnacle zone; and 

(11) Species diversity at the platforms was relatively high, although the number of 

species present in individual photographs was relatively low and species diversity 

at natural outcrops was higher (within comparable, shallow depth zones) than that 

observed at the platforms. 

There are few substrates comparable to those afforded by existing platform structures. 

Naturally-occurring rock substrates that mimic the entire depth range (i.e., continuous 

substrate) found on platforms do not exist, while intermittent or discontinuous outcrop features 

exhibiting limited vertical extent are limited (e.g., shallow nearshore outcrops; shelf and slope 

hard bottom features with vertical relief of 1 to 3 m). Submerged platform surfaces, including 

platform legs, are optimal settling plates which provide habitat for a variety of attached and 

motile biota, particularly in the shallower portions of a platform where Mytilus, Metridium 

senile, barnacles, and associated fauna and flora predominate. Mid and lower platform zones 

exhibit decreasing species diversity with depth, yet frequently contain unique taxa which 

suggest subtle differences in platform community structure affected by platform location. 

172
5.0 List of Preparers 

This report was prepared by Continental Shelf Associates, Inc. (CSA), Jupiter, FL and 

Salinas, CA under Contract No. 1435-01-98-CT-30865 to the MMS Pacific OCS Region, 

Camarillo, CA. 

The following individuals contributed to the technical content of this document: 

 Brian J. Balcom (CSA, Salinas, CA) – Degrees: M.S. Biology; B.S. Biological Sciences. 

25 years experience. 

 Alan D. Hart (CSA, Jupiter, FL) – Degrees: Ph.D. Oceanography; B.S. Zoology. 

22 years experience. 

 Robert P. Meek (ECOMAR, Inc., Goleta, CA) - Degrees: Ph.D. Zoology; M.S. 

Zoology; B.S. Biology. 36 years experience. 

 Robert B. Cady (CSA, Jupiter, FL) – Degrees: M.S. Oceanography; B.S. Marine 

Biology. 7 years experience. 

 John C. Ljubenkov (Dancing Coyote Ranch Taxonomy, Pauma Valley, CA) - 

Degrees: M.S. Marine Biology, B.S. Biology. 33 years experience. 

 Suzanne V. Benech (Benech Biological and Associates, Ventura, CA) – Degrees: 

M.S. Biological Sciences (Marine Biology); B.S. Biological Sciences. 29 years 

experience. 

 CSA recognizes the expert taxonomic support provided by Sue Benech and John 

Ljubenkov during analysis of videotapes and 35-mm slide transparencies, with frequent 

support from Dr. Meek. In addition, an expert group of marine invertebrate and algal 

specialists identified scraping specimens, including Nancy Carder (echinoderms), Dr. Doug 

Diener (crustaceans, echinoderms), John Ljubenkov (cnidarians, mollusks, and minor phyla), 

Larry Lovell (polychaetes), and Dr. Kathy Ann Miller (algae). Special thanks are also offered for 

Terry Orosco who providing sample sorting, cataloguing, and data entry support. 

 CSA also wishes to acknowledge the technical support, guidance, and review comments 

provided over the course of the project by members of the Quality Review Board – Dr. Jack 

Engle, Dr. Miriam Polne-Fuller, and Dr. James Ray. Their input provided during several early 

project meetings helped focus the field effort, while their review comments offered on the draft 

report outlined excellent recommendations to improve the scope of analysis and content of the 

final report. 

 In addition, CSA appreciates the support provided by various members of the MMS 

who provided excellent direction to the project and constructive, critical review of the draft 

report, including Ms. Mary Elaine Dunaway (Contracting Officer’s Technical Representative, 

173
Pacific OCS Region), Mr. Maurice Hill (Pacific OCS Region), Dr. Fred Piltz (Pacific OCS Region), 

Dr. Ann Bull (Pacific OCS Region), and Dr. Thomas Ahlfeld (MMS Headquarters). 

 CSA also wishes to note, with deepest regret, the recent passing of Dr. Robert Meek. As 

Principal Investigator on this project, Dr. Meek was instrumental in sampling design and 

collection of photographic, videotape, and scraping data at all of the platforms and natural rock 

outcrops. Dr. Meek personally lead the scientific dive teams and piloted the numerous ROV 

operations that acquired these data. He was also instrumental in the design and operation of 

the diver sampling (air lift) system employed during acquisition of the scraping samples from 

platforms Gail and Harvest. Dr. Meek’s knowledge and experience with California subtidal 

biology, and particularly his understanding of mussel communities on the offshore platforms, 

was an immeasurable asset to the project. 

174
6.0 Literature Cited 

Blake, J. A., and A. L. Lissner. 1993. Taxonomic atlas of the benthic fauna of the Santa Maria 

Basin and western Santa Barbara Channel. Final report, Volume 1. Introduction, 

benthic ecology, oceanography, Platyhelminthes, and Nemertea. Prepared for the U.S. 

Department of the Interior, Minerals Management Service, Pacific OCS Region, 

Camarillo, CA. OCS Study MMS 92-0042. 132 pp. 

Bram, J., M. Page, and J. Dugan. 2002. Early development of subtidal invertebrate assemblages 

on offshore oil platforms in the Santa Barbara Channel. Presentation at MMS Studies 

Presentations, May 2002, Camarillo, CA. 

Culver, C., B. Mardian, M. Page, and J. Dugan. 2002. Spatial patterns of distribution, 

abundance and dynamics of invertebrates on offshore oil platforms in the Santa Barbara 

Channel. Presentation at MMS Studies Presentations, May 2002, Camarillo, CA. 

Dailey, M. D., D. J. Reish, and J. W. Anderson. 1993. Ecology of the Southern California Bight – 

A Synthesis and Interpretation. University of California Press, Berkeley, CA. 926 pp. 

Dustan, P., J. Leard, O. Meier, M. Brill, and V. Kosmynin. 1999. PointCount’99®. University of 

Georgia. Website: http://www.cofc.edu/~coral/corallab.htm. 

Gosling, M. (ed.). 1992. The mussel Mytilus: ecology, physiology, genetics and culture. Elsevier 

Science, Amsterdam. 

Helmuth, B. S. T. 1998. Intertidal mussel microclimates: predicting the body temperature of a 

sessile invertebrate. Ecological Monographs 68(1):51-74. 

Lessios, H.A. 1996. Methods for quantifying abundance of marine organisms, pp. 149-157. 

In: Lang and Baldwin (eds.), Methods and Techniques of Underwater Research: 

Proceedings of the American Academy of Underwater Sciences 1996 Scientific Diving 

Symposium. Washington D.C. 

Love, M. S., M. Nishimoto, D. Schroeder, and J. Caselle. 1999. The ecological role of natural 

reefs and oil and gas production platforms on rocky reef fishes in Southern California. 

Final Interim Report. OCS Study MMS 99-0015. 

Love, M. S., D. M. Schroeder, and M. M. Nishimoto. 2003. The ecological role of oil and gas 

production platforms and natural outcrops on fishes in southern and central California: 

a synthesis of information. U.S. Department of the Interior, U.S. Geological Survey, 

Biological Resources Division, Seattle, WA. OCS Study MMS 2003-032. 

MBC Applied Environmental Sciences. 1987. Ecology of oil/gas platforms offshore California. 

Prepared for the U.S. Department of the Interior, Minerals Management Service, Pacific 

OCS Region, Camarillo, CA. February 1987. OCS Study MMS 86-0094. 92 pp. 

175
Miller, K. A. 2004. Nomenclatural and taxonomic changes for California seaweeds. Draft, 

March 2004. Kathy Ann Miller, University of Southern California, Wrigley Marine 

Science Center, Santa Catalina Island, CA. 12 pp. Accessed at: 

http://wrigley.usc.edu/PDF/CASeaweedsKAM2004.pdf. 

Page, H. M., J. E. Dugan, D. S. Dugan, J. B. Richards, and D. M. Hubbard. 1999. Effects of an 

offshore oil platform on the distribution and abundance of commercially important crab 

species. Mar. Eco. Prog. Ser. 185. 47-57. 

Science Applications International Corporation and Marine Ecological Consultants. 1995. 

Monitoring assessment of long-term changes in biological communities in the Santa 

Maria Basin: Phase III, Final Report. Prepared for the U.S. Department of the Interior, 

Minerals Management Service, Pacific OCS Region, Camarillo, CA and the National 

Biological Service. OCS Study MMS 95-0049. 

Seed, R. and T. H. Suchanek. 1992. Population and community ecology of Mytilus, pp. 87-169. 

In: E. M. Gosling (ed.). The mussel Mytilus: ecology, physiology, genetics and culture. 

Elsevier Science, Amsterdam. 

Southern California Association of Marine Invertebrate Taxonomists. 2001. A Taxonomic 

Listing of Soft Bottom Macro- and Megainvertebrates from Infaunal & Epibenthic 

Monitoring Programs in the Southern California Bight. Edition 4, 6 October 2001. 

Southern California Association of Marine Invertebrate Taxonomists, San Pedro, CA. 

196 pp. 

Steinhauer, M., and E. Imamura (eds.). 1990. California OCS Phase II Monitoring Program: 

Year Three Annual Report. Prepared for the U.S. Department of the Interior, Minerals 

Management Service, Pacific OCS Region, Camarillo, CA. OCS Study MMS 90-0055. 

University of California, Santa Barbara (UCSB), Coastal Marine Institute. 2004. Coastal Marine 

Institute, Program Year 10, Quarterly Report 3 for the Period January 1, 2004 – March 31, 

2004. April 9, 2004. 

U. S. Department of the Interior, Minerals Management Service. 2001. Status of leases and 

qualified companies, Pacific OCS Region (as of November 2001). Contributors: 

E. William-Flatts, J. Hall, S. Wolfson, and B. Bosserman. Camarillo, CA. 49 pp. 

U. S. Department of the Interior, Minerals Management Service. 2005. Pacific OCS platforms. 

Minerals Management Service, Pacific OCS Region, Camarillo, CA. Website: 

http://www.mms.gov/omm/pacific/offshore/platforms/platformintro.htm. 

Winn, R. N. 1985. Comparative ecology of three Cancrid crab species (Cancer anthonyi, C. 

antennarius, and C. productus) in marine subtidal habitats in southern California. Ph.D. 

dissertation, University of Southern California, Los Angeles. 

176
Appendices 

177
Appendix A 

Detailed Operational, Sampling, and Safety Procedures 

and Vessel Modifications 

A-1
Appendix A 

Detailed Operational, Sampling, and Safety Procedures 

and Vessel Modifications 

A.1 Operational Procedures 

Mooring Systems and the Mooring Process 

The preferred mooring plan was to tie to (1) the platform’s supply boat mooring buoy 

(usually set 213 to 305 m [700 to 1,000 ft] from each respective platform), and (2) the platform 

leg to be sampled via a stern tie. This arrangement allows movement forward and aft with 

good lateral stability. On occasion, currents and winds only allowed for a stern tie. For deeper 

water platforms or those without a convenient mooring buoy, a single stern tie was the only 

alternative. Changing currents and winds can make mooring arrangements tenuous. Use of a 

bottom-founded anchor was also considered on a site-specific basis for those platforms in 

<137 m (<450 ft) of water. 

The mooring systems and plan outlined above work well in good weather conditions in 

cases where there are nearby mooring buoys. In marginal weather and/or situations without 

available mooring buoys, the contingency mooring arrangement used during the Preliminary 

Survey (i.e., stern tie where winds and currents allow, with operations on the nearest leg[s]) 

were employed. This arrangement has inherent risks (with changing currents and winds) of 

disruptions in the day’s sampling efforts. In waters 91 to 107 m (300 to 350 ft) or less in depth, a 

bow anchor could have been deployed to stabilize the vessel. A sea anchor could also have 

been used. 

Platform Leg Selection 

 In all cases, the mooring location was the primary determining factor as to which legs 

were to be sampled. Deviations in site-specific conditions warranted adjustment to these 

preferred designations; recommendations for such adjustments were made in the field, on site, 

by the Principal Investigator and Project Manager, in consultation (either in person or via 

telephone) with the Minerals Management Service (MMS) Contracting Officer's Technical 

Representative (COTR). The relative positions of available moorings to each platform were 

reviewed and proximal legs designated below. Under optimal conditions (i.e., where available 

moorings and ambient oceanographic conditions allowed), the following legs were to be 

sampled: 

 Primary Platform Legs to be Sampled

Grace C3, C4 

Gail B1, B2 

Hidalgo B4, B5 

Harvest B4, B5 

A-3
Secondary Platform Leg to be Sampled

Habitat A1 

Hermosa B5 

Hondo inshore, downcurrent 

Irene A1 

Diver Mobilization 

Diver mobilization included the proper emplacement of hoses, dive helmets and 

associated gear, and topside equipment (including communications). 

Diving Equipment Suite 

Diving equipment included a KMB 17A dive hat for the scientific diver with surface 

supplied air. This system provides communication to the tender and deck personnel. A hooka 

system was provided for the scientist diver’s assistant. Both systems were supplied by a single 

40 cfm/300 psi diesel-powered compressor attached to a 60-gallon volume tank and air 

filtration system. Each diver system (i.e., hat, bailout, and hoses) was backed up with a 

redundant system. 

A.2 Sampling Procedures 

Diver Video 

The diver video system included a hand-held High 8 color camera and housing with a 

wide-angle lens. The system was pre-set at a focal length of 0.6 to 0.9 m (2 to 3 ft) and moved 

slowly (i.e., at a rate of 1.8 to 2.4 m [6 to 8 ft] per minute). Two 250-watt underwater lights were 

used to color fill the frame, aiding in video detail and proper color rendition (i.e., an aid to postsurvey video interpretation and biological identification). 

During some dives, annotation of the videotapes was augmented by placing a dive 

computer in the field of view that displayed depth and dive duration. This information, along 

with the audio log, facilitates analyses of diver videos. Although cumbersome, time 

consuming, and somewhat duplicative, the diver video was considered to be essential in depths 

above 9 to 12 m (30 to 40 ft) where the remotely operated vehicle (ROV) was more prone to 

wave surge instability. Divers anticipated and compensated for some of the surge and current 

and acquired better quality video for biological analyses in these upper depth regions. 

Diver Photography

Photographic data (photoquadrats) were collected via diver (hand-held) 35-mm color 

camera and a 0.0625 m2 photoquadrat frame (i.e., image area). Optimal results were achieved 

through the use of a Nikonos V camera equipped with a 28-mm Nikon lens and a dual strobe 

configuration. All photos and settings were logged verbally by the diver and recorded by the 

tender and quality assurance/quality control (QA/QC) personnel. The best aperture settings 

were determined to be f22 and f16, however f8 could have been used in those zones with 

exceptionally dark backgrounds. Proper focal distance for each photoquadrat was assured 

A-4
using a mounted framer. Resultant photoquadrat size was 0.0625 m2; photoquadrats and 

scrapings have identical dimensions (i.e., 1/16 m2 or about 10 inches per side). A total of 10 to 

15 photographs was taken per zone; photo location was predetermined using the 

randomization protocol (Appendix B). Zones sampled conformed to the zonation patterns 

defined by Sue Benech during Quality Review Board (QRB) Meeting #1 (i.e., summary of 

results of Task 1, Videotape Analysis). 

Diver Sampling (Air Lift) System 

The diver sampling system consisted of a 4-inch (diameter) air lift system with 30 m 

(100 ft) of hose attached to the vessel’s A-frame down weight. This 100-ft air lift system was 

also connected to a 100-ft diver sampling hose (4-inch diameter) that terminated on deck in a 

15-gallon aluminum “accumulator” drum (i.e., to allow slow deceleration of the sample). The 

sampling hose enters the accumulator horizontally near the top of the drum; an opening at the 

bottom of the drum allows water and entrained biota to exit. The drum was positioned over a 

sieve box (i.e., two nested screens) outfitted with removable Nytex mesh screening to capture 

scraped material as it exits the bottom of the drum. Use of a smaller diameter or more flexible 

hose was considered due to space and handling concerns. 

Divers employed a 0.0625 m2 quadrat (i.e., 25 cm x 25 cm) and a small pneumatic 

hammer and chisel to measure and dislodge the biological material within the quadrat frame. 

Scraped material was suctioned off the quadrat and conveyed to the surface via the lift system. 

The depth of the down weight and lift system were adjusted as needed, depending on diver 

depth and position. 

The lift system was activated prior to any scraping activity to assure that cryptic and 

motile interstitial fauna are collected. The lift system continued to operate for 20 to 30 seconds 

after scraping was completed to clear all specimens from the lift line (i.e., to assure that scraped 

specimens reached the surface). 

Lifted specimens flowed into an open conduit system designed to reduce stream 

velocity, minimizing damage to soft-bodied biota. Specimens were retained on Nitex mesh 

screening (1.0- and 0.5-mm sieve), relaxed, and fixed in buffered formalin. Observations of 

sample content were made prior to fixation. When practical, large algal specimens were 

processed separately to facilitate pressing. A total of eight scrapings was collected per zone per 

platform leg (with the exception of the mussel zone on a single leg on Platform Gail); biotic 

zones sampled, in order of importance, included (1) the mussel zone, (2) the intertidal zone, and 

(3) the barnacle/scallop zone, with lower zones being of lower priority. The location of each 

scraping was determined randomly (see Diver Photography and ROV Photographic Data 

Collection). 

Field preparation of algal and invertebrate samples was via buffered formalin 

preservation (i.e., no freezing; 4 percent formalin solution for algae; 10 percent formalin solution 

for invertebrates). Some pressing was required for larger algal specimens. Invertebrates were 

relaxed prior to preservation using either magnesium sulfate or magnesium chloride. All 

sample containers were labeled with a unique station number and date (i.e., platform and leg 

designation, sample depth); internal labels containing the same station and date information 

A-5
were also used. All samples (photographs, videotapes, vouchers) were properly logged upon 

collection. Sample collection and sample tracking forms were maintained by the QA/QC 

officer. Scrapings were only collected from Platforms Gail and Harvest. 

ROV Photographic Data Collection 

Photographs collected by the ROV were consistent with those collected by divers. 

Proper focal distance was assured through the use of an ROV-mounted laser sighting system 

maintained within the field of view of the videocamera. The ROV was handled using either the 

vessel’s davit (with side winch) or A-frame (with stern winch). Similarly, the sample air lift 

system and down weights were also handled using this arrangement. 

 The ROV was equipped with a Photosea PS 1000A 35-mm camera and 1500S strobe 

system for still photography. The Photosea camera was fitted with a 28-mm lens. Based on 

results from the Preliminary Survey, focal distance was preset at 16 inches (i.e., lens to subject 

distance) and lens aperture was set at f 22. The camera was bulk loaded with color slide film 

rated at 200 ASA. Use of the laser sighting system ensured precise and repeatable photographic 

distance (i.e., 16 inches with a 28-mm lens), and also provided a basis for estimating the relative 

size of biota within the image. 

Randomization of photographs was implemented. This was accomplished by 

referencing the zonation patterns determined during inspection videotape analysis for each 

platform, eliminating 0.6 m (2 ft) at the edges of each zone (i.e, transition zone), and 

implementing a randomization protocol for each biotic zone. A detailed discussion of the 

randomization process is provided in Appendix B. 

ROV Marine Growth Depth Probe 

A small, air-operated chipping hammer was fitted with a specially designed probe (i.e., 

1/4 inch by 1/4 inch tool steel, 8-inch long sharpened tip) designed to penetrate hard growth as 

a means of determining growth thickness. The probe, marked at 1-inch intervals, was placed 

within the image area of the ROV videocamera. The ROV operator brought the probe into 

contact with the growth and thrust forward while the hammer was powering up. The chisel 

was driven through existing platform growth to establish growth thickness. 

The marine growth depth probe (and other air-operated systems) was usable to 

approximately the 137-m (450-ft) depth. A 200-m (650-ft), 3/8-inch (ID) hose was used to 

supply air to the system from the surface compressor. The resistance to airflow creates lag time 

between start up and shut down of the system. The lag in start up can create difficulties 

holding the ROV in position while awaiting start up; after shut down, air continues to flow 

from the system for some time until the pressures at depth and within the supply hose equalize. 

Consideration was given to installation of an electronically activated solenoid at the tool or 

moving the supply of air nearer the tool by providing a high pressure source solenoid operated 

at or near the down weight. The probe also needed to be moved to one side of the video field 

since exhaust air significantly obscured the video image. 

A-6
ROV Video Data Collection 

 The ROV video system was operated at vertical speeds of 1.8 to 2.4 m (6 to 8 ft) per 

minute (i.e., appropriate for general biological characterization) at distances of 0.6 to 0.9 m (2 to 

3 ft). Zoom capabilities were employed, as needed, to investigate community components of 

interest. 

ROV Sonar System 

 The ROV was outfitted with a Kongberg Simrad MS 900 imaging sonar. The sonar was 

used to navigate between platform legs and to avoid major debris. The sonar has not proven to 

be a useful tool to scan and characterize the size (i.e., areal extent) of the mussel pile beneath 

each platform. 

ROV and Diver Recording and Annotation 

 Dual recording systems were used to provide two original S-VHS tapes for each ROV 

excursion. The second recorder in the series was hooked to a TV monitor where recorded video 

quality was continuously monitored. Diver video was copied from High 8 to S-VHS; the S-VHS 

copy was utilized during biological interpretation. Photographs were taken in slide format (i.e., 

E6); test strips were developed on board or at the end of each field day to ensure proper 

photograph collection (i.e., proper focal distance and aperture setting). All photographs were 

logged and annotated by both the tender and QA/QC personnel. 

 The ROV video and Photosea still camera were annotated directly with alphanumeric 

identifiers. A similar system does not exist for the diver video and still photographs. Depth 

and time readings can be periodically flashed in front of the diver video, but a similar system 

for the diver photographs has not been attempted. 

A.3 Safety and Emergency Procedures

 Safety and emergency procedures were to be implemented in the event of two major 

accidents, including (1) dive-related accidents, and (2) an accidental H2S release from the 

platform. 

 In the event of a dive-related accident, ECOMAR staff were responsible for 

• Immediately notifying the platform; and 

• Making immediate arrangements for medical evacuation. 

In the event of an accident, injured personnel were to be offloaded to the platform for helicopter 

evacuation.

 In the event of an accidental H2S release, gas monitors aboard the platform will sound 

an alarm. The Dawn was also equipped with an H2S monitor/alarm. Major response activities 

to an accidental H2S release include 

A-7
• Vessel personnel to take immediate shelter in the Dawn’s cabin, and doors are to 

be shut and sealed; 

• Emergency breathing apparatus will be issued; and 

• The Dawn will be moved upwind and off-site. 

 Depending on the nature of the sampling activities being conducted at the time and the 

relative position of the vessel to the platform, several vessel responses are possible. When the 

Dawn is moored upwind of the platform and an H2S alarm sounds, downwind mooring lines 

will be cut immediately and the vessel will motor upwind, or the anchor mooring line will be 

winched in should divers be in the water. Divers in the water at the time will be notified to 

remain at depth until ordered to surface (i.e., once the vessel has reached a safe distance 

upwind of the platform). When the Dawn is located lateral to or downwind of the platform, 

mooring lines will be cut and the vessel will either drift or motor away from the platform; diver 

safety will be a prime determining factor in a decision to motor. In all cases, topside personnel 

will take shelter in the cabin with the doors sealed. 

A.4 Vessel and Equipment Modifications and Sampling Efficiency

 In response to MMS comments and concerns (i.e., safety, space limitations) expressed 

following the Preliminary Survey, ECOMAR completed several vessel and equipment 

modifications, including the following: 

• Relocation of the dive compressor to below deck astern; advantages: clears 

additional deck space aft, eliminates a significant source of noise and exhaust 

fumes topside; 

• Relocation of the videotape and ROV control equipment from the main cabin to 

the bridge; advantages: consolidates ROV control operations on the bridge, clears 

needed space in the main cabin area; 

• Installation of an H2S monitor/sensor; advantages: supplements platform-based 

monitors, provides secondary alarm system to vessel crew; 

• Addition of safety and emergency procedures to the Sampling Plan; advantages: 

informs cruise participants of appropriate safety procedures; 

• Addition of emergency breathing apparatus; advantages: provides emergency air 

supply to the crew in the event of an H2S release aboard the platform; 

• Installation of fixed arms on the A-frame; advantages: provides a fixed point of 

deployment for the ROV and surface air systems; 

• Development of a closed “accumulator” system for the lift system samples; 

advantages: provides a closed system for receipt and retrieval of lift samples 

topside; and 

• Purchase of a more flexible lift hose; advantages: allows for additional deck 

space, as lift hose storage requirements are reduced. 

A-8
Appendix B 

Randomization of Photoquadrats 

B-1
Appendix B 

Randomization of Photoquadrats 

 Existing biotic zones and their depth of occurrence were determined for each of the six 

platforms based on the results of inspection videotape review, as summarized in Table B-1. 

Subsequent random selection of photograph location within each biotic zone was then 

established, taking into consideration the extent of each zone. Note: Randomization of photographs 

could not be implemented for the intertidal zone, given the limited extent of this zone and the relative size 

of the photoquadrats (~10 inches/side). As many as 15 photographs were collected in the intertidal 

wherever conditions would allow (i.e., across the face of the platform leg, regardless of water depth). 

 For the remaining zones (e.g., Mytilus, barnacle/scallop, etc.), whether photographed via 

diver or remotely operated vehicle (ROV), a 0.6-m (2-ft) buffer was established, encompassing 

the area in which a faunal transition between adjacent zones may occur. Buffers were 

established in both upper and lower reaches of each zone. Due to restrictions on diving 

operations, the maximum extent of the deepest diver sampled zone (e.g., barnacle/scallop zone 

on Grace) was truncated at 24.4 m (80 ft) subsurface. Note: The lower portions of such zones, beyond 

diver depths, were normally photographed using the ROV. For example, at Platform Grace, four 

major biotic zones were noted (in addition to the intertidal zone): 

 Zone Extent of Zone (ft subsurface) Adjusted Zone (ft subsurface)

Mytilus 6 to 45 8 to 43 

Barnacle/Scallop 45 to 90 47 to 88 

Anemone/Encruster 90 to 230 92 to 228 

Encruster/Sea Star 230 to 318 232 to 316 

The extent of each zone was then determined (e.g., Grace Mytilus zone = 35 ft) concurrently 

with the starting depth for each zone (i.e., at 8 ft subsurface for the Mytilus zone at Platform 

Grace): 

 Zone Adjusted Zone (ft subsurface) Extent (ft) Start Depth (ft subsurface)

Mytilus 8 to 43 35 8 

Barnacle/Scallop 47 to 88 41 47 

Anemone/Encruster 92 to 228 136 92 

Encruster/Sea Star 232 to 316 84 232 

 A random number table (Rand Corporation, Table A-1) was used (i.e., blind selection of 

a number within the table, numbers read across) to select a total of 25 numbers for each zone (to 

allow for potential duplicates), creating a unique random number set for each zone. Random 

numbers ranged from 00 through 99. 

 Selected numbers were then converted to a percentage (e.g., 45 became 45% or 0.45). 

The number representing the extent of each zone was subsequently multiplied by its unique 

random number set, with products rounded, as appropriate; the absolute value of the start 

depth was subsequently added. All final positive values were converted to negative to 

represent depth subsurface. For example, in the Grace Mytilus zone, the following was 

calculated, where 35 ft is the extent of the Mytilus zone and 8 ft subsurface was the start depth: 

B-3
Table B-1. Characteristics of platform biotic zones as determined during inspection 

videotape analysis. 

Biotic Zone 1 Zone Depth 

(m [ft] subsurface) 

Vertical Extent 

(m [ft]) 

Primary Platforms – 

Platform Gail 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Mytilus 1.8 to 12.1 (6 to 40) 10.3 (34) 

 Barnacle/Scallop 12.1 to 48.8 (40 to 160) 36.7 (120) 

 Corynactis/Encruster 48.8 to 115.8 (160 to 380) 67.0 (220) 

 Vase sponge/Encruster 115.8 to 192.0 (380 to 630) 76.2 (250) 

 Encruster/Sea Star/Cup Coral 192.0 to 225.2 (630 to 739) 33.2 (109) 

Platform Grace 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Mytilus 1.8 to 13.7 (6 to 45) 11.9 (39) 

 Barnacle/Scallop 13.7 to 27.4 (45 to 90) 13.7 (45) 

 Anemone/Encruster 27.4 to 70.1 (90 to 230) 42.6 (140) 

 Encruster/Sea Star 70.1 to 96.9 (230 to 318) 26.8 (88) 

Platform Harvest 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Mytilus 1.8 to 25.9 (6 to 85) 24.1 (79) 

 Barnacle/Corynactis 25.9 to 50.3 (85 to 165) 24.4 (80) 

 Anemone/Encruster 50.3 to 105.2 (165 to 345) 54.9 (180) 

 Vase Sponge/Encruster 105.2 to 169.2 (345 to 555) 64.0 (210) 

 Metridium/Sea Star 169.2 to 205.7 (555 to 675) 36.6 (120) 

Platform Hidalgo 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Mytilus 1.8 to 19.8 (6 to 65) 18.0 (59) 

 Barnacle 19.8 to 32.0 (65 to 105) 12.1 (40) 

 Metridium/Encruster 32.0 to 109.7 (105 to 360) 77.7 (255) 

 Sponges/Encruster 109.7 to 132.3 (360 to 434) 22.5 (74) 

Secondary Platforms – 

Platform Habitat 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Mytilus 1.8 to 18.3 (6 to 60) 16.5 (54) 

 Corynactis 18.3 to 54.9 (60 to 180) 36.6 (120) 

 Metridium/Encruster 54.9 to 88.4 (180 to 290) 33.5 (110) 

Platform Irene 

 Intertidal 0 to 1.8 (0 to 6) 1.8 (6) 

 Barnacle/Algae 2 1.8 to 10.7 (6 to 35) 8.8 (29) 

 Mytilus 10.7 to 25.9 (35 to 85) 15.2 (50) 

 Corynactis/Encruster 25.9 to 73.4 (85 to 242) 47.9 (157) 

 

1 Zonation patterns based on the results of inspection videotape review; zones verified via ROV 

observations. 

2 The barnacle/algae zone of Platform Irene represents an area recently cleaned. 

B-4
 First random number 31 

 Percentage conversion 0.31 

 Calculations (0.31 x 35) = 10.85 ≈ 11 

11 + │-8 │ = 19 ft 

 Photograph location: 19 ft subsurface 

Results of the photoquadrat randomization produced a listing of 15 photograph locations per 

biotic zone for each of the primary and secondary platforms. For primary platforms, where two 

legs were to be sampled, separate photoquadrat lists were generated for each leg using the 

random number assignment and calculation process described previously. 

B-5
Appendix C 

Data Appendix: Whole Slide Analysis 

C-1
Appendix C has been organized into three primary sections: 

 Table C-1 – this two-page table summarizes the taxa, undifferentiated assemblages and 

physical characteristics identified during quantitative slide analysis. 

 Table C-2 – this two-page table summarizes the density and percent cover estimates of 

select dominant species or taxa which resulted from tabularization and analysis of the 

observations from each photoquadrat. Data are organized by platform. 

 Whole Slide Analysis Data Set – separate spreadsheets (each containing four to seven 

pages) have been developed for the 10 platform legs and Diablo and Nifty Rocks. For 

each platform leg or outcrop, separate spreadsheets are provided for density (i.e., 

number of individuals/0.0625 m2, labeled as “counts”) and percent cover (i.e., 

coverage/0.0625 m2 – labeled as “%”). Site identifiers are located in the upper left corner 

of each spreadsheet (e.g., Platform Gail – Leg A1 counts). Within each spreadsheet, data 

are organized by water depth (i.e., from shallowest to deepest) in the horizontal plane. 

In the vertical plane, data are organized by dominant taxa (i.e., highest total number of 

individuals for density tables; highest average percent cover for percent cover tables), in 

descending order. Summary data (i.e., total, average, minimum, maximum, and 

frequency of occurrence) are provided on the last page of each separate set of 

spreadsheets. 

C-3
Table C-1. Taxa identified during the photographic analysis of six California platforms and Diablo and N

Dominant species or taxa, as determined via ranking of the top 12 taxa by density or percent cotype; dominant species shown separately for platforms (P), rock outcrops (R), or both (P+R). 

FLORA: Algae: 

Alga, brown, blade Alga, brown, clump Alga, coralline, encrusting Alga, encrusting (Lithothamnion) (R) 

Alga, green clump Alga, green clump (Codium-like) (R) 

Alga, green encrusting (P) Alga, green filamentous Algae, red filamentous (P+R) Algae, red foliose (P) Bossiella spp. (R)

Codium spp. Corallina spp. (P) 

Egregia spp. Rhodymenia ?lobata Rhodymenia spp. Ulva lactuca (P) 

Note: Algae broadly characterized due to limitations of 

photographic resolution and interpretation. 

FAUNA: Crustaceans:  Barnacles (Cirripedia): 

Balanus nubilus (P)

Balanus spp. (P+R)

Barnacle, unidentifiedChthalamus spp. (R) 

Pollicipes polymerus (P)

Tetraclita squamosa (P)

 Decapod crabs (Decapoda): 

Cancer antennarius Cancer spp.

Hemigrapsus nudus 

 Galatheid crabs (Galatheidae): 

Galathea californiensis

Echinoderms:  Sea stars (Asteroidea): 

Asterina miniata (=Patiria) 

Dermasterias imbricate Henricia leviuscula Henricia sanguinolenta Orthasterias koehleri Pisaster brevispinusPisaster giganteus Pisaster ochraceus (P)Poraniopsis inflata Pycnopodia helianthoides Stylasterias forreri 

 Urchins (Echinoidea): 

Allocentrotus fragilis Lytechinus pictus

Strongylocentrotus franciscanusStrongylocentrotus purpuratus (R)

 Brittle stars (Ophiuroidea): 

Amphipholis spp. (P)

Ophiocantha diplasia Ophiothrix spiculata (P+R)

Ophiuroid, unidentified (P) 

 Holothuroids (Holothuroidea): 

Dendrochirotida, unidentified (R) Parastichopus californicus 

 Crinoids (Crinoidea); 

Florometra serratissima 

Mollusks: 

Bivalves (Pelecypoda): 

Anomiidae, unidentified Bivalve, nestling, unidentified Chama arcana Crassadoma gigantea Mytilidae, unidentified Mytilus californianus (P+R)Mytilus spp. (P) 

 Gastropods (Gastropod

Aeolid (SF AeolAeolidia papillosaAeolidioidea, unAnisodoris nobilisArchidoris monteCalliostoma spp.Cypraea spadicea Dialula sandiegen

Dorid, white, unDorid, yellow, u

Doridacea, unidFlabellina iodineaGastropoda, uniHermissenda crasPleurobranchaea cSerpulorbis spp.Triopha catalin

 Chitons (Polyplacopho

Chiton, unident

Polychaetes:

Eudistylia polym

Sabellidae/Serp

(feather dus

Protula superba 

Salmacina spp. Serpulidae, unidSpionidae, unidSpirobranchus spTube worm, douTube worm, singWorm tubes, caWorm tubes, pl
Table C-1. Taxa identified during the photographic analysis of six California platforms and Diablo and N

Dominant species or taxa, as determined via ranking of the top 12 taxa by density or percent cotype; dominant species shown separately for platforms (P), rock outcrops (R), or both (P+R) (c

Cnidarians:  Anthozoans (Actiniaria): 

Actiniaria, brown Actiniaria, pink Amphianthus californicus Anemone, pink Anemone, unidentified Anthopleura elegantissima 

(rosy morph) (P+R)

Anthopleura spp. Anthopleura spp. (whitish, no rose) (P) Anthopleura xanthogrammica (R)Anthozoa, unidentified Astrangia spp. Balanophyllia elegans (R)

Coenocyathus bowersi (P)

Corynactis californica (P+R)Cup coral, white, unidentified Desmophyllum dianthus (P) Epiactis prolifera? Gorgonian, unidentified Metridium exilis (P)Metridium farcimen (P)

Metridium senile (P+R)Metridium spp. (P) Metridium spp., dark or Feather Duster Palythoa (tan zoanthid) (P) Palythoa (tan) Paracyathus stearnsii (P)Urticina spp. Zoanthid (Palythoa) (P) 

Zoanthid, colonial tan (P) Zoanthid, solitary tan 

Hydrozoans: 

Hydrozoa, colony Hydrozoa, tan clump Plumularia spp. (P) Eudendrium spp.? Hydroid, pink Hydroid, tan (P) Hydroid, tan branching (P) 

Hydroid, white 

Minor Phyla:  Sponges (Porifera): 

Cliona spp., yellow Halichondria panicea (P)Leucetta losangelensis (P)Leucilla nuttingiLeucetta spp. (P) Sponge, gray encrusting (P) Sponge, green encrusting (P) Sponge, orange encrusting (P) Sponge, orange round Sponge, purple encrusting Sponge, tan cup (P) Sponge, tan encrusting (P) Sponge, tan foliose encrusting Sponge, tan globose Sponge, unidentified (R) Sponge, white encrusting (P) Sponge, white finger Sponge, yellow encrusting (P) Staurocalyptus spp. (P)

 Bryozoans (Bryozoa): 

Bryozoa, staghorn, yellow (R) Bryozoa, tan branching (P) Bryozoa, white branching Bugula spp. Crisia/Filicrisia spp. Hippodiplosia spp. 

Tunicates (Urochordata, 

Amaroucium sppAplidium spp. Botrylloides spp. Halocynthia igaboStyela spp. Tunicate, encruTunicate, encruTunicate, globulTunicate, solitarUrochordata, un

Fishes (Osteichthyes): 

Oxylebius pictus Sebastes spp. 

Undifferentiated Assemb

Algae/hydrozoa Bryozoa turf (P) Encruster, blue Encruster, gray Encruster, green Encruster, lavenEncruster, orangEncruster, pink Encruster, red (PEncruster, tan (PEncruster, white Encruster, yelloTurf (P+R) 

Physical Characteristics: 

Bare metal (P) Line (P) 

Total: 173 taxa, including 

assemblages and echaracteristics 
Table C-2. Summary comparison of average density and/or percent cover estimates for select dominant taxa by p

via shading. 

Species or Taxon Gail Grace Harvest Hidalgo H

# 38.8-60.4 10.8-43.1 29.5-38.6 78.9-135.3 ↓↑ 1-213 1-165 1-90 1-275 % 31.8-41.7 3.7-36.6 29.5-38.5 34.9-46.7 

Metridium senile 

↓↑ 1-95 0.5-80 1-90 0.5-98 0

# 24.3-35.5 76.0-79.8 36.7-40.9 85.0-117.8 ↓↑ 2-160 4-240 1-110 5-220 3% 19.2-60.4 49.1-52.6 21.0-35.0 54.2-57.1 

Mytilus spp./Mytilus californianus 

↓↑ 5-90 5-85 5-90 3-85 4

# 9.1-9.5 24.9-27.3 4.2-5.9 2.5-5.4 

Balanus spp./B. nubilus/Tetraclita squamosa ↓↑ 1-30 1-100 1-27 1-25 

# 5.6-11.3 1.0-4.7 2.8-3.5 2.6-2.9 

Worm tubes, plain and calcareous ↓↑ 1-27 1-10 1-12 1-8 

% 1.2-3.5 3.5-11.3 5.3-16.1 0.5-3.0 

Sponge, yellow encrusting ↓↑ 0.5-20 0.5-30 1-70 0.5-3 0

% 4.0-10.5 6.6-9.8 7.5-30.0 7.8-10.0 

Sponge, tan encrusting ↓↑ 0.5-50 1-50 5-30 0.5-20 

% 6.0-8.4 25.6-37.4 19.3-21.3 18.2-30.1 

Turf ↓↑ 0.4-30 1-97 0.5-75 0.5-80 0

% 33.3-49.2 7.5-8.4 7.8-11.5 18.5-39.0 

Bare Metal ↓↑ 2-85 2-15 0.5-50 0.5-65 

# 159.7-448.9 211.9-344.2 35.8-168.0 27.8 4↓↑ 1-693 1-500 4-360 9-75 1% 22.8-64.0 42.6-69.2 11.0-42.0 9.0 

Corynactis californica 

↓↑ 0.5-98 0.5-100 1-90 2-25 1

# 20.3 13.6-25.9 7.8-9.4 84.9 ↓↑ 1-100 1-62 1-24 2-185 % 26.4 8.7-30.8 6.3-8.9 43.5 

Anthopleura elegantissima (rosy morph)

↓↑ 0.5-100 0.5-90 1-20 1-95 
Table C-2. Summary comparison of average density and/or percent cover estimates for select dominant taxa by p

via shading (continued). 

Species or Taxon Gail Grace Harvest Hidalgo H

# 15.8-24.2 26.7-46.9 23.0-44.7 57.7-78.4 

Ophiothrix spiculata/Ophiuroid, unidentified ↓↑ 1-66 1-180 1-180 1-430 

# 11.4 1.0-6.5 4.4 24.3-27.5 ↓↑ 1-88 1-18 3-8 19-42 % ND ND 37.0 17.5-21.7 

Metridium farcimen 

↓↑ ND ND 15-100 10-35 

# 11.1-27.9 1.0 21.4 NP ↓↑ 1-70 1 2-40 NP % ND 16.7-21.2 ND NP 

Filamentous red algae 

↓↑ ND 0.5-50 ND NP 

% 1.7 1.2-3.0 5.6-12.2 1.4-2.2 

Foliose red algae ↓↑ 1-2 0.5-5 0.5-30 0.5-10 

# 1.0 1.0 13.1-50.8 1.0 ↓↑ 1 1 1-80 1 % 10.0 6.2 14.8-48.8 25.3-30.5 

Leucetta/Leucetta losangelensis 

↓↑ 10 1-20 1-80 2-80 

# 4.0-9.0 26.8-71.9 1.0 NP 

Paracyathus stearnsii ↓↑ 1-12 1-201 1 NP 

% NP NP 35.4-49.6 22.4 

Red encruster ↓↑ NP NP 2-90 5-70 

# 146.9-340.0 32.3 NP NP ↓↑ 2-580 15-60 NP NP % 23.0-62.0 ND NP NP 

Metridium exilis 

↓↑ 1-95 ND NP NP 

% 0.5-0.75 0.8-1.8 13.1-16.0 12.1-30.0 

Yellow encruster ↓↑ 0.5-1 0.5-3 0.5-70 0.5-50 

Notes: # - average number of individuals (density)/0.0625 m2; % - average percent cover/0.0625 m2; density and percent cover va

range, reflecting averages representative of each leg. Solitary densities or percent cover estimates are for taxa from the secodominant species/taxa which only occurred on one leg of a primary platform; ↓↑ - minimum and maximum values (i.e., de

ND - present but not determined; NP - not present. 
Platform Gail - Leg A1 counts

DATE 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/1

PHOTO CODE 022gaD 023gaD 029gaD 030gaD 021gaD 026gaD 027gaD 028gaD 024gaD 025gaD 031gaD 032gaD 019

LEG A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A

DEPTH (ft) 4 4.1 5 5.1 6 6.1 6.2 6.3 7 7.1 7.2 7.3 9 

Corynactis californica, individualsMetridium exilis 30 220 30 250 375 200 65 200 130 165 30 150 13Metridium senile 4 8 3 2 42 26 2 22 7 4 1 filamentous reds Polysiphonia, Neoptilota, Antithamnion etc 45 20 40 20 30 20 40 25 20 60 70 3Ophiothrix spiculataMytilus 160 36 36 14 12 30 3 27 44 26 40 20 2DesmophyllumAnthopleura elegantissima (rosy morph) 8 1 37 3 8 1 1 Balanus sp 16 3 20 4 9 3 8 15 3 12 9 3Ophiuroid unidMetridium farcimenWorm tubes, plainGalathea californiensisBare MetalTurfBalanus nubilus (?)Sponge, tan encrusting Codium 3 3 

Worm tubes, calcareousParacyathus stearnsiSponge, yellow encrustingCrassadoma giganteaHydroid, tan branching 1 11 11 

Sponge, orange encrusting 

Sponge, green encrustingSponge, white encrustingCoenocyathus bowersi (colonies)Sponge, purple encrustingEncruster - orangeEncruster - whiteUrochordata Cystodytes, Aplidium, StyelaCancer antennariusChama arcanaEncruster - yellowFlorometra serratissimaHydroid, pinkOxylebius pictusSpirobranchusZoanthid, colonial tanAeolidoideaAmphianthus californicaBryozoa, white branching (colonies)Dermasterias imbricataDoridaceaencrusting corallineEudistylia polymorphaHemigrapsus nudus 1Orthasterias koehleriSebastes spSponge, cup tanTunicate, encrusting tan
Platform Gail - Leg A1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica, individualsMetridium exilisMetridium senilefilamentous reds Polysiphonia, Neoptilota, Antithamnion etcOphiothrix spiculataMytilusDesmophyllumAnthopleura elegantissima (rosy morph)Balanus spOphiuroid unidMetridium farcimenWorm tubes, plainGalathea californiensisBare MetalTurfBalanus nubilus (?)Sponge, tan encrustingCodiumWorm tubes, calcareousParacyathus stearnsiSponge, yellow encrustingCrassadoma giganteaHydroid, tan branchingSponge, orange encrustingSponge, green encrustingSponge, white encrustingCoenocyathus bowersi (colonies)Sponge, purple encrustingEncruster - orangeEncruster - whiteUrochordata Cystodytes, Aplidium, StyelaCancer antennariusChama arcanaEncruster - yellowFlorometra serratissimaHydroid, pinkOxylebius pictusSpirobranchusZoanthid, colonial tanAeolidoideaAmphianthus californicaBryozoa, white branching (colonies)Dermasterias imbricataDoridaceaencrusting corallineEudistylia polymorphaHemigrapsus nudusOrthasterias koehleriSebastes spSponge, cup tanTunicate, encrusting tan

10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/1

016gaD 015gaD 014gaD 013gaD 011gaD 010gaD 009gaD 008gaD 006gaD 088ga1336 005gaD 004gaD 087ga

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A

14 16 18 21 24 28 30 31 34 36 36.1 38 3

20 35

12 260 11 130 100 390 570 4

20 70 40 64 60 3 21 33 18 5 30 10 50 50 5 15 50 10 5 1

30 5 11 4 2

26 100 40 44 22 1

1 1

3 

1

1 111 11 

2 5 10

1 1 

1

11 1 1 1

1 11 

1 11

1

1 1 1

1

2

1 1

2

1

1
Platform Gail - Leg A1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica, individualsMetridium exilisMetridium senilefilamentous reds Polysiphonia, Neoptilota, Antithamnion etcOphiothrix spiculataMytilusDesmophyllumAnthopleura elegantissima (rosy morph)Balanus spOphiuroid unidMetridium farcimenWorm tubes, plainGalathea californiensisBare MetalTurfBalanus nubilus (?)Sponge, tan encrustingCodiumWorm tubes, calcareousParacyathus stearnsiSponge, yellow encrustingCrassadoma giganteaHydroid, tan branchingSponge, orange encrustingSponge, green encrustingSponge, white encrustingCoenocyathus bowersi (colonies)Sponge, purple encrustingEncruster - orangeEncruster - whiteUrochordata Cystodytes, Aplidium, StyelaCancer antennariusChama arcanaEncruster - yellowFlorometra serratissimaHydroid, pinkOxylebius pictusSpirobranchusZoanthid, colonial tanAeolidoideaAmphianthus californicaBryozoa, white branching (colonies)Dermasterias imbricataDoridaceaencrusting corallineEudistylia polymorphaHemigrapsus nudusOrthasterias koehleriSebastes spSponge, cup tanTunicate, encrusting tan

10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/1

080ga1329 079ga1329 078ga1329 077ga1328 076ga1328 075ga1327 073ga1326 072ga1326 071ga1325 070ga1325 068ga1324 067ga1323 066ga

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A

48 53 55 61 63 68 70 72 75 84 87 89 9

350 14 525 315 560 595 693 560 595 455 525 63

72 7 3 

64 19 90 24 34 1 21 8 

2 10 5

34 3 5 2 3 3

1 11 1111 1

1 1 223 11

111 11111 

11 1 11

1

1

1

111

1 1

1

1

1 1

1 
Platform Gail - Leg A1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica, individualsMetridium exilisMetridium senilefilamentous reds Polysiphonia, Neoptilota, Antithamnion etcOphiothrix spiculataMytilusDesmophyllumAnthopleura elegantissima (rosy morph)Balanus spOphiuroid unidMetridium farcimenWorm tubes, plainGalathea californiensisBare MetalTurfBalanus nubilus (?)Sponge, tan encrustingCodiumWorm tubes, calcareousParacyathus stearnsiSponge, yellow encrustingCrassadoma giganteaHydroid, tan branchingSponge, orange encrustingSponge, green encrustingSponge, white encrustingCoenocyathus bowersi (colonies)Sponge, purple encrustingEncruster - orangeEncruster - whiteUrochordata Cystodytes, Aplidium, StyelaCancer antennariusChama arcanaEncruster - yellowFlorometra serratissimaHydroid, pinkOxylebius pictusSpirobranchusZoanthid, colonial tanAeolidoideaAmphianthus californicaBryozoa, white branching (colonies)Dermasterias imbricataDoridaceaencrusting corallineEudistylia polymorphaHemigrapsus nudusOrthasterias koehleriSebastes spSponge, cup tanTunicate, encrusting tan

10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/1

063ga1321 062ga1318 061ga1316 060ga1315 059ga1315 057ga1314 056ga1313 055ga1312 054ga1312 053ga1311 052ga1310 051ga1309 050ga

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A

118 125 127 131 134 137 147 156 162 168 173 184 18630 693 693 560 420 630 693 665 630 350 490 245 63

40 103

7

18

10 6 12 8

1 12 12

111111 111112 5238 11 111111111

1 4 

6 12

2 2

1

21 

11
Platform Gail - Leg A1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica, individualsMetridium exilisMetridium senilefilamentous reds Polysiphonia, Neoptilota, Antithamnion etcOphiothrix spiculataMytilusDesmophyllumAnthopleura elegantissima (rosy morph)Balanus spOphiuroid unidMetridium farcimenWorm tubes, plainGalathea californiensisBare MetalTurfBalanus nubilus (?)Sponge, tan encrustingCodiumWorm tubes, calcareousParacyathus stearnsiSponge, yellow encrustingCrassadoma giganteaHydroid, tan branchingSponge, orange encrustingSponge, green encrustingSponge, white encrustingCoenocyathus bowersi (colonies)Sponge, purple encrustingEncruster - orangeEncruster - whiteUrochordata Cystodytes, Aplidium, StyelaCancer antennariusChama arcanaEncruster - yellowFlorometra serratissimaHydroid, pinkOxylebius pictusSpirobranchusZoanthid, colonial tanAeolidoideaAmphianthus californicaBryozoa, white branching (colonies)Dermasterias imbricataDoridaceaencrusting corallineEudistylia polymorphaHemigrapsus nudusOrthasterias koehleriSebastes spSponge, cup tanTunicate, encrusting tan

10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/1

047ga1305 046ga1305 045ga1258 044ga1257 043ga1256 041ga1253 040ga1252 039ga1251 038ga1248 037ga1247 036ga1245 035ga1243 034ga

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A

225 231 302 309 326 363 367 372 397 410 420 423 45

83 2 10

80 96 164 43 146 21 28 147 147 126 91 85 9

3 12 23 11 66 51 56 58 1

2 2

3 2

1

23 12 7 12 4

1 

1111111111111111111

11 1

3 116

1

1

1 11
Platform Gail - Leg A1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica, individualsMetridium exilisMetridium senilefilamentous reds Polysiphonia, Neoptilota, Antithamnion etcOphiothrix spiculataMytilusDesmophyllumAnthopleura elegantissima (rosy morph)Balanus spOphiuroid unidMetridium farcimenWorm tubes, plainGalathea californiensisBare MetalTurfBalanus nubilus (?)Sponge, tan encrustingCodiumWorm tubes, calcareousParacyathus stearnsiSponge, yellow encrustingCrassadoma giganteaHydroid, tan branchingSponge, orange encrustingSponge, green encrustingSponge, white encrustingCoenocyathus bowersi (colonies)Sponge, purple encrustingEncruster - orangeEncruster - whiteUrochordata Cystodytes, Aplidium, StyelaCancer antennariusChama arcanaEncruster - yellowFlorometra serratissimaHydroid, pinkOxylebius pictusSpirobranchusZoanthid, colonial tanAeolidoideaAmphianthus californicaBryozoa, white branching (colonies)Dermasterias imbricataDoridaceaencrusting corallineEudistylia polymorphaHemigrapsus nudusOrthasterias koehleriSebastes spSponge, cup tanTunicate, encrusting tan

10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/1

031ga1234 030ga1233 029ga1231 028ga1227 027ga1226 026ga1220 025ga1219 024ga1218 023ga1217 022ga1215 021ga1214 019ga1214 018ga

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A

515 525 548 569 577 620 628 633 646 660 664 675 67

87 82 111 107 179 213 178 162 91 113 192 1434 23 19 10 30

6 8 6 1 19 13 3 

88

2 2

1 12322 12

1111111111111

111 1

1

1 1

1

1

1
Platform Gail - Leg A1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica, individualsMetridium exilisMetridium senilefilamentous reds Polysiphonia, Neoptilota, Antithamnion etcOphiothrix spiculataMytilusDesmophyllumAnthopleura elegantissima (rosy morph)Balanus spOphiuroid unidMetridium farcimenWorm tubes, plainGalathea californiensisBare MetalTurfBalanus nubilus (?)Sponge, tan encrustingCodiumWorm tubes, calcareousParacyathus stearnsiSponge, yellow encrustingCrassadoma giganteaHydroid, tan branchingSponge, orange encrustingSponge, green encrustingSponge, white encrustingCoenocyathus bowersi (colonies)Sponge, purple encrustingEncruster - orangeEncruster - whiteUrochordata Cystodytes, Aplidium, StyelaCancer antennariusChama arcanaEncruster - yellowFlorometra serratissimaHydroid, pinkOxylebius pictusSpirobranchusZoanthid, colonial tanAeolidoideaAmphianthus californicaBryozoa, white branching (colonies)Dermasterias imbricataDoridaceaencrusting corallineEudistylia polymorphaHemigrapsus nudusOrthasterias koehleriSebastes spSponge, cup tanTunicate, encrusting tan

10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99

014ga1208 013ga1207 012ga1206 011ga1206 010ga1205 008ga1201 006ga1200 007ga1200

A1 A1 A1 A1 A1 A1 A1 A1 No. of

692 700 708 710 721 732 733 733.1 Total Average Photos Occurrence Max 

15263 448.9118 98 34 693 

4554 146.9032 98 31 570 

56 93 13 3 3 1 1 4227 60.38571 98 70 213 

752 27.85185 98 27 70 533 24.22727 98 22 66 497 35.5 98 14 160 

43 20 42 33 53 54 38 27 416 21.89474 98 19 54 

305 20.33333 98 15 100 145 9.0625 98 16 30 113 7.533333 98 15 34 103 11.44444 98 9 88 

62 8.857143 98 7 23 

2 3 4 2 5 5 3 4 47 2.35 98 20 5 1 1 1 1 1 1 1 1 38 1 98 38 1 1 35 1 98 35 1 

32 2.461538 98 13 8 31 1 98 31 1 28 4.666667 98 6 10 27 3.857143 98 7 11 18 9 98 2 12 

9 1 98 9 1 6 1.5 98 4 2 6 1 98 6 1 6 1 98 6 1 5 1 98 5 1 5 1 98 5 1 4 1.333333 98 3 2 4 1 98 4 1 3 1 98 3 1 3 1 98 3 1 3 1 98 3 1 2 1 98 2 1 2 2 98 1 2 2 1 98 2 1 2 1 98 2 1 2 1 98 2 1 2 1 98 2 1 2 2 98 1 2 2 1 98 2 1 1 1 98 1 1 1 1 98 1 1 1 1 98 1 1 

1 1 1 98 1 1 

1 1 98 1 1 1 1 98 1 1 1 1 98 1 1 1 1 98 1 1 

1 1 1 98 1 1 

1 1 98 1 1 1 1 98 1 1 1 1 98 1 1 
Platform Gail - Leg A1 %

DATE 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/1

PHOTO CODE 022gaD 023gaD 029gaD 030gaD 021gaD 026gaD 027gaD 028gaD 024gaD 025gaD 031gaD 032gaD 019

LEG A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A

DEPTH (ft) 4 4.1 5 5.1 6 6.1 6.2 6.3 7 7.1 7.2 7.3 9 

Corynactis californica (%)Mytilus 90 60 80 55 35 50 5 70 75 60 60 70 7Metridium senile % 2 5 1 1 20 15 1 10 3 2 1 Bare Metal (%)Anthopleura elegantissima (rosy morph) % 5 0.5 50 2 5 1 1 Metridium exilis % 5 35 5 40 60 30 10 30 20 25 5 15 2Zoanthid, colonial tan %Turf (%)Hydroid, tan branching % 5 55 5 10 Sponge, tan encrusting (%) Tunicate, encrusting tan %Sponge, orange encrusting % Sponge, purple encrusting %Hydroid, pink %Sponge, cup tan %Sponge, white encrusting (%)Encruster - white (%)Urochordata Cystodytes, Aplidium, Styela Sponge, yellow encrusting (%)Sponge, green encrusting %Encruster - orange (%)Encruster - yellow %
Platform Gail - Leg A1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)MytilusMetridium senile %Bare Metal (%)Anthopleura elegantissima (rosy morph) %Metridium exilis %Zoanthid, colonial tan %Turf (%)Hydroid, tan branching %Sponge, tan encrusting (%)Tunicate, encrusting tan %Sponge, orange encrusting %Sponge, purple encrusting %Hydroid, pink %Sponge, cup tan %Sponge, white encrusting (%)Encruster - white (%)Urochordata Cystodytes, Aplidium, Styela Sponge, yellow encrusting (%)Sponge, green encrusting %Encruster - orange (%)Encruster - yellow %

10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/1

016gaD 015gaD 014gaD 013gaD 011gaD 010gaD 009gaD 008gaD 006gaD 088ga1336 005gaD 004gaD 087ga

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A

14 16 18 21 24 28 30 31 34 36 36.1 38 3

4 5

20 70 40 40 50 2 25 30 10 5 30 99 40 100 50 1

2 40 2 20 15 60 80 1

2

5 2 2 2 2 2 

0.5 10 1 2 2

1

2 2

5 1

1

2 1 1

2 1 

2 11 
Platform Gail - Leg A1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)MytilusMetridium senile %Bare Metal (%)Anthopleura elegantissima (rosy morph) %Metridium exilis %Zoanthid, colonial tan %Turf (%)Hydroid, tan branching %Sponge, tan encrusting (%)Tunicate, encrusting tan %Sponge, orange encrusting %Sponge, purple encrusting %Hydroid, pink %Sponge, cup tan %Sponge, white encrusting (%)Encruster - white (%)Urochordata Cystodytes, Aplidium, Styela Sponge, yellow encrusting (%)Sponge, green encrusting %Encruster - orange (%)Encruster - yellow %

10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/1

080ga1329 079ga1329 078ga1329 077ga1328 076ga1328 075ga1327 073ga1326 072ga1326 071ga1325 070ga1325 068ga1324 067ga1323 066ga

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A

48 53 55 61 63 68 70 72 75 84 87 89 9

50 2 75 45 80 85 98 80 85 65 75 9

65 20 90 25 34 1 20 10 

15 2 1 

20 5 5 2 10 2 2 1

5 3 1 2 10 10 5 7 

224

1

2

0.5 1 0.5 1 2 0.5

1 1

0.5 1
Platform Gail - Leg A1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)MytilusMetridium senile %Bare Metal (%)Anthopleura elegantissima (rosy morph) %Metridium exilis %Zoanthid, colonial tan %Turf (%)Hydroid, tan branching %Sponge, tan encrusting (%)Tunicate, encrusting tan %Sponge, orange encrusting %Sponge, purple encrusting %Hydroid, pink %Sponge, cup tan %Sponge, white encrusting (%)Encruster - white (%)Urochordata Cystodytes, Aplidium, Styela Sponge, yellow encrusting (%)Sponge, green encrusting %Encruster - orange (%)Encruster - yellow %

10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/1

063ga1321 062ga1318 061ga1316 060ga1315 059ga1315 057ga1314 056ga1313 055ga1312 054ga1312 053ga1311 052ga1310 051ga1309 050ga

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A

118 125 127 131 134 137 147 156 162 168 173 184 18

90 98 98 80 60 90 98 95 90 50 70 35 9

7

8 25

2 2 2 1 3 5 5 10 10 25 2 2 2 1 5 2 5 5 15 1 10

1
Platform Gail - Leg A1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)MytilusMetridium senile %Bare Metal (%)Anthopleura elegantissima (rosy morph) %Metridium exilis %Zoanthid, colonial tan %Turf (%)Hydroid, tan branching %Sponge, tan encrusting (%)Tunicate, encrusting tan %Sponge, orange encrusting %Sponge, purple encrusting %Hydroid, pink %Sponge, cup tan %Sponge, white encrusting (%)Encruster - white (%)Urochordata Cystodytes, Aplidium, Styela Sponge, yellow encrusting (%)Sponge, green encrusting %Encruster - orange (%)Encruster - yellow %

10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/1

047ga1305 046ga1305 045ga1258 044ga1257 043ga1256 041ga1253 040ga1252 039ga1251 038ga1248 037ga1247 036ga1245 035ga1243 034ga

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A

225 231 302 309 326 363 367 372 397 410 420 423 45

10 1 1

80 80 95 45 73 49 30 39 85 90 85 85 9

5 2 20 40 25 50 60 60 10 10 15 15 1

20 20 5 15 2 1

51 5

1

1
Platform Gail - Leg A1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)MytilusMetridium senile %Bare Metal (%)Anthopleura elegantissima (rosy morph) %Metridium exilis %Zoanthid, colonial tan %Turf (%)Hydroid, tan branching %Sponge, tan encrusting (%)Tunicate, encrusting tan %Sponge, orange encrusting %Sponge, purple encrusting %Hydroid, pink %Sponge, cup tan %Sponge, white encrusting (%)Encruster - white (%)Urochordata Cystodytes, Aplidium, Styela Sponge, yellow encrusting (%)Sponge, green encrusting %Encruster - orange (%)Encruster - yellow %

10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/1

031ga1234 030ga1233 029ga1231 028ga1227 027ga1226 026ga1220 025ga1219 024ga1218 023ga1217 022ga1215 021ga1214 019ga1214 018ga

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A

515 525 548 569 577 620 628 633 646 660 664 675 67

85 80 67 85 70 70 80 60 44 33 75 615 20 33 15 30 30 20 40 55 66 66 25 3

5 15

0.5 1 0.5 0

1

3

2
Platform Gail - Leg A1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)MytilusMetridium senile %Bare Metal (%)Anthopleura elegantissima (rosy morph) %Metridium exilis %Zoanthid, colonial tan %Turf (%)Hydroid, tan branching %Sponge, tan encrusting (%)Tunicate, encrusting tan %Sponge, orange encrusting %Sponge, purple encrusting %Hydroid, pink %Sponge, cup tan %Sponge, white encrusting (%)Encruster - white (%)Urochordata Cystodytes, Aplidium, Styela Sponge, yellow encrusting (%)Sponge, green encrusting %Encruster - orange (%)Encruster - yellow %

10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99 10/19/99

014ga1208 013ga1207 012ga1206 011ga1206 010ga1205 008ga1201 006ga1200 007ga1200

A1 A1 A1 A1 A1 A1 A1 A1 No. of

692 700 708 710 721 732 733 733.1 Total Average Photos Occurrence Max 

2175 63.97059 98 34 98 

845 60.35714 98 14 90 

54 70 41 5 5 1 1 2916 41.65714 98 70 95 40 30 59 50 40 50 50 50 1266 33.31579 98 38 66 

396.5 26.43333 98 15 100 

714 23.03226 98 31 80 

20 10 98 2 15 

0.4 208.4 5.954286 98 35 25 

35 5.833333 98 6 10 

122.5 3.951613 98 31 15 

3 3 98 1 3 

17.5 2.916667 98 6 10 

9 2.25 98 4 4 4 2 98 2 2 2 2 98 1 2 9 1.8 98 5 5 4 1.333333 98 3 2 4 1.333333 98 3 2 

11 1.222222 98 9 2 

5.5 1.1 98 5 2 2.5 0.833333 98 3 1 1.5 0.75 98 2 1 
Platform Gail - Leg B1 counts

DATE 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 

PHOTO CODE 034gaD 032gaD 033gaD 035gaD 030gaD 031gaD 027gaD 028gaD 029gaD 023gaD 024gaD 025gaD 026gaD 

LEG B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

DEPTH (ft) 3 4 4.1 4.2 5 5.1 6 6.1 7 8 8.1 8.2 8.3 

Metridium exilis 100 315 165 552 415 400 405 550 490 420 450 415 Corynactis californica, individualsMetridium senile 73 14 56 5 16Mytilus 70 34 87 26 25 38 34 36 21 32 38 34 27 filamentous reds Polysiphonia, Neoptilota, Antithamnion etc 5 10 2 15 15 20 30 DesmophyllumOphiothrix spiculataBalanus sp 23 11 25 23 4 17 18 14 3 11 6 Worm tubes, calcareousProtula superbaWorm tubes, plainAmphipholisOphiuroid unidTurfBare Metal 1 Sponge, tan encrusting 1 11111Paracyathus stearnsiSponge, yellow encrusting 11 1 1Galathea californiensisSponge, green encrusting 1Ophiocantha diplasiaEncruster - whiteSponge, purple encrustingBalanus nubilus (?)Sponge, cup tanSponge, white encrusting 1Zoanthid , solitary tanZoanthid, tan (Palythoa)Encruster - orangeCup Coral, whiteFilamentous green algaFoliose red algae 1 1Hydroid, white 111Actiniaria, pinkAplidiumCrassadoma giganteaEncruster - tanEncruster - yellowHydroid, tan branchingLeucettaPleurobranchaea californicaSebastes spStylasterias forreriTunicate, globularAllocentrotus fragilisAsterina miniata = PatiriaBryozoa, tan branching (colonies)Chiton, unidDoridacea 1Gorgonian, unidHalichondria paniceaPisaster giganteusPycnopodia helianthoidesSponge, orange encrustingSponge, tan globoseUrochordata Cystodytes, Aplidium, Styela 1
Platform Gail - Leg B1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium exilisCorynactis californica, individualsMetridium senileMytilusfilamentous reds Polysiphonia, Neoptilota, Antithamnion etcDesmophyllumOphiothrix spiculataBalanus spWorm tubes, calcareousProtula superbaWorm tubes, plainAmphipholisOphiuroid unidTurfBare MetalSponge, tan encrustingParacyathus stearnsiSponge, yellow encrustingGalathea californiensisSponge, green encrustingOphiocantha diplasiaEncruster - whiteSponge, purple encrustingBalanus nubilus (?)Sponge, cup tanSponge, white encrustingZoanthid , solitary tanZoanthid, tan (Palythoa)Encruster - orangeCup Coral, whiteFilamentous green algaFoliose red algaeHydroid, whiteActiniaria, pinkAplidiumCrassadoma giganteaEncruster - tanEncruster - yellowHydroid, tan branchingLeucettaPleurobranchaea californicaSebastes spStylasterias forreriTunicate, globularAllocentrotus fragilisAsterina miniata = PatiriaBryozoa, tan branching (colonies)Chiton, unidDoridaceaGorgonian, unidHalichondria paniceaPisaster giganteusPycnopodia helianthoidesSponge, orange encrustingSponge, tan globoseUrochordata Cystodytes, Aplidium, Styela

10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 

019gaD 018gaD 017gaD 016gaD 015gaD 014gaD 013gaD 012gaD 011gaD 010gaD 009gaD 008gaD 007gaD 

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

16 18 21 22 24 28 30 31 33 34 36 38 42 

554 485 480 418 475 551 550 415 550 415 548 545 553 

46644 33 2

10 20 15 20 20 2 5 15 10 2 15 5 15 

4 1 3 21 1 

2 2 1 1

1

1 11 1 

1111 1 111

11 11 1 11

11 1 

1 1

11 1

1 1

1

1

1

1

1
Platform Gail - Leg B1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium exilisCorynactis californica, individualsMetridium senileMytilusfilamentous reds Polysiphonia, Neoptilota, Antithamnion etcDesmophyllumOphiothrix spiculataBalanus spWorm tubes, calcareousProtula superbaWorm tubes, plainAmphipholisOphiuroid unidTurfBare MetalSponge, tan encrustingParacyathus stearnsiSponge, yellow encrustingGalathea californiensisSponge, green encrustingOphiocantha diplasiaEncruster - whiteSponge, purple encrustingBalanus nubilus (?)Sponge, cup tanSponge, white encrustingZoanthid , solitary tanZoanthid, tan (Palythoa)Encruster - orangeCup Coral, whiteFilamentous green algaFoliose red algaeHydroid, whiteActiniaria, pinkAplidiumCrassadoma giganteaEncruster - tanEncruster - yellowHydroid, tan branchingLeucettaPleurobranchaea californicaSebastes spStylasterias forreriTunicate, globularAllocentrotus fragilisAsterina miniata = PatiriaBryozoa, tan branching (colonies)Chiton, unidDoridaceaGorgonian, unidHalichondria paniceaPisaster giganteusPycnopodia helianthoidesSponge, orange encrustingSponge, tan globoseUrochordata Cystodytes, Aplidium, Styela

10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 

003gaD 002gaD 084ga1348 082ga1346 080ga1345 077ga1344 076ga1344 075ga1342 073ga1338 72ga1338 071ga1337 070ga1337 069ga1332 

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

59 60 61 63 71 73 74 78 86 97 99 103 123 

150 280 400 200 200 300 80 100 250 420 288 65 

40 350 140 630 140 560 350 35 70 30 5

1 14 1 9 8 25 9263 1381 5 

1 1

111111 11 1 1 111 1 111 11

1

11111

21 11 2 

1 1

1 

1

1

1

1
Platform Gail - Leg B1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium exilisCorynactis californica, individualsMetridium senileMytilusfilamentous reds Polysiphonia, Neoptilota, Antithamnion etcDesmophyllumOphiothrix spiculataBalanus spWorm tubes, calcareousProtula superbaWorm tubes, plainAmphipholisOphiuroid unidTurfBare MetalSponge, tan encrustingParacyathus stearnsiSponge, yellow encrustingGalathea californiensisSponge, green encrustingOphiocantha diplasiaEncruster - whiteSponge, purple encrustingBalanus nubilus (?)Sponge, cup tanSponge, white encrustingZoanthid , solitary tanZoanthid, tan (Palythoa)Encruster - orangeCup Coral, whiteFilamentous green algaFoliose red algaeHydroid, whiteActiniaria, pinkAplidiumCrassadoma giganteaEncruster - tanEncruster - yellowHydroid, tan branchingLeucettaPleurobranchaea californicaSebastes spStylasterias forreriTunicate, globularAllocentrotus fragilisAsterina miniata = PatiriaBryozoa, tan branching (colonies)Chiton, unidDoridaceaGorgonian, unidHalichondria paniceaPisaster giganteusPycnopodia helianthoidesSponge, orange encrustingSponge, tan globoseUrochordata Cystodytes, Aplidium, Styela

10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 

065ga1330 064ga1330 063ga1330 062ga1329 061ga1329 060ga1327 059ga1327 058ga1326 057ga1325 056ga1317 054ga1316 053ga1314 52ga1312 

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

141 143 146 149 153 168 171 179 186 231 261 276 294 324 372 412 392 124 328 172 200 220 220 

20 140 41 1 65 

312 

10 13 16 26 

7 10 6 

1 2

11111111

11

1 1111111

563

111 1

11 1

1

1 
Platform Gail - Leg B1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium exilisCorynactis californica, individualsMetridium senileMytilusfilamentous reds Polysiphonia, Neoptilota, Antithamnion etcDesmophyllumOphiothrix spiculataBalanus spWorm tubes, calcareousProtula superbaWorm tubes, plainAmphipholisOphiuroid unidTurfBare MetalSponge, tan encrustingParacyathus stearnsiSponge, yellow encrustingGalathea californiensisSponge, green encrustingOphiocantha diplasiaEncruster - whiteSponge, purple encrustingBalanus nubilus (?)Sponge, cup tanSponge, white encrustingZoanthid , solitary tanZoanthid, tan (Palythoa)Encruster - orangeCup Coral, whiteFilamentous green algaFoliose red algaeHydroid, whiteActiniaria, pinkAplidiumCrassadoma giganteaEncruster - tanEncruster - yellowHydroid, tan branchingLeucettaPleurobranchaea californicaSebastes spStylasterias forreriTunicate, globularAllocentrotus fragilisAsterina miniata = PatiriaBryozoa, tan branching (colonies)Chiton, unidDoridaceaGorgonian, unidHalichondria paniceaPisaster giganteusPycnopodia helianthoidesSponge, orange encrustingSponge, tan globoseUrochordata Cystodytes, Aplidium, Styela

10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 

048ga1311 046ga1308 045ga1308 042ga1305 041ga1303 039ga1302 038ga1300 037ga1300 036ga1259 035ga1259 034ga1257 033ga1256 032ga1254 

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

322 363 365 376 413 420 454 459 460 464 492 500 518 

2 100

70

1 1 1 7 5 12 113 160 157 169 140 82 76 

2 5 8 28 28 51 28

14 7 10 13 18 1817 10 10 14 2 1 1

579421 

93

241

111111111 1111111111111111

1

1 

21 1 

1 1 

1 

1

1
Platform Gail - Leg B1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium exilisCorynactis californica, individualsMetridium senileMytilusfilamentous reds Polysiphonia, Neoptilota, Antithamnion etcDesmophyllumOphiothrix spiculataBalanus spWorm tubes, calcareousProtula superbaWorm tubes, plainAmphipholisOphiuroid unidTurfBare MetalSponge, tan encrustingParacyathus stearnsiSponge, yellow encrustingGalathea californiensisSponge, green encrustingOphiocantha diplasiaEncruster - whiteSponge, purple encrustingBalanus nubilus (?)Sponge, cup tanSponge, white encrustingZoanthid , solitary tanZoanthid, tan (Palythoa)Encruster - orangeCup Coral, whiteFilamentous green algaFoliose red algaeHydroid, whiteActiniaria, pinkAplidiumCrassadoma giganteaEncruster - tanEncruster - yellowHydroid, tan branchingLeucettaPleurobranchaea californicaSebastes spStylasterias forreriTunicate, globularAllocentrotus fragilisAsterina miniata = PatiriaBryozoa, tan branching (colonies)Chiton, unidDoridaceaGorgonian, unidHalichondria paniceaPisaster giganteusPycnopodia helianthoidesSponge, orange encrustingSponge, tan globoseUrochordata Cystodytes, Aplidium, Styela

10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 

028ga1249 027ga1247 026ga1246 025ga1245 024ga1244 023ga1244 022ga1243 021ga1242 020ga1241 019ga1241 018ga1240 017ga1240 016ga1239 

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

602 615 630 662 670 675 678 680 684 689 698 700 704 

59 66 40 9 4 5 17 6 15 20 1 1

6 6 11 9 14 12 18 15 7 7 17 17 

2 1312 1 22 

9556633512 33

2

11111111111111111111111111

1 111

1 11212222 1 

2 1

1 11 1 1

1 

1

2 1

1 1 

2

1 

1

1

1

1

1
Platform Gail - Leg B1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium exilisCorynactis californica, individualsMetridium senileMytilusfilamentous reds Polysiphonia, Neoptilota, Antithamnion etcDesmophyllumOphiothrix spiculataBalanus spWorm tubes, calcareousProtula superbaWorm tubes, plainAmphipholisOphiuroid unidTurfBare MetalSponge, tan encrustingParacyathus stearnsiSponge, yellow encrustingGalathea californiensisSponge, green encrustingOphiocantha diplasiaEncruster - whiteSponge, purple encrustingBalanus nubilus (?)Sponge, cup tanSponge, white encrustingZoanthid , solitary tanZoanthid, tan (Palythoa)Encruster - orangeCup Coral, whiteFilamentous green algaFoliose red algaeHydroid, whiteActiniaria, pinkAplidiumCrassadoma giganteaEncruster - tanEncruster - yellowHydroid, tan branchingLeucettaPleurobranchaea californicaSebastes spStylasterias forreriTunicate, globularAllocentrotus fragilisAsterina miniata = PatiriaBryozoa, tan branching (colonies)Chiton, unidDoridaceaGorgonian, unidHalichondria paniceaPisaster giganteusPycnopodia helianthoidesSponge, orange encrustingSponge, tan globoseUrochordata Cystodytes, Aplidium, Styela

10/16/99 10/16/99

012ga1235 011ga1234

B1 B1 No. of

734 736 Total Average Photos Occurrence Max Min

20739 339.9836 98 61 580 2

3035 159.7368 98 19 630 1

28 76 1669 38.81395 98 43 169 1

607 24.28 98 25 87 2277 11.08 98 25 30 1

4 210 12.35294 98 17 37 2

206 15.84615 98 13 51 1180 9.473684 98 19 25 1

1 158 11.28571 98 14 26 1

155 11.92308 98 13 28 1

4 3 124 5.636364 98 22 27 1

82 4.315789 98 19 9 153 2.65 98 20 8 1

1 1 46 1 98 46 1 11 1 42 1 98 42 1 1

34 1 98 34 1 128 4 98 7 7 127 1 98 27 1 119 1.461538 98 13 2 117 1 98 17 1 115 1.875 98 8 5 1

9 1 98 9 1 19 1 98 9 1 18 1.333333 98 6 2 16 1 98 6 1 15 1 98 5 1 15 1.666667 98 3 2 15 1 98 5 1 14 1 98 4 1 1

3 3 3 98 1 3 3

3 1 98 3 1 13 1 98 3 1 13 1 98 3 1 12 2 98 1 2 22 1 98 2 1 12 1 98 2 1 12 1 98 2 1 12 1 98 2 1 12 1 98 2 1 12 1 98 2 1 1

2 2 2 98 1 2 2

2 1 98 2 1 1

1 2 1 98 2 1 1

2 1 98 2 1 11 1 98 1 1 11 1 98 1 1 11 1 98 1 1 11 1 98 1 1 11 1 98 1 1 11 1 98 1 1 11 1 98 1 1 11 1 98 1 1 1

1 1 1 98 1 1 1

1 1 98 1 1 11 1 98 1 1 11 1 98 1 1 1
Platform Gail - Leg B1 %

DATE 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 

PHOTO CODE 034gaD 032gaD 033gaD 035gaD 030gaD 031gaD 027gaD 028gaD 029gaD 023gaD 024gaD 025gaD 026gaD 

LEG B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

DEPTH (ft) 3 4 4.1 4.2 5 5.1 6 6.1 7 8 8.1 8.2 8.3 

Metridium exilis % 15 50 25 90 65 60 65 90 80 70 75 70 Bare Metal (%) 15 Metridium senile % 25 5 20 2 5Halichondria panicea %Corynactis californica (%)Mytilus 45 45 50 85 5 20 25 25 10 20 10 15 20 Sponge, tan encrusting (%) 3 51225Leucetta %Sponge, tan globose (%)Sponge, cup tan %Turf (%)Zoanthid, tan (Palythoa) (%)Encruster - tan (%)Hydroid, tan branching %Sponge, yellow encrusting (%) 0.5 2 1 0.5Hydroid, white % 125Filamentous green alga %Sponge, purple encrusting %Sponge, orange encrusting %Sponge, green encrusting % 2Foliose red algae % 2 2Encruster - white (%)Aplidium %Encruster - orange (%)Sponge, white encrusting (%) 3Urochordata Cystodytes, Aplidium, Styela 1Encruster - yellow %
Platform Gail - Leg B1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium exilis %Bare Metal (%)Metridium senile %Halichondria panicea %Corynactis californica (%)MytilusSponge, tan encrusting (%)Leucetta %Sponge, tan globose (%)Sponge, cup tan %Turf (%)Zoanthid, tan (Palythoa) (%)Encruster - tan (%)Hydroid, tan branching %Sponge, yellow encrusting (%)Hydroid, white %Filamentous green alga %Sponge, purple encrusting %Sponge, orange encrusting %Sponge, green encrusting %Foliose red algae %Encruster - white (%)Aplidium %Encruster - orange (%)Sponge, white encrusting (%)Urochordata Cystodytes, Aplidium, Styela Encruster - yellow %

10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 

019gaD 018gaD 017gaD 016gaD 015gaD 014gaD 013gaD 012gaD 011gaD 010gaD 009gaD 008gaD 007gaD 

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

16 18 21 22 24 28 30 31 33 34 36 38 42 90 80 80 70 80 90 90 85 90 70 90 90 90 

2

30

10 10 10 5 5 5 5 5 

2 25 5 

10

10

2 1 3 5 3 10 5 20 

0.5 1 5

1 2 0.5 

2

0.5 0.5 2 0.5 3 0.5 0.5 

1 2

0.5 1
Platform Gail - Leg B1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium exilis %Bare Metal (%)Metridium senile %Halichondria panicea %Corynactis californica (%)MytilusSponge, tan encrusting (%)Leucetta %Sponge, tan globose (%)Sponge, cup tan %Turf (%)Zoanthid, tan (Palythoa) (%)Encruster - tan (%)Hydroid, tan branching %Sponge, yellow encrusting (%)Hydroid, white %Filamentous green alga %Sponge, purple encrusting %Sponge, orange encrusting %Sponge, green encrusting %Foliose red algae %Encruster - white (%)Aplidium %Encruster - orange (%)Sponge, white encrusting (%)Urochordata Cystodytes, Aplidium, Styela Encruster - yellow %

10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 

003gaD 002gaD 084ga1348 082ga1346 080ga1345 077ga1344 076ga1344 075ga1342 073ga1338 72ga1338 071ga1337 070ga1337 069ga1332 

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

59 60 61 63 71 73 74 78 86 97 99 103 123 25 70 85 50 70 72 20 35 65 85 40 10 40 10

6 50 20 90 20 80 50 5 10 1 10 0.5 2 5 1 25 50 

10

1 46

0.5 0.5

22 0.5 2 1 2 335225 0.5 1 7 1 2

1

2 

0.5
Platform Gail - Leg B1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium exilis %Bare Metal (%)Metridium senile %Halichondria panicea %Corynactis californica (%)MytilusSponge, tan encrusting (%)Leucetta %Sponge, tan globose (%)Sponge, cup tan %Turf (%)Zoanthid, tan (Palythoa) (%)Encruster - tan (%)Hydroid, tan branching %Sponge, yellow encrusting (%)Hydroid, white %Filamentous green alga %Sponge, purple encrusting %Sponge, orange encrusting %Sponge, green encrusting %Foliose red algae %Encruster - white (%)Aplidium %Encruster - orange (%)Sponge, white encrusting (%)Urochordata Cystodytes, Aplidium, Styela Encruster - yellow %

10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 

065ga1330 064ga1330 063ga1330 062ga1329 061ga1329 060ga1327 059ga1327 058ga1326 057ga1325 056ga1317 054ga1316 053ga1314 52ga1312 

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

141 143 146 149 153 168 171 179 186 231 261 276 294 

65 85 84 88 20 75 45 45 50 50 

60 75 

3 1 5 

3 20 3 0.5 10 

20 15 10 35 10 5 20 1

5

5 5 5 15 25 5 30 10 

2 5 1 10

2 0.5

0.5
Platform Gail - Leg B1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium exilis %Bare Metal (%)Metridium senile %Halichondria panicea %Corynactis californica (%)MytilusSponge, tan encrusting (%)Leucetta %Sponge, tan globose (%)Sponge, cup tan %Turf (%)Zoanthid, tan (Palythoa) (%)Encruster - tan (%)Hydroid, tan branching %Sponge, yellow encrusting (%)Hydroid, white %Filamentous green alga %Sponge, purple encrusting %Sponge, orange encrusting %Sponge, green encrusting %Foliose red algae %Encruster - white (%)Aplidium %Encruster - orange (%)Sponge, white encrusting (%)Urochordata Cystodytes, Aplidium, Styela Encruster - yellow %

10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 

048ga1311 046ga1308 045ga1308 042ga1305 041ga1303 039ga1302 038ga1300 037ga1300 036ga1259 035ga1259 034ga1257 033ga1256 032ga1254 

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

322 363 365 376 413 420 454 459 460 464 492 500 518 

1 15

60 65 75 80 85 85 50 15 20 20 20 30 30 20 5 5 10 5 5 49 84 79 80 80 68 50 10

5 30 20 10 10 10 0.5 0.5 0.5 0.5 2 5 

5 

1 2 
Platform Gail - Leg B1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium exilis %Bare Metal (%)Metridium senile %Halichondria panicea %Corynactis californica (%)MytilusSponge, tan encrusting (%)Leucetta %Sponge, tan globose (%)Sponge, cup tan %Turf (%)Zoanthid, tan (Palythoa) (%)Encruster - tan (%)Hydroid, tan branching %Sponge, yellow encrusting (%)Hydroid, white %Filamentous green alga %Sponge, purple encrusting %Sponge, orange encrusting %Sponge, green encrusting %Foliose red algae %Encruster - white (%)Aplidium %Encruster - orange (%)Sponge, white encrusting (%)Urochordata Cystodytes, Aplidium, Styela Encruster - yellow %

10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 10/16/99 

028ga1249 027ga1247 026ga1246 025ga1245 024ga1244 023ga1244 022ga1243 021ga1242 020ga1241 019ga1241 018ga1240 017ga1240 016ga1239 

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

602 615 630 662 670 675 678 680 684 689 698 700 704 

35 40 40 40 80 40 40 40 68 60 60 60 70 60 55 58 50 10 50 50 38 20 30 10 10

10 3 4 5

2 

5 5 2 10 10 10 10 10 10 10 5 5 5 

2 2 

2 

0.5 0.5 2 1 5

1
Platform Gail - Leg B1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium exilis %Bare Metal (%)Metridium senile %Halichondria panicea %Corynactis californica (%)MytilusSponge, tan encrusting (%)Leucetta %Sponge, tan globose (%)Sponge, cup tan %Turf (%)Zoanthid, tan (Palythoa) (%)Encruster - tan (%)Hydroid, tan branching %Sponge, yellow encrusting (%)Hydroid, white %Filamentous green alga %Sponge, purple encrusting %Sponge, orange encrusting %Sponge, green encrusting %Foliose red algae %Encruster - white (%)Aplidium %Encruster - orange (%)Sponge, white encrusting (%)Urochordata Cystodytes, Aplidium, Styela Encruster - yellow %

10/16/99 10/16/99

012ga1235 011ga1234

B1 B1 No. of

734 736 Total Average Photos Occurrence Max Min

3781 61.98361 98 61 95 1

65 75 2065 49.16667 98 42 85 225 24 1366 31.76744 98 43 84 1

30 30 98 1 30 30

433 22.78947 98 19 90 0.5480 19.2 98 25 85 5

356.5 10.48529 98 34 50 0.5

20 10 98 2 10 1010 10 98 1 10 10

59.5 9.916667 98 6 46 0.5

10 1 388 8.434783 98 46 30 0.5

34 6.8 98 5 15 2

7 3.5 98 2 5 27 3.5 98 2 5 2

94 3.481481 98 27 20 0.5

8 2.666667 98 3 5 1

6.5 2.166667 98 3 5 0.5

19 2.111111 98 9 5 0.5

2 2 98 1 2 2

33 1.941176 98 17 7 0.5

5 1.666667 98 3 2 1

13.5 1.5 98 9 5 0.5

3 1.5 98 2 2 1

5.5 1.375 98 4 2 0.56.5 1.3 98 5 3 0.5

1 1 98 1 1 11 0.5 98 2 0.5 0.5
Platform Grace - Leg C1 counts

DATE 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10

PHOTO CODE 026grD 027grD 024grD 025grD 028grD 022grD 023grD 020grD 021grD 029grD 017grD 018grD 019grD 016grD 0

LEG C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 

DEPTH (ft) 3 3.1 4 4.1 4.2 5 5.1 6 6.1 6.2 7 7.1 7.2 8 

Corynactis californica, individualsParacyathus stearnsiMytilus 77 73 82 99 84 81 136 73 89 67 190 77 Ophiothrix spiculata 9 10 2 25 32 1 Balanus spp 19 29 48 26 24 64 53 45 44 34 32 26 Anthopleura elegantissima (rosy morph) 1 Mytilus californianus 64 60Worm tubes, calcareousCoenocyathus bowersi (colonies)Turf 1 11111111 1Balanus sp 21 42Metridium senile 36 2 12 filamentous reds Polysiphonia, Neoptilota, Antithamnion etc 11 11111 1111Crassadoma giganteaSponge, tan encrusting Sponge, yellow encrustingAsterina miniata = PatiriaBryozoa, tan branching (colonies)Balanus nubilus (?)Hydroid, pinkOphiuroid unidAnthopleura xanthogrammica 2 4Hydroid, tan branching 1 11Sponge, white encrusting 1 1Urticina 2 2Bryozoa, white branching (colonies)Sebastes spSponge, gray encrustingSponge, purple encrustingStrongylocentrotus purpuratus 1 2Stylasterias forreriAnemone, unid 2Bare MetalDorid, yellow (?Doriopsilla)Hermissenda crassicornisLeucilla nuttingi (colonies)Metridium farcimenParastichopus californicusAnemone, pink 1Anisodoris nobilisBryozoa turf 1Dialula sandiegensis Hydroid, tan Oxylebius pictusStyela sp
Platform Grace - Leg C1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica, individualsParacyathus stearnsiMytilusOphiothrix spiculataBalanus sppAnthopleura elegantissima (rosy morph)Mytilus californianusWorm tubes, calcareousCoenocyathus bowersi (colonies)TurfBalanus spMetridium senilefilamentous reds Polysiphonia, Neoptilota, Antithamnion etcCrassadoma giganteaSponge, tan encrustingSponge, yellow encrustingAsterina miniata = PatiriaBryozoa, tan branching (colonies)Balanus nubilus (?)Hydroid, pinkOphiuroid unidAnthopleura xanthogrammicaHydroid, tan branchingSponge, white encrustingUrticinaBryozoa, white branching (colonies)Sebastes spSponge, gray encrustingSponge, purple encrustingStrongylocentrotus purpuratusStylasterias forreriAnemone, unidBare MetalDorid, yellow (?Doriopsilla)Hermissenda crassicornisLeucilla nuttingi (colonies)Metridium farcimenParastichopus californicusAnemone, pinkAnisodoris nobilisBryozoa turfDialula sandiegensisHydroid, tanOxylebius pictusStyela sp

10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/23/99 10/24/99 10/23/99 10/23/99 10/23/99 10

010grD 011grD 009grD 008grD 007grD 006grD 005grD 004grD 003grD 065gr1322 002grD 064gr1321 062gr1319 060gr1318 05

C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 

19 19.1 22 24 25 28 30 31 34 35 35.1 38 52 55 

135 30 310 130 370 

13

3 15 35 2 17 60 4 72 180 21 

41331

25 60 20 20 20 30 30 40 41 20 62

111111111111 1111111 1 1 1 11 1111 1 11 

1

1

1 1

1

1
Platform Grace - Leg C1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica, individualsParacyathus stearnsiMytilusOphiothrix spiculataBalanus sppAnthopleura elegantissima (rosy morph)Mytilus californianusWorm tubes, calcareousCoenocyathus bowersi (colonies)TurfBalanus spMetridium senilefilamentous reds Polysiphonia, Neoptilota, Antithamnion etcCrassadoma giganteaSponge, tan encrustingSponge, yellow encrustingAsterina miniata = PatiriaBryozoa, tan branching (colonies)Balanus nubilus (?)Hydroid, pinkOphiuroid unidAnthopleura xanthogrammicaHydroid, tan branchingSponge, white encrustingUrticinaBryozoa, white branching (colonies)Sebastes spSponge, gray encrustingSponge, purple encrustingStrongylocentrotus purpuratusStylasterias forreriAnemone, unidBare MetalDorid, yellow (?Doriopsilla)Hermissenda crassicornisLeucilla nuttingi (colonies)Metridium farcimenParastichopus californicusAnemone, pinkAnisodoris nobilisBryozoa turfDialula sandiegensisHydroid, tanOxylebius pictusStyela sp

10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10

051gr1312 050gr1312 047gr1309 043gr1306 037gr1303 035gr1302 036gr1302 034gr1301 032gr1258 031gr1256 030gr1255 029gr1254 028gr1253 027gr1252 02

C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 

73 77 81 84 87 88 88.1 93 111 119 126 131 136 144 

385 380 260 250 390 260 400 190 150 180 155 95 120 95 

8 8 34 96 72 117 

4 37 15 14 45 26 35 20 24 

1

2 

1 2 2 1 4 4 

11 1111111111

44 3 6

1 1 1 1 1

111111 1111111

10

1 6

12 

1 11

1 

1 1

1
Platform Grace - Leg C1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica, individualsParacyathus stearnsiMytilusOphiothrix spiculataBalanus sppAnthopleura elegantissima (rosy morph)Mytilus californianusWorm tubes, calcareousCoenocyathus bowersi (colonies)TurfBalanus spMetridium senilefilamentous reds Polysiphonia, Neoptilota, Antithamnion etcCrassadoma giganteaSponge, tan encrustingSponge, yellow encrustingAsterina miniata = PatiriaBryozoa, tan branching (colonies)Balanus nubilus (?)Hydroid, pinkOphiuroid unidAnthopleura xanthogrammicaHydroid, tan branchingSponge, white encrustingUrticinaBryozoa, white branching (colonies)Sebastes spSponge, gray encrustingSponge, purple encrustingStrongylocentrotus purpuratusStylasterias forreriAnemone, unidBare MetalDorid, yellow (?Doriopsilla)Hermissenda crassicornisLeucilla nuttingi (colonies)Metridium farcimenParastichopus californicusAnemone, pinkAnisodoris nobilisBryozoa turfDialula sandiegensisHydroid, tanOxylebius pictusStyela sp

10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10

022gr1247 021gr1246 019gr1241 020gr1242 018gr1239 017gr1238 016gr1237 015gr1237 014gr1236 013gr1236 012gr1236 011gr1236 010gr1235 009gr1234 00

C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 

172 174 205 205.1 232 238 242 245 248 249 251 256 257 259 

1

201 198 126 97 100 30 79 103 16 38 40 67 32 28 

11 1 5

3 1 6 5 6 5 4 3 8 3 4 8 

7 13 111111111111111

12 2 111

111 1 17111 1

11 1

1 

1 1

1

1

1
Platform Grace - Leg C1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica, individualsParacyathus stearnsiMytilusOphiothrix spiculataBalanus sppAnthopleura elegantissima (rosy morph)Mytilus californianusWorm tubes, calcareousCoenocyathus bowersi (colonies)TurfBalanus spMetridium senilefilamentous reds Polysiphonia, Neoptilota, Antithamnion etcCrassadoma giganteaSponge, tan encrustingSponge, yellow encrustingAsterina miniata = PatiriaBryozoa, tan branching (colonies)Balanus nubilus (?)Hydroid, pinkOphiuroid unidAnthopleura xanthogrammicaHydroid, tan branchingSponge, white encrustingUrticinaBryozoa, white branching (colonies)Sebastes spSponge, gray encrustingSponge, purple encrustingStrongylocentrotus purpuratusStylasterias forreriAnemone, unidBare MetalDorid, yellow (?Doriopsilla)Hermissenda crassicornisLeucilla nuttingi (colonies)Metridium farcimenParastichopus californicusAnemone, pinkAnisodoris nobilisBryozoa turfDialula sandiegensisHydroid, tanOxylebius pictusStyela sp

10/23/99

004gr1229

C1 No. of

308 Total Average Photos Occurrence Max Min

5720 211.8519 73 27 450 1

10 2085 71.89655 73 29 201 1

1357 79.82353 73 17 190 13

987 26.67568 73 37 180 1564 26.85714 73 21 68 1441 25.94118 73 17 62 1124 62 73 2 64 60

5 90 4.736842 73 19 10 1

89 6.846154 73 13 21 1

1 64 1 73 64 1 1

63 31.5 73 2 42 2154 10.8 73 5 36 125 1 73 25 1 122 4.4 73 5 6 320 1 73 20 1 118 1 73 18 1 1

1 10 1.25 73 8 2 1

10 10 73 1 10 10

7 3.5 73 2 6 17 1 73 7 1 17 7 73 1 7 76 3 73 2 4 24 1 73 4 1 14 1 73 4 1 14 2 73 2 2 23 1.5 73 2 2 13 1 73 3 1 13 1 73 3 1 13 1 73 3 1 13 1.5 73 2 2 13 1 73 3 1 12 2 73 1 2 22 1 73 2 1 12 1 73 2 1 12 1 73 2 1 12 1 73 2 1 12 1 73 2 1 12 1 73 2 1 11 1 73 1 1 11 1 73 1 1 11 1 73 1 1 11 1 73 1 1 11 1 73 1 1 11 1 73 1 1 11 1 73 1 1 1
Platform Grace - Leg C1 %

DATE 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10

PHOTO CODE 026grD 027grD 024grD 025grD 028grD 022grD 023grD 020grD 021grD 029grD 017grD 018grD 019grD 016grD 0

LEG C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 

DEPTH (ft) 3 3.1 4 4.1 4.2 5 5.1 6 6.1 6.2 7 7.1 7.2 8 

Mytilus 35 50 50 55 60 35 50 50 50 80 70 55 Corynactis californica (%)Turf (%) 50 25 40 10 15 10 40 20 10 1 Anthopleura elegantissima (rosy morph) % 0.5 Hydroid, tan % filamentous reds Polysiphonia, Neoptilota, 40 20 10 50 40 10 20 25 10 15 25 Bryozoa turf % 20Sponge, gray encrusting %Hydroid, tan branching % 15 30 15Sponge, yellow encrusting (%)Sponge, tan encrusting (%) Bare Metal (%)Sponge, purple encrusting %Metridium senile % 12 1 4 Sponge, white encrusting (%) 0.5 0.5Hydroid, pink %Encruster - blue (%)Foliose red algae %Encruster - white (%)Encruster - pink (%)Line (%)Obelia sp % 1Polyclinum planum %Sponge, orange encrusting %Tunicate, encrusting tan % 1Encruster - yellow %Hydroid, white clump % 0.5 0.1 1 1
Platform Grace - Leg C1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

MytilusCorynactis californica (%)Turf (%)Anthopleura elegantissima (rosy morph) %Hydroid, tan %filamentous reds Polysiphonia, Neoptilota, Bryozoa turf %Sponge, gray encrusting %Hydroid, tan branching %Sponge, yellow encrusting (%)Sponge, tan encrusting (%)Bare Metal (%)Sponge, purple encrusting %Metridium senile %Sponge, white encrusting (%)Hydroid, pink %Encruster - blue (%)Foliose red algae %Encruster - white (%)Encruster - pink (%)Line (%)Obelia sp %Polyclinum planum %Sponge, orange encrusting %Tunicate, encrusting tan %Encruster - yellow %Hydroid, white clump %

10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/23/99 10/24/99 10/23/99 10/23/99 10/23/99 10

010grD 011grD 009grD 008grD 007grD 006grD 005grD 004grD 003grD 065gr1322 002grD 064gr1321 062gr1319 060gr1318 05

C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 

19 19.1 22 24 25 28 30 31 34 35 35.1 38 52 55 

5

25 5 60 25 80 

20 10 50 60 70 10 20 10 10 30 5 15 15 50 15 15 15 30 40 75 60 9040 40 25 15 15 10 5 10 0.5 

10

15 

20 10 5 50 2 10 10 3 30 2 

5 10

1 0.5

1
Platform Grace - Leg C1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

MytilusCorynactis californica (%)Turf (%)Anthopleura elegantissima (rosy morph) %Hydroid, tan %filamentous reds Polysiphonia, Neoptilota, Bryozoa turf %Sponge, gray encrusting %Hydroid, tan branching %Sponge, yellow encrusting (%)Sponge, tan encrusting (%)Bare Metal (%)Sponge, purple encrusting %Metridium senile %Sponge, white encrusting (%)Hydroid, pink %Encruster - blue (%)Foliose red algae %Encruster - white (%)Encruster - pink (%)Line (%)Obelia sp %Polyclinum planum %Sponge, orange encrusting %Tunicate, encrusting tan %Encruster - yellow %Hydroid, white clump %

10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10

051gr1312 050gr1312 047gr1309 043gr1306 037gr1303 035gr1302 036gr1302 034gr1301 032gr1258 031gr1256 030gr1255 029gr1254 028gr1253 027gr1252 02

C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 

73 77 81 84 87 88 88.1 93 111 119 126 131 136 144 75 75 50 50 85 50 85 40 30 35 30 20 25 20 15 10 4 20 15 15 5 5 5 10 5 10 

15 25

5 15 15 3 15 15 15 20 15 30 10 20 2 

1 2 5 5 5 

1

1

2

1 2 0.5

1

1

2 
Platform Grace - Leg C1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

MytilusCorynactis californica (%)Turf (%)Anthopleura elegantissima (rosy morph) %Hydroid, tan %filamentous reds Polysiphonia, Neoptilota, Bryozoa turf %Sponge, gray encrusting %Hydroid, tan branching %Sponge, yellow encrusting (%)Sponge, tan encrusting (%)Bare Metal (%)Sponge, purple encrusting %Metridium senile %Sponge, white encrusting (%)Hydroid, pink %Encruster - blue (%)Foliose red algae %Encruster - white (%)Encruster - pink (%)Line (%)Obelia sp %Polyclinum planum %Sponge, orange encrusting %Tunicate, encrusting tan %Encruster - yellow %Hydroid, white clump %

10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10

022gr1247 021gr1246 019gr1241 020gr1242 018gr1239 017gr1238 016gr1237 015gr1237 014gr1236 013gr1236 012gr1236 011gr1236 010gr1235 009gr1234 00

C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 C1 

172 174 205 205.1 232 238 242 245 248 249 251 256 257 259 

0.5

30 50 75 97 90 80 85 90 85 85 90 95 90 90 

5 

10

215 1 1

2 1

1

0.5 0.5 1 1 0.5
Platform Grace - Leg C1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

MytilusCorynactis californica (%)Turf (%)Anthopleura elegantissima (rosy morph) %Hydroid, tan %filamentous reds Polysiphonia, Neoptilota, Bryozoa turf %Sponge, gray encrusting %Hydroid, tan branching %Sponge, yellow encrusting (%)Sponge, tan encrusting (%)Bare Metal (%)Sponge, purple encrusting %Metridium senile %Sponge, white encrusting (%)Hydroid, pink %Encruster - blue (%)Foliose red algae %Encruster - white (%)Encruster - pink (%)Line (%)Obelia sp %Polyclinum planum %Sponge, orange encrusting %Tunicate, encrusting tan %Encruster - yellow %Hydroid, white clump %

10/23/99

004gr1229

C1 No. of

308 Total Average Photos Occurrence Max Min

835 49.11765 73 17 80 5

1150.5 42.61111 73 27 95 0.5

90 2394 37.40625 73 64 97 1

461.5 30.76667 73 15 90 0.5

25 25 73 1 25 25

530.5 21.22 73 25 50 0.5

20 20 73 1 20 2050 16.66667 73 3 25 1062 15.5 73 4 30 2

203 11.27778 73 18 30 1195 9.75 73 20 50 1

15 7.5 73 2 10 516 5.333333 73 3 10 1

18.5 3.7 73 5 12 0.5

12 3 73 4 10 0.5

11.5 1.642857 73 7 5 0.5

3 1.5 73 2 2 1

3.5 1.166667 73 3 2 0.5

4 1 73 4 2 0.51 1 73 1 1 11 1 73 1 1 11 1 73 1 1 11 1 73 1 1 11 1 73 1 1 11 1 73 1 1 1

6.5 0.8125 73 8 2 0.52.6 0.65 73 4 1 0.1
Platform Grace - Leg C4 counts

DATE 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 

PHOTO CODE 029grD 030grD 031grD 026grD 027grD 028grD 023grD 024grD 025grD 021grD 022grD 032grD 033grD 

LEG C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 

DEPTH (ft) 3 3.1 3.2 4 4.1 4.2 5 5.1 5.2 6 6.1 6.2 6.3 

Corynactis californica, individualsMytilus 240 75 80 120 100 110 170 110 74 50 120 75 Metridium senile 15 2 16 9 5 8 2 23 Ophiothrix spiculata 6 4 Balanus sp 55 56 24 40 55 48 18 13 Paracyathus stearnsiBalanus spp 57 100 14 4Anthopleura elegantissima (rosy morph) 12 4 5 10 Metridium exilis?Metridium farcimenTurf 1 1 1 1 1 1 1 1 Balanus nubilus (?)filamentous reds Polysiphonia, Neoptilota, Antithamnion etc 1 1 1 1 1 1 1 1 1 1 Crassadoma giganteaUlva lactuca 15 5 2Bryozoa, tan branching (colonies)Ophiuroid unidHydroid, tan 11 1 111Coenocyathus bowersi (colonies)Zoanthid, colonial tanStrongylocentrotus purpuratus 1 2 

Bare Metal 1 1LeucettaSebastes spSponge, tan encrustingCliona, yellowAeolid unid Anthozoa, unidHermissenda crassicornisHydroid, tan branchingSponge, white encrustingStylasterias forreriWorm tubes, calcareous
Platform Grace - Leg C4 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica, individualsMytilusMetridium senileOphiothrix spiculataBalanus spParacyathus stearnsiBalanus sppAnthopleura elegantissima (rosy morph)Metridium exilis?Metridium farcimenTurfBalanus nubilus (?)filamentous reds Polysiphonia, Neoptilota, Antithamnion etcCrassadoma giganteaUlva lactucaBryozoa, tan branching (colonies)Ophiuroid unidHydroid, tanCoenocyathus bowersi (colonies)Zoanthid, colonial tanStrongylocentrotus purpuratusBare MetalLeucettaSebastes spSponge, tan encrustingCliona, yellowAeolid unid Anthozoa, unidHermissenda crassicornisHydroid, tan branchingSponge, white encrustingStylasterias forreriWorm tubes, calcareous

10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10

017grD 016grD 015grD 014grD 013grD 012grD 011grD 010grD 009grD 008grD 006grD 007grD 005grD 004grD 13

C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 

10 11 12 13 14 26 28 29 33 35 39 39.1 40 42 

10

66 55 75 50 65 4 5 13 5

10 20 75 50 35 70 80 70 

50 50 50 30 20 60 180 70 7 70 60 60 32 50 

5 2

6654 1

23 14 18 16 26 30 2

111 111 1 11 111111 1 111 

1111 1

2

1 11 1 

1 1
Platform Grace - Leg C4 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica, individualsMytilusMetridium senileOphiothrix spiculataBalanus spParacyathus stearnsiBalanus sppAnthopleura elegantissima (rosy morph)Metridium exilis?Metridium farcimenTurfBalanus nubilus (?)filamentous reds Polysiphonia, Neoptilota, Antithamnion etcCrassadoma giganteaUlva lactucaBryozoa, tan branching (colonies)Ophiuroid unidHydroid, tanCoenocyathus bowersi (colonies)Zoanthid, colonial tanStrongylocentrotus purpuratusBare MetalLeucettaSebastes spSponge, tan encrustingCliona, yellowAeolid unid Anthozoa, unidHermissenda crassicornisHydroid, tan branchingSponge, white encrustingStylasterias forreriWorm tubes, calcareous

10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10

128gr1553 126gr1551 123gr1550 122gr1549 121gr1548 120gr1547 119gr1547 118gr1546 117gr1546 115gr1545 111gr1543 109gr1542 105gr1540 101gr1537 10

C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 

52 57 61 67 69 72 74 76 79 81 83 85 87 88 

50 310 390 500 250 55 495 490 500 480 485 470 475 

80 57 22

120 60 20 30 60 15 3 

15 22 60

1 11 2223433

2 632122 

15

1
Platform Grace - Leg C4 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica, individualsMytilusMetridium senileOphiothrix spiculataBalanus spParacyathus stearnsiBalanus sppAnthopleura elegantissima (rosy morph)Metridium exilis?Metridium farcimenTurfBalanus nubilus (?)filamentous reds Polysiphonia, Neoptilota, Antithamnion etcCrassadoma giganteaUlva lactucaBryozoa, tan branching (colonies)Ophiuroid unidHydroid, tanCoenocyathus bowersi (colonies)Zoanthid, colonial tanStrongylocentrotus purpuratusBare MetalLeucettaSebastes spSponge, tan encrustingCliona, yellowAeolid unid Anthozoa, unidHermissenda crassicornisHydroid, tan branchingSponge, white encrustingStylasterias forreriWorm tubes, calcareous

10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10

095gr1530 092gr1527 091gr1526 090gr1526 089gr1523 088gr1521 087gr1521 086gr1520 085gr1519 084gr1516 083gr1516 082gr1514 081gr1514 079gr1514 08

C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 

133 146 148 150 165 191 193 197 202 250 255 264 265 266 365 385 180 150 12

101 20 42 65 41 

33 8

1 19 10 48 57 10 21 48

1 8 1 8 18 14 2 4 

1111111111 1 11

1

10 1 1 

2 51

1 1 

1 1 

11 1

1

1

11

1
Platform Grace - Leg C4 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica, individualsMytilusMetridium senileOphiothrix spiculataBalanus spParacyathus stearnsiBalanus sppAnthopleura elegantissima (rosy morph)Metridium exilis?Metridium farcimenTurfBalanus nubilus (?)filamentous reds Polysiphonia, Neoptilota, Antithamnion etcCrassadoma giganteaUlva lactucaBryozoa, tan branching (colonies)Ophiuroid unidHydroid, tanCoenocyathus bowersi (colonies)Zoanthid, colonial tanStrongylocentrotus purpuratusBare MetalLeucettaSebastes spSponge, tan encrustingCliona, yellowAeolid unid Anthozoa, unidHermissenda crassicornisHydroid, tan branchingSponge, white encrustingStylasterias forreriWorm tubes, calcareous

10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99

075gr1512 074gr1510 073gr1509 072gr1508 071gr1507 070gr1507 069gr1506

C4 C4 C4 C4 C4 C4 C4 No. of

279 285 290 291 299 304 310 Total Average Photos Occurrence Max Min

7917 344.2174 77 23 500 101824 76 77 24 240 4

9 12 75 60 66 50 165 1769 43.14634 77 41 165 1

1548 46.90909 77 33 180 2

351 27 77 13 56 2214 26.75 77 8 57 1197 21.88889 77 9 100 1191 13.64286 77 14 30 2

97 32.33333 77 3 60 1571 6.454545 77 11 18 1

1 1 1 1 1 1 1 46 1 77 46 1 1

39 2.785714 77 14 8 124 1 77 24 1 122 2.2 77 10 6 122 7.333333 77 3 15 215 15 77 1 15 15

2 15 3 77 5 10 1

11 1 77 11 1 1

8 2.666667 77 3 5 1

1 1 1 7 1 77 7 1 1

6 1.5 77 4 2 1

1 5 1 77 5 1 1

5 1 77 5 1 1

1 4 1 77 4 1 1

4 1 77 4 1 12 1 77 2 1 11 1 77 1 1 11 1 77 1 1 11 1 77 1 1 11 1 77 1 1 11 1 77 1 1 1

1 1 1 77 1 1 1

1 1 77 1 1 1
Platform Grace - Leg C4 %

DATE 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 

PHOTO CODE 029grD 030grD 031grD 026grD 027grD 028grD 023grD 024grD 025grD 021grD 022grD 032grD 033grD 

LEG C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 

DEPTH (ft) 3 3.1 3.2 4 4.1 4.2 5 5.1 5.2 6 6.1 6.2 6.3 

Corynactis californica (%)Mytilus 85 80 65 65 68 83 78 69 77 60 50 55 Zoanthid, colonial tan %

Metridium senile % 5 0.5 5 7 1 2 1 10 Turf (%) 5 15 15 5 5 1 10 5 Hydroid, tan % 15 15 5 20 20 20filamentous reds Polysiphonia, Neoptilota, Antithamnion etc % 20 15 10 10 15 25 10 15 15 20 Cliona, yellow %Anthozoa, unid (%)Anthopleura elegantissima (rosy morph) % 5 2 2 5 Bare Metal (%) 5 2Sponge, tan encrusting (%)Leucetta %Sponge, yellow encrusting (%)Foliose red algae %Sponge, yellow erect (%)Encruster - yellow %Sponge, cup tan %Encruster - white (%)Hydroid, tan branching %Sponge, white encrusting (%)Sponge, tan foliose (%)Encruster - blue (%)Encruster - pink (%)
Platform Grace - Leg C4 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)MytilusZoanthid, colonial tan %Metridium senile %Turf (%)Hydroid, tan %filamentous reds Polysiphonia, Neoptilota, Antithamnion etc %Cliona, yellow %Anthozoa, unid (%)Anthopleura elegantissima (rosy morph) %Bare Metal (%)Sponge, tan encrusting (%)Leucetta %Sponge, yellow encrusting (%)Foliose red algae %Sponge, yellow erect (%)Encruster - yellow %Sponge, cup tan %Encruster - white (%)Hydroid, tan branching %Sponge, white encrusting (%)Sponge, tan foliose (%)Encruster - blue (%)Encruster - pink (%)

10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10/24/99 10

017grD 016grD 015grD 014grD 013grD 012grD 011grD 010grD 009grD 008grD 006grD 007grD 005grD 004grD 13

C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 

10 11 12 13 14 26 28 29 33 35 39 39.1 40 42 

2

75 35 40 30 55 5 5 10 10

10 20 75 50 35 70 80 70 

5 20 20 15 50 20 10 1 1 

60 15 10 10 10

20 50 30 50 20 10 5 1 3 2 

10 10

15 10 20 10 15 15 2

20 3 1 5 

1 
Platform Grace - Leg C4 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)MytilusZoanthid, colonial tan %Metridium senile %Turf (%)Hydroid, tan %filamentous reds Polysiphonia, Neoptilota, Antithamnion etc %Cliona, yellow %Anthozoa, unid (%)Anthopleura elegantissima (rosy morph) %Bare Metal (%)Sponge, tan encrusting (%)Leucetta %Sponge, yellow encrusting (%)Foliose red algae %Sponge, yellow erect (%)Encruster - yellow %Sponge, cup tan %Encruster - white (%)Hydroid, tan branching %Sponge, white encrusting (%)Sponge, tan foliose (%)Encruster - blue (%)Encruster - pink (%)

10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10

128gr1553 126gr1551 123gr1550 122gr1549 121gr1548 120gr1547 119gr1547 118gr1546 117gr1546 115gr1545 111gr1543 109gr1542 105gr1540 101gr1537 10

C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 

52 57 61 67 69 72 74 76 79 81 83 85 87 88 

10 60 75 100 50 10 99 99 99 98 98 95 95 

75 65 10

20 2

5 10

5 10 1 0.5 5 5 

0.5 1 2
Platform Grace - Leg C4 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)MytilusZoanthid, colonial tan %Metridium senile %Turf (%)Hydroid, tan %filamentous reds Polysiphonia, Neoptilota, Antithamnion etc %Cliona, yellow %Anthozoa, unid (%)Anthopleura elegantissima (rosy morph) %Bare Metal (%)Sponge, tan encrusting (%)Leucetta %Sponge, yellow encrusting (%)Foliose red algae %Sponge, yellow erect (%)Encruster - yellow %Sponge, cup tan %Encruster - white (%)Hydroid, tan branching %Sponge, white encrusting (%)Sponge, tan foliose (%)Encruster - blue (%)Encruster - pink (%)

10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10

095gr1530 092gr1527 091gr1526 090gr1526 089gr1523 088gr1521 087gr1521 086gr1520 085gr1519 084gr1516 083gr1516 082gr1514 081gr1514 079gr1514 08

C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 C4 

133 146 148 150 165 191 193 197 202 250 255 264 265 266 

70 80 33 30 8

75 25 

50 25 50 65 41 

5 10 10 20 10 15 25 25 90 50 50 66 

10

10 

10 7 110 0.5 3

2

3

1

1

0.5

0.1

0.1
Platform Grace - Leg C4 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)MytilusZoanthid, colonial tan %Metridium senile %Turf (%)Hydroid, tan %filamentous reds Polysiphonia, Neoptilota, Antithamnion etc %Cliona, yellow %Anthozoa, unid (%)Anthopleura elegantissima (rosy morph) %Bare Metal (%)Sponge, tan encrusting (%)Leucetta %Sponge, yellow encrusting (%)Foliose red algae %Sponge, yellow erect (%)Encruster - yellow %Sponge, cup tan %Encruster - white (%)Hydroid, tan branching %Sponge, white encrusting (%)Sponge, tan foliose (%)Encruster - blue (%)Encruster - pink (%)

10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99 10/23/99

075gr1512 074gr1510 073gr1509 072gr1508 071gr1507 070gr1507 069gr1506

C4 C4 C4 C4 C4 C4 C4 No. of

279 285 290 291 299 304 310 Total Average Photos Occurrence Max Min

1591 69.17391 77 23 100 21263 52.625 77 24 85 5

90 35 5 263 37.57143 77 7 90 3

9 12 75 60 66 50 20 1500.5 36.59756 77 41 80 0.5

10 60 25 40 30 50 80 1178 25.6087 77 46 90 1

200 18.18182 77 11 60 5401 16.70833 77 24 50 1

20 10 77 2 10 1010 10 77 1 10 10

122 8.714286 77 14 20 1

10 42 8.4 77 5 15 2

33 6.6 77 5 10 131 6.2 77 5 20 146 3.538462 77 13 10 0.5

6 3 77 2 5 12 2 77 1 2 2

0.5 3.5 1.75 77 2 3 0.5

3 1.5 77 2 2 1

3.5 1.166667 77 3 2 0.5

1 1 77 1 1 11 1 77 1 1 1

0.5 0.5 77 1 0.5 0.50.1 0.1 77 1 0.1 0.10.1 0.1 77 1 0.1 0.1
Platform Harvest - Leg B1 counts

DATE 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/9

PHOTO CODE 029haD 028haD 027haD 026haD 023haD 025haD 024haD 022haD 021haD 020haD 019haD 018haD 017ha

LEG B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

DEPTH (ft) 3 4 5 6 6.1 6.2 7 10 12 14 16 18 22 

Metridium senile 4 2 5 5 1 2 2 2 2 Ophiuroid unidMytilus 50 55 46 55 54 63 75 45 45 42 47 40 38 Corynactis californica, individualsLeucetta 2 5Balanus sp 6 8 9 13 9 6 9 15 4 18 5 12 11 Anthopleura elegantissima (rosy morph) 16 3 5 4 3 13 18 9 24 4 4 12 1 Worm tubes, calcareousTurf 1111111111111Tunicate, encrusting translucentBare MetalEncruster, redBalanus nubilus Barnacle, unidFoliose red algae 11111 1 1111Metridium farcimenZoanthid, solitary tanEncruster - tanEncruster - yellowEncruster, pinkGalathea californiensisWorm tubes, plainBivalve, nestlingLeucetta losangelensisEncruster, green 1Pollicipes polymerus 7Plumularia sp 1 1Sebastes spBryozoa, white branching (colonies) (count)Bryozoa, tan branching (colonies)Encruster, lavenderSponge, yellow encrusting 1Metridium spSponge, tan encrustingAeolidia papillosa?Botrylloides sp.Crassadoma giganteaEgregia 1Encruster - whiteHermissenda crassicornis 1Leucilla nuttingi (colonies)Pisaster ochraceus Spionidae 1Stylasterias forreriZoanthid, colonial tan
Platform Harvest - Leg B1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileOphiuroid unidMytilusCorynactis californica, individualsLeucettaBalanus spAnthopleura elegantissima (rosy morph) Worm tubes, calcareousTurfTunicate, encrusting translucentBare MetalEncruster, redBalanus nubilus Barnacle, unidFoliose red algaeMetridium farcimenZoanthid, solitary tanEncruster - tanEncruster - yellowEncruster, pinkGalathea californiensisWorm tubes, plainBivalve, nestlingLeucetta losangelensisEncruster, greenPollicipes polymerusPlumularia spSebastes spBryozoa, white branching (colonies) (count)Bryozoa, tan branching (colonies)Encruster, lavenderSponge, yellow encrustingMetridium spSponge, tan encrustingAeolidia papillosa?Botrylloides sp.Crassadoma giganteaEgregiaEncruster - whiteHermissenda crassicornisLeucilla nuttingi (colonies)Pisaster ochraceusSpionidaeStylasterias forreriZoanthid, colonial tan

11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/9

013haD 012haD 011haD 010haD 009haD 008haD 007haD 006haD 005haD 004haD 003haD 002haD 001ha

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

29 31 33 35 37 41 46 48 51 58 65 68 72 

40 75 50 80 75 90 90 90 15 68 90 

3 1 1 4 62 12 34 60 33 18 

17 1 4 3

5 15 20 15 5 5 5 30 5 10 

364 1

1

111111 11 11

211 233571

1111111 113 4

1 1

1

2 3 1 111

11 1

1 11 11

1

1 1

1

1
Platform Harvest - Leg B1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileOphiuroid unidMytilusCorynactis californica, individualsLeucettaBalanus spAnthopleura elegantissima (rosy morph) Worm tubes, calcareousTurfTunicate, encrusting translucentBare MetalEncruster, redBalanus nubilus Barnacle, unidFoliose red algaeMetridium farcimenZoanthid, solitary tanEncruster - tanEncruster - yellowEncruster, pinkGalathea californiensisWorm tubes, plainBivalve, nestlingLeucetta losangelensisEncruster, greenPollicipes polymerusPlumularia spSebastes spBryozoa, white branching (colonies) (count)Bryozoa, tan branching (colonies)Encruster, lavenderSponge, yellow encrustingMetridium spSponge, tan encrustingAeolidia papillosa?Botrylloides sp.Crassadoma giganteaEgregiaEncruster - whiteHermissenda crassicornisLeucilla nuttingi (colonies)Pisaster ochraceusSpionidaeStylasterias forreriZoanthid, colonial tan

11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/9

062ha1240 061ha1240 060ha1239 057ha1231 058ha1233 059ha1234 056ha1230 055ha1230 054ha1228 053ha1227 051ha1225 052ha1226 050ha12

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

108 110 120 124 125 126 135 137 144 149 154 157 158 

80 80 25 70 76 50 60 30 25 70 50 70 50 

100 29 120 35 30 50 2

60 12

20 20 35 5 12 40 7 15 6 2

2 544264 

3 2 

1111111

1 1 111 

111 

27 4 4

1 111 1 

11111 1

11 1 1

1 1

1 1

1

1

1
Platform Harvest - Leg B1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileOphiuroid unidMytilusCorynactis californica, individualsLeucettaBalanus spAnthopleura elegantissima (rosy morph) Worm tubes, calcareousTurfTunicate, encrusting translucentBare MetalEncruster, redBalanus nubilus Barnacle, unidFoliose red algaeMetridium farcimenZoanthid, solitary tanEncruster - tanEncruster - yellowEncruster, pinkGalathea californiensisWorm tubes, plainBivalve, nestlingLeucetta losangelensisEncruster, greenPollicipes polymerusPlumularia spSebastes spBryozoa, white branching (colonies) (count)Bryozoa, tan branching (colonies)Encruster, lavenderSponge, yellow encrustingMetridium spSponge, tan encrustingAeolidia papillosa?Botrylloides sp.Crassadoma giganteaEgregiaEncruster - whiteHermissenda crassicornisLeucilla nuttingi (colonies)Pisaster ochraceusSpionidaeStylasterias forreriZoanthid, colonial tan

11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/9

046ha1221 045ha1221 044ha1220 043ha1219 042ha1218 041ha1217 040ha1216 039ha1215 038ha1214 037ha1213 036ha1212 035ha1211 034ha12

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

199 209 225 238 243 260 278 288 292 301 314 329 335 

30 30 25 20 30 25 20 25 30 12 15 30 25 

8 5 3 16 13 3 12 16 11 1 5 

17 8

1 3 1

2 433 54 76111 1 111 11

15 

111 1111 111111111111 111

16

1 11 

1 11 11111 

11111 1

1 1

1

1

1 1

1

1
Platform Harvest - Leg B1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileOphiuroid unidMytilusCorynactis californica, individualsLeucettaBalanus spAnthopleura elegantissima (rosy morph) Worm tubes, calcareousTurfTunicate, encrusting translucentBare MetalEncruster, redBalanus nubilus Barnacle, unidFoliose red algaeMetridium farcimenZoanthid, solitary tanEncruster - tanEncruster - yellowEncruster, pinkGalathea californiensisWorm tubes, plainBivalve, nestlingLeucetta losangelensisEncruster, greenPollicipes polymerusPlumularia spSebastes spBryozoa, white branching (colonies) (count)Bryozoa, tan branching (colonies)Encruster, lavenderSponge, yellow encrustingMetridium spSponge, tan encrustingAeolidia papillosa?Botrylloides sp.Crassadoma giganteaEgregiaEncruster - whiteHermissenda crassicornisLeucilla nuttingi (colonies)Pisaster ochraceusSpionidaeStylasterias forreriZoanthid, colonial tan

11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/9

030ha1205 029ha1204 028ha1203 027ha1203 026ha1157 025ha1157 024ha1156 023ha1154 022ha1153 021ha1151 019ha1147 020ha1148 018ha1

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

395 399 402 409 418 425 432 455 481 504 519 519.1 533 

30 50 30 50 25 10 25 25 20 10 60 50 70 

2

2 2 7 9 11 2 1 3 1 111111111111 

15 1 

111111111111111111111111111

1 

16 2

111

0.5

1

1
Platform Harvest - Leg B1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileOphiuroid unidMytilusCorynactis californica, individualsLeucettaBalanus spAnthopleura elegantissima (rosy morph) Worm tubes, calcareousTurfTunicate, encrusting translucentBare MetalEncruster, redBalanus nubilus Barnacle, unidFoliose red algaeMetridium farcimenZoanthid, solitary tanEncruster - tanEncruster - yellowEncruster, pinkGalathea californiensisWorm tubes, plainBivalve, nestlingLeucetta losangelensisEncruster, greenPollicipes polymerusPlumularia spSebastes spBryozoa, white branching (colonies) (count)Bryozoa, tan branching (colonies)Encruster, lavenderSponge, yellow encrustingMetridium spSponge, tan encrustingAeolidia papillosa?Botrylloides sp.Crassadoma giganteaEgregiaEncruster - whiteHermissenda crassicornisLeucilla nuttingi (colonies)Pisaster ochraceusSpionidaeStylasterias forreriZoanthid, colonial tan

11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99

014ha1139 013ha1139 012ha1138 011ha1137 010ha1136 009ha1135 008ha1134 007ha1133 006ha1132 005ha1131 004ha1130 003ha1129

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

597 601 614 618 625 635 641 647 650 659 664 669 Tota

40 50 60 30 30 30 75 50 50 2 25 3168 

1 782 

734 672 354 188 124 

2 21 105 1 1 1 1 1 1 1 1 1 1 72 

2 50 

1 1 1 1 1 1 1 1 1 1 1 48 1 1 1 1 1 1 1 1 1 1 1 48 

31 25 22 

8 3 4 22 

16 13 13 13 

2 1 1 4 11 

1 1 11 

9 9 7 7 4 

1 4 

3.5 

3 3 3 

2 2 

1 2 

1 1 

1 1 1 1 1 1 1 1 

1 1 

1 
Platform Harvest - Leg B1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileOphiuroid unidMytilusCorynactis californica, individualsLeucettaBalanus spAnthopleura elegantissima (rosy morph) Worm tubes, calcareousTurfTunicate, encrusting translucentBare MetalEncruster, redBalanus nubilus Barnacle, unidFoliose red algaeMetridium farcimenZoanthid, solitary tanEncruster - tanEncruster - yellowEncruster, pinkGalathea californiensisWorm tubes, plainBivalve, nestlingLeucetta losangelensisEncruster, greenPollicipes polymerusPlumularia spSebastes spBryozoa, white branching (colonies) (count)Bryozoa, tan branching (colonies)Encruster, lavenderSponge, yellow encrustingMetridium spSponge, tan encrustingAeolidia papillosa?Botrylloides sp.Crassadoma giganteaEgregiaEncruster - whiteHermissenda crassicornisLeucilla nuttingi (colonies)Pisaster ochraceusSpionidaeStylasterias forreriZoanthid, colonial tan

Max Min

90 1

120 1

75 1

360 12

40 218 124 111 1

1 1

15 1

1 11 17 18 21 18 3

16 16

1 11 11 14 16 13 11 11 17 71 11 11 0.51 11 11 12 21 11 11 11 11 11 11 11 11 11 11 11 1
Platform Harvest - Leg B1 %

DATE 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/9

PHOTO CODE 029haD 028haD 027haD 026haD 023haD 025haD 024haD 022haD 021haD 020haD 019haD 018haD 017ha

LEG B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

DEPTH (ft) 3 4 5 6 6.1 6.2 7 10 12 14 16 18 22 

Corynactis californica (%)Metridium senile % 4 2 5 5 1 2 2 2 2 Metridium farcimen %Encruster, red %Encruster, lavender (%)Turf (%) 70 50 50 60 50 70 70 50 20 75 30 70 40 Mytilus 15 20 20 15 40 10 25 30 50 10 50 15 25 Botrylloides sp. %Leucetta losangelensis (%) 1 5Encruster - yellow (%)Foliose red algae (%) 25 20 15 5 5 10 10 7 10 20 Bare Metal (%)Egregia % 10Encruster - tan (%)Sponge, tan encrusting (%)Tunicate, encrusting translucent %Anthopleura elegantissima (rosy morph) % 15 2 5 2 1 13 5 7 20 3 3 15 1 Plumularia sp % 5 10Sponge, yellow encrusting (%) 1Encruster - white (%)Encruster, green % 1Encruster, pink %Zoanthid, colonial tan %Bryozoa, tan branching (colonies) (%)Leucilla nuttingi (colonies) (%)line %
Platform Harvest - Leg B1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)Metridium senile %Metridium farcimen %Encruster, red %Encruster, lavender (%)Turf (%)MytilusBotrylloides sp. %Leucetta losangelensis (%)Encruster - yellow (%)Foliose red algae (%)Bare Metal (%)Egregia %Encruster - tan (%)Sponge, tan encrusting (%)Tunicate, encrusting translucent %Anthopleura elegantissima (rosy morph) %Plumularia sp %Sponge, yellow encrusting (%)Encruster - white (%)Encruster, green %Encruster, pink %Zoanthid, colonial tan %Bryozoa, tan branching (colonies) (%)Leucilla nuttingi (colonies) (%)line %

11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/9

013haD 012haD 011haD 010haD 009haD 008haD 007haD 006haD 005haD 004haD 003haD 002haD 001ha

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

29 31 33 35 37 41 46 48 51 58 65 68 72 

40 75 50 80 75 90 90 90 15 60 90 

25 3025 15 25 5 25 5 5 5 10 2515 10 15 5

20

10 20 15 10 5 5 5 20 15 10 

15 30 10 1 10 2 5 2 1

5 10

10

1

5 10

5 1 5 0.5 1

0.5
Platform Harvest - Leg B1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)Metridium senile %Metridium farcimen %Encruster, red %Encruster, lavender (%)Turf (%)MytilusBotrylloides sp. %Leucetta losangelensis (%)Encruster - yellow (%)Foliose red algae (%)Bare Metal (%)Egregia %Encruster - tan (%)Sponge, tan encrusting (%)Tunicate, encrusting translucent %Anthopleura elegantissima (rosy morph) %Plumularia sp %Sponge, yellow encrusting (%)Encruster - white (%)Encruster, green %Encruster, pink %Zoanthid, colonial tan %Bryozoa, tan branching (colonies) (%)Leucilla nuttingi (colonies) (%)line %

11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/9

062ha1240 061ha1240 060ha1239 057ha1231 058ha1233 059ha1234 056ha1230 055ha1230 054ha1228 053ha1227 051ha1225 052ha1226 050ha12

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

108 110 120 124 125 126 135 137 144 149 154 157 158 

15 3

80 80 25 70 75 50 60 30 25 70 50 70 50 

2 10 2 5 5 20 15 10 20 20 

20 20 20 30 20 27 25 15 5 5

10 5 10

1 2 5 5 5 

3 10 10 15 5 

2 5

0.5 0.5 0.5 0.50.5
Platform Harvest - Leg B1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)Metridium senile %Metridium farcimen %Encruster, red %Encruster, lavender (%)Turf (%)MytilusBotrylloides sp. %Leucetta losangelensis (%)Encruster - yellow (%)Foliose red algae (%)Bare Metal (%)Egregia %Encruster - tan (%)Sponge, tan encrusting (%)Tunicate, encrusting translucent %Anthopleura elegantissima (rosy morph) %Plumularia sp %Sponge, yellow encrusting (%)Encruster - white (%)Encruster, green %Encruster, pink %Zoanthid, colonial tan %Bryozoa, tan branching (colonies) (%)Leucilla nuttingi (colonies) (%)line %

11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/9

046ha1221 045ha1221 044ha1220 043ha1219 042ha1218 041ha1217 040ha1216 039ha1215 038ha1214 037ha1213 036ha1212 035ha1211 034ha12

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

199 209 225 238 243 260 278 288 292 301 314 329 335 

30 30 25 20 30 25 20 25 30 12 15 30 25 

5 20 30 60 30 10 25 60 30 55 40 60 

15 65

10 15 5 10 10 1 10 10 

25 7

1 65 25 5 30 2 10 5 

20 20 5 1 15 10 10 5 10 10 10 20 15 

15 

5

0.5

3 0.5 0.5 0.5 1 0.5

1

0.5
Platform Harvest - Leg B1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)Metridium senile %Metridium farcimen %Encruster, red %Encruster, lavender (%)Turf (%)MytilusBotrylloides sp. %Leucetta losangelensis (%)Encruster - yellow (%)Foliose red algae (%)Bare Metal (%)Egregia %Encruster - tan (%)Sponge, tan encrusting (%)Tunicate, encrusting translucent %Anthopleura elegantissima (rosy morph) %Plumularia sp %Sponge, yellow encrusting (%)Encruster - white (%)Encruster, green %Encruster, pink %Zoanthid, colonial tan %Bryozoa, tan branching (colonies) (%)Leucilla nuttingi (colonies) (%)line %

11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/9

030ha1205 029ha1204 028ha1203 027ha1203 026ha1157 025ha1157 024ha1156 023ha1154 022ha1153 021ha1151 019ha1147 020ha1148 018ha1

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

395 399 402 409 418 425 432 455 481 504 519 519.1 533 

30 50 30 50 25 10 25 25 20 10 60 50 70 25 40 40 45 70 65 50 35 30 30 30 30 25 

3

10 10 5 10 10 20 20 25 50 30 5 10 

25 5 5 2 10 10 10 10 5 15 10 10 1 

15 1 

0.5

0.5
Platform Harvest - Leg B1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)Metridium senile %Metridium farcimen %Encruster, red %Encruster, lavender (%)Turf (%)MytilusBotrylloides sp. %Leucetta losangelensis (%)Encruster - yellow (%)Foliose red algae (%)Bare Metal (%)Egregia %Encruster - tan (%)Sponge, tan encrusting (%)Tunicate, encrusting translucent %Anthopleura elegantissima (rosy morph) %Plumularia sp %Sponge, yellow encrusting (%)Encruster - white (%)Encruster, green %Encruster, pink %Zoanthid, colonial tan %Bryozoa, tan branching (colonies) (%)Leucilla nuttingi (colonies) (%)line %

11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99 11/12/99

014ha1139 013ha1139 012ha1138 011ha1137 010ha1136 009ha1135 008ha1134 007ha1133 006ha1132 005ha1131 004ha1130 003ha1129

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

597 601 614 618 625 635 641 647 650 659 664 669 Tota

168 

40 50 60 30 30 30 75 50 50 2 25 3159 

100 15 15 185 

50 45 20 60 50 50 20 50 30 20 25 1699 

83 

5 2 5 10 15 10 2 10 25 10 1537 

420 

20 

400 

170.5 

268 

10 5 20 5 20 15 5 10 15 25 50 554 

10 

119 

5 15 

2 50 

100 

22 16 

5 

14 

14.5 

1 

1.5 0.5 0.5 
Platform Harvest - Leg B1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)Metridium senile %Metridium farcimen %Encruster, red %Encruster, lavender (%)Turf (%)MytilusBotrylloides sp. %Leucetta losangelensis (%)Encruster - yellow (%)Foliose red algae (%)Bare Metal (%)Egregia %Encruster - tan (%)Sponge, tan encrusting (%)Tunicate, encrusting translucent %Anthopleura elegantissima (rosy morph) %Plumularia sp %Sponge, yellow encrusting (%)Encruster - white (%)Encruster, green %Encruster, pink %Zoanthid, colonial tan %Bryozoa, tan branching (colonies) (%)Leucilla nuttingi (colonies) (%)line %

Max Min

90 390 1

100 15

75 265 375 150 520 2030 165 0.530 150 110 1020 110 515 120 110 210 1

5 55 0.55 0.51 1

0.5 0.50.5 0.50.5 0.5
Platform Harvest - Leg B2 counts

DATE 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/9

PHOTO CODE 025haD 024haD 018haD 021haD 026haD 027haD 032haD 020haD 029haD 022haD 023haD 028haD 030ha

LEG B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 

DEPTH (ft) 2 3 4 4.1 4.2 4.3 4.4 5 5.1 6 6.1 6.2 7 

Metridium senile 2 2 5 2 Ophiuroid unid 2Leucetta 6 

Mytilus 110 33 32 53 45 53 41 40 43 53 34 90 65 Corynactis californica, individualsBalanus sp 52 34112292Anthopleura elegantissima (rosy morph) 2 2 7 10 5 12 5 10 10 10 20 7 15 filamentous reds Polysiphonia, Neoptilota, Antithamnion etc 40 40 10 15 2Turf 1111111111111Worm tubes, calcareousEncruster, redPollicipes polymerus 20 5 6 5Bare MetalBryozoa, white branching (colonies) (count)Foliose red algae 111 11111111Tunicate, encrusting translucentBalanus nubilus Encruster, pinkLeucetta losangelensis 1 

Sponge, yellow encrusting 1 11 1 Encruster - yellow Bryozoa, tan branching (colonies)Encruster, green 1 1Encruster - tan Encruster - white Galathea californiensisLeucilla nuttingi (colonies)Aeolidia papillosa?egg caseEudendrium sp? 1 1Plumularia spSponge, tan encrustingAnomiidaeBivalve, nestlingCalliostoma spCancer antennariusEudistylia polymorpha Gastropoda, unidOxylebius pictusParacyathus stearnsi 1Sebastes spSponge, white encrustingWorm tubes, plain
Platform Harvest - Leg B2 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileOphiuroid unidLeucettaMytilusCorynactis californica, individualsBalanus spAnthopleura elegantissima (rosy morph) filamentous reds Polysiphonia, Neoptilota, Antithamnion etcTurfWorm tubes, calcareousEncruster, redPollicipes polymerusBare MetalBryozoa, white branching (colonies) (count)Foliose red algaeTunicate, encrusting translucentBalanus nubilus Encruster, pinkLeucetta losangelensisSponge, yellow encrustingEncruster - yellowBryozoa, tan branching (colonies)Encruster, greenEncruster - tanEncruster - whiteGalathea californiensisLeucilla nuttingi (colonies)Aeolidia papillosa?egg caseEudendrium sp?Plumularia spSponge, tan encrustingAnomiidaeBivalve, nestlingCalliostoma spCancer antennariusEudistylia polymorphaGastropoda, unidOxylebius pictusParacyathus stearnsiSebastes spSponge, white encrustingWorm tubes, plain

11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/9

016haD 015haD 014haD 013haD 012haD 011haD 010haD 009haD 008haD 007haD 006haD 005haD 004ha

B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 

12 14 18 24 25 27 30 40 42 47 52 54 64 30 25 70 50 50 90 45 50 60 50 25 30 30 

2 3 4 15 12 25 30 80 

35 40 25 50 40 10 30 50 40 50 60 60 70 

3 1 29 23

4 80 40

10 1 27 1 5 3 4 3 7 2 4 

3

11111 11111 1 1111 11 111 1

11

1
Platform Harvest - Leg B2 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileOphiuroid unidLeucettaMytilusCorynactis californica, individualsBalanus spAnthopleura elegantissima (rosy morph) filamentous reds Polysiphonia, Neoptilota, Antithamnion etcTurfWorm tubes, calcareousEncruster, redPollicipes polymerusBare MetalBryozoa, white branching (colonies) (count)Foliose red algaeTunicate, encrusting translucentBalanus nubilus Encruster, pinkLeucetta losangelensisSponge, yellow encrustingEncruster - yellowBryozoa, tan branching (colonies)Encruster, greenEncruster - tanEncruster - whiteGalathea californiensisLeucilla nuttingi (colonies)Aeolidia papillosa?egg caseEudendrium sp?Plumularia spSponge, tan encrustingAnomiidaeBivalve, nestlingCalliostoma spCancer antennariusEudistylia polymorphaGastropoda, unidOxylebius pictusParacyathus stearnsiSebastes spSponge, white encrustingWorm tubes, plain

11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/9

060ha1309 059ha1308 058ha1308 057ha1308 056ha1307 055ha1307 054ha1305 053ha1305 052ha1305 051ha1303 050ha1302 049ha1302 048ha13

B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 

90 95 100 101 105 111 122 127 129 145 150 153 155 25 15 20 20 20 25 25 20 15 30 25 20 20 

150 100 65 180 150 140 100 60 70

75 55 80 75 75 77 80 76 69 50 12

40 15

3 1 4 3 2 8 4 14 4 4 

1 11111

1 1

1111 

1 11 

11 1

19 111

1111 1

1 1

1 1 11 1

1

1
Platform Harvest - Leg B2 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileOphiuroid unidLeucettaMytilusCorynactis californica, individualsBalanus spAnthopleura elegantissima (rosy morph) filamentous reds Polysiphonia, Neoptilota, Antithamnion etcTurfWorm tubes, calcareousEncruster, redPollicipes polymerusBare MetalBryozoa, white branching (colonies) (count)Foliose red algaeTunicate, encrusting translucentBalanus nubilus Encruster, pinkLeucetta losangelensisSponge, yellow encrustingEncruster - yellowBryozoa, tan branching (colonies)Encruster, greenEncruster - tanEncruster - whiteGalathea californiensisLeucilla nuttingi (colonies)Aeolidia papillosa?egg caseEudendrium sp?Plumularia spSponge, tan encrustingAnomiidaeBivalve, nestlingCalliostoma spCancer antennariusEudistylia polymorphaGastropoda, unidOxylebius pictusParacyathus stearnsiSebastes spSponge, white encrustingWorm tubes, plain

11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/9

044ha1258 043ha1257 042ha1257 040ha1255 041ha1256 039ha1255 038ha1254 037ha1254 036ha1254 035ha1253 034ha1252 033ha1252 032ha12

B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 

229 241 244 259 266 271 292 294 295 303 320 325 330 

25 25 25 40 15 15 20 25 25 25 15 50 20 21 4 50 4 5 11 26 8 6 3 8 3 

1

4 1

111111111 11

11 1232123 111111111111111 1 1111 

1 223 

11 111 11

1

1 11 

1 1

1

1 1 

1

2 

1 1

1
Platform Harvest - Leg B2 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileOphiuroid unidLeucettaMytilusCorynactis californica, individualsBalanus spAnthopleura elegantissima (rosy morph) filamentous reds Polysiphonia, Neoptilota, Antithamnion etcTurfWorm tubes, calcareousEncruster, redPollicipes polymerusBare MetalBryozoa, white branching (colonies) (count)Foliose red algaeTunicate, encrusting translucentBalanus nubilus Encruster, pinkLeucetta losangelensisSponge, yellow encrustingEncruster - yellowBryozoa, tan branching (colonies)Encruster, greenEncruster - tanEncruster - whiteGalathea californiensisLeucilla nuttingi (colonies)Aeolidia papillosa?egg caseEudendrium sp?Plumularia spSponge, tan encrustingAnomiidaeBivalve, nestlingCalliostoma spCancer antennariusEudistylia polymorphaGastropoda, unidOxylebius pictusParacyathus stearnsiSebastes spSponge, white encrustingWorm tubes, plain

11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/9

028ha1249 027ha1249 026ha1248 025ha1247 024ha1247 023ha1246 021ha1245 020ha1245 019ha1244 018ha1244 017ha1243 015ha1241 014ha12

B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 

390 392 407 411 413 427 442 444 477 483 504 557 558 

20 20 25 5 15 25 25 25 15 30 45 50 50 

1

1

11111111111112 1 2 10 12 4 4 2 3 

111111111111111111 1111 1

2

5 10

1

111 1
Platform Harvest - Leg B2 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileOphiuroid unidLeucettaMytilusCorynactis californica, individualsBalanus spAnthopleura elegantissima (rosy morph) filamentous reds Polysiphonia, Neoptilota, Antithamnion etcTurfWorm tubes, calcareousEncruster, redPollicipes polymerusBare MetalBryozoa, white branching (colonies) (count)Foliose red algaeTunicate, encrusting translucentBalanus nubilus Encruster, pinkLeucetta losangelensisSponge, yellow encrustingEncruster - yellowBryozoa, tan branching (colonies)Encruster, greenEncruster - tanEncruster - whiteGalathea californiensisLeucilla nuttingi (colonies)Aeolidia papillosa?egg caseEudendrium sp?Plumularia spSponge, tan encrustingAnomiidaeBivalve, nestlingCalliostoma spCancer antennariusEudistylia polymorphaGastropoda, unidOxylebius pictusParacyathus stearnsiSebastes spSponge, white encrustingWorm tubes, plain

11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99

010ha1238 009ha1238 008ha1238 007ha1236 006ha1234 005ha1232

B2 B2 B2 B2 B2 B2 No. of

579 580 583 585 607 612 Total Average Photos Occurrence Max Min

60 50 40 25 50 60 2216 29.54667 86 75 90 2

1566 44.74286 86 35 180 11473 50.7931 86 29 80 6

858 40.85714 86 21 110 1179 35.8 86 5 80 4169 4.225 86 40 27 1160 9.411765 86 17 20 2107 21.4 86 5 40 2

1 1 1 1 1 1 71 1 86 71 1 1

2 68 2.833333 86 24 12 1

1 1 1 1 1 1 43 1 86 43 1 1

36 9 86 4 20 5

1 1 1 1 1 1 34 1 86 34 1 1

3 27 2.25 86 12 6 1

20 1 86 20 1 1

1 16 5.333333 86 3 10 1

13 4.333333 86 3 9 113 1 86 13 1 1

8 1 86 8 1 18 1 86 8 1 17 1 86 7 1 16 1 86 6 1 14 1 86 4 1 14 1 86 4 1 14 1 86 4 1 1

1 2 1 4 1.333333 86 3 2 1

4 1 86 4 1 1

1 3 1.5 86 2 2 1

3 1.5 86 2 2 12 1 86 2 1 12 1 86 2 1 12 1 86 2 1 11 1 86 1 1 11 1 86 1 1 1

1 1 1 86 1 1 1

1 1 86 1 1 11 1 86 1 1 11 1 86 1 1 11 1 86 1 1 11 1 86 1 1 1

1 1 1 86 1 1 1

1 1 86 1 1 11 1 86 1 1 1
Platform Harvest - Leg B2 %

DATE 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/9

PHOTO CODE 025haD 024haD 018haD 021haD 026haD 027haD 032haD 020haD 029haD 022haD 023haD 028haD 030ha

LEG B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 

DEPTH (ft) 2 3 4 4.1 4.2 4.3 4.4 5 5.1 6 6.1 6.2 7 

Encruster, red %Leucetta losangelensis (%) 5 Mytilus 90 40 40 50 60 60 30 35 35 35 25 60 20 Sponge, tan encrusting (%)Metridium senile % 2 2 5 2 Encruster - tan (%) Turf (%) 5 70 70 30 15 5 70 50 50 30 50 15 60 Sponge, yellow encrusting (%) 15 5 10 2 Encruster - yellow (%) Corynactis californica (%)Anthopleura elegantissima (rosy morph) % 2 2 5 10 5 12 5 10 10 10 20 7 15 Bare Metal (%)Encruster - white (%) Foliose red algae (%) 10 0.5 10 15 3 0.5 5 25 5 5 5 Tunicate, encrusting translucent %Bryozoa, tan branching (colonies) (%)Encruster, green % 1 2Eudendrium sp? % 2 5Plumularia sp %Sponge, white encrusting (%)Encruster, pink %Leucilla nuttingi (colonies) (%)
Platform Harvest - Leg B2 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Encruster, red %Leucetta losangelensis (%)MytilusSponge, tan encrusting (%)Metridium senile %Encruster - tan (%)Turf (%)Sponge, yellow encrusting (%)Encruster - yellow (%)Corynactis californica (%)Anthopleura elegantissima (rosy morph) %Bare Metal (%)Encruster - white (%)Foliose red algae (%)Tunicate, encrusting translucent %Bryozoa, tan branching (colonies) (%)Encruster, green %Eudendrium sp? %Plumularia sp %Sponge, white encrusting (%)Encruster, pink %Leucilla nuttingi (colonies) (%)

11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/9

016haD 015haD 014haD 013haD 012haD 011haD 010haD 009haD 008haD 007haD 006haD 005haD 004ha

B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 

12 14 18 24 25 27 30 40 42 47 52 54 64 50 40 28 15 25 8 29 45 35 45 50 60 65 35 5 10 1030 25 70 50 50 90 45 50 60 50 25 30 30 25 25 5 20 5 5 5 5 5 10 2 

1 20 10

2

5 10 2 5 0.5 1 12 10
Platform Harvest - Leg B2 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Encruster, red %Leucetta losangelensis (%)MytilusSponge, tan encrusting (%)Metridium senile %Encruster - tan (%)Turf (%)Sponge, yellow encrusting (%)Encruster - yellow (%)Corynactis californica (%)Anthopleura elegantissima (rosy morph) %Bare Metal (%)Encruster - white (%)Foliose red algae (%)Tunicate, encrusting translucent %Bryozoa, tan branching (colonies) (%)Encruster, green %Eudendrium sp? %Plumularia sp %Sponge, white encrusting (%)Encruster, pink %Leucilla nuttingi (colonies) (%)

11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/9

060ha1309 059ha1308 058ha1308 057ha1308 056ha1307 055ha1307 054ha1305 053ha1305 052ha1305 051ha1303 050ha1302 049ha1302 048ha13

B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 

90 95 100 101 105 111 122 127 129 145 150 153 155 

5 10 5 3 

70 65 80 75 75 75 75 70 80 55 1025 15 20 20 20 25 25 20 15 30 25 20 20 

5 5 5 10 25 40 

5 1

20 4

1 10 1 

1 5

0.5 1 0.5 

1 1 1
Platform Harvest - Leg B2 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Encruster, red %Leucetta losangelensis (%)MytilusSponge, tan encrusting (%)Metridium senile %Encruster - tan (%)Turf (%)Sponge, yellow encrusting (%)Encruster - yellow (%)Corynactis californica (%)Anthopleura elegantissima (rosy morph) %Bare Metal (%)Encruster - white (%)Foliose red algae (%)Tunicate, encrusting translucent %Bryozoa, tan branching (colonies) (%)Encruster, green %Eudendrium sp? %Plumularia sp %Sponge, white encrusting (%)Encruster, pink %Leucilla nuttingi (colonies) (%)

11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/9

044ha1258 043ha1257 042ha1257 040ha1255 041ha1256 039ha1255 038ha1254 037ha1254 036ha1254 035ha1253 034ha1252 033ha1252 032ha12

B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 

229 241 244 259 266 271 292 294 295 303 320 325 330 

25 30 30 50 20 30 50 60 60 70 50 40 80 

30 30

25 25 25 40 15 15 20 25 25 25 15 50 20 50

2 2 5 1 15 30 5 25 10 20 20 

80

70 25 5 

2 2 10 5 1 5 5 

3 10 

10 15

2

0.5 0.5 0.5 0.5 0.5 0.5 0.5

0.5
Platform Harvest - Leg B2 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Encruster, red %Leucetta losangelensis (%)MytilusSponge, tan encrusting (%)Metridium senile %Encruster - tan (%)Turf (%)Sponge, yellow encrusting (%)Encruster - yellow (%)Corynactis californica (%)Anthopleura elegantissima (rosy morph) %Bare Metal (%)Encruster - white (%)Foliose red algae (%)Tunicate, encrusting translucent %Bryozoa, tan branching (colonies) (%)Encruster, green %Eudendrium sp? %Plumularia sp %Sponge, white encrusting (%)Encruster, pink %Leucilla nuttingi (colonies) (%)

11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/9

028ha1249 027ha1249 026ha1248 025ha1247 024ha1247 023ha1246 021ha1245 020ha1245 019ha1244 018ha1244 017ha1243 015ha1241 014ha12

B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 B2 

390 392 407 411 413 427 442 444 477 483 504 557 558 

60 80 70 90 70 75 75 60 60 70 50 50 50 20 20 25 5 15 25 25 25 15 30 45 50 50 10 25 25 25 30 20 15 15 10 5 5 10 10 

2

20 5 5 1 1 10 10 0.5 5 2 

5 10

1 0.5 2 1
Platform Harvest - Leg B2 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Encruster, red %Leucetta losangelensis (%)MytilusSponge, tan encrusting (%)Metridium senile %Encruster - tan (%)Turf (%)Sponge, yellow encrusting (%)Encruster - yellow (%)Corynactis californica (%)Anthopleura elegantissima (rosy morph) %Bare Metal (%)Encruster - white (%)Foliose red algae (%)Tunicate, encrusting translucent %Bryozoa, tan branching (colonies) (%)Encruster, green %Eudendrium sp? %Plumularia sp %Sponge, white encrusting (%)Encruster, pink %Leucilla nuttingi (colonies) (%)

11/13/99 11/13/99 11/13/99 11/13/99 11/13/99 11/13/99

010ha1238 009ha1238 008ha1238 007ha1236 006ha1234 005ha1232

B2 B2 B2 B2 B2 B2 No. of

579 580 583 585 607 612 Total Average Photos Occurrence Max Min

25 20 40 60 30 30 2133 49.60465 86 43 90 3

1414 48.75862 86 29 80 5

700 35.00 86 20 90 5

60 30 86 2 30 30

60 50 40 25 50 60 2216 29.54667 86 75 90 2

105 26.25 86 4 50 5

5 5 5 10 5 5 1367.5 19.26056 86 71 70 0.5

129 16.125 86 8 80 2112 16 86 7 70 1

55 11 86 5 20 1

152 8.941176 86 17 20 2

10 25 20 25 20 5 265.5 7.808824 86 34 25 0.5

30 7.5 86 4 15 2

111.5 5.575 86 20 25 0.5

1 16 5.333333 86 3 10 1

29.5 4.916667 86 6 15 0.5

15 3.75 86 4 10 1

7 3.5 86 2 5 26 3 86 2 5 12 2 86 1 2 2

13.5 1.038462 86 13 5 0.5

3.5 0.875 86 4 1 0.5
Platform Hidalgo - Leg A1 counts

DATE 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 

PHOTO CODE 023hiD 020hiD 021hiD 019hiD 022hiD 017hiD 018hiD 016hiD 015hiD 014hiD 013hi 012hiD 011hiD 

LEG A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

DEPTH (ft) 3 5 5.1 6 6.1 7 7.1 8 14 15 18 21 24 

Metridium senile 38 41 1 33 30 40 55 130 88 150 180 Ophiuroid unid 1 3 4 3 7 8 13 24 53 45 Mytilus 194 156 164 109 120 115 82 84 69 28 22 16 26 Corynactis californica, individualsBalanus nubilus 5 8 7 4 13 6 4 Metridium farcimenWorm tubes, calcareousTurf 1 1 1 1 1 1 1 1 1 1Eudistylia polymorpha 6 13 3 3 2 5Leucetta losangelensis Tetraclita squamosa 23Bare MetalEncruster - tanFoliose red algae 1 1 1 1 1Pollicipes polymerus 11122321Zoanthid , solitary tanLeucilla nuttingi (colonies)Worm tubes, plainAstrangia sp. 2 Bryozoa, tan branching (colonies)Strongylocentrotus purpuratus 1 11Balanus sp 4Bryozoa, white branching (colonies) (count)Encruster, lavenderSponge, tan encrustingAlga, encrusting green egg case Encruster - whiteEncruster - yellowPisaster giganteus 1Pisaster ochraceusStylasterias forreriAmaroucium 1Archidoris montereyensis Oxylebius pictusPisaster brevispinisSebastes spSponge, tan folioseSponge, yellow encrusting
Platform Hidalgo - Leg A1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileOphiuroid unidMytilusCorynactis californica, individualsBalanus nubilus Metridium farcimenWorm tubes, calcareousTurfEudistylia polymorphaLeucetta losangelensisTetraclita squamosaBare MetalEncruster - tanFoliose red algaePollicipes polymerusZoanthid , solitary tanLeucilla nuttingi (colonies)Worm tubes, plainAstrangia sp.Bryozoa, tan branching (colonies)Strongylocentrotus purpuratusBalanus spBryozoa, white branching (colonies) (count)Encruster, lavenderSponge, tan encrustingAlga, encrusting greenegg caseEncruster - whiteEncruster - yellowPisaster giganteusPisaster ochraceusStylasterias forreriAmarouciumArchidoris montereyensisOxylebius pictusPisaster brevispinisSebastes spSponge, tan folioseSponge, yellow encrusting

11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 1

006hiD 005hiD 004hiD 003hiD 002hiD 001hiD 044hi1253 043hi1252 042hi1252 041hi1251 040hi1251 039hi1250 038hi1250 037hi1249 03

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

44 47 52 55 58 60 72 76 78 82 85 86 88 91 

255 240 250 250 275 240 235 225 70 90 150 180 240 225 

87 50 27 28 20 45 47 88 125 225 250 130 30 70 

15 30 75 10

12111 3322141 11111111111111

1

111 1 1 

1

1

1 

1
Platform Hidalgo - Leg A1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileOphiuroid unidMytilusCorynactis californica, individualsBalanus nubilus Metridium farcimenWorm tubes, calcareousTurfEudistylia polymorphaLeucetta losangelensisTetraclita squamosaBare MetalEncruster - tanFoliose red algaePollicipes polymerusZoanthid , solitary tanLeucilla nuttingi (colonies)Worm tubes, plainAstrangia sp.Bryozoa, tan branching (colonies)Strongylocentrotus purpuratusBalanus spBryozoa, white branching (colonies) (count)Encruster, lavenderSponge, tan encrustingAlga, encrusting greenegg caseEncruster - whiteEncruster - yellowPisaster giganteusPisaster ochraceusStylasterias forreriAmarouciumArchidoris montereyensisOxylebius pictusPisaster brevispinisSebastes spSponge, tan folioseSponge, yellow encrusting

11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 1

031hi1247 030hi1246 029hi1245 028hi1245 027hi1244 026hi1243 025hi1243 024hi1242 023hi1237 022hi1236 021hi1235 020hi1234 019hi1232 018hi1231 01

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

100 101 118 133 145 163 171 189 222 243 256 285 299 318 178 120 145 68 72 118 60 120 122 145 120 148 75 77 

78 231 120 430 288 275 133 87 85 7 6 14 8 10 

9

2 4

22 4

1 1 11111

11111 111

1 1 111

11111 111 1

1 11 1

1 5

1 1 111

1 1

1 

1 1

1 1

1
Platform Hidalgo - Leg A1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileOphiuroid unidMytilusCorynactis californica, individualsBalanus nubilus Metridium farcimenWorm tubes, calcareousTurfEudistylia polymorphaLeucetta losangelensisTetraclita squamosaBare MetalEncruster - tanFoliose red algaePollicipes polymerusZoanthid , solitary tanLeucilla nuttingi (colonies)Worm tubes, plainAstrangia sp.Bryozoa, tan branching (colonies)Strongylocentrotus purpuratusBalanus spBryozoa, white branching (colonies) (count)Encruster, lavenderSponge, tan encrustingAlga, encrusting greenegg caseEncruster - whiteEncruster - yellowPisaster giganteusPisaster ochraceusStylasterias forreriAmarouciumArchidoris montereyensisOxylebius pictusPisaster brevispinisSebastes spSponge, tan folioseSponge, yellow encrusting

11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99

013hi1223 012hi1222 011hi1221 010hi1220 009hi1220 008hi1219 007hi1218 006hi1218 005hi1217 004hi1217

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 No. of

398 401 409 415 418 420 424 427 429 430 Total Average Photos Occurrence 

76 148 125 25 35 70 91 7849 135.3276 63 58 

2 4 3842 78.40816 63 49 

1190 85 63 14 

139 27.8 63 5 

92 3.407407 63 27 

34 20 19 73 24.33333 63 3 

1 2 6 2 3 1 2 2 8 5 47 2.9375 63 16 1 1 1 1 1 1 1 1 1 1 34 1 63 34 

32 5.333333 63 6 30 1 63 30 23 23 63 1 

1 1 1 1 1 1 1 1 1 17 1 63 17 

1 1 15 1 63 15 

13 1 63 13 13 1.625 63 8 

12 13 6.5 63 2 

7 1 63 7 

1 7 2.333333 63 3 

6 3 63 2 6 1 63 6 

1 1 5 1 63 5 

4 4 63 1 3 1 63 3 

1 1 3 1 63 3 

3 1 63 3 2 1 63 2 

1 2 1 63 2 

2 1 63 2 2 1 63 2 

1 2 1 63 2 

2 1 63 2 

2 2 2 63 1 

1 1 63 1 1 1 63 1 1 1 63 1 1 1 63 1 1 1 63 1 

1 1 1 63 1 

1 1 63 1 
Platform Hidalgo - Leg A1 %

DATE 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/

PHOTO CODE 023hiD 020hiD 021hiD 019hiD 022hiD 017hiD 018hiD 016hiD 015hiD 014hiD 013hi 012hiD 011hiD 01

LEG A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

DEPTH (ft) 3 5 5.1 6 6.1 7 7.1 8 14 15 18 21 24 

Mytilus 75 65 65 85 85 85 60 60 80 30 45 35 25 Metridium senile % 15 12 3 10 10 15 20 45 30 50 60 Encruster - yellow (%)Leucetta losangelensis (%) 

Metridium farcimen %Sponge, tan foliose (%)Bare Metal (%)Turf (%) 15 20 20 15 30 25 20 20 15 2 Encruster - tan (%)Encruster, lavender (%)Corynactis californica (%)Sponge, tan encrusting (%)Bryozoa, tan branching (colonies) (%)Sponge, yellow encrusting (%)Foliose red algae (%) 10 3 4 5 0.5 Amaroucium % 1Leucilla nuttingi (colonies) (%)Encruster - white (%)Alga, encrusting green (%) 
Platform Hidalgo - Leg A1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

MytilusMetridium senile %Encruster - yellow (%)Leucetta losangelensis (%)Metridium farcimen %Sponge, tan foliose (%)Bare Metal (%)Turf (%)Encruster - tan (%)Encruster, lavender (%)Corynactis californica (%)Sponge, tan encrusting (%)Bryozoa, tan branching (colonies) (%)Sponge, yellow encrusting (%)Foliose red algae (%)Amaroucium %Leucilla nuttingi (colonies) (%)Encruster - white (%)Alga, encrusting green (%)

11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/9

006hiD 005hiD 004hiD 003hiD 002hiD 001hiD 044hi1253 043hi1252 042hi1252 041hi1251 040hi1251 039hi1250 038hi1250 037hi1249 036hi12

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

44 47 52 55 58 60 72 76 78 82 85 86 88 91 93 85 80 85 85 90 80 80 75 25 30 50 60 80 75 75 10 20 15 15 10 20 20 25 25 35 30 5 20 23 25 

5

5 10 25 2

0.5

1

1 1 0.5 

0.5 0.5 0.5
Platform Hidalgo - Leg A1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

MytilusMetridium senile %Encruster - yellow (%)Leucetta losangelensis (%)Metridium farcimen %Sponge, tan foliose (%)Bare Metal (%)Turf (%)Encruster - tan (%)Encruster, lavender (%)Corynactis californica (%)Sponge, tan encrusting (%)Bryozoa, tan branching (colonies) (%)Sponge, yellow encrusting (%)Foliose red algae (%)Amaroucium %Leucilla nuttingi (colonies) (%)Encruster - white (%)Alga, encrusting green (%)

11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/9

031hi1247 030hi1246 029hi1245 028hi1245 027hi1244 026hi1243 025hi1243 024hi1242 023hi1237 022hi1236 021hi1235 020hi1234 019hi1232 018hi1231 017hi12

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

100 101 118 133 145 163 171 189 222 243 256 285 299 318 338 

60 40 50 25 25 40 20 40 40 50 40 50 25 25 50 

10 50

40 60 30 30 15 25 25 40

3 1 0.5 15 15 15 5 10 25 20 15 15 10 10 

10 10 50 60 25 20 1 25 25 5 

3

20 

2 3 5 15 15

0.5 0.5 3 0.5

0.5 1
Platform Hidalgo - Leg A1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

MytilusMetridium senile %Encruster - yellow (%)Leucetta losangelensis (%)Metridium farcimen %Sponge, tan foliose (%)Bare Metal (%)Turf (%)Encruster - tan (%)Encruster, lavender (%)Corynactis californica (%)Sponge, tan encrusting (%)Bryozoa, tan branching (colonies) (%)Sponge, yellow encrusting (%)Foliose red algae (%)Amaroucium %Leucilla nuttingi (colonies) (%)Encruster - white (%)Alga, encrusting green (%)

11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99 11/15/99

013hi1223 012hi1222 011hi1221 010hi1220 009hi1220 008hi1219 007hi1218 006hi1218 005hi1217 004hi1217

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 No. of

398 401 409 415 418 420 424 427 429 430 Total Average Photos Occurrence Ma

800 57.14286 63 14 8

25 50 50 35 35 30 25 2710 46.72414 63 58 9

60 30 63 2 5

758 25.26667 63 30 6

35 10 20 65 21.66667 63 3 3

20 20 20 63 1 2

30 5 10 10 10 25 50 60 40 314.5 18.5 63 17 630 35 25 30 15 25 40 15 30 25 619 18.20588 63 34 4

2 2 260 17.33333 63 15 6

5 15 45 15 63 3 2

45 9 63 5 2

23.5 7.833333 63 3 2

41 6.833333 63 6 1

3 3 63 1 3 

28.5 2.192308 63 13 1

1 1 63 1 1 6 0.857143 63 7 3 

1.5 0.75 63 2 1 

1 0.5 63 2 0.
Platform Hidalgo - Leg B1 counts

DATE 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 

PHOTO CODE 033hiD 032hiD 024hiD 025hiD 028hiD 023hiD 027hiD 021hiD 022hiD 026hiD 020hiD 031hiD 019hiD 

LEG B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

DEPTH (ft) 0 1 3 3.1 3.2 4 4.1 5 5.1 5.2 6 6.1 7 

Metridium senile 25 60 27 6 1 4 20 14 4 10 45 Mytilus 122 124 180 142 112 124 100 170 152 130 144 96 180 Ophiuroid unid 252 11Anthopleura elegantissima (rosy morph) 3 4 

Balanus sp 5 5 5 4 9 5 Metridium farcimenTurf 1 1 1 1 1 1 1 1 1 1 1 1 1Worm tubes, calcareousOphiothrix spiculata 12 5 Tetraclita squamosa 6 6 8 59Balanus nubilus Leucetta losangelensis Eudistylia polymorpha 2 2 2 2 2 2 1 2 3 1Encruster, redEncruster - blueBivalve, nestlingFoliose red algae 1 1 1Plumularia sp 1 1 1 1 1 1 1 1 1Encruster - yellowBryozoa, white branching (colonies) (count)Worm tubes, plainBare MetalEncruster - tanPisaster giganteus 2Pollicipes polymerus 2 1 

Encruster - whiteEncruster, greenStrongylocentrotus purpuratus 1 1 1Tunicate, encrusting translucentZoanthid , solitary tanLeucilla nuttingi (colonies)Metridium spProtula superbaRhodymeniaZoanthid, colonial tanAsterina miniata = PatiriaBryozoa, tan branching (colonies)Egregia 1Encruster - grayEncruster, pinkOrthasterias koehleriPisaster ochraceusSponge, tan encrustingSponge, yellow encrustingStylasterias forreri
Platform Hidalgo - Leg B1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileMytilusOphiuroid unidAnthopleura elegantissima (rosy morph) Balanus spMetridium farcimenTurfWorm tubes, calcareousOphiothrix spiculataTetraclita squamosaBalanus nubilus Leucetta losangelensisEudistylia polymorphaEncruster, redEncruster - blueBivalve, nestlingFoliose red algaePlumularia spEncruster - yellowBryozoa, white branching (colonies) (count)Worm tubes, plainBare MetalEncruster - tanPisaster giganteusPollicipes polymerusEncruster - whiteEncruster, greenStrongylocentrotus purpuratusTunicate, encrusting translucentZoanthid , solitary tanLeucilla nuttingi (colonies)Metridium spProtula superbaRhodymeniaZoanthid, colonial tanAsterina miniata = PatiriaBryozoa, tan branching (colonies)EgregiaEncruster - grayEncruster, pinkOrthasterias koehleriPisaster ochraceusSponge, tan encrustingSponge, yellow encrustingStylasterias forreri

11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 1

015hiD 014hiD 016hiD 013hiD 012hiD 011hiD 010hiD 009hiD 008hiD 007hiD 006hiD 005hiD 004hiD 003hiD 

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

12 14 14.1 15 18 21 27 29 36 40 45 48 50 54 78 25 140 69 58 18 12 72 21 27 180 150 161 56 47 142 56 30 10

6 13 29 6 10 37 86 10 50 100 

40 100 150 185 100 180 85

4 1 

1111111 11

2 2

31 1 262

1 1111111

2 82 101 1 1 111 1

1

1

1 11

1

1 

1 1

1 1

1

1

1
Platform Hidalgo - Leg B1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileMytilusOphiuroid unidAnthopleura elegantissima (rosy morph) Balanus spMetridium farcimenTurfWorm tubes, calcareousOphiothrix spiculataTetraclita squamosaBalanus nubilus Leucetta losangelensisEudistylia polymorphaEncruster, redEncruster - blueBivalve, nestlingFoliose red algaePlumularia spEncruster - yellowBryozoa, white branching (colonies) (count)Worm tubes, plainBare MetalEncruster - tanPisaster giganteusPollicipes polymerusEncruster - whiteEncruster, greenStrongylocentrotus purpuratusTunicate, encrusting translucentZoanthid , solitary tanLeucilla nuttingi (colonies)Metridium spProtula superbaRhodymeniaZoanthid, colonial tanAsterina miniata = PatiriaBryozoa, tan branching (colonies)EgregiaEncruster - grayEncruster, pinkOrthasterias koehleriPisaster ochraceusSponge, tan encrustingSponge, yellow encrustingStylasterias forreri

11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 1

053hi1441 052hi1441 051hi1440 050hi1439 049hi1439 048hi1439 047hi1438 046hi1438 045hi1438 044hi1437 043hi1437 042hi1437 041hi1437 040hi1434 03

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

78 79 81 83 85 87 89 90 92 95 96 100 103 121 

145 138 118 147 165 118 201 185 199 170 165 95 30 60 

90 110 95 110 30 48 20 16 12 23 15 100 260 250 

1

211 3111111111111111

1

1

1 1

1 1
Platform Hidalgo - Leg B1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileMytilusOphiuroid unidAnthopleura elegantissima (rosy morph) Balanus spMetridium farcimenTurfWorm tubes, calcareousOphiothrix spiculataTetraclita squamosaBalanus nubilus Leucetta losangelensisEudistylia polymorphaEncruster, redEncruster - blueBivalve, nestlingFoliose red algaePlumularia spEncruster - yellowBryozoa, white branching (colonies) (count)Worm tubes, plainBare MetalEncruster - tanPisaster giganteusPollicipes polymerusEncruster - whiteEncruster, greenStrongylocentrotus purpuratusTunicate, encrusting translucentZoanthid , solitary tanLeucilla nuttingi (colonies)Metridium spProtula superbaRhodymeniaZoanthid, colonial tanAsterina miniata = PatiriaBryozoa, tan branching (colonies)EgregiaEncruster - grayEncruster, pinkOrthasterias koehleriPisaster ochraceusSponge, tan encrustingSponge, yellow encrustingStylasterias forreri

11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 1

035hi1427 034hi1426 033hi1425 031hi1424 030hi1422 029hi1420 025hi1417 024hi1416 022hi1413 020hi1411 019hi1408 018hi1407 017hi1405 016hi1404 01

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

181 199 215 232 255 279 299 315 329 340 368 381 389 391 

43 112 47 28 59 30 60 54 57 42 34 31 19 37 

200 32 10 35 28 18 1 5 3

11 11111111135322 3 1222 1

1 1

1111111111111111 1111111

1 1 111111 1223

2 3 

11111

1 1 1 

11 1

3

2

1 1

1

1
Platform Hidalgo - Leg B1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileMytilusOphiuroid unidAnthopleura elegantissima (rosy morph) Balanus spMetridium farcimenTurfWorm tubes, calcareousOphiothrix spiculataTetraclita squamosaBalanus nubilus Leucetta losangelensisEudistylia polymorphaEncruster, redEncruster - blueBivalve, nestlingFoliose red algaePlumularia spEncruster - yellowBryozoa, white branching (colonies) (count)Worm tubes, plainBare MetalEncruster - tanPisaster giganteusPollicipes polymerusEncruster - whiteEncruster, greenStrongylocentrotus purpuratusTunicate, encrusting translucentZoanthid , solitary tanLeucilla nuttingi (colonies)Metridium spProtula superbaRhodymeniaZoanthid, colonial tanAsterina miniata = PatiriaBryozoa, tan branching (colonies)EgregiaEncruster - grayEncruster, pinkOrthasterias koehleriPisaster ochraceusSponge, tan encrustingSponge, yellow encrustingStylasterias forreri

11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99

011hi1400 010hi1400 009hi1400 008hi1359 007hi1359 006hi1358 005hi1358

B1 B1 B1 B1 B1 B1 B1 No. of

421 423 425 427 430 431 433 Total Average Photos Occurrence Max Min

5048 78.875 78 64 245 12710 117.8261 78 23 220 10

1 2659 59.08889 78 45 260 1

849 84.9 78 10 185 2

56 4.666667 78 12 9 1

13 42 55 27.5 78 2 42 13

1 1 1 1 1 1 1 49 1 78 49 1 12 2 3 3 3 3 49 2.578947 78 19 5 1

42 7 78 6 17 138 5.428571 78 7 9 232 2.461538 78 13 7 132 1 78 32 1 131 2.214286 78 14 8 117 1 78 17 1 115 1 78 15 1 112 6 78 2 10 211 1 78 11 1 111 1 78 11 1 110 1 78 10 1 1

9 1.8 78 5 3 1

1 9 2.25 78 4 3 1

1 1 1 1 1 1 1 8 1 78 8 1 1

6 1 78 6 1 16 1.2 78 5 2 16 1.5 78 4 2 15 1 78 5 1 15 1 78 5 1 15 1 78 5 1 14 1 78 4 1 13 3 78 1 3 32 1 78 2 1 1

1 1 2 1 78 2 1 1

2 2 78 1 2 22 1 78 2 1 12 1 78 2 1 1

1 1 1 78 1 1 1

1 1 78 1 1 11 1 78 1 1 11 1 78 1 1 11 1 78 1 1 1

1 1 1 78 1 1 1

1 1 78 1 1 11 1 78 1 1 11 1 78 1 1 1

1 1 1 78 1 1 1
Platform Hidalgo - Leg B1 %

DATE 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 

PHOTO CODE 033hiD 032hiD 024hiD 025hiD 028hiD 023hiD 027hiD 021hiD 022hiD 026hiD 020hiD 031hiD 019hiD 

LEG B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

DEPTH (ft) 0 1 3 3.1 3.2 4 4.1 5 5.1 5.2 6 6.1 7 

Mytilus % 64 50 80 60 70 70 75 60 60 74 74 55 70 Anthopleura elegantissima (rosy morph) % 2 2 

Bare Metal (%)Metridium senile % 10 25 10 2 0.5 2 7 5 1 5 20 Leucetta losangelensis (%) Turf (%) 25 25 15 25 20 5 20 25 25 15 20 25 20 Encruster, red %Metridium farcimen %Encruster - blue %Encruster - yellow (%)Encruster - tan (%)Sponge, tan encrusting (%)Zoanthid, colonial tan %

Plumularia sp % 5 2 5 25 2 5 10 5 10 Encruster - white (%)Egregia % 5Rhodymenia %Encruster - gray %Encruster, green %Tunicate, encrusting translucent %Encruster, pink %Foliose red algae (%) 1 0.5 1Fishing line %Leucilla nuttingi (colonies) (%)Bryozoa, tan branching (colonies) (%)Sponge, yellow encrusting (%)
Platform Hidalgo - Leg B1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Mytilus %Anthopleura elegantissima (rosy morph) %Bare Metal (%)Metridium senile %Leucetta losangelensis (%)Turf (%)Encruster, red %Metridium farcimen %Encruster - blue %Encruster - yellow (%)Encruster - tan (%)Sponge, tan encrusting (%)Zoanthid, colonial tan %Plumularia sp %Encruster - white (%)Egregia %Rhodymenia %Encruster - gray %Encruster, green %Tunicate, encrusting translucent %Encruster, pink %Foliose red algae (%)Fishing line %Leucilla nuttingi (colonies) (%)Bryozoa, tan branching (colonies) (%)Sponge, yellow encrusting (%)

11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 1

015hiD 014hiD 016hiD 013hiD 012hiD 011hiD 010hiD 009hiD 008hiD 007hiD 006hiD 005hiD 004hiD 003hiD 

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

12 14 14.1 15 18 21 27 29 36 40 45 48 50 54 

3 10 75 19 35 10

20 50 75 95 50 90 50

2

25 10 50 20 20 5 4 25 7 10 90 70 80 

10 10 25 3 30 10 25 10 

70 80 25 30 25 5 10 0.5 2

10

2

2 7

1 

2 0.5 2 0.5 5 1 2

0.5
Platform Hidalgo - Leg B1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Mytilus %Anthopleura elegantissima (rosy morph) %Bare Metal (%)Metridium senile %Leucetta losangelensis (%)Turf (%)Encruster, red %Metridium farcimen %Encruster - blue %Encruster - yellow (%)Encruster - tan (%)Sponge, tan encrusting (%)Zoanthid, colonial tan %Plumularia sp %Encruster - white (%)Egregia %Rhodymenia %Encruster - gray %Encruster, green %Tunicate, encrusting translucent %Encruster, pink %Foliose red algae (%)Fishing line %Leucilla nuttingi (colonies) (%)Bryozoa, tan branching (colonies) (%)Sponge, yellow encrusting (%)

11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 1

053hi1441 052hi1441 051hi1440 050hi1439 049hi1439 048hi1439 047hi1438 046hi1438 045hi1438 044hi1437 043hi1437 042hi1437 041hi1437 040hi1434 03

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

78 79 81 83 85 87 89 90 92 95 96 100 103 121 60 60 50 60 80 50 90 85 90 80 75 40 15 25 40 35 40 30 20 45 10 15 10 20 25 60 70 75 

10

5 5

0.5

0.5 1
Platform Hidalgo - Leg B1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Mytilus %Anthopleura elegantissima (rosy morph) %Bare Metal (%)Metridium senile %Leucetta losangelensis (%)Turf (%)Encruster, red %Metridium farcimen %Encruster - blue %Encruster - yellow (%)Encruster - tan (%)Sponge, tan encrusting (%)Zoanthid, colonial tan %Plumularia sp %Encruster - white (%)Egregia %Rhodymenia %Encruster - gray %Encruster, green %Tunicate, encrusting translucent %Encruster, pink %Foliose red algae (%)Fishing line %Leucilla nuttingi (colonies) (%)Bryozoa, tan branching (colonies) (%)Sponge, yellow encrusting (%)

11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 1

035hi1427 034hi1426 033hi1425 031hi1424 030hi1422 029hi1420 025hi1417 024hi1416 022hi1413 020hi1411 019hi1408 018hi1407 017hi1405 016hi1404 01

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 

181 199 215 232 255 279 299 315 329 340 368 381 389 391 

20 50 20 15 30 20 35 30 30 20 15 20 25 15 80 30

25 25 20 25 15 40 30 30 25 30 60 

5 25 20 20 30 10 15 20 15 20 25 15 

25 15 20 10 5 1 0.5 5 15 10 10 

20 10 1 25 50 10 0.5 1 1 

5 15 0.5 2 10

0.5 15

10 1 10 

21 1

2

0.5 0.5

0.5
Platform Hidalgo - Leg B1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Mytilus %Anthopleura elegantissima (rosy morph) %Bare Metal (%)Metridium senile %Leucetta losangelensis (%)Turf (%)Encruster, red %Metridium farcimen %Encruster - blue %Encruster - yellow (%)Encruster - tan (%)Sponge, tan encrusting (%)Zoanthid, colonial tan %Plumularia sp %Encruster - white (%)Egregia %Rhodymenia %Encruster - gray %Encruster, green %Tunicate, encrusting translucent %Encruster, pink %Foliose red algae (%)Fishing line %Leucilla nuttingi (colonies) (%)Bryozoa, tan branching (colonies) (%)Sponge, yellow encrusting (%)

11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99 11/14/99

011hi1400 010hi1400 009hi1400 008hi1359 007hi1359 006hi1358 005hi1358

B1 B1 B1 B1 B1 B1 B1 No. of

421 423 425 427 430 431 433 Total Average Photos Occurrence Max Min

1246 54.17391 78 23 80 3

435 43.5 78 10 95 1

20 25 50 40 65 60 50 312 39 78 8 65 2

2233.5 34.89844 78 64 98 0.5

975 30.46875 78 32 80 2

75 65 50 60 10 20 50 1472.5 30.05102 78 49 80 0.5

380 22.35294 78 17 70 5

20 15 35 17.5 78 2 20 15

196.5 13.1 78 15 30 0.5120.5 12.05 78 10 50 0.5

62.5 10.41667 78 6 30 0.5

10 10 78 1 10 10

15.5 7.75 78 2 15 0.5

76 6.909091 78 11 25 2

25.5 5.1 78 5 10 0.5

5 5 78 1 5 59 4.5 78 2 7 23 3 78 1 3 3

13.5 2.7 78 5 5 0.5

9 2.25 78 4 5 12 2 78 1 2 2

16 1.454545 78 11 5 0.5

0.5 3 4.5 1.125 78 4 3 0.5

1.5 0.75 78 2 1 0.50.5 0.5 78 1 0.5 0.50.5 0.5 78 1 0.5 0.5
Platform Habitat - Leg A1 counts

DATE 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 

PHOTO CODE 021habD 026habD 016habD 020habD 019habD 025habD 018habD 022habD 027habD 024habD 029habD 023habD 028habD 

LEG A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

DEPTH (ft) 4 4.1 4.2 5 6 6.1 7 7.1 7.2 8 8.1 9 9.1 

Corynactis californica 12Mytilus sp 6 12 7 14 60 16 60 14 25 48 35 80 15 Metridium senile 6 16 32 18 22 29 2 35 8 55 60 11 Ophiothrix spiculata 2 23 30 9 6 7 10 Balanus nubilus 18 11 12 31 26 36 15 44 22 30 34 7 Anthopleura elegantissima (rosy morph) 15 19 75 2 26 26 21 4 6 Paracyathus stearnsiTriopha catalinaeMetridium spCorallinaStaurocalyptusTurfCrisia/FilicrisiaOxylebius pictusfilamentous reds Polysiphonia, Neoptilota, 1 1 1 111111111Crassadoma giganteaMytilus californianusBugulaSponge, tan encrusting 1 1 1 1 1 1 Foliose red algaeSponge, white encrustingHenricia sanguinolente?Zoanthid (Palythoa)Flabellina iodineaHydrozoa colony 1 51 Encruster - yellow Sponge, yellow encrusting 1Barnacle, unidBryozoa, tan branching (colonies)Anthopleura sp Encruster - whiteParastichopus californicusWorm tubes, calcareousBare MetalBryozoa, white branching (colonies)Encruster - greenEncruster - tanEncrusting corallineHippodiplosiaOrthasterias koehleriPoraniopsis inlataSalmacinaUlva 1Worm, Feather Duster
Platform Habitat - Leg A1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica Mytilus spMetridium senileOphiothrix spiculataBalanus nubilusAnthopleura elegantissima (rosy morph)Paracyathus stearnsiTriopha catalinaeMetridium spCorallinaStaurocalyptusTurfCrisia/FilicrisiaOxylebius pictusfilamentous reds Polysiphonia, Neoptilota, Crassadoma giganteaMytilus californianusBugulaSponge, tan encrustingFoliose red algaeSponge, white encrustingHenricia sanguinolente?Zoanthid (Palythoa)Flabellina iodineaHydrozoa colonyEncruster - yellowSponge, yellow encrustingBarnacle, unidBryozoa, tan branching (colonies)Anthopleura spEncruster - whiteParastichopus californicusWorm tubes, calcareousBare MetalBryozoa, white branching (colonies)Encruster - greenEncruster - tanEncrusting corallineHippodiplosiaOrthasterias koehleriPoraniopsis inlataSalmacinaUlvaWorm, Feather Duster

10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 

013habD 012habD 011habD 010habD 009habD 008habD 007habD 006habD 005habD 004habD 003habD 002habD 001habD 

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

19 24 29 30 34 35 37 41 45 46 48 52 56 

700 

3 4 13 7 10 66 66 75 50 50

11 14 4 22 22 22 48 30

5 17 25 7 60 13 73 66 17 10 2 2 3 1 8 75 9 12 11 1 10

5 15 

5 20 10 5

1 

4 20

1 111 1 111 

4 

13 3 3

1 1111

5 6

1 1

1

125

1 11

3

1

1

1

1
Platform Habitat - Leg A1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica Mytilus spMetridium senileOphiothrix spiculataBalanus nubilusAnthopleura elegantissima (rosy morph)Paracyathus stearnsiTriopha catalinaeMetridium spCorallinaStaurocalyptusTurfCrisia/FilicrisiaOxylebius pictusfilamentous reds Polysiphonia, Neoptilota, Crassadoma giganteaMytilus californianusBugulaSponge, tan encrustingFoliose red algaeSponge, white encrustingHenricia sanguinolente?Zoanthid (Palythoa)Flabellina iodineaHydrozoa colonyEncruster - yellowSponge, yellow encrustingBarnacle, unidBryozoa, tan branching (colonies)Anthopleura spEncruster - whiteParastichopus californicusWorm tubes, calcareousBare MetalBryozoa, white branching (colonies)Encruster - greenEncruster - tanEncrusting corallineHippodiplosiaOrthasterias koehleriPoraniopsis inlataSalmacinaUlvaWorm, Feather Duster

? ?

10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/

041hh1520 039hh1519 038hh1518 036hh1516 035hh1516 034hh1516 033hh1515 032hh1513 031hh1513 029hh1511 030hh1512 028hh1509 027hh1507 026h

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A

68 70 72 76 77 78 80 81 83 94 94.1 108 120 1

515 520 680 540 650 640 690 630 650 640 600 475 350 2

3 

15 1 10 5 2 2 1 12 3 1 12 6 

5 1 2 5 3 5 3 6 231 

1 5 12 

2 5 1 0.5 0.5 1 0.5 2 5 

1

2 

1 1 1 1 11111

3 4 1 3 1 13 1

1 21 3 1

11 

1 1 

1 0.5 9

11 1 1

1

1

1

0.5 

1

1
Platform Habitat - Leg A1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica Mytilus spMetridium senileOphiothrix spiculataBalanus nubilusAnthopleura elegantissima (rosy morph)Paracyathus stearnsiTriopha catalinaeMetridium spCorallinaStaurocalyptusTurfCrisia/FilicrisiaOxylebius pictusfilamentous reds Polysiphonia, Neoptilota, Crassadoma giganteaMytilus californianusBugulaSponge, tan encrustingFoliose red algaeSponge, white encrustingHenricia sanguinolente?Zoanthid (Palythoa)Flabellina iodineaHydrozoa colonyEncruster - yellowSponge, yellow encrustingBarnacle, unidBryozoa, tan branching (colonies)Anthopleura spEncruster - whiteParastichopus californicusWorm tubes, calcareousBare MetalBryozoa, white branching (colonies)Encruster - greenEncruster - tanEncrusting corallineHippodiplosiaOrthasterias koehleriPoraniopsis inlataSalmacinaUlvaWorm, Feather Duster

10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 

022hh1502 021hh1501 020hh1500 019hh1459 018hh1459 017hh1456 016hh1456 014hh1454 015hh1455 013hh1453 012hh1452 011hh1452 010hh1451 009hh145

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

152 158 172 175 178 190 192 196 196.1 205 213 217 223 233 365 250 300 345 305 365 405 465 475 302 35

5 18 8 1

28 52 13 15 15 7 21 26 3

10 10 25 10 15 15 10 10 15 5 20 10 2 

1 1 5 20 11 25 14 

56164718451111 111111111

1 1

1 4 3 1 3 2 0.5 1

1

1 11

3 2 1

0.5 2

1
Platform Habitat - Leg A1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica Mytilus spMetridium senileOphiothrix spiculataBalanus nubilusAnthopleura elegantissima (rosy morph)Paracyathus stearnsiTriopha catalinaeMetridium spCorallinaStaurocalyptusTurfCrisia/FilicrisiaOxylebius pictusfilamentous reds Polysiphonia, Neoptilota, Crassadoma giganteaMytilus californianusBugulaSponge, tan encrustingFoliose red algaeSponge, white encrustingHenricia sanguinolente?Zoanthid (Palythoa)Flabellina iodineaHydrozoa colonyEncruster - yellowSponge, yellow encrustingBarnacle, unidBryozoa, tan branching (colonies)Anthopleura spEncruster - whiteParastichopus californicusWorm tubes, calcareousBare MetalBryozoa, white branching (colonies)Encruster - greenEncruster - tanEncrusting corallineHippodiplosiaOrthasterias koehleriPoraniopsis inlataSalmacinaUlvaWorm, Feather Duster

10/12/99 10/12/99 10/12/99 10/12/99

005hh1446 004hh1445 003hh1444 002hh1444

A1 A1 A1 A1 No. of

270 275 279 283 Total Average Photos Occurrence Max Min

14799 448.4545 70 33 700 12

847 32.57692 70 26 80 3594 22.84615 70 26 60 1

1 1 575 14.375 70 40 73 1

483 12.71053 70 38 64 1333 19.58824 70 17 75 1331 20.6875 70 16 53 1

95 324.5 10.81667 70 30 95 0.5

1 2 8 3 107 7.642857 70 14 25 1

53 4.416667 70 12 8 153 6.625 70 8 20 2

1 29 1 70 29 1 1

26 2 70 13 4 124 12 70 2 20 4

23 1 70 23 1 122 2.444444 70 9 5 120 5 70 4 13 1

19.5 1.772727 70 11 4 0.5

14 1 70 14 1 111 5.5 70 2 6 511 1 70 11 1 1

10.5 3.5 70 3 9 0.5

10 1.666667 70 6 3 1

8 2.666667 70 3 5 18 2 70 4 5 1

1 6 1 70 6 1 1

4 1 70 4 1 13 3 70 1 3 3

2.5 1.25 70 2 2 0.5

2 2 70 1 2 22 1 70 2 1 12 1 70 2 1 12 1 70 2 1 11 1 70 1 1 11 1 70 1 1 11 1 70 1 1 1

1 1 1 70 1 1 1

1 0.5 70 2 0.5 0.51 1 70 1 1 11 1 70 1 1 11 1 70 1 1 11 1 70 1 1 11 1 70 1 1 11 1 70 1 1 1
Platform Habitat - Leg A1 %

DATE 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 

PHOTO CODE 021habD 026habD 016habD 020habD 019habD 025habD 018habD 022habD 027habD 024habD 029habD 023habD 028habD 

LEG A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

DEPTH (ft) 4 4.1 4.2 5 6 6.1 7 7.1 7.2 8 8.1 9 9.1 

Corynactis californica (%) 1Mytilus sp (%) 7 15 9 18 60 20 60 18 31 60 44 100 19 Zoanthid (Palythoa) (%)Anthopleura elegantissima (rosy morph) (%) 19 5.5 95 3 33 33 13.5 5 8 filamentous reds Polysiphonia, Neoptilota, 15 50 50 40 10 50 5 40 40 2 40 10 Shadow (%) 33 12 5 5 33 10 15 15Metridium senile % 3 8 16 9 11 15 1 18 4 28 30 6 Ophiothrix spiculata (%) 2 23 30 9 6 7 10 Turf (%)Sponge, tan encrusting (%) 3 2 15 1 1 2 Paracyathus stearnsi (%)Sponge, white encrusting (%)Ulva (%) 2Bare Metal (%)Sponge, yellow encrusting (%) 0.5Encruster - yellow % Encruster - white (%)Encruster - green (%)Encruster - tan (%)
Platform Habitat - Leg A1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)Mytilus sp (%)Zoanthid (Palythoa) (%)Anthopleura elegantissima (rosy morph) (%)filamentous reds Polysiphonia, Neoptilota, Shadow (%)Metridium senile %Ophiothrix spiculata (%)Turf (%)Sponge, tan encrusting (%)Paracyathus stearnsi (%)Sponge, white encrusting (%)Ulva (%)Bare Metal (%)Sponge, yellow encrusting (%)Encruster - yellow %Encruster - white (%)Encruster - green (%)Encruster - tan (%)

10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 10/13/99 

013habD 012habD 011habD 010habD 009habD 008habD 007habD 006habD 005habD 004habD 003habD 002habD 001habD 

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

19 24 29 30 34 35 37 41 45 46 48 52 56 

100 

4 5 16 9 12 82 83 94 80 70

1

10 95 11 15 14 1 1350 40 50 5 3 1 5 2 

6 7 2 11 11 11 5 275 17 25 7 60 13 15 5 1

0.5 

5 15 40 3 10

0.5 2.5

0.5 1 0.5

0.5
Platform Habitat - Leg A1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)Mytilus sp (%)Zoanthid (Palythoa) (%)Anthopleura elegantissima (rosy morph) (%)filamentous reds Polysiphonia, Neoptilota, Shadow (%)Metridium senile %Ophiothrix spiculata (%)Turf (%)Sponge, tan encrusting (%)Paracyathus stearnsi (%)Sponge, white encrusting (%)Ulva (%)Bare Metal (%)Sponge, yellow encrusting (%)Encruster - yellow %Encruster - white (%)Encruster - green (%)Encruster - tan (%)

10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/

041hh1520 039hh1519 038hh1518 036hh1516 035hh1516 034hh1516 033hh1515 032hh1513 031hh1513 029hh1511 030hh1512 028hh1509 027hh1507 026h

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A

68 70 72 76 77 78 80 81 83 94 94.1 108 120 190 90 98 90 95 95 98 95 95 95 90 80 70 

1 0

5 1 2 2 1 1 1 5 2 1 12 12 

2 5 1 0.5 0.5 1 0.5 2 5 

124

0.5 10 

0.5 0.5 0.5 0.5

0.5
Platform Habitat - Leg A1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)Mytilus sp (%)Zoanthid (Palythoa) (%)Anthopleura elegantissima (rosy morph) (%)filamentous reds Polysiphonia, Neoptilota, Shadow (%)Metridium senile %Ophiothrix spiculata (%)Turf (%)Sponge, tan encrusting (%)Paracyathus stearnsi (%)Sponge, white encrusting (%)Ulva (%)Bare Metal (%)Sponge, yellow encrusting (%)Encruster - yellow %Encruster - white (%)Encruster - green (%)Encruster - tan (%)

10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 10/12/99 

022hh1502 021hh1501 020hh1500 019hh1459 018hh1459 017hh1456 016hh1456 014hh1454 015hh1455 013hh1453 012hh1452 011hh1452 010hh1451 009hh145

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

152 158 172 175 178 190 192 196 196.1 205 213 217 223 233 

70 40 50 70 50 65 75 80 80 50 5

3 2 1 

5 18 8 1

10 10 25 10 15 15 10 10 15 5 20 10 2 

1

6 10 10 8 8 5 1 2 3

5 2 10
Platform Habitat - Leg A1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica (%)Mytilus sp (%)Zoanthid (Palythoa) (%)Anthopleura elegantissima (rosy morph) (%)filamentous reds Polysiphonia, Neoptilota, Shadow (%)Metridium senile %Ophiothrix spiculata (%)Turf (%)Sponge, tan encrusting (%)Paracyathus stearnsi (%)Sponge, white encrusting (%)Ulva (%)Bare Metal (%)Sponge, yellow encrusting (%)Encruster - yellow %Encruster - white (%)Encruster - green (%)Encruster - tan (%)

10/12/99 10/12/99 10/12/99 10/12/99

005hh1446 004hh1445 003hh1444 002hh1444

A1 A1 A1 A1 No. of

270 275 279 283 Total Average Photos Occurrence Max Min

2427 73.54545 70 33 100 11055 40.57692 70 26 100 4

99 95 3 355 32.27273 70 11 99 1

391 23 70 17 95 1519 22.56522 70 23 50 1128 16 70 8 33 5

293.5 11.28846 70 26 30 0.5

1 1 431 10.775 70 40 60 1

95 305 10.51724 70 29 95 0.5

111 7.928571 70 14 40 1

83 5.1875 70 16 10 1

51.5 4.681818 70 11 10 0.5

2 2 70 1 2 21 1 70 1 1 1

2.5 0.625 70 4 1 0.5

0.5 3 0.5 70 6 0.5 0.5

1 0.5 70 2 0.5 0.5

0.5 0.5 70 1 0.5 0.5

0.5 0.5 0.5 70 1 0.5 0.5
Platform Irene - Leg A1 counts

DATE 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 1

PHOTO CODE 014irD 030irD 013irD 033irD 016irD 031irD 011irD 019irD 020irD 023irD 032irD 029irD 010irD 018irD 0

LEG A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

DEPTH (ft) 1 1.1 2 2.1 3 3.1 4 4.1 4.2 4.3 4.4 6 8 8.1 

Metridium senile 375 125 165 45 27 150 15 250 350 Mytilus californianus 21 21 35 5 35 28 47 124 105 56 21 42 70 42 Tetraclita squamosa 56 57 7 200 35 50 22 34 10 20 57 50 33 26Balanus sp Anthopleura elegantissima (rosy morph) 17 

Worm tubes, calcareousCorynactis californica, individuals 4 15 10 33 4 9 15 3 7 Ophiothrix spiculata MytilusAnthopleura sp (whitish, no rose) 22Sponge, yellow encrustingPisaster ochraceusMetridium, dark or Feather DusterCancer antennariusMetridium farcimenStrongylocentrotus purpuratus 21 2 Feather Duster WormPollicipes polymerus 1 14Fuzz 11 1 1 Serpulidae (feather duster)Sponge, tan encrustingActiniaria, brownCancer sp ?Lytechinus pictus 1 1Crassadoma giganteafilamentous reds Polysiphonia, Neoptilota, Antithamnion etc # clumps Alga, small red foliose, col count 1Alga, encrusting greenAsterina miniata = Patiria miniataEncruster - whiteEncruster, redEpiactis prolifera ? Hydroid, tan branchingLeucilla nuttingi (colonies)Mytilidae, unidOphiacantha diplasiaSebastes spTunicate, encrusting tanUlva 1
Platform Irene - Leg A1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileMytilus californianusTetraclita squamosaBalanus spAnthopleura elegantissima (rosy morph) Worm tubes, calcareousCorynactis californica, individualsOphiothrix spiculataMytilusAnthopleura sp (whitish, no rose) Sponge, yellow encrustingPisaster ochraceusMetridium, dark or Feather DusterCancer antennariusMetridium farcimenStrongylocentrotus purpuratusFeather Duster WormPollicipes polymerusFuzzSerpulidae (feather duster)Sponge, tan encrustingActiniaria, brownCancer sp?Lytechinus pictusCrassadoma giganteafilamentous reds Polysiphonia, Neoptilota, Antithamnion etc # clumpsAlga, small red foliose, col countAlga, encrusting greenAsterina miniata = Patiria miniataEncruster - whiteEncruster, redEpiactis prolifera ?Hydroid, tan branchingLeucilla nuttingi (colonies)Mytilidae, unidOphiacantha diplasiaSebastes spTunicate, encrusting tanUlva

11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 1

004irD 003irD 002irD 045ir1127 044ir1126 043ir1126 042ir1125 041ir1125 039ir1124 040ir1124 038ir1124 037ir1123 036ir1122 035ir1122 03

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

14 15 17 19 21 23 24 25 27 27.1 28 31 38 39 

300 350 300 400 380 330 375 370 380 380 425 250 200 250 

56 42 56 28 35 47 35 35 35 35 65 70 

7 8

14 1 

5 1 10 10 13 25 11 14 15 

3 3523 3

2 

1 

11221121

1 2

1

3 2 3

11

1 

1

1
Platform Irene - Leg A1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileMytilus californianusTetraclita squamosaBalanus spAnthopleura elegantissima (rosy morph) Worm tubes, calcareousCorynactis californica, individualsOphiothrix spiculataMytilusAnthopleura sp (whitish, no rose) Sponge, yellow encrustingPisaster ochraceusMetridium, dark or Feather DusterCancer antennariusMetridium farcimenStrongylocentrotus purpuratusFeather Duster WormPollicipes polymerusFuzzSerpulidae (feather duster)Sponge, tan encrustingActiniaria, brownCancer sp?Lytechinus pictusCrassadoma giganteafilamentous reds Polysiphonia, Neoptilota, Antithamnion etc # clumpsAlga, small red foliose, col countAlga, encrusting greenAsterina miniata = Patiria miniataEncruster - whiteEncruster, redEpiactis prolifera ?Hydroid, tan branchingLeucilla nuttingi (colonies)Mytilidae, unidOphiacantha diplasiaSebastes spTunicate, encrusting tanUlva

11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 1

030ir1120 029ir1119 028ir1119 027ir1119 025ir1118 026ir1119 024ir1118 023ir1118 022ir1117 021ir1117 020ir1117 019ir1115 017ir1112 016ir1109 01

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

49 51 55 58 62 62.1 65 68 71 75 79 98 115 131 

500 510 430 375 400 390 425 430 430 330 370 400 400 370 

13 11

4 6 9 17 14 22 16 34 15 7 4 2

3 6 24

1 111111 

1 13

3 2 1 13

5

1

1

1

1
Platform Irene - Leg A1 counts

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senileMytilus californianusTetraclita squamosaBalanus spAnthopleura elegantissima (rosy morph) Worm tubes, calcareousCorynactis californica, individualsOphiothrix spiculataMytilusAnthopleura sp (whitish, no rose) Sponge, yellow encrustingPisaster ochraceusMetridium, dark or Feather DusterCancer antennariusMetridium farcimenStrongylocentrotus purpuratusFeather Duster WormPollicipes polymerusFuzzSerpulidae (feather duster)Sponge, tan encrustingActiniaria, brownCancer sp?Lytechinus pictusCrassadoma giganteafilamentous reds Polysiphonia, Neoptilota, Antithamnion etc # clumpsAlga, small red foliose, col countAlga, encrusting greenAsterina miniata = Patiria miniataEncruster - whiteEncruster, redEpiactis prolifera ?Hydroid, tan branchingLeucilla nuttingi (colonies)Mytilidae, unidOphiacantha diplasiaSebastes spTunicate, encrusting tanUlva

11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00

010ir1104 009ir1103 008ir1101 007ir1100 006ir1057 004ir1056 005ir1056 003ir1054 002ir1052 001ir1049

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 No. of

173 179 182 189 201 206 206.1 215 221 232 Total Average Photos Occurrence 400 395 390 385 450 425 450 420 250 25 19522 330.8814 64 59 

1401 42.45455 64 33 

672 42 64 16 190 10 64 19 129 10.75 64 12 

100 103 51.5 64 2 

101 10.1 64 10 

36 4 64 9 23 3.833333 64 6 22 22 64 1 

1 1 1 1 1 1 1 19 1 64 19 

1 3 15 1.5 64 10 

14 7 64 2 13 1.857143 64 7 

12 12 12 64 1 

10 2 64 5 

8 2.666667 64 3 6 2 64 3 5 1 64 5 5 5 64 1 

1 5 1 64 5 

4 2 64 2 3 1 64 3 2 1 64 2 2 1 64 2 2 1 64 2 2 1 64 2 1 1 64 1 

1 1 1 64 1 

1 1 64 1 1 1 64 1 1 1 64 1 1 1 64 1 

1 1 1 64 1 

1 1 64 1 1 1 64 1 

1 1 1 64 1 

1 1 64 1 1 1 64 1 
Platform Irene - Leg A1 %

DATE 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 1

PHOTO CODE 014irD 030irD 013irD 033irD 016irD 031irD 011irD 019irD 020irD 023irD 032irD 029irD 010irD 018irD 0

LEG A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

DEPTH (ft) 1 1.1 2 2.1 3 3.1 4 4.1 4.2 4.3 4.4 6 8 8.1 

Metridium senile % 75 25 33 15 5 30 3 50 70 Tunicate, encrusting tan %Tetraclita squamosa % 85 85 10 90 50 75 33 50 15 30 85 60 50 43Sponge, tan encrusting (%)Mytilus californianus % 15 15 25 10 25 20 33 85 75 40 15 30 50 30 Worm tubes, calcareous (%)Sponge, gray encrusting % 

Fuzz % 5 10 10 1 Alga, encrusting green (%)Anthopleura elegantissima (rosy morph) % 7 

Sponge, yellow encrusting (%)Ulva % 3Encruster, red %Encruster - white (%)Hydroid, tan branching %Leucilla nuttingi (colonies) (%)cable %
Platform Irene - Leg A1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senile %Tunicate, encrusting tan %Tetraclita squamosa %Sponge, tan encrusting (%)Mytilus californianus %Worm tubes, calcareous (%)Sponge, gray encrusting %Fuzz %Alga, encrusting green (%)Anthopleura elegantissima (rosy morph) %Sponge, yellow encrusting (%)Ulva %Encruster, red %Encruster - white (%)Hydroid, tan branching %Leucilla nuttingi (colonies) (%)cable %

11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 1

004irD 003irD 002irD 045ir1127 044ir1126 043ir1126 042ir1125 041ir1125 039ir1124 040ir1124 038ir1124 037ir1123 036ir1122 035ir1122 03

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

14 15 17 19 21 23 24 25 27 27.1 28 31 38 39 60 70 60 80 75 66 75 75 75 75 85 50 40 50 

50

10 10

1 50 

40 30 40 20 25 33 25 25 25 25 20 50 

2 0.5 3 3 4 10 4 5 5 

0.1 
Platform Irene - Leg A1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senile %Tunicate, encrusting tan %Tetraclita squamosa %Sponge, tan encrusting (%)Mytilus californianus %Worm tubes, calcareous (%)Sponge, gray encrusting %Fuzz %Alga, encrusting green (%)Anthopleura elegantissima (rosy morph) %Sponge, yellow encrusting (%)Ulva %Encruster, red %Encruster - white (%)Hydroid, tan branching %Leucilla nuttingi (colonies) (%)cable %

11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 1

030ir1120 029ir1119 028ir1119 027ir1119 025ir1118 026ir1119 024ir1118 023ir1118 022ir1117 021ir1117 020ir1117 019ir1115 017ir1112 016ir1109 01

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 

49 51 55 58 62 62.1 65 68 71 75 79 98 115 131 90 90 86 75 80 80 85 85 85 66 75 80 80 75 

9 8

10 5 15 10 20 20 15 15 15 30 25 15 20 25 

15 0.1 3 1 5 1 1 

1

1
Platform Irene - Leg A1 %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Metridium senile %Tunicate, encrusting tan %Tetraclita squamosa %Sponge, tan encrusting (%)Mytilus californianus %Worm tubes, calcareous (%)Sponge, gray encrusting %Fuzz %Alga, encrusting green (%)Anthopleura elegantissima (rosy morph) %Sponge, yellow encrusting (%)Ulva %Encruster, red %Encruster - white (%)Hydroid, tan branching %Leucilla nuttingi (colonies) (%)cable %

11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00 11/4/00

010ir1104 009ir1103 008ir1101 007ir1100 006ir1057 004ir1056 005ir1056 003ir1054 002ir1052 001ir1049

A1 A1 A1 A1 A1 A1 A1 A1 A1 A1 No. of

173 179 182 189 201 206 206.1 215 221 232 Total Average Photos Occurrence 

80 80 80 80 90 85 90 85 50 5 3894 66 64 59 

50 50 64 1 

781 48.8125 64 16 

1 162 32.4 64 5 

975 29.54545 64 33 

50 51 25.5 64 2 

15 2 10 419 17.45833 64 24 

51 10.2 64 5 10 10 64 1 

 46.5 3.875 64 12 

1 10 15 2 2 2 3 63.4 3.336842 64 19 

3 3 64 1 1 1 64 1 1 1 64 1 1 1 64 1 

1 1 1 64 1 

1 1 1 64 1 
Diablo Rock and Nifty Rock - counts

DATE 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/9

PHOTO CODE 014drD 019drD 021drD 011drD 023drD 025drD 029drD 003drD2 006drD 031drD 033drD 035drD 012drD

LEG D frame D no frame D frame D frame D frame D frame D frame D frame D frame D frame D frame D no frame D frame 

DEPTH (ft) 25 25.1 25.2 35 35.1 35.2 35.3 40 45 45.1 45.2 45.3 45.4 

Corynactis californica, individuals 10 25 50 250 50 100 165 125 250 Chthalamus sp. 4 3 47 Balanus sp 60 2 5Anthopleura xanthogrammica 24 3 7 1Ophiothrix spiculata 21 

Mytilus californianus 31 10 4Anthopleura elegantissima (rosy morph) 30 7Metridium senileBalanophylliaBossiella sp. 131 1Strongylocentrotus purpuratus 2 5 2 1 2 1 2 1Dendrochirotida 15 4 Halocynthia igaboja 19 3Paracyathus stearnsiAnthopleura sp. 15 1 1

Alga, encrusting (Lithothamnion) 1 1 1 1 1 1Ophiuroid unid 1 11 

Strongylocentrotus franciscanus 1 61Tube worm, single fan 1 14Worm tubes, calcareous 2 6Alga, green clump (Codium-like) Tube worm, double spiral 2 4Turf 1Bryozoa, Staghorn, yellow 1 Urticina 3 Alga, green clump 2 1Parastichopus californicus Hydrozoa tan clumpAlga, brown, bladesFlabellina iodinea 1Henricia leviuscula 1 1Tunicate, solitary ? Algae, brown, clump Algae/Hydrozoa mix

Cypraea spadiceaDorid, white 1Serpulorbis 1Sponge, gray encrusting 1Sponge, orange encrusting Sponge, Orange roundSponge, unid 1Sponge, white finger 1Tunicate, globular 1Worm tubes, plain 1
Diablo Rock and Nifty Rock - count

DATE

PHOTO CODE

LEG

DEPTH (ft)

Corynactis californica, individualsChthalamus sp. Balanus spAnthopleura xanthogrammicaOphiothrix spiculataMytilus californianusAnthopleura elegantissima (rosy morph)Metridium senileBalanophylliaBossiella sp.Strongylocentrotus purpuratusDendrochirotidaHalocynthia igabojaParacyathus stearnsiAnthopleura sp.Alga, encrusting (Lithothamnion)Ophiuroid unidStrongylocentrotus franciscanusTube worm, single fanWorm tubes, calcareousAlga, green clump (Codium-like)Tube worm, double spiralTurfBryozoa, Staghorn, yellowUrticinaAlga, green clumpParastichopus californicusHydrozoa tan clumpAlga, brown, bladesFlabellina iodineaHenricia leviuscula Tunicate, solitary? Algae, brown, clumpAlgae/Hydrozoa mixCypraea spadiceaDorid, whiteSerpulorbisSponge, gray encrustingSponge, orange encrustingSponge, Orange roundSponge, unidSponge, white fingerTunicate, globularWorm tubes, plain

10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98

034nrD2 029nrD2 027nrD2 024nrD2 020nrD2 017nrD2

N no frame N no frame N no frame N no frame N no frame N no frame No. of

15 25 35 45 50 55 Total Average Photos Occurrence Max Min

375 50 250 250 1982 132.1333 22 15 375 2

4 4 3 180 20 22 9 54 3

67 22.33333 22 3 60 2

25 60 12 22 5 25 1

52 26 22 2 31 2145 15 22 3 31 437 18.5 22 2 30 7

33 33 33 22 1 33 33

31 31 31 22 1 31 31

10 10 26 4.333333 22 6 10 1

1 25 2.272727 22 11 7 1

24 8 22 3 15 4

2 24 8 22 3 19 2

1 21 22 11 22 2 21 1

17 5.666667 22 3 15 1

1 1 1 1 1 14 1 22 14 1 1

1 14 3.5 22 4 11 1

1 1 10 2 22 5 6 1

4 10 2.5 22 4 4 1

8 4 22 2 6 2

1 6 3 22 2 5 1

6 3 22 2 4 2

1 1 1 1 1 6 1 22 6 1 1

1 1 1 5 1 22 5 1 1

5 2.5 22 2 3 24 1.333333 22 3 2 14 4 22 1 4 4

1 2 3 1.5 22 2 2 1

1 1 2 1 22 2 1 1

1 2 1 22 2 1 1

2 1 22 2 1 12 2 22 1 2 21 1 22 1 1 1

1 1 1 22 1 1 1

1 1 1 22 1 1 1

1 1 22 1 1 11 1 22 1 1 11 1 22 1 1 11 1 22 1 1 1

1 1 1 22 1 1 1

1 1 22 1 1 11 1 22 1 1 11 1 22 1 1 11 1 22 1 1 1
Diablo Rock and Nifty Rock %

DATE 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/9

PHOTO CODE 014drD 019drD 021drD 011drD 023drD 025drD 029drD 003drD2 006drD 031drD 033drD 035drD 012drD

LEG D frame D no frame D frame D frame D frame D frame D frame D frame D frame D frame D frame D no frame D frame 

DEPTH (ft) 25 25.1 25.2 35 35.1 35.2 35.3 40 45 45.1 45.2 45.3 45.4 

Sponge, unid (%) 50Encruster, all (%) 2 50 50Chthalamus sp. (%) 3 2 70 Corynactis californica (%) 2 5 10 50 10 20 33 25 50 filamentous reds Polysiphonia, Neoptilota, Antithamnion etc (%) 10 20 1 75 40 20 10 7 40 66 Alga, encrusting (Lithothamnion) % 10 5 10 60 0.5 5 Balanus sp (%) 60 2 2Foliose red algae (%) 20Turf (%) 10Alga, green clump (Codium-like) % Ophiothrix spiculata (%) 20 5Shadow (%) 10 

Bryozoa, Staghorn, yellow (%) 20 Foliose brown algae (%) 5 5Ophiuroid unid (%) 5 5Algae/Hydrozoa mix (%)Codium (%) 5Bossiella sp. (%) 0.5 3 1 1Alga, green foliose (%) 3Encruster - white (%) 2 5Anthopleura elegantissima (rosy morph) % 2 0.5Alga, brown, blades (%)Rock, bare (%) 1Sponge, orange encrusting % Sponge, white finger (%) 1Encruster, green % 0.5Sponge, gray encrusting % 0.5Ulva (%) 0.1 0.1 1Encruster, red %
Diablo Rock and Nifty Rock %

DATE

PHOTO CODE

LEG

DEPTH (ft)

Sponge, unid (%)Encruster, all (%)Chthalamus sp. (%)Corynactis californica (%)filamentous reds Polysiphonia, Neoptilota, Antithamnion etc (%)Alga, encrusting (Lithothamnion) %Balanus sp (%)Foliose red algae (%)Turf (%)Alga, green clump (Codium-like) %Ophiothrix spiculata (%)Shadow (%)Bryozoa, Staghorn, yellow (%)Foliose brown algae (%)Ophiuroid unid (%)Algae/Hydrozoa mix (%)Codium (%)Bossiella sp. (%)Alga, green foliose (%)Encruster - white (%)Anthopleura elegantissima (rosy morph) %Alga, brown, blades (%)Rock, bare (%)Sponge, orange encrusting %Sponge, white finger (%)Encruster, green %Sponge, gray encrusting %Ulva (%)Encruster, red %

10/11/98 10/11/98 10/11/98 10/11/98 10/11/98 10/11/98

034nrD2 029nrD2 027nrD2 024nrD2 020nrD2 017nrD2

N no frame N no frame N no frame N no frame N no frame N no frame No. of

15 25 35 45 50 55 Total Average Photos Occurrence Max Min

50 50 22 1 50 50

102 34 22 3 50 2

5 5 2 257 28.55556 22 9 80 2

75 10 50 50 396.5 26.43333 22 15 75 0.5

2 1 10 3 370 21.76471 22 17 75 1

40 20 10 10 50 300.5 21.46429 22 14 60 0.5

64 21.33333 22 3 60 220 20 22 1 20 20

5 15 30 15 30 105 17.5 22 6 30 5

5 25 12.5 22 2 20 5

25 12.5 22 2 20 5

5 15 45 11.25 22 4 15 5

10 10 5 45.5 9.1 22 5 20 0.5

10 5 22 2 5 510 5 22 2 5 5

5 5 5 22 1 5 5

5 5 22 1 5 5

10 10 25.5 4.25 22 6 10 0.5

5 8 4 22 2 5 3

0.1 2 9.1 2.275 22 4 5 0.1

2.5 1.25 22 2 2 0.5

1 1 2 1 22 2 1 1

1 1 22 1 1 11 1 22 1 1 11 1 22 1 1 1

1 0.1 1.6 0.533333 22 3 1 0.1

0.5 0.5 22 1 0.5 0.51.2 0.4 22 3 1 0.1

0.1 0.1 0.1 22 1 0.1 0.1
Appendix D 

Scraping Data – Platforms Harvest and Gail 

D-1
Appendix D has been organized into eight primary sections: 

 Table D-1 – this two-page table summarizes the taxa identified during scraping analysis 

at both platforms Gail and Harvest. 

 Platform Harvest, Taxa vs. Station (quadrat) Matrix – this five-page table summarizes 

the relative abundance of identified taxa from Harvest scraping samples. Taxa are 

organized by abundance (i.e., highest mean abundance) and frequency of occurrence. 

 Platform Harvest, Taxa by Individual Station – this 17-page table lists all identifiable 

taxa and their relative abundance, by station (quadrat). 

 Platform Harvest, Scraping Weight Summary – this two-page table summarizes total 

sample weight, mussel weight, non-mussel weight, and percent mussel (by weight) for 

each sample collected at Platform Harvest. 

 Platform Harvest, Mussel Measurements – this 20-page table summarizes individual 

length, width, and height measurements and weights for the mussels collected from 

Platform Harvest. 

 Platform Harvest, Mussel Measurement Statistics – this five-page table summarizes 

basic statistics (e.g., mean, mode, standard deviation) for the mussels collected from 

individual quadrats at Platform Harvest. 

 Platform Gail, Taxa vs. Station (quadrat) Matrix – this two-page table summarizes the 

relative abundance of identified taxa from Gail scraping samples. Taxa are organized by 

abundance (i.e., highest mean abundance) and frequency of occurrence. 

 Platform Gail, Taxa by Individual Station – this 16-page table lists all identifiable taxa 

and their relative abundance, by station (quadrat). 

D-3
Table D-1. Taxa identified during the analysis of scraping samples from the intertidal, barnacle, and m

platforms Gail and Harvest. Taxa common to both platforms denoted in bold. 

FLORA:  Algae: 

Acrosorium venulosum Antithamnion hubbsii Branchioglossum bipinnatifidum Callophyllis spp. Ceramium camouii Delesseriaceae, unidentified Heterosiphonia japonica? 1

Membranoptera multiramosa 2

Polysiphonia scopularum Pterosiphonia dendroidea 

 Pugetia fragillissima 

Pugetia spp. (juvenile) Rhodymenia californica Rhodymenia pacifica

FAUNA:  Crustaceans:  Barnacles (Cirripedia): 

Balanus nubilus Balanus spp. (juvenile) Balanus trigonus Megabalanus californicus Tetraclita rubescens

 Caprellid amphipods: 

Caprella alaskana Caprella equilibra Caprella ferrea Caprella verrucosa 

Gammarid amphipods: 

Aoroides spp. Dulichiella appendiculata Elasmopus cf. holgurus Elasmopus holgurus Ericthonius brasiliensis Gammaropsis thompsoni 

 Gammarid amphipods, continued: 

Janiralata occidentalis Jassa slatteryi Leucothoe alata Monocorophium spp.

Parapleustes pugettensis Podocerus brasiliensis Quadrimaera reishi 

cf. Sinocorophium spp. 

Stenothoe estacola 

 Crabs (Brachyura, Cancridea): 

Cancer branneri Cancer jordani Cancer productus Cancer spp. (juvenile)

Maera simile Pachycheles pubescens Pachycheles rudis Pachygrapsus crassipes Paraxanthias taylori Pilumnus spinohirsutus Podocerus brasiliensis Scyra acutifrons 

 Isopods (Isopoda): 

Janiropsis tridens 

 Sea spiders (Pycnogonida): 

Anoplodactylus nodosus Pycnogonida, unidentified (juvenile) Pycnogonum stearnsi

 Mysids (Mysidacea): 

Mysidacea, unidentified (fragment) 

Echinoderms:  Brittle stars (Ophiuroidea): 

Ophiactis simplex Ophiopteris papillosa Ophiothrix spiculata Ophiuroidea, unidentified (juvenile) 

 Holothuroids (Holot

HolothuroideaHolothuroideaParastichopus cPentamera lisso

 Urchins (Echinoidea

Echinoidea, unLytechinus pictuStrongylocentro

Mollusks:  Bivalves (Pelecypod

Anomia peruviaChama arcana Crassadoma giCrassostrea gigaGregariella chenGregariella coar

Hiatella arcticIrus lamellifer Kellia suborbicLithophaga pluModiolus capaMya arenaria 

Musculus (=Mu

Mytilus californMytilus spp. Mytilus spp. (juMytilus trossuluOstrea conchaphPetricola spp. (j

Pododesmus cePseudochama ex

 Gastropods (Gastrop

Amphissa reticuAmphissa versic

Anisodoris nobilDoridacea, uni

Iselica ovoidea 
Table D-1. Taxa identified during the analysis of scraping samples from the intertidal, barnacle, and m

Platforms Gail and Harvest. Taxa common to both platforms denoted in bold (continued). 

 Gastropods (continued): 

Iselica spp. 

Seila montereyensis

Tritonia diomedea

Chitons (Polyplacaphores): 

Mopalia porifera

Polychaetes: 

Arabella iricolor Arabella semimaculata Brania spp. Cirratulus, unidentified Dodecaceria concharum Dodecaceria fewkesi Dodecaceria, unidentified Eudistylia polymorpha Halosydna brevisetosa Halosydna johnsoni Harmothoe ? hirsuta Harmothoe spp. 

Lepidonotus spiculus Myxicola spp.Naineris dendritica Nereis eakini Nereis mendocinana Nereis pelagica neonigripes Paleanotus bellis Pholoides asperus Phyllochaetopterus prolifica Phyllodoce medipapillata Phyllodoce spp.Polydora spp. Proceraea cf. kiiensis Proceraea spp. Sabellidae, unidentified Serpula columbiana Spirobranchus spinosus Syllidae, unidentified Syllis gracilis 

Polychaetes (continued): 

Trypanosyllis spp. Typosyllis spp. 

Cnidarians:  Anthozoans (Actiniaria): 

Actiniidae, unidentified Anthopleura elegantissima (rosy morph) Anthopleura elegantissima Corynactis californica Diadumene cincta Metridium exilis Metridium senile

 Hydrozoans: 

Campanularia spp.

Campanulariidae, unidentified Eucopella everta Filellum serpens Halecium spp. Halecium tenellum Lafoea adnata Obelia geniculata Obelia nr. surcularis Obelia plicata Obelia spp. Plumularia alicia Plumularia alicia complex 

Plumularia nr. septata 

Plumularia spp. Sertularella tenellaSyncoryne eximia 

Minor Phyla:  Bryozoans (Ectoprocta or Bryozoa): 

Callopora spp. Celleporella spp. Celleporina spp. Costazia spp. Crisia spp. Cyclostomata, unidentified 

 Bryozoans, continue

Ectoprocta, unFilicrisia spp. Scrupocellaria sTegella spp. 

 Flatworms (Platyhel

Rhabdocoela, uStylochoplana loStylochus spp. 

 Nemerteans (Nemer

Amphiporus sppCarinoma mutabLineus rubescenNemertea, uniParanemertes ca

Tetrastemma s

 Sipunculids (Sipunc

Phascolosoma 

 Sponges (Porifera): 

Haplosclerida nPorifera sp. A Porifera, unideRhabdodermella 

 Tunicates (Urochord

Aplidium spp. Aplousobranch

unidentifie

Styela coriacea Styela truncata Tunicate, unid

Total: 181 taxonomic e

monospecific ta

Footnotes: 1 - Heterosiph

Heterosiphonia densiuscu(2004); 2 – Membranopte

= Membranoptera platylGardner) Kylin, per Mi
PLATFORM HARVEST - Taxa vs. All Stations/Quadrats

Species or Taxon

HA-B1-B-47

HA-B1-B-54

HA-B1-B-78

HA-B1-B-79

HA-B1-M-18

HA-B1-M-20

HA-B1-M-24

HA-B1-M-25

HA-B1-M-28

HA-B1-M-30

HA-B1-M-32

HA-B1-M-40

HA-B2-B-47

HA-B2-B-50

HA-B2-B-60

HA-B2-M-11

HA-B2-M-13

HA-B2-M-14 

HA-B2-M-15

HA-B2-M-17

HA-B2-M-19

Ophiothrix spiculata 1 1 1 1 1 2 1 1 1 3 1 1 1 1 1 1 1 1 1 1 1 

Rhodymenia californica 2 1 2 2 1 1 1 1 1 1 1 1 Mytilus spp. 2 1 

Membranoptera multiramosa 1 2 2 1 2 Caprella alaskana 2 2 3 2 1 1 2 2 2 1 2 2 2 2 2 1 1 1 1 1 1 

Megabalanus californicus 3 3 2 1 1 1 2 3 1 1 3 3 2 1 1 2 1 1 1 Mytilus californianus 1 3 3 3 3 2 3 3 3 3 1 1 1 1 1 1 Halosydna brevisetosa 3 2 2 2 2 2 2 1 3 3 2 3 1 1 2 1 1 1 Anthopleura elegantissima 2 Pugetia fragillissima 2 2 Rhodymenia pacifica 2 2 Metridium senile 1 1 1 1 1 2 3 3 3 2 2 2 3 2 3 1 2 1 1 3 3 Elasmopus cf hologurus 2 1 2 1 2 2 2 2 2 2 2 2 2 3 2 2 2 2 2 2 2 Phyllochaetopterus prolifica 3 1 1 3 2 3 2 1 1 2 3 2 3 1 3 3 2 3 Syllis gracilis 3 3 1 1 3 2 2 3 3 3 1 1 1 2 1 3 3 3 3 Jassa slatteryi 3 2 2 2 2 2 2 3 3 2 2 2 2 2 2 2 2 2 3 3 Maera simile 2 2 2 2 3 2 2 2 3 3 3 2 2 2 2 2 2 2 2 3 3 Pycnogonum stearnsi 2 3 3 3 2 2 2 2 3 2 3 2 2 3 2 3 2 2 2 2 2 Celleporina sp 2 3 

Typosyllis spp. 3 3 3 3 3 1 3 3 2 3 1 

Caprella equlibra 3 2 3 2 Cirratulus unidentified 2 3 3 Corynactis californica 2 3 3 Tetraclita rubescens 2 3 3 Porifera sp A 1 1 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 Caprella verrucosa 3 2 3 2 3 2 2 3 3 3 3 2 3 3 

Balanus nubilus 3 3 3 2 3 3 3 3 3 3 3 2 2 2 3 3 2 3 Polydora sp. 3 3 3 2 

Podocerus brasiliensis 3 3 2 3 3 2 3 3 3 3 3 2 3 3 3 2 3 Stenothoe estacola 333323 3 3 3 3 3 2 2 2 3 3 3 

Hiatella arctica 3 3 3 3 3 1 3 3 3 3 3 3 3 3 3 1 3 3 3 3 3 
PLATFORM HARVEST - Taxa vs. All Stations/Quadrats

Species or Taxon

HA-B1-B-47

HA-B1-B-54

HA-B1-B-78

HA-B1-B-79

HA-B1-M-18

HA-B1-M-20

HA-B1-M-24

HA-B1-M-25

HA-B1-M-28

HA-B1-M-30

HA-B1-M-32

HA-B1-M-40

HA-B2-B-47

HA-B2-B-50

HA-B2-B-60

HA-B2-M-11

HA-B2-M-13

HA-B2-M-14 

HA-B2-M-15

HA-B2-M-17

HA-B2-M-19

Erichthonius brasiliensis 3332 33 

Anthopleura elegantissima (rosy form) 2 33333 

Pododesmus cepio 3 3 2 3 2 3 3 3 3 3 3 3 3 3 

Obelia geniculata 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

Pseudochama exogyra 3 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 Halosydna johnsoni 23 3 33 3333 

Balanus trigonus 3 3 2 3 3 3 3 3 3 3 Phyllodoce medipapillata 2 3 3 3 3 3 3 3 3 3 3 

Filicrisia sp 3 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Phascolosoma agassizi 2 3 3 3 3 3 3 3 3 3 3 3 3 

Actiniidae , juv 3 

Amphiporus sp 3 

Anomia peruviana Anoplodactylus nodosus 3 Arabella semimaculata 3 Balanus sp juv 3 

Brania sp. 3 

Cancer branneri 3 Cancer jordani 3 Cancer productus 3 Costazia sp 3 

Crisia sp Dodecaceria fewkesi 3 Dodecaceria unidentified 3 

Echinoidea juv 3 Ectoprocta, unidentified 3 Eucopella everta 3 Eudistylia polymorpha 3 Family Delesseriaceae 3 Gregariella chenui 3 

Halecium tenellum 3 
PLATFORM HARVEST - Taxa vs. All Stations/Quadrats

Species or Taxon

HA-B1-B-47

HA-B1-B-54

HA-B1-B-78

HA-B1-B-79

HA-B1-M-18

HA-B1-M-20

HA-B1-M-24

HA-B1-M-25

HA-B1-M-28

HA-B1-M-30

HA-B1-M-32

HA-B1-M-40

HA-B2-B-47

HA-B2-B-50

HA-B2-B-60

HA-B2-M-11

HA-B2-M-13

HA-B2-M-14 

HA-B2-M-15

HA-B2-M-17

HA-B2-M-19

Holothuroid, unid 3 Irus lamellifera 3 Lafoea adnata 3 Mopalia porifera Mya arenaria 3 Mytilus spp juv 3 

Myxicola sp. 3 

Nemertea 3 Nemertea unid 3 Obelia sp 3 

Paranemertes californica 3 Pentamera lissoplaca 3 Petricola sp juv 3 Pholoides asperus 3 Plumularia alicia complex 3 Plumularia nr septata 3 Porifera 3 Rhabdodermella nuttingi 3 Sabellidae unidentified 3 Scrupocellaria sp 3 

Sertularella tenella 3 Tetrastemma signifer 3 Tritonia diomedea 3 Tunicate 3 Aoroides sp 3 3 

Caprella ferrea 3 3 Carinoma mutabilis 3 3 Ectoprocta 3 3 Iselica ovoidea 3 3 Paleanotus bellis 3 3 Parastichopus californicus 3 3 
PLATFORM HARVEST - Taxa vs. All Stations/Quadrats

Species or Taxon

HA-B1-B-47

HA-B1-B-54

HA-B1-B-78

HA-B1-B-79

HA-B1-M-18

HA-B1-M-20

HA-B1-M-24

HA-B1-M-25

HA-B1-M-28

HA-B1-M-30

HA-B1-M-32

HA-B1-M-40

HA-B2-B-47

HA-B2-B-50

HA-B2-B-60

HA-B2-M-11

HA-B2-M-13

HA-B2-M-14 

HA-B2-M-15

HA-B2-M-17

HA-B2-M-19

Plumularia alicia 3 3 

Plumularia sp 3 3 

Proceraea cf. kiiensis 3 3 

Rhabdocoela 3 3 Serpula columbiana 3 3 Styela coriacea 3 3 Tegella sp. 3 

Amphissa versicolor 3 3 Chama arcana 3 3 3 Crassadoma gigantea 3 3 3 Janiralata occidentalis 3 3 3 Mytilus trossulus/gallo 3 3 3 Nereis eakini 3 3 3 Styela truncata 3 3 Stylochoplana longipenis 3 3 3 Stylochus spp 3 3 3 

Anisodoris nobilis 3 3 3 3 Campanularia sp 3 3 3 Pachycheles pubescens 3 3 3 3 Scyra acutifrons 3 3 3 3 Lepidonotus spiculus 3 3 3 3 3 Paraxanthias taylori 3 3333 

Campanulariidae 3 3 3 3 3 Cancer sp juv 3 3 3 3 3 3 

Halecium sp 33333 

Lithophaga plumula 3 3 3 3 3 3 Spirobranchus spinosus 3 3 3 3 3 3 Callopora sp 3 3 3 3 3 3 

Cyclostomata 3 33333 

Ophiopteris papillosa 3333333 

Syncoryne eximia 3 3 3 3 3 3 3 
PLATFORM HARVEST - Taxa vs. All Stations/Quadrats

Species or Taxon

HA-B1-B-47

HA-B1-B-54

HA-B1-B-78

HA-B1-B-79

HA-B1-M-18

HA-B1-M-20

HA-B1-M-24

HA-B1-M-25

HA-B1-M-28

HA-B1-M-30

HA-B1-M-32

HA-B1-M-40

HA-B2-B-47

HA-B2-B-50

HA-B2-B-60

HA-B2-M-11

HA-B2-M-13

HA-B2-M-14 

HA-B2-M-15

HA-B2-M-17

HA-B2-M-19

Modiolus capax 3 3 3 3 3 3 Celleporella sp 3 3 3 3 3 3 3 3 3 3 

Filellum serpens 3 3 3 3 3 3 3 3 

Pachycheles rudis 3 3 3 3 3 3 3 3 3 3 3 3 3 3 

Nereis pelagica neonigripes 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Kellia suborbicularis 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Count: 18 25 28 36 32 36 33 37 32 25 36 29 34 32 37 63 51 46 54 37 41 
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B1-B-47 Membranoptera multiramosa 1 Key:

Metridium senile 1 1 = abundant

Ophiothrix spiculata 1 2 = moderately

Porifera sp A 1 abundant

Caprella alaskana 2 3 = limited, sparse

Elasmopus cf hologurus 2

Maera simile 2

Pycnogonum stearnsi 2

Balanus nubilus 3

Erichthonius brasiliensis 3

Filicrisia sp 3

Halosydna brevisetosa 3

Hiatella arctica 3

Pachycheles rudis 3

Pholoides asperus 3

Pododesmus cepio 3

Pseudochama exogyra 3

Syllis gracilis 3

HA-B1-B-54 Elasmopus cf hologurus 1

Metridium senile 1

Ophiothrix spiculata 1

Porifera sp A 1

Caprella alaskana 2

Celleporina sp 2

Corynactis californica 2

Filicrisia sp 2

Maera simile 2

Pugetia fragillissima 2

Rhodymenia californica 2

Balanus nubilus 3

Balanus trigonus 3

Erichthonius brasiliensis 3

Hiatella arctica 3

Jassa slatteryi 3

Kellia suborbicularis 3

Megabalanus californicus 3

Nereis pelagica neonigripes 3

Phyllochaetopterus prolifica 3

Podocerus brasiliensis 3

Pododesmus cepio 3

Pycnogonum stearnsi 3

Stenothoe estacola 3

Syllis gracilis 3

HA-B1-B-78 Metridium senile 1

Ophiothrix spiculata 1

Phyllochaetopterus prolifica 1

Syllis gracilis 1

Cirratulus unidentified 2

D-11
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B1-B-78 Elasmopus cf hologurus 2

(continued) Filicrisia sp 2

Halosydna brevisetosa 2

Halosydna johnsoni 2

Jassa slatteryi 2

Maera simile 2

Obelia geniculata 2

Phascolosoma agassizi 2

Phyllodoce medipapillata 2

Pododesmus cepio 2

Porifera sp A 2

Aoroides sp 3

Balanus nubilus 3

Caprella alaskana 3

Chama arcana 3

Crassadoma gigantea 3

Erichthonius brasiliensis 3

Hiatella arctica 3

Janiralata occidentalis 3

Kellia suborbicularis 3

Podocerus brasiliensis 3

Pycnogonum stearnsi 3

Stenothoe estacola 3

Typosyllis spp. 3

HA-B1-B-79 Elasmopus cf hologurus 1

Metridium senile 1

Ophiothrix spiculata 1

Phyllochaetopterus prolifica 1

Syllis gracilis 1

Caprella alaskana 2

Erichthonius brasiliensis 2

Jassa slatteryi 2

Maera simile 2

Obelia geniculata 2

Podocerus brasiliensis 2

Porifera sp A 2

Pseudochama exogyra 2

Aoroides sp 3

Balanus trigonus 3

Caprella ferrea 3

Caprella verrucosa 3

Filicrisia sp 3

Gregariella chenui 3

Halosydna johnsoni 3

Hiatella arctica 3

Janiralata occidentalis 3

Kellia suborbicularis 3

Lithophaga plumula 3

D-12
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B1-B-79 Megabalanus californicus 3

(continued) Modiolus capax 3

Nereis pelagica neonigripes 3

Pachycheles rudis 3

Phascolosoma agassizi 3

Phyllodoce medipapillata 3

Plumularia alicia 3

Pododesmus cepio 3

Polydora sp. 3

Pycnogonum stearnsi 3

Stenothoe estacola 3

Typosyllis spp. 3

HA-B1-M-18 Caprella alaskana 1

Metridium senile 1

Mytilus californianus 1

Ophiothrix spiculata 1

Rhodymenia californica 1

Caprella verrucosa 2

Elasmopus cf hologurus 2

Halosydna brevisetosa 2

Megabalanus californicus 2

Pododesmus cepio 2

Pseudochama exogyra 2

Pycnogonum stearnsi 2

Callopora sp 3

Celleporella sp 3

Family Delesseriaceae 3

Filicrisia sp 3

Hiatella arctica 3

Jassa slatteryi 3

Kellia suborbicularis 3

Maera simile 3

Nereis pelagica neonigripes 3

Obelia geniculata 3

Pachycheles pubescens 3

Pachycheles rudis 3

Phyllochaetopterus prolifica 3

Phyllodoce medipapillata 3

Podocerus brasiliensis 3

Porifera sp A 3

Stenothoe estacola 3

Syllis gracilis 3

Syncoryne eximia 3

Typosyllis spp. 3

HA-B1-M-20 Caprella alaskana 1

Hiatella arctica 1

Megabalanus californicus 1

Balanus nubilus 2

D-13
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B1-M-20 Balanus trigonus 2

(continued) Caprella verrucosa 2

Elasmopus cf hologurus 2

Halosydna brevisetosa 2

Jassa slatteryi 2

Maera simile 2

Membranoptera multiramosa 2

Metridium senile 2

Ophiothrix spiculata 2

Phyllochaetopterus prolifica 2

Pycnogonum stearnsi 2

Rhodymenia californica 2

Stenothoe estacola 2

Syllis gracilis 2

Anisodoris nobilis 3

Campanulariidae 3

Cancer sp juv 3

Dodecaceria unidentified 3

Filicrisia sp 3

Kellia suborbicularis 3

Mytilus californianus 3

Obelia geniculata 3

Pachycheles rudis 3

Phascolosoma agassizi 3

Phyllodoce medipapillata 3

Plumularia alicia 3

Plumularia sp 3

Podocerus brasiliensis 3

Pododesmus cepio 3

Porifera sp A 3

Pseudochama exogyra 3

Syncoryne eximia 3

HA-B1-M-24

Megabalanus californicus 1

Ophiothrix spiculata 1

Caprella alaskana 2

Elasmopus cf hologurus 2

Halosydna brevisetosa 2

Jassa slatteryi 2

Maera simile 2

Membranoptera multiramosa 2

Mytilus spp. 2

Pycnogonum stearnsi 2

Rhodymenia californica 2

Rhodymenia pacifica 2

Syllis gracilis 2

Balanus nubilus 3

Balanus trigonus 3

D-14
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B1-M-24 Caprella verrucosa 3

(continued) Ectoprocta, unidentified 3

Filicrisia sp 3

Hiatella arctica 3

Kellia suborbicularis 3

Metridium senile 3

Mytilus californianus 3

Mytilus trossulus/gallo 3

Obelia geniculata 3

Pachycheles pubescens 3

Pachycheles rudis 3

Paraxanthias taylori 3

Phyllochaetopterus prolifica 3

Phyllodoce medipapillata 3

Porifera sp A 3

Sabellidae unidentified 3

Stenothoe estacola 3

Styela coriacea 3

HA-B1-M-25 Megabalanus californicus 1

Mytilus spp. 1

Ophiothrix spiculata 1

Rhodymenia californica 1

Caprella alaskana 2

Caprella verrucosa 2

Elasmopus cf hologurus 2

Halosydna brevisetosa 2

Jassa slatteryi 2

Maera simile 2

Phyllochaetopterus prolifica 2

Podocerus brasiliensis 2

Pycnogonum stearnsi 2

Actiniidae, juv 3

Balanus nubilus 3

Cancer sp juv 3

Celleporella sp 3

Chama arcana 3

Filicrisia sp 3

Halosydna johnsoni 3

Hiatella arctica 3

Metridium senile 3

Modiolus capax 3

Mytilus californianus 3

Mytilus trossulus/gallo 3

Nereis eakini 3

Nereis pelagica neonigripes 3

Obelia geniculata 3

Pachycheles pubescens 3

Pachycheles rudis 3

D-15
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B1-M-25 Phyllodoce medipapillata 3

(continued) Pododesmus cepio 3

Porifera sp A 3

Pseudochama exogyra 3

Stenothoe estacola 3

Syllis gracilis 3

Syncoryne eximia 3

HA-B1-M-28 Ophiothrix spiculata 1

Phyllochaetopterus prolifica 1

Caprella alaskana 2

Elasmopus cf hologurus 2

Halosydna brevisetosa 2

Megabalanus californicus 2

Balanus nubilus 3

Cancer sp juv 3

Caprella verrucosa 3

Carinoma mutabilis 3

Celleporella sp 3

Filellum serpens 3

Filicrisia sp 3

Hiatella arctica 3

Jassa slatteryi 3

Maera simile 3

Metridium senile 3

Mytilus californianus 3

Obelia geniculata 3

Pachycheles pubescens 3

Pachycheles rudis 3

Phascolosoma agassizii 3

Phyllodoce medipapillata 3

Podocerus brasiliensis 3

Pododesmus cepio 3

Polydora sp. 3

Porifera sp A 3

Pseudochama exogyra 3

Pycnogonum stearnsi 3

Serpula columbiana 3

Syllis gracilis 3

Typosyllis spp. 3

HA-B1-M-30 Caprella alaskana 1

Phyllochaetopterus prolifica 1

Rhodymenia californica 1

Caprella verrucosa 2

Elasmopus cf hologurus 2

Metridium senile 2

Pycnogonum stearnsi 2

Balanus nubilus 3

Celleporina sp 3

D-16
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B1-M-30 Filellum serpens 3

(continued) Filicrisia sp 3

Hiatella arctica 3

Jassa slatteryi 3

Kellia suborbicularis 3

Maera simile 3

Megabalanus californicus 3

Obelia geniculata 3

Ophiothrix spiculata 3

Peudochama exogyra 3

Phascolosoma agassizi 3

Podocerus brasiliensis 3

Porifera sp A 3

Stenothoe estacola 3

Syllis gracilis 3

Tunicate 3

HA-B1-M-32 Halosydna brevisetosa 1

Megabalanus californicus 1

Ophiothrix spiculata 1

Rhodymenia californica 1

Syllis gracilis 1

Anthopleura elegantissima (rosy form) 2

Caprella alaskana 2

Caprella verrucosa 2

Elasmopus cf hologurus 2

Jassa slatteryi 2

Metridium senile 2

Mytilus californianus 2

Phyllochaetopterus prolifica 2

Balanus nubilus 3

Celleporella sp 3

Filicrisia sp 3

Hiatella arctica 3

Kellia suborbicularis 3

Lepidonotus spiculus 3

Lithophaga plumula 3

Maera simile 3

Modiolus capax 3

Nereis eakini 3

Nereis pelagica neonigripes 3

Obelia geniculata 3

Pachycheles rudis 3

Phascolosoma agassizii 3

Phyllodoce medipapillata 3

Plumularia nr septata 3

Podocerus brasiliensis 3

Pododesmus cepio 3

Porifera sp A 3

D-17
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B1-M-32 Pseudochama exogyra 3

(continued) Pycnogonum stearnsi 3

Spirobranchus spinosus 3

Syncoryne eximia 3

HA-B1-M-40 Megabalanus californicus 1

Ophiothrix spiculata 1

Rhodymenia californica 1

Syllis gracilis 1

Caprella alaskana 2

Elasmopus cf hologurus 2

Jassa slatteryi 2

Maera simile 2

Metridium senile 2

Pycnogonum stearnsi 2

Balanus nubilus 3

Cancer productus 3

Caprella verrucosa 3

Dodecaceria fewkesi 3

Filicrisia sp 3

Halosydna brevisetosa 3

Hiatella arctica 3

Kellia suborbicularis 3

Lithophaga plumula 3

Mytilus californianus 3

Nereis pelagica neonigripes 3

Obelia geniculata 3

Phyllochaetopterus prolifica 3

Plumularia alicia complex 3

Podocerus brasiliensis 3

Pododesmus cepio 3

Porifera sp A 3

Pseudochama exogyra 3

Stenothoe estacola 3

HA-B2-B-47 Ophiothrix spiculata 1

Rhodymenia californica 1

Syllis gracilis 1

Caprella alaskana 2

Elasmopus cf hologurus 2

Jassa slatteryi 2

Maera simile 2

Phyllochaetopterus prolifica 2

Pycnogonum stearnsi 2

Balanus nubilus 3

Balanus trigonus 3

Brania sp. 3

Cancer branneri 3

Cancer sp juv 3

Caprella verrucosa 3

D-18
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B2-B-47 Chama arcana 3

(continued) Filicrisia sp 3

Halosydna brevisetosa 3

Hiatella arctica 3

Kellia suborbicularis 3

Megabalanus californicus 3

Metridium senile 3

Mytilus californianus 3

Myxicola sp. 3

Nereis pelagica neonigripes 3

Obelia geniculata 3

Pachycheles rudis 3

Plumularia sp 3

Podocerus brasiliensis 3

Pododesmus cepio 3

Porifera sp A 3

Proceraea cf. kiiensis 3

Pseudochama exogyra 3

Scyra acutifrons 3

HA-B2-B-50 Membranoptera multiramosa 1

Ophiothrix spiculata 1

Balanus nubilus 2

Caprella alaskana 2

Halosydna brevisetosa 2

Jassa slatteryi 2

Maera simile 2

Metridium senile 2

Podocerus brasiliensis 2

Syllis gracilis 2

Balanus sp juv 3

Balanus trigonus 3

Cirratulus unidentified 3

Cyclostomata 3

Elasmopus cf hologurus 3

Erichthonius brasiliensis 3

Filicrisia sp 3

Halosydna johnsoni 3

Hiatella arctica 3

Kellia suborbicularis 3

Lepidonotus spiculus 3

Megabalanus californicus 3

Mytilus californianus 3

Obelia geniculata 3

Phascolosoma agassizi 3

Phyllochaetopterus prolifica 3

Polydora sp. 3

Porifera sp A 3

Pseudochama exogyra 3

D-19
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B2-B-50 Pycnogonum stearnsi 3

(continued) Stenothoe estacola 3

Syncoryne eximia 3

HA-B2-B-60 Ophiothrix spiculata 1

Phyllochaetopterus prolifica 1

Rhodymenia californica 1

Syllis gracilis 1

Balanus nubilus 2

Caprella alaskana 2

Elasmopus cf hologurus 2

Jassa slatteryi 2

Maera simile 2

Megabalanus californicus 2

Polydora sp. 2

Pycnogonum stearnsi 2

Amphissa versicolor 3

Cancer jordani 3

Erichthonius brasiliensis 3

Filicrisia sp 3

Halosydna brevisetosa 3

Halosydna johnsoni 3

Hiatella arctica 3

Kellia suborbicularis 3

Lepidonotus spiculus 3

Lithophaga plumula 3

Metridium senile 3

Mytilus californianus 3

Nereis pelagica neonigripes 3

Obelia geniculata 3

Ophiopteris papillosa 3

Paleanotus bellis 3

Phascolosoma agassizi 3

Podocerus brasiliensis 3

Pododesmus cepio 3

Porifera sp A 3

Pseudochama exogyra 3

Serpula columbiana 3

Spirobranchus spinosus 3

Stenothoe estacola 3

Typosyllis spp. 3

HA-B2-M-11 Caprella alaskana 1

Halosydna brevisetosa 1

Hiatella arctica 1

Megabalanus californicus 1

Metridium senile 1

Mytilus californianus 1

Ophiothrix spiculata 1

Typosyllis spp. 1

D-20
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B2-M-11 Anthopleura elegantissima 2

(continued) Balanus nubilus 2

Elasmopus cf hologurus 2

Jassa slatteryi 2

Maera simile 2

Pycnogonum stearnsi 2

Stenothoe estacola 2

Tetraclita rubescens 2

Amphiporus sp 3

Anthopleura elegantissima (rosy form) 3

Arabella semimaculata 3

Balanus trigonus 3

Callopora sp 3

Campanulariidae 3

Caprella equilibra 3

Caprella ferrea 3

Caprella verrucosa 3

Celleporella sp 3

Costazia sp 3

Crassadoma gigantea 3

Cyclostomata 3

Eudistylia polymorpha 3

Filellum serpens 3

Filicrisia sp 3

Halecium sp 3

Halecium tenellum 3

Irus lamellifera 3

Iselica ovoidea 3

Kellia suborbicularis 3

Lafoea adnata 3

Modiolus capax 3

Mytilus spp juv 3

Mytilus trossulus/gallo 3

Nereis pelagica neonigripes 3

Obelia sp 3

Ophiopteris papillosa 3

Pachycheles rudis 3

Parastichopus californicus 3

Petricola sp juv 3

Phascolosoma agassizii 3

Phyllochaetopterus prolifica 3

Phyllodoce medipapillata 3

Podocerus brasiliensis 3

Pododesmus cepio 3

Porifera sp A 3

Pseudochama exogyra 3

Rhabdodermella nuttingi 3

Sertularella tenella 3

D-21
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B2-M-11 Spirobranchus spinosus 3

(continued) Styela coriacea 3

Styela truncata 3

Stylochoplana longipenis 3

Stylochus spp 3

Syllis gracilis 3

Syncoryne eximia 3

HA-B2-M-13 Caprella alaskana 1

Halosydna brevisetosa 1

Megabalanus californicus 1

Mytilus californianus 1

Ophiothrix spiculata 1

Elasmopus cf hologurus 2

Jassa slatteryi 2

Maera simile 2

Membranoptera multiramosa 2

Metridium senile 2

Pugetia fragillissima 2

Pycnogonum stearnsi 2

Stenothoe estacola 2

Anthopleura elegantissima (rosy form) 3

Balanus nubilus 3

Balanus trigonus 3

Callopora sp 3

Campanularia sp 3

Campanulariidae 3

Caprella ferrea 3

Caprella verrucosa 3

Celleporella sp 3

Corynactis californica 3

Crassadoma gigantea 3

Cyclostomata 3

Echinoidea juv 3

Eucopella everta 3

Filellum serpens 3

Filicrisia sp 3

Halecium sp 3

Halosydna johnsoni 3

Hiatella arctica 3

Kellia suborbicularis 3

Modiolus capax 3

Mya arenaria 3

Nereis pelagica neonigripes 3

Ophiopteris papillosa 3

Pachycheles rudis 3

Paranemertes californica 3

Podocerus brasiliensis 3

Porifera 3

D-22
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B2-M-13 Porifera sp A 3

(continued) Rhabdocoela 3

Scyra acutifrons 3

Spirobranchus spinosus 3

Stylochoplana longipenis 3

Stylochus spp 3

Tetraclita rubescens 3

Tetrastemma signifer 3

Tritonia diomedea 3

Typosyllis spp. 3

HA-B2-M-14 Caprella alaskana 1

Metridium senile 1

Mytilus californianus 1

Ophiothrix spiculata 1

Rhodymenia californica 1

Caprella verrucosa 2

Elasmopus cf hologurus 2

Halosydna brevisetosa 2

Jassa slatteryi 2

Maera simile 2

Megabalanus californicus 2

Podocerus brasiliensis 2

Pycnogonum stearnsi 2

Rhodymenia pacifica 2

Stenothoe estacola 2

Anisodoris nobilis 3

Anthopleura elegantissima (rosy form) 3

Balanus nubilus 3

Carinoma mutabilis 3

Celleporella sp 3

Crassadoma gigantea 3

Cyclostomata 3

Ectoprocta 3

Filellum serpens 3

Filicrisia sp 3

Halecium sp 3

Halosydna johnsoni 3

Hiatella arctica 3

Janiralata occidentalis 3

Lepidonotus spiculus 3

Nereis eakini 3

Nereis pelagica neonigripes 3

Obelia geniculata 3

Ophiopteris papillosa 3

Pachycheles rudis 3

Parastichopus californicus 3

Paraxanthias taylori 3

Phascolosoma agassizi 3

D-23
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B2-M-14 Phyllochaetopterus prolifica 3

(continued) Phyllodoce medipapillata 3

Porifera sp A 3

Proceraea cf. kiiensis 3

Pseudochama exogyra 3

Scyra acutifrons 3

Syllis gracilis 3

Tetraclita rubescens 3

Typosyllis spp. 3

HA-B2-M-15 Caprella alaskana 1

Halosydna brevisetosa 1

Megabalanus californicus 1

Metridium senile 1

Mytilus californianus 1

Ophiothrix spiculata 1

Balanus nubilus 2

Elasmopus cf hologurus 2

Jassa slatteryi 2

Maera simile 2

Phyllochaetopterus prolifica 2

Pycnogonum stearnsi 2

Typosyllis spp. 2

Anisodoris nobilis 3

Anoplodactylus nodosus 3

Anthopleura elegantissima (rosy form) 3

Balanus trigonus 3

Callopora sp 3

Campanularia sp. 3

Cancer sp juv 3

Caprella verrucosa 3

Celleporella sp 3

Cirratulus unidentified 3

Crassadoma gigantea 3

Cyclostomata 3

Ectoprocta 3

Filellum serpens 3

Filicrisia sp 3

Halecium sp 3

Halosydna johnsoni 3

Hiatella arctica 3

Iselica ovoidea 3

Kellia suborbicularis 3

Lepidonotus spiculus 3

Lithophaga plumula 3

Modiolus capax 3

Nemertea unid 3

Nereis pelagica neonigripes 3

Obelia geniculata 3

D-24
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B2-M-15 Ophiopteris papillosa 3

(continued) Pachycheles rudis 3

Paraxanthias taylori 3

Pentamera lissoplaca 3

Phascolosoma agassizi 3

Phyllodoce medipapillata 3

Podocerus brasiliensis 3

Porifera sp A 3

Rhabdocoela 3

Scrupocellaria sp 3

Spirobranchus spinosus 3

Stenothoe estacola 3

Stylochoplana longipenis 3

Syllis gracilis 3

Syncoryne eximia 3

HA-B2-M-17 Caprella alaskana 1

Halosydna brevisetosa 1

Megabalanus californicus 1

Mytilus californianus 1

Ophiothrix spiculata 1

Rhodymenia californica 1

Elasmopus cf hologurus 2

Pycnogonum stearnsi 2

Amphissa versicolor 3

Anthopleura elegantissima (rosy form) 3

Balanus trigonus 3

Callopora sp 3

Campanulariidae 3

Caprella verrucosa 3

Celleporella sp 3

Cyclostomata 3

Filellum serpens 3

Filicrisia sp 3

Halecium sp 3

Halosydna johnsoni 3

Hiatella arctica 3

Holothuroid, unid 3

Jassa slatteryi 3

Kellia suborbicularis 3

Maera simile 3

Metridium senile 3

Nereis pelagica neonigripes 3

Ophiopteris papillosa 3

Pachycheles rudis 3

Paraxanthias taylori 3

Phascolosoma agassizii 3

Pododesmus cepio 3

Porifera sp A 3

D-25
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B2-M-17 Pseudochama exogyra 3

(continued) Scyra acutifrons 3

Stenothoe estacola 3

Typosyllis spp. 3

HA-B2-M-19 Caprella alaskana 1

Halosydna brevisetosa 1

Megabalanus californicus 1

Mytilus californianus 1

Ophiothrix spiculata 1

Typosyllis spp. 1

Caprella verrucosa 2

Elasmopus cf hologurus 2

Porifera sp A 2

Pycnogonum stearnsi 2

Anisodoris nobilis 3

Balanus nubilus 3

Callopora sp 3

Campanularia sp 3

Campanulariidae 3

Cancer sp juv 3

Celleporella sp 3

Corynactis californica 3

Filellum serpens 3

Filicrisia sp 3

Hiatella arctica 3

Jassa slatteryi 3

Kellia suborbicularis 3

Lithophaga plumula 3

Maera simile 3

Metridium senile 3

Nemertea 3

Nereis pelagica neonigripes 3

Obelia geniculata 3

Ophiopteris papillosa 3

Paleanotus bellis 3

Paraxanthias taylori 3

Phascolosoma agassizii 3

Phyllochaetopterus prolifica 3

Pseudochama exogyra 3

Spirobranchus spinosus 3

Stenothoe estacola 3

Styela truncata 3

Stylochus spp 3

Syllis gracilis 3

Syncoryne eximia 3

HA-B2-M-21 Caprella alaskana 1

Megabalanus californicus 1

Mytilus californianus 1

D-26
PLATFORM HARVEST - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

HA-B2-M-21 Ophiothrix spiculata 1

(continued) Elasmopus cf hologurus 2

Anomia peruviana 3

Anthopleura elegantissima (rosy form) 3

Campanularia sp 3

Caprella verrucosa 3

Cyclostomata 3

Filellum serpens 3

Halecium sp 3

Hiatella arctica 3

Jassa slatteryi 3

Metridium senile 3

Modiolus capax 3

Porifera sp A 3

Pycnogonum stearnsi 3

Stenothoe estacola 3

Tegella sp. 3

HA-B2-M-22 Megabalanus californicus 1

Mytilus californianus 1

Ophiothrix spiculata 1

Caprella alaskana 2

Amphissa versicolor 3

Balanus nubilus 3

Balanus trigonus 3

Callopora sp 3

Campanulariidae 3

Caprella equlibra 3

Caprella verrucosa 3

Crisia sp 3

Elasmopus cf hologurus 3

Filellum serpens 3

Filicrisia sp 3

Halosydna brevisetosa 3

Hiatella arctica 3

Kellia suborbicularis 3

Maera simile 3

Modiolus capax 3

Mopalia porifera 3

Nereis pelagica neonigripes 3

Phyllochaetopterus prolifica 3

Podocerus brasiliensis 3

Pododesmus cepio 3

Pseudochama exogyra 3

Pycnogonum stearnsi 3

Stenothoe estacola 3

Styela truncata 3

Syllis gracilis 3

Typosyllis spp. 3

D-27
WEIGHTS - ALL SAMPLES:

Station/Quadrat Total Weight 

(grams)

Mussel Weight 

(grams)

Non-Mussel Weight 

(grams) Percent Mussel Weight

HA-B1-B-47 909.00 0.00 909.00 0.0000

HA-B1-B-54 651.00 0.00 651.00 0.0000

HA-B1-B-78 1171.00 0.00 1171.00 0.0000

HA-B1-B-79 1335.00 0.00 1335.00 0.0000

HA-B1-M-18 5059.00 4025.00 1034.00 79.5612

HA-B1-M-20 149.10 1.65 147.45 1.1066

HA-B1-M-24 2916.00 589.00 2327.00 20.1989

HA-B1-M-25 3456.00 535.00 2921.00 15.4803

HA-B1-M-28 3615.00 266.00 3349.00 7.3582

HA-B1-M-30 1139.00 0.00 1139.00 0.0000

HA-B1-M-32 3493.00 906.00 2587.00 25.9376

HA-B1-M-40 1790.00 82.00 1708.00 4.5810

HA-B2-B-47 2828.10 7.10 2821.00 0.2511

HA-B2-B-50 2281.00 2.00 2279.00 0.0877

HA-B2-B-60 2944.80 0.80 2944.00 0.0272

HA-B2-M-11-BK34 6820.00 6114.00 706.00 89.6481

HA-B2-M-11-BK37 6024.00 4304.00 1720.00 71.4475

HA-B2-M-11-BK38 2465.00 1540.00 925.00 62.4746

HA-B2-M-11 total 15309.00 11958.00 3351.00 78.1109

HA-B2-M-13-BK14 3715.00 3267.00 448.00 87.9408

HA-B2-M-13-BK21 5328.00 3722.00 1606.00 69.8574

HA-B2-M-13-BK22 5387.00 4669.00 718.00 86.6716

HA-B2-M-13 total 14430.00 11658.00 2772.00 80.7900

HA-B2-M-14-BK19 114.16 56.39 57.77 49.3956

HA-B2-M-14-BK20 5769.00 3696.00 2073.00 64.0666

HA-B2-M-14 total 5883.16 3752.39 2130.77 63.7819

HA-B2-M-15-BK24 7148.00 6551.00 597.00 91.6480

HA-B2-M-15-BK35 5365.00 2920.00 2445.00 54.4268

HA-B2-M-15-BK36 5148.00 2465.00 2683.00 47.8827

HA-B2-M-15 total 17661.00 11936.00 5725.00 67.5839

HA-B2-M-17 7305.00 5843.00 1462.00 79.9863

HA-B2-M-19-BK14 6625.00 4745.00 1880.00 71.6226

HA-B2-M-19-BK15 6283.00 4345.00 1938.00 69.1549

HA-B2-M-19 total 20213.00 14933.00 5280.00 73.8782

HA-B2-M-21 5690.00 4941.00 749.00 86.8366

HA-B2-M-22 5440.00 4062.00 1378.00 74.6691

D-28
SUMMARY:

Station/Quadrat Total Weight 

(grams)

Mussel Weight 

(grams)

Non-Mussel Weight 

(grams) Percent Mussel Weight

HA-B1-B-47 909.00 0.00 909.00 0.0000

HA-B1-B-54 651.00 0.00 651.00 0.0000

HA-B1-B-78 1171.00 0.00 1171.00 0.0000

HA-B1-B-79 1335.00 0.00 1335.00 0.0000

HA-B1-M-18 5059.00 4025.00 1034.00 79.5612

HA-B1-M-20 149.10 1.65 147.45 1.1066

HA-B1-M-24 2916.00 589.00 2327.00 20.1989

HA-B1-M-25 3456.00 535.00 2921.00 15.4803

HA-B1-M-28 3615.00 266.00 3349.00 7.3582

HA-B1-M-30 1139.00 0.00 1139.00 0.0000

HA-B1-M-32 3493.00 906.00 2587.00 25.9376

HA-B1-M-40 1790.00 82.00 1708.00 4.5810

HA-B2-B-47 2828.10 7.10 2821.00 0.2511

HA-B2-B-50 2281.00 2.00 2279.00 0.0877

HA-B2-B-60 2944.80 0.80 2944.00 0.0272

HA-B2-M-11 15309.00 11958.00 3351.00 78.1109

HA-B2-M-13 14430.00 11658.00 2772.00 80.7900

HA-B2-M-14 5883.16 3752.39 2130.77 63.7819

HA-B2-M-15 17661.00 11936.00 5725.00 67.5839

HA-B2-M-17 7305.00 5843.00 1462.00 79.9863

HA-B2-M-19 20213.00 14933.00 5280.00 73.8782

HA-B2-M-21 5690.00 4941.00 749.00 86.8366

HA-B2-M-22 5440.00 4062.00 1378.00 74.6691

Total - Both Legs: 125668.16 75497.94 50170.22 --

Mean: 5463.83 3282.52 2181.31 33.05

Maximum: 20213.00 14933.00 5725.00 86.84

Minimum: 149.10 0.00 147.45 0.00

Total - Leg B1: 25683.10 6404.65 19278.45 --

Mean: 2140.26 533.72 1606.54 12.85

Maximum: 5059.00 4025.00 3349.00 79.56

Minimum: 149.10 0.00 147.45 0.00

Total - Leg B2: 99985.06 69093.29 30891.77 --

Mean: 9089.55 6281.21 2808.34 55.09

Maximum: 20213.00 14933.00 5725.00 86.84

Minimum: 2281.00 0.80 749.00 0.03

D-29
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B1-M-18 (BK4) 16.4 6.2 6.4 322

HA-B1-M-18 (BK4) 18.9 7.9 7.7 466

HA-B1-M-18 (BK4) 13.4 6.1 4.5 129

HA-B1-M-18 (BK4) 17.6 7.3 6.8 296

HA-B1-M-18 (BK4) 18 7 7.4 437

HA-B1-M-18 (BK4) 12.6 5.7 4.4 114

HA-B1-M-18 (BK4) 11.6 4.2 4 86

HA-B1-M-18 (BK4) 10.7 5.2 3.6 89

HA-B1-M-18 (BK4) 11.1 6.4 4 88

HA-B1-M-18 (BK4) 11.4 5.6 4.4 90

HA-B1-M-18 (BK4) 10.9 5.5 4.6 75

HA-B1-M-18 (BK4) 10.8 5.2 3.9 68

HA-B1-M-18 (BK4) 9.9 5 3.5 67

HA-B1-M-18 (BK4) 9.4 5.2 3.6 62

HA-B1-M-18 (BK4) 8.3 4.2 2.9 35

HA-B1-M-18 (BK4) 8.4 4.7 3.3 45

HA-B1-M-18 (BK4) 7.9 4 3 35

HA-B1-M-18 (BK4) 7.9 3.9 2.5 31

HA-B1-M-18 (BK4) 7.9 4.3 3.2 40

HA-B1-M-18 (BK4) 6.1 4.1 2.4 24

HA-B1-M-18 (BK4) 5.9 3.2 2.1 18

HA-B1-M-18 (BK4) 5.4 3.1 2.2 16

HA-B1-M-18 (BK4) 3.6 2.2 1.4 6

HA-B1-M-18 (BK4) 5.9 3 2.3 16

HA-B1-M-18 (BK4) 5.8 3.7 2.4 22

HA-B1-M-18 (BK4) 14.6 6.2 4.5 147

HA-B1-M-18 (BK4) 10.4 5.1 3.5 13

HA-B1-M-18 (BK4) 10 4.5 3.7 67

HA-B1-M-18 (BK4) 8.6 4.4 3.2 49

HA-B1-M-18 (BK4) 10 5.2 3.7 68

HA-B1-M-18 (BK4) 9.4 4.9 3.7 60

HA-B1-M-18 (BK4) 8.9 4.6 3 45

HA-B1-M-18 (BK4) 8.3 4.7 2.9 36

HA-B1-M-18 (BK4) 7.4 3.7 2.6 29

HA-B1-M-18 (BK4) 7.2 4.2 2.7 34

HA-B1-M-18 (BK4) 5.6 3.4 2 15

HA-B1-M-18 (BK4) 5.5 2.7 2.3 13

HA-B1-M-18 (BK4) 6.6 4.2 2.6 28

HA-B1-M-18 (BK4) 5.7 3.3 2.3 13

HA-B1-M-18 (BK4) 4.4 2.7 1.6 9

HA-B1-M-18 (BK4) 4.9 2.9 1.6 12

HA-B1-M-18 (BK4) 5.4 2.9 1.9 14

HA-B1-M-18 (BK4) 3.9 2.4 1.4 6

HA-B1-M-18 (BK4) 3.5 1.9 1.4 5

HA-B1-M-18 (BK4) 3.4 2.8 1.1 3

HA-B1-M-18 (BK4) 2.9 1.5 0.9 2

HA-B1-M-18 (BK4) 2.9 1.7 1.1 3

HA-B1-M-18 (BK4) 2.7 1.5 1 3

D-30
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B1-M-18 (BK4) 2.4 1.5 0.9 2

HA-B1-M-18 (BK4) 2.3 1.3 0.8 2

HA-B1-M-18 (BK4) 2.4 1.4 0.8 2

HA-B1-M-18 (BK4) 2.3 1.4 0.9 1

HA-B1-M-18 (BK4) 1.9 1.4 0.7 1

HA-B1-M-18 (BK4) 1.9 1.1 0.7 0.1

HA-B1-M-18 (BK4) 2 1.4 0.7 1

HA-B1-M-18 (BK4) 1.6 1.2 0.6 0.1

HA-B1-M-18 (BK4) 1.5 1 0.6 0.1

HA-B1-M-18 (BK4) 1.6 1.2 0.6 1

HA-B1-M-18 (BK4) 1.5 1 0.6 1

HA-B1-M-18 (BK4) 1.4 1.1 0.5 0.1

HA-B1-M-18 (BK4) 8.3 4.2 3.1 42

HA-B1-M-18 (BK4) 8.4 4.2 3.2 46

HA-B1-M-18 (BK4) 8.3 4.4 3.7 47

HA-B1-M-20 (BK5) 7.4 3.8 2.6 29

HA-B1-M-20 (BK5) 4.9 2.5 1.7 10

HA-B1-M-20 (BK5) 3.3 2.2 1.7 4

HA-B1-M-20 (BK5) 0.9 0.5 0.3 0.1

HA-B1-M-24 (BK?) 9.7 5.4 4.2 84

HA-B1-M-24 (BK?) 11 5.3 4.5 126

HA-B1-M-24 (BK?) 10.2 5.8 4.3 109

HA-B1-M-24 (BK?) 8.1 4.3 3.1 47

HA-B1-M-24 (BK?) 6.3 3.3 2.1 23

HA-B1-M-24 (BK?) 6.6 3.7 2.5 28

HA-B1-M-24 (BK?) 5.4 3.1 2.1 16

HA-B1-M-24 (BK?) 5.4 3.1 2.5 23

HA-B1-M-24 (BK?) 4.4 2.5 1.9 13

HA-B1-M-24 (BK?) 3 1.9 1.5 4

HA-B1-M-24 (BK?) 3.3 1.6 1.2 4

HA-B1-M-24 (BK?) 3.1 1.7 1.2 4

HA-B1-M-24 (BK?) 2.9 1.5 1.1 2

HA-B1-M-24 (BK?) 2.2 1.4 0.9 2

HA-B1-M-24 (BK?) 2.4 1.8 1 2

HA-B1-M-24 (BK?) 1.9 1.4 1 1

HA-B1-M-24 (BK?) 1.8 1.3 0.7 1

HA-B1-M-24 (BK?) 1.7 1.5 1.1 3

HA-B1-M-24 (BK?) 1.9 1 0.7 1

HA-B1-M-24 (BK?) 1.6 1.2 1.1 2

HA-B1-M-24 (BK?) 1.6 1.4 1.2 2

HA-B1-M-24 (BK?) 1.5 1 1 1

HA-B1-M-24 (BK?) 0.7 0.9 1.1 0.1

HA-B1-M-24 (BK?) 0.8 0.8 0.5 0.1

HA-B1-M-24 (BK?) 0.8 0.8 0.4 0.1

HA-B1-M-24 (BK?) 0.7 0.7 0.4 0.1

D-31
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B1-M-25 (BK?) 14.9 6.6 5.5 186

HA-B1-M-25 (BK?) 9.4 4.7 3.4 56

HA-B1-M-25 (BK?) 7.5 4.7 2.4 27

HA-B1-M-25 (BK?) 8.4 4.6 3.3 48

HA-B1-M-25 (BK?) 8.3 4.1 2.9 41

HA-B1-M-25 (BK?) 6.9 3.6 2.4 24

HA-B1-M-25 (BK?) 5.3 2.8 1.8 14

HA-B1-M-25 (BK?) 5.5 3 2.2 16

HA-B1-M-25 (BK?) 5.3 3.1 1.9 13

HA-B1-M-25 (BK?) 5.5 3 2.2 16

HA-B1-M-25 (BK?) 4.4 2.5 1.8 11

HA-B1-M-25 (BK?) 4.2 2 1.4 8

HA-B1-M-25 (BK?) 4.2 2.5 1.7 8

HA-B1-M-25 (BK?) 3.4 1.9 1.1 4

HA-B1-M-25 (BK?) 3.1 1.8 1 2

HA-B1-M-25 (BK?) 2.3 1.5 0.8 1

HA-B1-M-25 (BK?) 2.1 1.3 0.9 1

HA-B1-M-25 (BK?) 1.6 1 0.6 1

HA-B1-M-25 (BK?) 1.4 0.9 0.5 0.1

HA-B1-M-25 (BK?) 1.5 0.9 0.6 1

HA-B1-M-25 (BK?) 1.7 1.2 0.6 1

HA-B1-M-25 (BK?) 1.4 1.1 0.6 0.1

HA-B1-M-32 (BK?) 15 7 5.2 200

HA-B1-M-32 (BK?) 8.4 3.9 2.6 35

HA-B1-M-32 (BK?) 8 4.5 2.8 38

HA-B1-M-32 (BK?) 6.5 4.2 2.6 31

HA-B1-M-32 (BK?) 7.4 4.1 2.5 29

HA-B1-M-32 (BK?) 7.8 5 3.2 49

HA-B1-M-32 (BK?) 6.4 3.9 2.4 27

HA-B1-M-32 (BK?) 6.4 3.3 2 19

HA-B1-M-32 (BK?) 5.7 2.7 2 15

HA-B1-M-32 (BK?) 4.9 3.2 2.2 13

HA-B1-M-32 (BK?) 5.7 2.7 1.9 14

HA-B1-M-32 (BK?) 4.5 2.4 1.7 9

HA-B1-M-32 (BK?) 4.7 2.4 1.9 12

HA-B1-M-32 (BK?) 4.9 2.6 1.7 11

HA-B1-M-32 (BK?) 2.8 1.6 0.9 2

HA-B1-M-32 (BK?) 2.2 1.2 0.8 1

HA-B1-M-32 (BK?) 2.1 1.2 0.9 1

HA-B1-M-32 (BK?) 1.7 0.9 0.7 0.1

HA-B1-M-32 (BK?) 1.7 1 0.6 0.1

HA-B1-M-32 (BK?) 1.6 0.9 0.5 1

HA-B2-M-11 (BK34) 22.4 8.2 6.4 418

HA-B2-M-11 (BK34) 18.6 7.7 7 327

HA-B2-M-11 (BK34) 15.5 6.7 5.7 221

HA-B2-M-11 (BK34) 18.5 7.2 6.2 324

D-32
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-11 (BK34) 16 6.8 5.9 151

HA-B2-M-11 (BK34) 16.7 7 5.9 180

HA-B2-M-11 (BK34) 13.8 5.1 5 167

HA-B2-M-11 (BK34) 13.9 5.8 4.5 133

HA-B2-M-11 (BK34) 12.4 6.5 4.5 158

HA-B2-M-11 (BK34) 12.1 5.9 4.4 113

HA-B2-M-11 (BK34) 12.6 5.8 4.6 118

HA-B2-M-11 (BK34) 11.5 5.3 3.8 77

HA-B2-M-11 (BK34) 10.3 4.7 3.7 69

HA-B2-M-11 (BK34) 9.7 4.7 3.5 38

HA-B2-M-11 (BK34) 9 4.4 3.2 34

HA-B2-M-11 (BK34) 8.9 4.1 3.2 40

HA-B2-M-11 (BK34) 8.7 4.4 3.2 39

HA-B2-M-11 (BK34) 7.9 4.4 2.7 25

HA-B2-M-11 (BK34) 7.4 3.6 2.6 26

HA-B2-M-11 (BK34) 6.6 3.5 2.3 21

HA-B2-M-11 (BK34) 7.7 3.6 2.6 21

HA-B2-M-11 (BK34) 6.4 3.2 2.3 20

HA-B2-M-11 (BK34) 13.9 6.5 5.3 230

HA-B2-M-11 (BK34) 14.7 6.3 5.5 188

HA-B2-M-11 (BK34) 13.9 6.5 5.3 230

HA-B2-M-11 (BK34) 13.4 5.8 4.6 160

HA-B2-M-11 (BK34) 11.7 5.6 3.3 103

HA-B2-M-11 (BK34) 11.5 5.1 3.6 71

HA-B2-M-11 (BK34) 9.4 4.9 3 51

HA-B2-M-11 (BK34) 8.5 4.2 3.1 42

HA-B2-M-11 (BK34) 7.9 3.8 2.8 30

HA-B2-M-11 (BK34) 8.4 4.4 2.9 44

HA-B2-M-11 (BK34) 8.2 4 2.8 42

HA-B2-M-11 (BK34) 7.4 4 2.4 26

HA-B2-M-11 (BK34) 7.7 3.9 2.6 27

HA-B2-M-11 (BK34) 8.9 4.4 2.9 50

HA-B2-M-11 (BK34) 6.9 4 2.3 20

HA-B2-M-11 (BK34) 6.8 3.3 2.1 19

HA-B2-M-11 (BK34) 8.1 3.8 2.7 31

HA-B2-M-11 (BK34) 6.5 3.5 2.1 23

HA-B2-M-11 (BK34) 6.6 3.1 2.3 18

HA-B2-M-11 (BK34) 6 2.9 1.9 19

HA-B2-M-11 (BK34) 5.9 3.4 2 15

HA-B2-M-11 (BK34) 5.3 2.8 1.8 12

HA-B2-M-11 (BK34) 4.9 2.5 1.7 9

HA-B2-M-11 (BK34) 6 2.4 1.8 10

HA-B2-M-11 (BK34) 4.4 2.1 1.7 7

HA-B2-M-11 (BK34) 4.6 2.5 1.6 9

HA-B2-M-11 (BK34) 4.9 2.7 1.7 9

HA-B2-M-11 (BK34) 4.7 2.4 1.8 9

HA-B2-M-11 (BK34) 4.4 2.4 1.4 7

HA-B2-M-11 (BK34) 4.7 2.3 1.7 9

D-33
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-11 (BK34) 4 2.3 1.2 6

HA-B2-M-11 (BK34) 3.9 2.1 1.2 5

HA-B2-M-11 (BK34) 4.6 2.5 1.5 9

HA-B2-M-11 (BK34) 4 2.3 1.2 6

HA-B2-M-11 (BK34) 3.9 2.1 1.2 5

HA-B2-M-11 (BK34) 3.4 1.9 1.1 2

HA-B2-M-11 (BK34) 3.4 1.9 1.1 3

HA-B2-M-11 (BK34) 3.3 1.6 1 3

HA-B2-M-11 (BK34) 3.4 2 1.4 4

HA-B2-M-11 (BK34) 2.9 1.7 1 1

HA-B2-M-11 (BK34) 2.9 1.6 1 3

HA-B2-M-11 (BK34) 2.5 1.5 0.9 2

HA-B2-M-11 (BK34) 2.7 1.4 0.9 2

HA-B2-M-11 (BK34) 2.7 1.6 0.9 2

HA-B2-M-11 (BK34) 2.4 1.3 0.8 1

HA-B2-M-11 (BK34) 2.4 1.3 0.7 2

HA-B2-M-11 (BK34) 2.2 1.3 0.7 2

HA-B2-M-11 (BK34) 2 1.2 0.7 1

HA-B2-M-11 (BK34) 1.9 1 0.7 0.1

HA-B2-M-11 (BK34) 1.9 1.1 0.7 0.1

HA-B2-M-11 (BK34) 11.4 5.6 4 104

HA-B2-M-11 (BK37) 17.6 6.7 5.5 246

HA-B2-M-11 (BK37) 18.6 7.2 7.1 310

HA-B2-M-11 (BK37) 14.5 6.5 4.6 154

HA-B2-M-11 (BK37) 16.4 6.8 5.3 186

HA-B2-M-11 (BK37) 17.5 6.9 4.8 188

HA-B2-M-11 (BK37) 15.1 6.9 5.2 179

HA-B2-M-11 (BK37) 22 7.5 7.5 634

HA-B2-M-11 (BK37) 18.8 6.4 6.2 328

HA-B2-M-11 (BK37) 13.7 6.6 4.4 134

HA-B2-M-11 (BK37) 11.7 5.2 4 97

HA-B2-M-11 (BK37) 12.7 5.6 3.9 96

HA-B2-M-11 (BK37) 21.5 7.5 7.5 524

HA-B2-M-11 (BK37) 16.9 7.1 5.5 272

HA-B2-M-11 (BK37) 12.8 5.8 4.2 110

HA-B2-M-11 (BK37) 14.5 5.7 5 169

HA-B2-M-11 (BK37) 11.4 4.9 3.8 26

HA-B2-M-11 (BK37) 10.1 5 3.2 55

HA-B2-M-11 (BK37) 9.4 4.3 2.8 43

HA-B2-M-11 (BK37) 8.5 4.5 2.8 44

HA-B2-M-11 (BK37) 9.4 4.2 2.8 42

HA-B2-M-11 (BK37) 8.1 3.9 2.8 38

HA-B2-M-11 (BK37) 5.4 2.9 1.7 14

HA-B2-M-11 (BK37) 4.9 3 1.8 13

HA-B2-M-11 (BK37) 4 2.2 1.2 8

HA-B2-M-11 (BK37) 4 2.2 1.3 8

HA-B2-M-11 (BK37) 2.8 1.4 0.9 4

HA-B2-M-11 (BK37) 2.5 1.4 0.9 3

D-34
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-11 (BK37) 2.8 1.7 0.8 4

HA-B2-M-11 (BK37) 2.1 1.1 0.7 4

HA-B2-M-11 (BK37) 2.1 1 0.8 5

HA-B2-M-11 (BK37) 1.8 1.1 0.6 3

HA-B2-M-11 (BK37) 1.8 0.9 0.6 3

HA-B2-M-11 (BK37) 1.3 0.8 0.4 2

HA-B2-M-11 (BK37) 1.3 0.8 0.5 2

HA-B2-M-11 (BK38) 18.4 7.7 6.2 326

HA-B2-M-11 (BK38) 21.1 8.1 7 458

HA-B2-M-11 (BK38) 15.2 7.1 4.9 211

HA-B2-M-11 (BK38) 16.8 6.8 5.5 271

HA-B2-M-11 (BK38) 19.6 7.5 7 407

HA-B2-M-11 (BK38) 14.4 6.4 4.9 159

HA-B2-M-11 (BK38) 12.4 5.8 4.1 90

HA-B2-M-11 (BK38) 14 6 4.8 175

HA-B2-M-11 (BK38) 15.1 6.3 4.8 186

HA-B2-M-11 (BK38) 12 5.5 3.8 104

HA-B2-M-11 (BK38) 12.7 5.7 4.1 119

HA-B2-M-11 (BK38) 11.6 5.7 3.6 81

HA-B2-M-11 (BK38) 8.9 4.1 2.9 41

HA-B2-M-11 (BK38) 10.1 4.8 3.3 56

HA-B2-M-11 (BK38) 10.3 4.9 3.3 54

HA-B2-M-11 (BK38) 10.7 5.1 3.5 59

HA-B2-M-11 (BK38) 9.2 4.5 3.1 77

HA-B2-M-11 (BK38) 8.9 4.5 2.9 43

HA-B2-M-11 (BK38) 10.2 4.9 3.5 58

HA-B2-M-11 (BK38) 7.7 4.1 2.3 30

HA-B2-M-11 (BK38) 7.5 4.3 3.4 49

HA-B2-M-11 (BK38) 8.6 4.4 3.2 46

HA-B2-M-11 (BK38) 7.8 4.8 2.7 35

HA-B2-M-11 (BK38) 7.1 3.6 2.3 29

HA-B2-M-11 (BK38) 7.6 3.9 2.6 31

HA-B2-M-11 (BK38) 6.8 3.8 2.8 33

HA-B2-M-11 (BK38) 6.6 3.7 2.4 25

HA-B2-M-11 (BK38) 6.6 3.3 2 18

HA-B2-M-11 (BK38) 5.6 2.8 2 14

HA-B2-M-11 (BK38) 5.6 2.8 1.8 12

HA-B2-M-11 (BK38) 4.3 2.1 1.5 7

HA-B2-M-11 (BK38) 3.2 2.1 1 3

HA-B2-M-11 (BK38) 3.9 2.2 1.2 5

HA-B2-M-11 (BK38) 2.8 1.5 0.9 2

HA-B2-M-11 (BK38) 2.8 1.5 1 2

HA-B2-M-11 (BK38) 1.3 1.3 0.8 1

HA-B2-M-11 (BK38) 2.2 1.3 0.8 4

HA-B2-M-11 (BK34) 8.2 4 2.8 42

HA-B2-M-11 (BK34) 5.2 2.8 1.9 9

HA-B2-M-11 (BK34) 5.1 3.1 2.1 14

HA-B2-M-11 (BK34) 5.3 2.4 1.8 12

D-35
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-11 (BK34) 5.9 2.9 1.9 13

HA-B2-M-13 (BK?) 14.1 6.2 5 143

HA-B2-M-13 (BK?) 14.9 6 5.4 153

HA-B2-M-13 (BK?) 11.4 6.2 5 116

HA-B2-M-13 (BK?) 10.8 4.9 3.6 69

HA-B2-M-13 (BK?) 10 5.3 3.6 70

HA-B2-M-13 (BK?) 11 5.3 3.5 69

HA-B2-M-13 (BK?) 10.9 5 3.8 67

HA-B2-M-13 (BK?) 8.9 4 2.9 40

HA-B2-M-13 (BK?) 8.4 4.2 2.9 37

HA-B2-M-13 (BK?) 9.3 4.6 3.8 66

HA-B2-M-13 (BK?) 7.8 3.9 2.4 29

HA-B2-M-13 (BK?) 8 3.6 2.2 28

HA-B2-M-13 (BK?) 5.6 3.3 2.2 17

HA-B2-M-13 (BK?) 6.6 3.7 2.5 22

HA-B2-M-13 (BK14) 20.4 7.4 7.2 491

HA-B2-M-13 (BK14) 20.3 7.6 7.3 513

HA-B2-M-13 (BK14) 20.3 7.5 6.6 374

HA-B2-M-13 (BK14) 18.7 7 4.8 310

HA-B2-M-13 (BK14) 18.5 6.5 5.1 206

HA-B2-M-13 (BK14) 15.5 6.7 5.1 179

HA-B2-M-13 (BK14) 16 7.3 5.1 212

HA-B2-M-13 (BK14) 14.1 5.8 4.4 125

HA-B2-M-13 (BK21) 21.8 8.6 6.8 459

HA-B2-M-13 (BK21) 20.4 6.9 7.3 447

HA-B2-M-13 (BK21) 17.1 7.2 5.8 280

HA-B2-M-13 (BK21) 17.3 6.9 5.9 263

HA-B2-M-13 (BK21) 14.6 6.2 4.8 145

HA-B2-M-13 (BK21) 14.4 6.4 4.7 162

HA-B2-M-13 (BK21) 11.3 6.6 5.1 219

HA-B2-M-13 (BK21) 15.1 6.5 4.9 227

HA-B2-M-13 (BK21) 12.1 5.8 4.1 91

HA-B2-M-13 (BK21) 12.5 5.7 3.8 101

HA-B2-M-13 (BK21) 11.4 4.9 4 84

HA-B2-M-13 (BK21) 12.6 5.3 4.1 109

HA-B2-M-13 (BK21) 11.3 5 3.4 70

HA-B2-M-13 (BK21) 11.2 6.1 4.3 94

HA-B2-M-13 (BK21) 8.8 4 3 38

HA-B2-M-13 (BK21) 11.7 5 4.2 98

HA-B2-M-13 (BK21) 9.7 5.2 3.2 58

HA-B2-M-13 (BK21) 11.6 5.8 4.3 99

HA-B2-M-13 (BK21) 10.2 5.1 3.7 67

HA-B2-M-13 (BK21) 9 4.2 2.8 40

HA-B2-M-13 (BK21) 8.5 4.5 2.9 45

HA-B2-M-13 (BK21) 6.5 3.2 2.1 16

HA-B2-M-13 (BK21) 6.1 3.2 2.1 11

HA-B2-M-13 (BK21) 9.8 4.6 3.1 50

D-36
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-13 (BK21) 7.6 4.1 2.4 30

HA-B2-M-13 (BK21) 4.8 2.4 1.6 9

HA-B2-M-13 (BK21) 4.4 2.3 1.5 8

HA-B2-M-13 (BK21) 4.5 2.4 1.5 7

HA-B2-M-13 (BK21) 3.7 1.9 1.1 4

HA-B2-M-13 (BK21) 4.4 2.2 1.3 7

HA-B2-M-13 (BK21) 3.2 1.6 1 2

HA-B2-M-13 (BK21) 3.1 1.7 1.1 2

HA-B2-M-13 (BK21) 2.8 1.4 0.9 2

HA-B2-M-13 (BK21) 2.4 1.3 0.9 2

HA-B2-M-13 (BK21) 2.5 1.4 1 2

HA-B2-M-13 (BK21) 2.3 1.3 0.7 1

HA-B2-M-13 (BK21) 1.7 1 0.6 1

HA-B2-M-13 (BK21) 1.9 1 0.6 0.1

HA-B2-M-13 (BK21) 1.9 0.8 0.7 0.1

HA-B2-M-13 (BK21) 1.9 1.2 0.7 0.1

HA-B2-M-13 (BK21) 1.6 0.9 0.5 0.1

HA-B2-M-13 (BK22) 21.9 9.1 8.2 928

HA-B2-M-13 (BK22) 20.9 7.2 8.8 782

HA-B2-M-13 (BK22) 22.4 7.3 7.3 626

HA-B2-M-13 (BK22) 18.8 7.1 5.6 267

HA-B2-M-13 (BK22) 15.7 7 5.6 253

HA-B2-M-13 (BK22) 16.7 6.3 5.5 212

HA-B2-M-13 (BK22) 18.4 6.7 5.8 304

HA-B2-M-13 (BK22) 17.4 7.3 5.7 296

HA-B2-M-13 (BK22) 12.4 5.5 4.2 102

HA-B2-M-13 (BK22) 9.8 4.6 3.1 49

HA-B2-M-13 (BK22) 9.7 4.6 3.3 56

HA-B2-M-13 (BK22) 7.8 4.2 2.7 34

HA-B2-M-13 (BK22) 7.6 3.6 2.5 27

HA-B2-M-13 (BK22) 9.1 4.4 3.4 52

HA-B2-M-13 (BK22) 8 3.9 2.7 30

HA-B2-M-13 (BK22) 8.4 4.4 3 43

HA-B2-M-13 (BK22) 9.5 4.4 3.1 51

HA-B2-M-13 (BK22) 7.7 4.5 3.5 49

HA-B2-M-13 (BK22) 7.7 3.9 2.6 31

HA-B2-M-13 (BK22) 7.1 3.6 2.1 24

HA-B2-M-13 (BK22) 7.6 3.9 2.3 32

HA-B2-M-13 (BK22) 7.3 3.8 2 24

HA-B2-M-13 (BK22) 8.9 5 3 45

HA-B2-M-13 (BK22) 7.4 3.6 2.5 27

HA-B2-M-13 (BK22) 7.1 3.6 2.3 23

HA-B2-M-13 (BK22) 8.1 4.1 3 38

HA-B2-M-13 (BK22) 7.9 4.2 2.6 30

HA-B2-M-13 (BK22) 6.4 3.6 2.5 24

HA-B2-M-13 (BK22) 6.6 3.1 2 20

HA-B2-M-13 (BK22) 7.1 3.6 2.3 25

HA-B2-M-13 (BK22) 6.1 3 1.9 15

D-37
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-13 (BK22) 6.4 3.9 2 20

HA-B2-M-13 (BK22) 5.6 3 1.9 13

HA-B2-M-13 (BK22) 3.4 1.7 1.1 4

HA-B2-M-13 (BK22) 3.3 1.7 1.2 4

HA-B2-M-13 (BK22) 3.6 1.9 1.2 5

HA-B2-M-13 (BK22) 1.9 1.2 7 1

HA-B2-M-13 (BK22) 8.3 4.7 3.4 69

HA-B2-M-13 (BK22) 8.9 4.4 3 43

HA-B2-M-14 (BK19) 19.9 7.9 7.9 536

HA-B2-M-14 (BK19) 20 8.3 6.5 442

HA-B2-M-14 (BK19) 19.1 7.9 6.3 443

HA-B2-M-14 (BK19) 10.4 5.2 4 83

HA-B2-M-14 (BK19) 10.7 5.5 3.7 80

HA-B2-M-14 (BK19) 10.2 5.1 3.5 88

HA-B2-M-14 (BK19) 9.8 4.8 3.8 67

HA-B2-M-14 (BK19) 8.1 4.4 3 43

HA-B2-M-14 (BK19) 8.2 4.2 2.5 31

HA-B2-M-14 (BK19) 8.7 4.6 3 45

HA-B2-M-14 (BK19) 8.2 4.5 2.9 40

HA-B2-M-14 (BK19) 7.2 4.1 2.6 38

HA-B2-M-14 (BK19) 6.3 2.9 2.2 17

HA-B2-M-14 (BK19) 5.7 3.5 2.3 21

HA-B2-M-14 (BK19) 5.9 3.4 1.9 19

HA-B2-M-14 (BK19) 5.2 2.9 1.7 15

HA-B2-M-14 (BK19) 5.9 3.2 1.9 18

HA-B2-M-14 (BK19) 4.9 2.4 1.4 10

HA-B2-M-14 (BK19) 5.1 2.9 1.7 13

HA-B2-M-14 (BK19) 3 1.5 1 7

HA-B2-M-14 (BK19) 2.4 1.4 0.9 1

HA-B2-M-14 (BK19) 2.5 1.3 0.8 1

HA-B2-M-14 (BK19) 2.2 1.1 0.7 1

HA-B2-M-14 (BK20) 21.7 7.1 8.6 716

HA-B2-M-14 (BK20) 21.4 9.2 6.5 461

HA-B2-M-14 (BK20) 19.9 8.3 6.7 423

HA-B2-M-14 (BK20) 18.4 8.4 6.8 425

HA-B2-M-14 (BK20) 17.8 8.6 6.8 400

HA-B2-M-14 (BK20) 16.4 7 5.8 226

HA-B2-M-14 (BK20) 14.4 6.9 4.9 220

HA-B2-M-14 (BK20) 11.9 5.8 4.3 114

HA-B2-M-14 (BK20) 10.4 5.4 3.7 75

HA-B2-M-14 (BK20) 10.4 5.5 4.1 87

HA-B2-M-14 (BK20) 8.8 4.5 2.6 40

HA-B2-M-14 (BK20) 8.4 4.6 3 46

HA-B2-M-14 (BK20) 7.6 3.6 2.7 30

HA-B2-M-14 (BK20) 6.6 3.5 2.3 20

HA-B2-M-14 (BK20) 5.4 2.9 1.7 11

HA-B2-M-14 (BK20) 5.1 2.7 1.8 10

D-38
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-14 (BK20) 4.5 2.6 2.1 11

HA-B2-M-14 (BK20) 5.3 2.6 1.7 12

HA-B2-M-14 (BK20) 3.9 2.1 1.2 5

HA-B2-M-14 (BK20) 3.3 1.8 1 3

HA-B2-M-14 (BK20) 3.2 1.6 1 3

HA-B2-M-14 (BK20) 2.9 1.8 1 2

HA-B2-M-14 (BK20) 3.1 2.1 1.1 3

HA-B2-M-14 (BK20) 2.1 1.3 0.3 1

HA-B2-M-14 (BK20) 2 1.1 0.6 1

HA-B2-M-14 (BK20) 1.9 1.2 0.6 1

HA-B2-M-14 (BK20) 1.2 0.6 0.4 1

HA-B2-M-15 (BK24) 18.1 7.9 6.2 294

HA-B2-M-15 (BK24) 18.7 7.2 6.5 355

HA-B2-M-15 (BK24) 15.8 6.6 5.7 212

HA-B2-M-15 (BK24) 14.7 5.9 4.9 166

HA-B2-M-15 (BK24) 14.7 6.6 6 206

HA-B2-M-15 (BK24) 16.1 6.7 5.9 228

HA-B2-M-15 (BK24) 15.1 6.3 4.6 160

HA-B2-M-15 (BK24) 13.5 6 4.5 120

HA-B2-M-15 (BK24) 13.2 5.8 4.3 134

HA-B2-M-15 (BK24) 12 5.8 4.1 108

HA-B2-M-15 (BK24) 11.4 5.2 3.4 81

HA-B2-M-15 (BK24) 10.4 4.8 3.2 62

HA-B2-M-15 (BK24) 8.6 4.3 3 41

HA-B2-M-15 (BK24) 7.9 3.9 2.7 32

HA-B2-M-15 (BK24) 11.4 5.7 3.9 83

HA-B2-M-15 (BK24) 11.8 5.3 3.8 102

HA-B2-M-15 (BK24) 12.2 5.8 4.2 99

HA-B2-M-15 (BK24) 17.6 7.5 5.9 283

HA-B2-M-15 (BK24) 11.1 5.5 3.5 75

HA-B2-M-15 (BK24) 11 5.9 3.7 94

HA-B2-M-15 (BK24) 10.9 4.6 3.8 68

HA-B2-M-15 (BK24) 10.6 4.7 3.6 63

HA-B2-M-15 (BK24) 8.7 4.3 2.9 36

HA-B2-M-15 (BK24) 8.4 4.7 3.4 55

HA-B2-M-15 (BK24) 7.5 4 2.2 25

HA-B2-M-15 (BK24) 8.1 3.8 2.7 33

HA-B2-M-15 (BK24) 7.3 3.8 2.2 23

HA-B2-M-15 (BK24) 6.8 3.8 2.3 21

HA-B2-M-15 (BK24) 6.9 3.4 2.4 20

HA-B2-M-15 (BK24) 6.9 3.1 2.5 20

HA-B2-M-15 (BK24) 7 3.7 2.4 28

HA-B2-M-15 (BK24) 7.1 3.7 2.8 34

HA-B2-M-15 (BK24) 8.1 4.3 2.8 2.8

HA-B2-M-15 (BK24) 6 3.4 2.4 21

HA-B2-M-15 (BK24) 6.1 3.3 2 16

HA-B2-M-15 (BK24) 6.4 3.9 2.4 18

D-39
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-15 (BK24) 5.9 3.1 1.8 11

HA-B2-M-15 (BK24) 5.4 2.7 2 12

HA-B2-M-15 (BK24) 5.4 3.1 1.9 12

HA-B2-M-15 (BK24) 5 3 1.6 11

HA-B2-M-15 (BK24) 5 2.3 1.9 12

HA-B2-M-15 (BK24) 4.5 2.5 1.8 10

HA-B2-M-15 (BK24) 5.3 3 2 12

HA-B2-M-15 (BK24) 4.6 2.6 1.5 8

HA-B2-M-15 (BK24) 4.9 2.6 2 12

HA-B2-M-15 (BK24) 5 2.7 1.7 14

HA-B2-M-15 (BK24) 4.7 2.5 1.6 8

HA-B2-M-15 (BK24) 4.9 3 2 14

HA-B2-M-15 (BK24) 4.4 2.3 1.4 5

HA-B2-M-15 (BK24) 4.4 2.4 1.4 7

HA-B2-M-15 (BK24) 4.2 2.6 1.8 8

HA-B2-M-15 (BK24) 3.4 1.7 1.3 4

HA-B2-M-15 (BK24) 3.4 1.8 1.2 3

HA-B2-M-15 (BK24) 3.2 1.7 1.1 3

HA-B2-M-15 (BK24) 3.3 1.6 1.3 3

HA-B2-M-15 (BK24) 2.9 1.6 1.1 3

HA-B2-M-15 (BK24) 3.4 1.8 1.2 4

HA-B2-M-15 (BK24) 2.9 1.6 1 2

HA-B2-M-15 (BK24) 2.8 1.3 0.9 2

HA-B2-M-15 (BK24) 2.4 1.4 0.9 2

HA-B2-M-15 (BK24) 1.7 1 0.6 0.1

HA-B2-M-15 (BK35) 19.6 7.1 8.8 723

HA-B2-M-15 (BK35) 19.9 7 7.7 898

HA-B2-M-15 (BK35) 10.9 5 3.6 91

HA-B2-M-15 (BK35) 11.9 6 4 98

HA-B2-M-15 (BK35) 14.5 6.2 5.2 198

HA-B2-M-15 (BK35) 13.5 6.3 4.6 176

HA-B2-M-15 (BK35) 16.4 7.2 5.3 290

HA-B2-M-15 (BK35) 13.9 5.9 4.9 150

HA-B2-M-15 (BK35) 11.6 5.6 3.6 81

HA-B2-M-15 (BK35) 13.4 6 4.6 153

HA-B2-M-15 (BK35) 12 5.7 4.2 108

HA-B2-M-15 (BK35) 10.4 4.9 3.3 71

HA-B2-M-15 (BK35) 8.9 4.2 2.8 37

HA-B2-M-15 (BK35) 8.7 4.6 4.1 49

HA-B2-M-15 (BK35) 8.9 4.4 2.8 41

HA-B2-M-15 (BK35) 8.9 4.5 3.2 55

HA-B2-M-15 (BK35) 10.4 5.1 3.1 63

HA-B2-M-15 (BK35) 9.4 4.7 3.2 55

HA-B2-M-15 (BK35) 8.1 4 2.8 35

HA-B2-M-15 (BK35) 6.5 3.5 2.5 23

HA-B2-M-15 (BK35) 6.8 3.6 2.5 28

HA-B2-M-15 (BK35) 7.3 3.7 2.2 25

HA-B2-M-15 (BK35) 8.7 4.3 2.9 41

D-40
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-15 (BK35) 7.8 3.8 2.8 35

HA-B2-M-15 (BK35) 6.4 4.1 2.8 26

HA-B2-M-15 (BK35) 7.5 3.5 2.3 22

HA-B2-M-15 (BK35) 7.4 3.8 2.3 24

HA-B2-M-15 (BK35) 6.6 3.5 2.6 22

HA-B2-M-15 (BK35) 7.7 3.7 2.7 29

HA-B2-M-15 (BK35) 7.5 3.5 3 33

HA-B2-M-15 (BK35) 7.2 3.5 2.3 24

HA-B2-M-15 (BK35) 6.1 3.5 2.4 23

HA-B2-M-15 (BK35) 6.9 3.5 2.1 20

HA-B2-M-15 (BK35) 6.2 3.3 2.3 16

HA-B2-M-15 (BK35) 5.9 3 2.4 21

HA-B2-M-15 (BK35) 6.4 3.1 2.2 11

HA-B2-M-15 (BK35) 6.9 3.3 2.5 25

HA-B2-M-15 (BK35) 4.1 3.1 2 16

HA-B2-M-15 (BK35) 5.9 2.8 2 14

HA-B2-M-15 (BK35) 5.6 3.3 2 14

HA-B2-M-15 (BK35) 6.4 3.3 1.9 16

HA-B2-M-15 (BK35) 5.3 2.8 2 13

HA-B2-M-15 (BK35) 5.4 2.9 1.8 13

HA-B2-M-15 (BK35) 5.4 2.8 1.8 12

HA-B2-M-15 (BK35) 5.1 3 1.8 11

HA-B2-M-15 (BK35) 5.1 2.9 1.8 11

HA-B2-M-15 (BK35) 3.9 2.1 1.2 4

HA-B2-M-15 (BK35) 2.9 1.6 1 2

HA-B2-M-15 (BK35) 3.8 2.1 1.5 7

HA-B2-M-15 (BK35) 2.4 1.4 0.9 2

HA-B2-M-15 (BK35) 3.8 2 1.4 5

HA-B2-M-15 (BK35) 6.3 3 2 16

HA-B2-M-15 (BK35) 4.7 2.7 1.7 10

HA-B2-M-15 (BK35) 4.4 2.4 1.4 6

HA-B2-M-15 (BK35) 3.4 2.8 1.2 3

HA-B2-M-15 (BK35) 4.9 2.9 2.3 15

HA-B2-M-15 (BK35) 3.9 2.3 1.2 4

HA-B2-M-15 (BK35) 2.9 1.7 1.1 2

HA-B2-M-15 (BK35) 4.9 2.4 1.8 11

HA-B2-M-15 (BK35) 5.8 2.7 1.7 10

HA-B2-M-15 (BK35) 5.9 2.8 2.1 15

HA-B2-M-15 (BK35) 5.3 2.9 2.1 13

HA-B2-M-15 (BK35) 4.2 2.1 1.5 5

HA-B2-M-15 (BK35) 5 2.9 1.7 11

HA-B2-M-15 (BK35) 5.4 2.8 1.9 11

HA-B2-M-15 (BK35) 4.6 3.1 2 12

HA-B2-M-15 (BK35) 3.9 2.3 1.3 7

HA-B2-M-15 (BK35) 3.8 2 1.3 6

HA-B2-M-15 (BK35) 4.9 2.5 1.7 10

HA-B2-M-15 (BK35) 1.9 1.2 0.7 0.1

HA-B2-M-15 (BK35) 1.6 0.9 0.7 0.1

D-41
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-15 (BK35) 1.9 1 0.6 0.1

HA-B2-M-15 (BK35) 1.2 0.7 0.5 0.1

HA-B2-M-15 (BK36) 7.9 7.3 7.3 434

HA-B2-M-15 (BK36) 18.1 7.6 5.8 259

HA-B2-M-15 (BK36) 18.1 7 6 270

HA-B2-M-15 (BK36) 13 5.7 4.2 140

HA-B2-M-15 (BK36) 13.3 6.7 4.5 140

HA-B2-M-15 (BK36) 14.1 6.3 4.3 149

HA-B2-M-15 (BK36) 13.6 6.1 4.6 144

HA-B2-M-15 (BK36) 11.8 5.7 4.1 92

HA-B2-M-15 (BK36) 9.9 4.3 3.8 73

HA-B2-M-15 (BK36) 9.4 4.7 3.8 61

HA-B2-M-15 (BK36) 10.1 4.9 3.9 61

HA-B2-M-15 (BK36) 7.9 4 2.6 33

HA-B2-M-15 (BK36) 8.2 4.2 3.5 46

HA-B2-M-15 (BK36) 7.6 4.1 2.7 32

HA-B2-M-15 (BK36) 6.5 2.7 2.5 25

HA-B2-M-15 (BK36) 5.3 3 2 12

HA-B2-M-15 (BK36) 5.2 2.9 2 13

HA-B2-M-15 (BK36) 5.3 2.9 1.7 13

HA-B2-M-15 (BK36) 4.9 2.6 2 11

HA-B2-M-15 (BK36) 4.9 2.6 1.7 9

HA-B2-M-15 (BK36) 5.2 2.7 1.7 8

HA-B2-M-15 (BK36) 4.4 2.2 1.4 7

HA-B2-M-15 (BK36) 3.9 1.9 1.3 5

HA-B2-M-15 (BK36) 3.9 2.3 1.4 6

HA-B2-M-15 (BK36) 3 1.5 1 2

HA-B2-M-15 (BK36) 3.7 1.9 1.2 4

HA-B2-M-15 (BK36) 4.1 2.1 1.4 5

HA-B2-M-15 (BK36) 3.3 1.8 1.1 2

HA-B2-M-15 (BK36) 2.4 1.4 1.8 1

HA-B2-M-15 (BK36) 2.6 1.4 0.9 2

HA-B2-M-15 (BK36) 2 1 0.7 1

HA-B2-M-15 (BK36) 1.7 1 0.5 0.1

HA-B2-M-15 (BK36) 18.4 7.2 6 466

HA-B2-M-17 (BK16) 18.2 7.2 6.2 403

HA-B2-M-17 (BK16) 23.2 8.3 7.9 599

HA-B2-M-17 (BK16) 17.6 7.5 6.7 324

HA-B2-M-17 (BK16) 17.9 6.7 6.7 298

HA-B2-M-17 (BK16) 17.5 6.6 6.4 315

HA-B2-M-17 (BK16) 14.9 6.6 5.2 173

HA-B2-M-17 (BK16) 13.4 6.3 4.7 173

HA-B2-M-17 (BK16) 11.4 5.6 4 98

HA-B2-M-17 (BK16) 11.4 5.7 4.6 105

HA-B2-M-17 (BK16) 10.9 5.2 4.2 110

HA-B2-M-17 (BK16) 12.7 6 4.5 121

HA-B2-M-17 (BK16) 9.8 4.8 3.3 53

D-42
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-17 (BK16) 8.9 4.7 3.2 50

HA-B2-M-17 (BK16) 8.9 4.8 3.2 51

HA-B2-M-17 (BK16) 9.6 5 3.2 59

HA-B2-M-17 (BK16) 8.3 4.3 2.9 42

HA-B2-M-17 (BK16) 8.6 4.5 3.1 47

HA-B2-M-17 (BK16) 8.4 4.1 2.6 36

HA-B2-M-17 (BK16) 6.9 3.6 2.7 30

HA-B2-M-17 (BK16) 6.6 3.3 2.5 24

HA-B2-M-17 (BK16) 6.9 3.3 2.3 22

HA-B2-M-17 (BK16) 6.5 3.1 2.4 18

HA-B2-M-17 (BK16) 5.9 3.3 2.2 17

HA-B2-M-17 (BK16) 5.8 3 2 16

HA-B2-M-17 (BK16) 5.5 3.4 2.1 17

HA-B2-M-17 (BK16) 5.1 2.8 1.8 14

HA-B2-M-17 (BK16) 5 2.8 1.5 11

HA-B2-M-17 (BK16) 4.7 2.5 1.7 9

HA-B2-M-17 (BK16) 4.5 2.4 4.5 7

HA-B2-M-17 (BK16) 4.5 2.4 1.8 10

HA-B2-M-17 (BK16) 3 2.1 1.2 4

HA-B2-M-17 (BK16) 3.3 1.9 1.1 4

HA-B2-M-17 (BK16) 1.9 1.2 0.7 1

HA-B2-M-17 (BK16) 2.7 1.8 0.9 2

HA-B2-M-17 (BK16) 11.4 4.8 3.9 79

HA-B2-M-17 (BK16) 10.4 5.1 3.7 69

HA-B2-M-17 (BK16) 9.4 4.6 3.7 59

HA-B2-M-17 (BK16) 8.6 4.2 3 40

HA-B2-M-17 (BK16) 9.6 5.1 3.3 58

HA-B2-M-17 (BK16) 8.8 4.6 3.3 52

HA-B2-M-17 (BK16) 8.9 4.3 3.6 68

HA-B2-M-17 (BK16) 8.6 4.7 3.1 55

HA-B2-M-17 (BK16) 8.7 4.5 3.2 50

HA-B2-M-17 (BK16) 11 4.9 3.5 85

HA-B2-M-17 (BK16) 9.4 4.7 3.5 54

HA-B2-M-17 (BK16) 9.3 4.3 3.5 56

HA-B2-M-17 (BK16) 7.9 3.9 2.9 35

HA-B2-M-17 (BK16) 7.3 3.4 2.7 25

HA-B2-M-17 (BK16) 6.9 4.3 2.9 31

HA-B2-M-17 (BK16) 7.4 3.9 2.3 26

HA-B2-M-17 (BK16) 6.9 3.6 2.1 23

HA-B2-M-17 (BK16) 7.6 3.6 2.6 29

HA-B2-M-17 (BK16) 6.4 3.4 2.3 21

HA-B2-M-17 (BK16) 6.3 3.4 2.4 18

HA-B2-M-17 (BK16) 6.1 3 2.2 17

HA-B2-M-17 (BK16) 5.4 2.7 1.7 11

HA-B2-M-17 (BK16) 5.7 3.1 1.8 13

HA-B2-M-17 (BK16) 5.8 3 2 19

HA-B2-M-17 (BK16) 5.4 3 2 16

HA-B2-M-17 (BK16) 5.7 3.2 1.8 15

D-43
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-17 (BK16) 5.3 2.9 1.7 13

HA-B2-M-17 (BK16) 5.3 3.3 1.7 16

HA-B2-M-17 (BK16) 4.8 2.8 1.9 9

HA-B2-M-17 (BK16) 3.8 2.2 1.3 6

HA-B2-M-17 (BK16) 4.8 2.7 1.5 13

HA-B2-M-17 (BK16) 3.1 1.8 1.2 5

HA-B2-M-17 (BK16) 3.4 2.9 1.1 4

HA-B2-M-17 (BK16) 3.4 2.1 1.3 5

HA-B2-M-17 (BK16) 3.5 2.1 1.3 5

HA-B2-M-17 (BK16) 3.1 1.8 1.1 3

HA-B2-M-17 (BK16) 3.3 1.8 1.1 3

HA-B2-M-17 (BK16) 2.7 1.6 1 2

HA-B2-M-17 (BK16) 2.6 1.6 1 3

HA-B2-M-17 (BK16) 2.4 1.5 1 2

HA-B2-M-17 (BK16) 2.4 1.4 0.9 2

HA-B2-M-17 (BK16) 2.6 1.6 0.9 2

HA-B2-M-17 (BK16) 2.5 1.5 0.9 2

HA-B2-M-17 (BK16) 3.3 1.4 0.9 2

HA-B2-M-17 (BK16) 1.7 0.9 0.7 1

HA-B2-M-17 (BK16) 2.1 1.5 0.7 1

HA-B2-M-17 (BK16) 1.6 1.1 0.6 0.1

HA-B2-M-17 (BK16) 1.5 0.9 0.6 1

HA-B2-M-17 (BK16) 1.5 1 0.6 1

HA-B2-M-17 (BK16) 1.5 1 0.5 0.1

HA-B2-M-17 (BK16) 1.4 0.8 0.5 0.1

HA-B2-M-17 (BK16) 1.4 0.8 0.5 0.1

HA-B2-M-17 (BK16) 1.2 0.7 0.4 0.1

HA-B2-M-19 (BK14) 18.4 7.9 7.5 642

HA-B2-M-19 (BK14) 16.6 7.2 6.1 295

HA-B2-M-19 (BK14) 18.4 8 6.7 523

HA-B2-M-19 (BK14) 13.4 6.1 4.6 150

HA-B2-M-19 (BK14) 14.2 6.5 5 211

HA-B2-M-19 (BK14) 11.8 5.6 3.9 100

HA-B2-M-19 (BK14) 13.6 6.1 4.6 151

HA-B2-M-19 (BK14) 11.5 5.8 3.2 43

HA-B2-M-19 (BK14) 9.9 4.5 3 59

HA-B2-M-19 (BK14) 10.1 5.4 3.5 89

HA-B2-M-19 (BK14) 8 4.1 2.9 38

HA-B2-M-19 (BK14) 10.7 5 4.5 64

HA-B2-M-19 (BK14) 9.5 5 3.6 51

HA-B2-M-19 (BK14) 8.4 4.3 3.8 38

HA-B2-M-19 (BK14) 8.5 4.6 2.6 44

HA-B2-M-19 (BK14) 7 3.5 2.6 30

HA-B2-M-19 (BK14) 8.7 4.2 2.8 31

HA-B2-M-19 (BK14) 8.8 4.7 3.6 51

HA-B2-M-19 (BK14) 7.4 3.4 2.4 28

HA-B2-M-19 (BK14) 7.4 4 2.4 31

D-44
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-19 (BK14) 7.1 3.4 2.5 21

HA-B2-M-19 (BK14) 6.1 3.5 2.8 27

HA-B2-M-19 (BK14) 6.2 3.6 2.1 14

HA-B2-M-19 (BK14) 6.7 3.3 2.1 23

HA-B2-M-19 (BK14) 6.5 3.7 2.6 25

HA-B2-M-19 (BK14) 6.1 3.1 2 16

HA-B2-M-19 (BK14) 6.4 3.8 2.7 28

HA-B2-M-19 (BK14) 6.9 3.6 2.3 24

HA-B2-M-19 (BK14) 7 3.3 2.3 23

HA-B2-M-19 (BK14) 6.3 3 2.2 16

HA-B2-M-19 (BK14) 5.4 3 1.8 13

HA-B2-M-19 (BK14) 4.9 2.9 1.6 13

HA-B2-M-19 (BK14) 5.4 2.9 1.9 13

HA-B2-M-19 (BK14) 5.4 2.6 1.8 11

HA-B2-M-19 (BK14) 5.3 2.5 1.7 10

HA-B2-M-19 (BK14) 4.8 2.8 1.8 9

HA-B2-M-19 (BK14) 4.2 2.6 1.8 7

HA-B2-M-19 (BK14) 4.6 2.4 1.3 7

HA-B2-M-19 (BK14) 6 2.2 1.8 9

HA-B2-M-19 (BK14) 4.9 2.3 1.8 10

HA-B2-M-19 (BK14) 4.5 2.3 1.5 8

HA-B2-M-19 (BK14) 4.5 2.1 1.5 7

HA-B2-M-19 (BK14) 3.8 2.1 1.3 5

HA-B2-M-19 (BK14) 4.1 2 1.3 5

HA-B2-M-19 (BK14) 3.9 2.7 1.5 6

HA-B2-M-19 (BK14) 3.9 2.2 1.4 5

HA-B2-M-19 (BK14) 3.8 2 1.2 5

HA-B2-M-19 (BK14) 4.5 2.3 1.5 6

HA-B2-M-19 (BK14) 3.4 1.9 0.9 3

HA-B2-M-19 (BK14) 3.5 1.9 1.2 3

HA-B2-M-19 (BK14) 3.2 1.8 1 2

HA-B2-M-19 (BK14) 3.4 1.7 1.2 4

HA-B2-M-19 (BK14) 3.5 2 1.2 4

HA-B2-M-19 (BK14) 2.7 1.7 1 2

HA-B2-M-19 (BK14) 2.8 1.8 1 2

HA-B2-M-19 (BK14) 2.8 1.6 1 1

HA-B2-M-19 (BK14) 2.6 1.6 0.8 2

HA-B2-M-19 (BK14) 2.4 1.4 0.9 2

HA-B2-M-19 (BK14) 2.4 1.5 0.9 2

HA-B2-M-19 (BK14) 1.9 1.2 0.7 1

HA-B2-M-19 (BK14) 2.2 1.4 0.8 1

HA-B2-M-19 (BK14) 1.5 1 0.6 0.1

HA-B2-M-19 (BK14) 1.8 1 0.7 0.1

HA-B2-M-19 (BK14) 1.7 1 0.7 1

HA-B2-M-19 (BK14) 1.2 0.9 0.5 0.1

HA-B2-M-19 (BK14) 1.2 0.7 0.4 0.1

HA-B2-M-19 (BK14) 1.8 1.2 0.6 1

HA-B2-M-19 (BK15) 6.3 3 2.2 20

D-45
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-19 (BK15) 10.1 5.2 3.4 70

HA-B2-M-19 (BK15) 8.1 4.4 3.3 41

HA-B2-M-19 (BK15) 19.3 7.8 7.2 532

HA-B2-M-19 (BK15) 18.8 7.5 6.7 450

HA-B2-M-19 (BK15) 18.6 6.9 6.7 366

HA-B2-M-19 (BK15) 17.4 7.2 7.2 397

HA-B2-M-19 (BK15) 17.1 7 5.5 382

HA-B2-M-19 (BK15) 16.6 7 5.5 284

HA-B2-M-19 (BK15) 17.8 7.4 6.3 366

HA-B2-M-19 (BK15) 14.6 67 4.4 169

HA-B2-M-19 (BK15) 11.7 5.7 4.2 110

HA-B2-M-19 (BK15) 13.2 6.3 4.5 131

HA-B2-M-19 (BK15) 12.2 6.8 4.3 104

HA-B2-M-19 (BK15) 10.8 3.3 3.8 68

HA-B2-M-19 (BK15) 11.2 5.4 3.8 82

HA-B2-M-19 (BK15) 9.7 4.4 3.5 64

HA-B2-M-19 (BK15) 9.9 4.4 3.2 68

HA-B2-M-19 (BK15) 10.1 5.2 3.4 78

HA-B2-M-19 (BK15) 8.1 4.5 3.3 47

HA-B2-M-19 (BK15) 8.6 4.3 3.1 45

HA-B2-M-19 (BK15) 8.9 4.8 3.4 59

HA-B2-M-19 (BK15) 8.2 4.2 3.8 46

HA-B2-M-19 (BK15) 8.2 3.3 3.1 67

HA-B2-M-19 (BK15) 9.1 4.5 3.1 52

HA-B2-M-19 (BK15) 8.1 3.6 2.6 35

HA-B2-M-19 (BK15) 6.7 3.8 2.4 22

HA-B2-M-19 (BK15) 7.6 3.8 2.6 29

HA-B2-M-19 (BK15) 7.6 3.9 2.9 36

HA-B2-M-19 (BK15) 7.6 3.6 2.8 33

HA-B2-M-19 (BK15) 6.9 3.9 2.9 28

HA-B2-M-19 (BK15) 5.6 3 2.4 23

HA-B2-M-19 (BK15) 5.4 3.1 2.2 20

HA-B2-M-19 (BK15) 6.4 3.2 2.1 21

HA-B2-M-19 (BK15) 8 3.7 2.3 33

HA-B2-M-19 (BK15) 6.4 3.2 2.1 22

HA-B2-M-19 (BK15) 5.8 3.1 2.2 18

HA-B2-M-19 (BK15) 5.7 3.2 2.1 18

HA-B2-M-19 (BK15) 6.3 3.2 2.2 20

HA-B2-M-19 (BK15) 6.2 2.8 2.2 15

HA-B2-M-19 (BK15) 7.7 4.2 3 39

HA-B2-M-19 (BK15) 5.5 3 1.9 13

HA-B2-M-19 (BK15) 5.9 3 2.1 14

HA-B2-M-19 (BK15) 6.3 3.5 2.5 22

HA-B2-M-19 (BK15) 5.6 3 2 15

HA-B2-M-19 (BK15) 5.6 2.8 1.7 12

HA-B2-M-19 (BK15) 5.7 3.2 2.2 17

HA-B2-M-19 (BK15) 4.4 1.9 1.2 12

HA-B2-M-19 (BK15) 3.7 2.6 1.6 5

D-46
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-19 (BK15) 5.2 3 1.8 13

HA-B2-M-19 (BK15) 4.3 2.2 1.4 7

HA-B2-M-19 (BK15) 4.6 2.2 1.6 8

HA-B2-M-19 (BK15) 3.6 2 1.2 5

HA-B2-M-19 (BK15) 3.5 1.4 1.3 3

HA-B2-M-19 (BK15) 3.1 1.8 1.1 4

HA-B2-M-19 (BK15) 2.7 1.4 1 2

HA-B2-M-19 (BK15) 3.4 1.7 1.2 4

HA-B2-M-19 (BK15) 3.5 1.9 1.2 3

HA-B2-M-19 (BK15) 2.3 1.4 0.9 2

HA-B2-M-19 (BK15) 2.3 1.3 0.9 1

HA-B2-M-19 (BK15) 2.2 1.2 0.8 0.1

HA-B2-M-19 (BK15) 1.7 1 0.6 1

HA-B2-M-19 (BK15) 1.7 1 0.5 0.1

HA-B2-M-21 (BK12) 19.4 7.3 6.4 328

HA-B2-M-21 (BK12) 18.7 7.8 6.6 321

HA-B2-M-21 (BK12) 20.4 7.7 7.2 457

HA-B2-M-21 (BK12) 18.9 6.7 7.1 270

HA-B2-M-21 (BK12) 21.1 8.1 8 431

HA-B2-M-21 (BK12) 18 6.1 6.8 289

HA-B2-M-21 (BK12) 15.4 6.7 4.9 158

HA-B2-M-21 (BK12) 18 7.3 6.2 286

HA-B2-M-21 (BK12) 14.6 6.4 4.7 129

HA-B2-M-21 (BK12) 15.6 6.2 4.7 185

HA-B2-M-21 (BK12) 11 5.5 4.5 90

HA-B2-M-21 (BK12) 12.6 5 4.3 120

HA-B2-M-21 (BK12) 11.1 5.2 3.7 69

HA-B2-M-21 (BK12) 9.9 4.8 3.2 49

HA-B2-M-21 (BK12) 9.9 4.9 3.4 60

HA-B2-M-21 (BK12) 9.9 5 3.1 47

HA-B2-M-21 (BK12) 10.4 4.7 3.6 67

HA-B2-M-21 (BK12) 9.9 4.7 3.4 54

HA-B2-M-21 (BK12) 9.3 4.5 3 43

HA-B2-M-21 (BK12) 8.8 4.5 3 38

HA-B2-M-21 (BK12) 8.9 4.3 3.1 41

HA-B2-M-21 (BK12) 10.9 5.4 3.8 73

HA-B2-M-21 (BK12) 11.9 5.5 3.9 87

HA-B2-M-21 (BK12) 6.9 3.6 2.6 22

HA-B2-M-21 (BK12) 6.4 3.5 2.7 24

HA-B2-M-21 (BK12) 5.4 2.7 1.7 10

HA-B2-M-21 (BK12) 9.4 4.3 3.3 46

HA-B2-M-21 (BK12) 8.5 4.2 2.8 36

HA-B2-M-21 (BK12) 8.3 4.3 2.6 29

HA-B2-M-21 (BK12) 6.4 3.8 2.8 24

HA-B2-M-21 (BK12) 6.9 3.4 2.3 22

HA-B2-M-21 (BK12) 7.4 4.2 3.7 32

HA-B2-M-21 (BK12) 7.1 3.9 2.7 30

D-47
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-21 (BK12) 7.5 3.6 2.5 25

HA-B2-M-21 (BK12) 6.8 3.5 2.3 20

HA-B2-M-21 (BK12) 6.9 3.1 2.2 19

HA-B2-M-21 (BK12) 7.5 3.8 2.3 24

HA-B2-M-21 (BK12) 6.5 4.1 2.2 20

HA-B2-M-21 (BK12) 6.6 3.2 1.8 16

HA-B2-M-21 (BK12) 5.7 4.4 2.1 16

HA-B2-M-21 (BK12) 6.6 3 2.3 21

HA-B2-M-21 (BK12) 6.8 3.2 2.2 20

HA-B2-M-21 (BK12) 5.9 3.2 2.3 18

HA-B2-M-21 (BK12) 6 3.2 2 14

HA-B2-M-21 (BK12) 4.9 2.7 1.7 6

HA-B2-M-21 (BK12) 5.3 3.1 2.5 15

HA-B2-M-21 (BK12) 6 3.3 2.2 16

HA-B2-M-21 (BK12) 5.4 3.4 1.9 20

HA-B2-M-21 (BK12) 4.5 2.6 1.6 9

HA-B2-M-21 (BK12) 4.6 2.4 1.5 8

HA-B2-M-21 (BK12) 4.4 2.4 1.4 8

HA-B2-M-21 (BK12) 4.4 2.2 1.5 7

HA-B2-M-21 (BK12) 4.4 2.1 1.4 6

HA-B2-M-21 (BK12) 4 2 1.4 5

HA-B2-M-21 (BK12) 3.6 2.2 1.6 7

HA-B2-M-21 (BK12) 4 2 1.3 6

HA-B2-M-21 (BK12) 3.1 1.7 1 3

HA-B2-M-21 (BK12) 3.1 1.7 1.1 4

HA-B2-M-21 (BK12) 2.4 1.4 0.9 2

HA-B2-M-21 (BK12) 2.1 1.3 0.7 2

HA-B2-M-21 (BK12) 2.1 1.4 0.8 0.1

HA-B2-M-21 (BK12) 1.7 1.1 0.7 0.1

HA-B2-M-21 (BK12) 1.6 1 0.6 0.1

HA-B2-M-22 (BK10) 19.8 8 7.9 466

HA-B2-M-22 (BK10) 20.7 8.8 7.6 563

HA-B2-M-22 (BK10) 17.4 7 7.2 276

HA-B2-M-22 (BK10) 19.5 7.6 7.8 377

HA-B2-M-22 (BK10) 14.4 7.5 6.2 172

HA-B2-M-22 (BK10) 12.7 7 5.6 126

HA-B2-M-22 (BK10) 12.8 5.8 5.1 107

HA-B2-M-22 (BK10) 12.2 5.7 3.6 86

HA-B2-M-22 (BK10) 12.8 5.6 4.9 106

HA-B2-M-22 (BK10) 11.9 5.8 4.6 105

HA-B2-M-22 (BK10) 12.3 5.5 4.1 89

HA-B2-M-22 (BK10) 11.3 5.4 3.7 85

HA-B2-M-22 (BK10) 12.2 5.4 4.4 98

HA-B2-M-22 (BK10) 11 5.3 3.7 69

HA-B2-M-22 (BK10) 10.9 5.1 3.7 81

HA-B2-M-22 (BK10) 10.4 5.1 3.7 70

HA-B2-M-22 (BK10) 10.1 5.1 3.7 83

D-48
PLATFORM HARVEST - Mussel Measurements

Station/Quadrat Length 

(cm)

Width 

(cm)

Height 

(cm)

Weight 

(gms)

HA-B2-M-22 (BK10) 8.9 4.4 3.2 45

HA-B2-M-22 (BK10) 8.5 4.3 2.7 34

HA-B2-M-22 (BK10) 9.3 4.7 3.2 47

HA-B2-M-22 (BK10) 7.8 3.7 2.8 28

HA-B2-M-22 (BK10) 7.5 4.1 2.8 38

HA-B2-M-22 (BK10) 8.9 4.3 3 53

HA-B2-M-22 (BK10) 7.5 3.8 2.7 29

HA-B2-M-22 (BK10) 8.4 4 2.6 34

HA-B2-M-22 (BK10) 7.6 3.7 2.3 30

HA-B2-M-22 (BK10) 7.9 3.8 2.8 32

HA-B2-M-22 (BK10) 6.9 3.6 2.3 20

HA-B2-M-22 (BK10) 7.2 3.7 2.3 25

HA-B2-M-22 (BK10) 6.8 3.7 2.2 22

HA-B2-M-22 (BK10) 5.9 3.4 2.2 13

HA-B2-M-22 (BK10) 5.9 3.2 2 18

HA-B2-M-22 (BK10) 5.9 3 1.9 15

HA-B2-M-22 (BK10) 5.9 3 2.1 16

HA-B2-M-22 (BK10) 5.4 2.6 1.7 10

HA-B2-M-22 (BK10) 5.4 2.8 1.7 14

HA-B2-M-22 (BK10) 4.7 2.4 1.4 9

HA-B2-M-22 (BK10) 4.6 2.5 1.4 8

HA-B2-M-22 (BK10) 4.3 2.2 1.6 7

HA-B2-M-22 (BK10) 3.8 2.3 1.3 4

HA-B2-M-22 (BK10) 4.4 2.3 1.5 8

HA-B2-M-22 (BK10) 4.3 2.3 1.4 6

HA-B2-M-22 (BK10) 3.7 1.2 1.3 5

HA-B2-M-22 (BK10) 3.9 2.1 1.3 5

HA-B2-M-22 (BK10) 3.3 1.8 1.1 3

HA-B2-M-22 (BK10) 2.3 1.3 0.3 1

HA-B2-M-22 (BK10) 2.3 1.5 0.8 1

HA-B2-M-22 (BK10) 2.2 1.2 0.8 1

HA-B2-M-22 (BK10) 1.8 0.1 0.7 1

D-49
MUSSEL MEASUREMENTS - STATISTICS

Quadrat/Parameter Length (cm) Width (cm) Height (cm) Weight (gms)

HA-B1-M-18:

Mean 7.23 3.68 2.69 55.51

Standard Error 0.55 0.22 0.21 11.80

Median 7.2 4 2.6 28

Mode 8.3 4.2 3.7 1

Standard Deviation 4.40 1.78 1.69 93.65

Sample Variance 19.34 3.18 2.84 8770.86

Kurtosis 0.149706745 -0.749250115 1.028096656 10.30707924

Skewness 0.708772082 0.154299079 0.93116508 3.147967186

Range 17.5 6.9 7.2 465.9

Minimum 1.4 1 0.5 0.1

Maximum 18.9 7.9 7.7 466

Sum 455.8 232.1 169.6 3497.4

Count 63 63 63 63

Confidence Level(95.0%) 1.11 0.45 0.42 23.59

HA-B1-M-20:

Mean 4.13 2.25 1.58 10.78

Standard Error 1.37 0.68 0.48 6.41

Median 4.1 2.35 1.7 7

Mode #N/A #N/A 1.7 #N/A

Standard Deviation 2.73 1.36 0.95 12.81

Sample Variance 7.47 1.84 0.90 164.20

Kurtosis -0.113953843 1.366951267 1.834270762 2.005156132

Skewness 0.048608574 -0.431536903 -0.771249453 1.433864847

Range 6.5 3.3 2.3 28.9

Minimum 0.9 0.5 0.3 0.1

Maximum 7.4 3.8 2.6 29

Sum 16.5 9 6.3 43.1

Count 4 4 4 4

Confidence Level(95.0%) 4.35 2.16 1.51 20.39

HA-B1-M-24:

Mean 3.81 2.25 1.67 19.17

Standard Error 0.61 0.30 0.23 6.77

Median 2.65 1.55 1.15 2.5

Mode 5.4 1.4 1.1 2

Standard Deviation 3.10 1.53 1.19 34.53

Sample Variance 9.61 2.35 1.42 1192.64

Kurtosis 0.187012975 0.273587781 0.860081563 4.302013949

Skewness 1.126419561 1.177719254 1.323222297 2.258829386

Range 10.3 5.1 4.1 125.9

Minimum 0.7 0.7 0.4 0.1

Maximum 11 5.8 4.5 126

Sum 99 58.4 43.3 498.4

Count 26 26 26 26

Confidence Level(95.0%) 1.25 0.62 0.48 13.95

D-50
MUSSEL MEASUREMENTS - STATISTICS

Quadrat/Parameter Length (cm) Width (cm) Height (cm) Weight (gms)

HA-B1-M-25:

Mean 4.92 2.67 1.80 21.78

Standard Error 0.71 0.33 0.26 8.55

Median 4.3 2.5 1.75 9.5

Mode 5.3 4.7 0.6 1

Standard Deviation 3.34 1.54 1.22 40.08

Sample Variance 11.16 2.36 1.49 1606.44

Kurtosis 2.347923874 0.342423955 2.62702799 14.47868564

Skewness 1.320932704 0.863525544 1.387838789 3.585475394

Range 13.5 5.7 5 185.9

Minimum 1.4 0.9 0.5 0.1

Maximum 14.9 6.6 5.5 186

Sum 108.3 58.8 39.6 479.2

Count 22 22 22 22

Confidence Level(95.0%) 1.48 0.68 0.54 17.77

HA-B1-M-32:

Mean 5.42 2.94 1.96 25.36

Standard Error 0.71 0.36 0.25 9.74

Median 5.3 2.7 1.95 13.5

Mode 6.4 3.9 2.6 1

Standard Deviation 3.18 1.60 1.11 43.55

Sample Variance 10.14 2.57 1.23 1896.97

Kurtosis 3.120295248 0.533221648 2.59345907 15.18890291

Skewness 1.267176194 0.67994094 1.113368113 3.708845105

Range 13.4 6.1 4.7 199.9

Minimum 1.6 0.9 0.5 0.1

Maximum 15 7 5.2 200

Sum 108.4 58.7 39.1 507.2

Count 20 20 20 20

Confidence Level(95.0%) 1.49 0.75 0.52 20.38

HA-B2-M-11:

Mean 8.67 4.02 2.93 78.94

Standard Error 0.43 0.16 0.15 9.24

Median 7.8 4 2.7 31

Mode 8.9 4.4 2.8 2

Standard Deviation 5.24 1.98 1.78 112.80

Sample Variance 27.46 3.93 3.16 12723.13

Kurtosis -0.397724006 -1.042871215 -0.362198636 5.880506061

Skewness 0.643020016 0.191055845 0.663083304 2.278660866

Range 21.1 7.4 7.1 633.9

Minimum 1.3 0.8 0.4 0.1

Maximum 22.4 8.2 7.5 634

Sum 1291.9 599.2 437.3 11762.2

Count 149 149 149 149

Confidence Level(95.0%) 0.85 0.32 0.29 18.26

D-51
MUSSEL MEASUREMENTS - STATISTICS

Quadrat/Parameter Length (cm) Width (cm) Height (cm) Weight (gms)

HA-B2-M-13:

Mean 9.90 4.48 3.42 111.42

Standard Error 0.54 0.19 0.19 16.36

Median 8.9 4.4 3.05 45

Mode 1.9 3.6 3 2

Standard Deviation 5.44 1.96 1.89 165.26

Sample Variance 29.65 3.82 3.57 27310.61

Kurtosis -0.435074615 -0.663078831 -0.069904367 8.281295882

Skewness 0.557638611 -0.039343764 0.638138054 2.675405903

Range 20.8 8.3 8.3 927.9

Minimum 1.6 0.8 0.5 0.1

Maximum 22.4 9.1 8.8 928

Sum 1010.1 457.4 348.8 11364.4

Count 102 102 102 102

Confidence Level(95.0%) 1.07 0.38 0.37 32.46

HA-B2-M-14:

Mean 8.55 4.12 2.99 108.12

Standard Error 0.84 0.34 0.31 24.79

Median 6.9 3.55 2.4 25.5

Mode 10.4 2.9 1.7 1

Standard Deviation 5.95 2.38 2.17 175.30

Sample Variance 35.39 5.65 4.69 30729.25

Kurtosis -0.232103023 -0.705126191 -0.01431437 2.690628472

Skewness 0.933315772 0.562832362 0.954046708 1.912224491

Range 20.5 8.6 8.3 715

Minimum 1.2 0.6 0.3 1

Maximum 21.7 9.2 8.6 716

Sum 427.6 205.8 149.5 5406

Count 50 50 50 50

Confidence Level(95.0%) 1.69 0.68 0.62 49.82

HA-B2-M-15:

Mean 7.53 3.69 2.67 61.40

Standard Error 0.33 0.13 0.12 8.97

Median 6.4 3.3 2.3 20

Mode 4.9 3 2 11

Standard Deviation 4.27 1.71 1.54 115.97

Sample Variance 18.26 2.91 2.36 13449.34

Kurtosis 0.394239661 -0.500005078 1.682091388 22.84287362

Skewness 1.012640442 0.560494941 1.26489547 4.214344122

Range 18.7 7.2 8.3 897.9

Minimum 1.2 0.7 0.5 0.1

Maximum 19.9 7.9 8.8 898

Sum 1257.8 615.6 445.4 10254.4

Count 167 167 167 167

Confidence Level(95.0%) 0.65 0.26 0.23 17.72

D-52
MUSSEL MEASUREMENTS - STATISTICS

Quadrat/Parameter Length (cm) Width (cm) Height (cm) Weight (gms)

HA-B2-M-17:

Mean 6.80 3.40 2.46 50.44

Standard Error 0.47 0.18 0.17 10.17

Median 5.9 3.3 2.2 17

Mode 6.9 4.3 0.9 2

Standard Deviation 4.39 1.72 1.59 94.86

Sample Variance 19.26 2.97 2.53 8999.01

Kurtosis 2.019493814 -0.116844004 1.42490753 15.51374235

Skewness 1.263042824 0.539420941 1.158642617 3.673085426

Range 22 7.6 7.5 598.9

Minimum 1.2 0.7 0.4 0.1

Maximum 23.2 8.3 7.9 599

Sum 591.5 295.8 213.9 4388.5

Count 87 87 87 87

Confidence Level(95.0%) 0.94 0.37 0.34 20.22

HA-B2-M-19:

Mean 7.05 3.93 2.51 59.54

Standard Error 0.38 0.51 0.14 10.12

Median 6.2 3.2 2.2 20

Mode 6.3 3 1.2 2

Standard Deviation 4.34 5.85 1.58 115.44

Sample Variance 18.88 34.20 2.51 13325.82

Kurtosis 0.891526258 106.849472 1.395254956 9.860544779

Skewness 1.149494357 9.87609095 1.256025045 3.133181947

Range 18.1 66.3 7.1 641.9

Minimum 1.2 0.7 0.4 0.1

Maximum 19.3 67 7.5 642

Sum 916.9 510.7 326.1 7739.6

Count 130 130 130 130

Confidence Level(95.0%) 0.75 1.01 0.28 20.03

HA-B2-M-21:

Mean 8.44 3.98 2.95 68.32

Standard Error 0.63 0.22 0.22 13.39

Median 6.9 3.8 2.5 24

Mode 9.9 3.2 2.3 20

Standard Deviation 4.97 1.77 1.76 106.25

Sample Variance 24.72 3.13 3.08 11289.30

Kurtosis 0.369299546 -0.294812527 0.899981009 4.612027153

Skewness 1.033804999 0.488831859 1.167515881 2.295114932

Range 19.5 7.1 7.4 456.9

Minimum 1.6 1 0.6 0.1

Maximum 21.1 8.1 8 457

Sum 531.7 250.5 185.8 4304.3

Count 63 63 63 63

Confidence Level(95.0%) 1.25 0.45 0.44 26.76

D-53
MUSSEL MEASUREMENTS - STATISTICS

Quadrat/Parameter Length (cm) Width (cm) Height (cm) Weight (gms)

HA-B2-M-22:

Mean 8.48 4.06 3.04 72.27

Standard Error 0.67 0.28 0.27 16.60

Median 7.6 3.8 2.7 30

Mode 5.9 3.7 3.7 1

Standard Deviation 4.66 1.95 1.91 116.23

Sample Variance 21.67 3.81 3.66 13509.70

Kurtosis 0.484709989 -0.224871212 0.709903003 8.815968167

Skewness 0.881437802 0.38698279 1.097189705 2.920676156

Range 18.9 8.7 7.6 562

Minimum 1.8 0.1 0.3 1

Maximum 20.7 8.8 7.9 563

Sum 415.6 198.7 148.9 3541

Count 49 49 49 49

Confidence Level(95.0%) 1.34 0.56 0.55 33.39

Mussels Measured by Quadrat

Station Count

HA-B1-M-18 63

HA-B1-M-20 4

HA-B1-M-24 26

HA-B1-M-25 22

HA-B1-M-32 20

HA-B2-M-11 149

HA-B2-M-13 102

HA-B2-M-14 50

HA-B2-M-15 167

HA-B2-M-17 87

HA-B2-M-19 130

HA-B2-M-21 63

HA-B2-M-22 49

Total 932

D-54
PLATFORM GAIL - Taxa vs. All Stations/Quadrats

Species or Taxon

GA-A1-B/S-49

GA-A1-B/S-56

GA-A1-B/S-63

GA-A1-B/S-68

GA-A1-B/S-75

GA-A1-B/S-78

GA-A1-I-1

GA-A1-I-2

GA-A1-I-3

GA-A1-I-4

GA-A1-I-5

GA-A1-M-10

GA-A1-M-19

GA-A1-M-22

GA-A1-M-34

GA-A1-M-35

GA-A1-M-37

GA-B1-B/S-5

GA-B1-B/S-6

GA-B1-I-1

GA-B1-I-2

GA-B1-I-3

GA-B1-M-9

GA-B1-M-12

GA-B1-M-18

GA-B1-M-24

GA-B1-M-25

GA-B1-M-29

GA-B1-M-30

GA-B1-M-33

GA-B1-M-34

Heterosiphonia japonica? Pterosiphonia dendroidea (Mont.) Falk. 1 11 1111 11 1 1 1 1 1 1 1 1 1 1 

Anthopleura elegantissima 1 

Metridium senile 1 1 2 1 1 1 1 1 1 1 1 1 1 Spirobranchus spinosus 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 1 1 1 Ophiothrix spiculata 1111111111111111111 2 1111111212 

Elasmopus hologurus 2111111221111211131 1 11111111111 

Diadumene cincta 1 1 1 2 Balanus trigonus 1122111111111111111 3 31211211212 

Metridium exilis 1 2 3 1 1 1 1 2 1 1 2 1 2 1 1 1 1 1 1 1 1 1 2 2 2 

Tetraclita rubescens 12222 2 1 1 1 

Chama arcana 3 1 2 3 1 2 1 2 2 1 1 1 1 1 1 1 1 1 2 3 1 2 1 3 

Ophiactis simplex 22 22 1 2222222 1 12222221121 

Haplosclerida nr. Haliclona sp 1 1 1 2 1 2 2 3 1 2 2 2 2 2 3 3 2 2 2 2 1 1 1 

Phyllodoce medipapillata 1 1 2 2 2 2 1 2 2 2 2 2 2 2 2 2 2 2 2 2 

Caprella equilibra 12 21 3 32122 2 2 222112 2213 

Nereis mendocinana 2 2 1 2 2 2 2 2 2 2 2 2 2 2 2 2 

Lithophaga plumula 1 2 3 3 3 2 2 2 2 2 3 1 1 2 1 2 1 3 

Antithamnion hubbsii Dawson 2 2 2 2 2 2 2 2 2 2 

Pododesmus cepio 3 1 1 3 1 2 3 Polysiphonia scopulorum var. villosum (J. Ag.) Hollenb. 2 2 2 2 2 2 

Crassadoma gigantea 2 

Obelia nr. surcularis 2 

Stronglyocentrotus purpuratus 2 

Hiatella arctica 2 2 3 1 2 1 2 3 2 2 2 2 2 1 1 3 2 2 3 3 

Mytilus spp 3 3 3 1 3 3 3 3 3 3 1 1 1 2 1 2 1 2 1 3 3 1 

Megabalanus californicus 223312322223333 2 1 113 313 

Jassa slatteryi 3 3 2 322 122123 23 3 

Aplidium sp 3 3 3 1 1 3 2 2 3 3 1 

Gammaropsis thompsoni 223322 23322 32 22 322 Ericthonius brasiliensis 232 3 2 

Leucothoe alata 22 2223 33 3 3233 3 32 23222 Kellia suborbicularis 3 3 3 2 3 2 3 2 3 1 3 2 

Balanus nubilus 22 33 1 3 3 3 3 

Monocorophium sp 3233 3 23 33 223 3213 

Halosydna brevisetosa 2 3 3 2 2 3 3 2 2 3 2 3 2 3 3 3 3 2 2 3 3 3 

Ostrea conchaphila 3 2 3 2 3 Dulichiella appendiculata 233 3 

Phascolosoma agassizi 3 3 3 3 3 3 3 2 3 3 1 3 3 Pachygrapsus crassipes 3333 33 2 23 33 

Parapleutes pugettensis 2 33 33 3 

Phyllochaetopterus prolifica 3 2 3 3 3 3 3 3 3 3 3 3 3 3 3 Aplousobranchia (Diplosoma) 3 3 3 3 3 3 3 3 Filicrisia sp 3 3 3 3 3 3 3 3 

Syllis gracilis 3 3 3 3 3 3 3 3 Ceramium camouii Dawson 3 3 3 3 3 3 

Paraxanthias taylori 3 3 33 3 3 

Acrosorium venulosum (Zanardini) Kylin 3 3 3 3 3 Harmothoe ? hirsuta 3 3 3 3 3 Arabella iricolor 3 3 3 3 Branchioglossum bipinnatifidum (Mont.) Wynne 3 3 3 3 
PLATFORM GAIL - Taxa vs. All Stations/Quadrats

Species or Taxon

GA-A1-B/S-49

GA-A1-B/S-56

GA-A1-B/S-63

GA-A1-B/S-68

GA-A1-B/S-75

GA-A1-B/S-78

GA-A1-I-1

GA-A1-I-2

GA-A1-I-3

GA-A1-I-4

GA-A1-I-5

GA-A1-M-10

GA-A1-M-19

GA-A1-M-22

GA-A1-M-34

GA-A1-M-35

GA-A1-M-37

GA-B1-B/S-5

GA-B1-B/S-6

GA-B1-I-1

GA-B1-I-2

GA-B1-I-3

GA-B1-M-9

GA-B1-M-12

GA-B1-M-18

GA-B1-M-24

GA-B1-M-25

GA-B1-M-29

GA-B1-M-30

GA-B1-M-33

GA-B1-M-34

Crisia sp 3 3 3 3 

Obelia dichotoma 3 3 33 

Trypanosyllis sp. 3 3 3 3 Callophyllis sp. 3 3 3 

Modiolus capax 3 3 3 Pilumnus spinohirsutus 3 3 3 

Stenothoe estacola 3 33 

Aoroides sp 3 3 

Gregariella coarctata 3 3 Janiropsis tridens 3 3 

Naineris dentritica 3 3 Obelia geniculata 3 3 Pachycheles pubescens 3 3 Paleonotus bellis 3 3 Syllidae 3 3 Amphissa reticulata (dead) 3 

Campanularia sp 3 

cf. Sinocorophium sp 3 Corynactis californica 3 

Crassostrea gigas 3 

Dodecaceria concharum 3 Doridacea 3 Harmothoe sp. 3 Holothuroidea juv unid 3 

Iselica sp 3 

Lineus rubescens 3 

Lytechinus pictus 3 

Musculus sp damaged 3 Mysidacea frag 3 

Obelia plicata 3 

Ophiopteris papillosa 3 

Ophioroidea juv unid 3 

Phyllodoce sp. 3 

Procerarea sp. 3 

Pugettia sp juv 3 Pycnogonida , juv 3 

Quadrimaera reishi 3 

Seila montereyensis 3 Tetrastemma signifer 3 Count: 30 18 13 18 27 18 23 22 16 20 23 22 19 31 25 29 20 20 36 20 19 20 19 28 41 27 23 25 23 27 21
PLATFORM GAIL - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

GA-A1-B/S-49 Balanus trigonus 1 Key:

Caprella equilibra 1 1 = abundant

Haplosclerida nr. Haliclona sp 1 2 = moderately

Lithophaga plumula 1 abundant

Metridium exilis 1 3 = limited, sparse

Ophiothrix spiculata 1

Phyllodoce medipapillata 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Balanus nubilus 2

Elasmopus hologurus 2

Gammaropsis thompsoni 2

Halosydna brevisetosa 2

Hiatella arctica 2

Leucothoe alata 2

Megabalanus californicus 2

Nereis mendocinana 2

Ophiactis simplex 2

Aplidium sp 3

Aplousobranchia (Diplosoma) 3

Callophyllis sp. 3

Chama arcana 3

Crisia sp 3

Filicrisia sp 3

Kellia suborbicularis 3

Monocorophium sp 3

Obelia dichotoma 3

Ophioroidea juv unid 3

Pilumnus spinohirsutus 3

Pododesmus cepio 3

GA-A1-B/S-56 Balanus trigonus 1

Chama arcana 1

Elasmopus hologurus 1

Haplosclerida nr. Haliclona sp 1

Metridium senile 1

Ophiothrix spiculata 1

Phyllodoce medipapillata 1

Pododesmus cepio 1

Balanus nubilus 2

Caprella equilibra 2

Gammaropsis thompsoni 2

Leucothoe alata 2

Megabalanus californicus 2

Monocorophium sp 2

Nereis mendocinana 2

Ophiactis simplex 2

Halosydna brevisetosa 3

Jassa slatteryi 3

D-57
PLATFORM GAIL - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

GA-A1-B/S-63 Elasmopus hologurus 1

Haplosclerida nr. Haliclona sp 1

Ophiothrix spiculata 1

Pododesmus cepio 1

Spirobranchus spinosus 1

Balanus trigonus 2

Chama arcana 2

Dulichiella appendiculata 2

Phyllodoce medipapillata 2

Gammaropsis thompsoni 3

Megabalanus californicus 3

Monocorophium sp 3

Phyllochaetopterus prolifica 3

GA-A1-B/S-68 Elasmopus hologurus 1

Metridium senile 1

Ophiothrix spiculata 1

Spirobranchus spinosus 1

Balanus trigonus 2

Ericthonius brasiliensis 2

Haplosclerida nr. Haliclona sp 2

Leucothoe alata 2

Phyllodoce medipapillata 2

Aoroides sp 3

Balanus nubilus 3

Campanularia sp 3

Dulichiella appendiculata 3

Gammaropsis thompsoni 3

Jassa slatteryi 3

Megabalanus californicus 3

Monocorophium sp 3

Obelia dichotoma 3

GA-A1-B/S-75 Balanus trigonus 1

Elasmopus hologurus 1

Haplosclerida nr. Haliclona sp 1

Megabalanus californicus 1

Nereis mendocinana 1

Ophiothrix spiculata 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Antithamnion hubbsii Dawson 2

Caprella equilibra 2

Gammaropsis thompsoni 2

Leucothoe alata 2

Metridium exilis 2

Metridium senile 2

Phyllochaetopterus prolifica 2

Polysiphonia scopulorum var. villosum (J. Ag.) Hol 2

Aoroides sp 3

Aplousobranchia (Diplosoma) 3

D-58
PLATFORM GAIL - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

GA-A1-B/S-75 Balanus nubilus 3

(continued) Branchioglossum bipinnatifidum (Mont.) Wynne 3

Chama arcana 3

Dodecaceria concharum 3

Dulichiella appendiculata 3

Ericthonius brasiliensis 3

Filicrisia sp 3

Halosydna brevisetosa 3

Pododesmus cepio 3

Syllis gracilis 3

GA-A1-B/S-78 Balanus trigonus 1

Caprella equilibra 1

Elasmopus hologurus 1

Metridium senile 1

Ophiothrix spiculata 1

Pododesmus cepio 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Ericthonius brasiliensis 2

Gammaropsis thompsoni 2

Halosydna brevisetosa 2

Haplosclerida nr. Haliclona sp 2

Hiatella arctica 2

Leucothoe alata 2

Megabalanus californicus 2

Polysiphonia scopulorum var. villosum (J. Ag.) Hol 2

Acrosorium venulosum (Zanardini) Kylin 3

Lytechinus pictus 3

Phyllochaetopterus prolifica 3

GA-A1-I-1 Anthopleura elegantissima 1

Balanus nubilus 1

Balanus trigonus 1

Chama arcana 1

Elasmopus hologurus 1

Ophiothrix spiculata 1

Spirobranchus spinosus 1

Antithamnion hubbsii Dawson 2

Haplosclerida nr. Haliclona sp 2

Nereis mendocinana 2

Ophiactis simplex 2

Parapleutes pugettensis 2

Phyllodoce medipapillata 2

Aplidium sp 3

Ceramium camouii Dawson 3

Filicrisia sp 3

Hiatella arctica 3

Leucothoe alata 3

Megabalanus californicus 3

Metridium exilis 3

D-59
PLATFORM GAIL - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

GA-A1-I-1 Mytilus spp 3

(continued) Obelia plicata 3

Pachygrapsus crassipes 3

GA-A1-I-2 Balanus trigonus 1

Hiatella arctica 1

Metridium exilis 1

Ophiothrix spiculata 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Spirobranchus spinosus 1

Tetraclita rubescens 1

Antithamnion hubbsii Dawson 2

Chama arcana 2

Elasmopus hologurus 2

Lithophaga plumula 2

Megabalanus californicus 2

Nereis mendocinana 2

Ophiactis simplex 2

Phyllodoce medipapillata 2

Polysiphonia scopulorum var. villosum (J. Ag.) Hol 2

Caprella equilibra 3

Crassostrea gigas 3

Monocorophium sp 3

Mytilus spp 3

Obelia geniculata 3

Phyllochaetopterus prolifica 3

GA-A1-I-3 Balanus trigonus 1

Chama arcana 1

Metridium exilis 1

Ophiothrix spiculata 1

Phyllodoce medipapillata 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Elasmopus hologurus 2

Halosydna brevisetosa 2

Megabalanus californicus 2

Obelia nr. surcularis 2

Tetraclita rubescens 2

Arabella iricolor 3

Haplosclerida nr. Haliclona sp 3

Mytilus spp 3

Pachygrapsus crassipes 3

Phyllochaetopterus prolifica 3

GA-A1-I-4 Balanus trigonus 1

Elasmopus hologurus 1

Haplosclerida nr. Haliclona sp 1

Metridium exilis 1

Mytilus spp 1

Ophiothrix spiculata 1

Pterosiphonia dendroidea (Mont.) Falk. 1

D-60
PLATFORM GAIL - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

GA-A1-I-4 Spirobranchus spinosus 1

(continued) Antithamnion hubbsii Dawson 2

Chama arcana 2

Hiatella arctica 2

Megabalanus californicus 2

Nereis mendocinana 2

Phyllodoce medipapillata 2

Tetraclita rubescens 2

Filicrisia sp 3

Janiropsis tridens 3

Pachycheles pubescens 3

Phascolosoma agassizi 3

Phyllochaetopterus prolifica 3

GA-A1-I-5 Balanus trigonus 1

Elasmopus hologurus 1

Hiatella arctica 1

Metridium exilis 1

Ophiactis simplex 1

Ophiothrix spiculata 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Spirobranchus spinosus 1

Antithamnion hubbsii Dawson 2

Chama arcana 2

Megabalanus californicus 2

Phyllodoce medipapillata 2

Tetraclita rubescens 2

Arabella iricolor 3

Gregariella coarctata 3

Halosydna brevisetosa 3

Kellia suborbicularis 3

Leucothoe alata 3

Lithophaga plumula 3

Pachygrapsus crassipes 3

Phascolosoma agassizi 3

Phyllochaetopterus prolifica 3

Trypanosyllis sp. 3

GA-A1-M-10 Balanus trigonus 1

Caprella equilibra 3

Chama arcana 1

Elasmopus hologurus 1

Gammaropsis thompsoni 2

Halosydna brevisetosa 3

Hiatella arctica 2

Jassa slatteryi 2

Kellia suborbicularis 3

Leucothoe alata 3

Lithophaga plumula 3

Megabalanus californicus 3

D-61
PLATFORM GAIL - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

GA-A1-M-10 Metridium exilis 2

(continued) Metridium senile 1

Monocorophium sp 2

Mytilus spp 3

Ophiothrix spiculata 1

Phyllochaetopterus prolifica 3

Phyllodoce medipapillata 2

Spirobranchus spinosus 1

Stronglyocentrotus purpuratus 2

Tetraclita rubescens 2

GA-A1-M-19 Balanus trigonus 1

Chama arcana 1

Elasmopus hologurus 1

Metridium exilis 1

Ophiothrix spiculata 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Spirobranchus spinosus 1

Caprella equilibra 2

Ophiactis simplex 2

Phyllodoce medipapillata 2

Gammaropsis thompsoni 3

Hiatella arctica 3

Lithophaga plumula 3

Megabalanus californicus 3

Monocorophium sp 3

Ostrea conchaphila 3

Pachygrapsus crassipes 3

Phascolosoma agassizi 3

Phyllodoce sp. 3

GA-A1-M-22 Balanus trigonus 1

Caprella equilibra 1

Chama arcana 1

Metridium exilis 1

Ophiothrix spiculata 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Spirobranchus spinosus 1

Antithamnion hubbsii Dawson 2

Crassadoma gigantea 2

Elasmopus hologurus 2

Halosydna brevisetosa 2

Haplosclerida nr. Haliclona sp 2

Hiatella arctica 2

Lithophaga plumula 2

Nereis mendocinana 2

Ophiactis simplex 2

Polysiphonia scopulorum var. villosum (J. Ag.) Hol 2

Acrosorium venulosum (Zanardini) Kylin 3

Aplidium sp 3

D-62
PLATFORM GAIL - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

GA-A1-M-22 Balanus nubilus 3

(continued) Branchioglossum bipinnatifidum (Mont.) Wynne 3

Callophyllis sp. 3

Corynactis californica 3

Crisia sp 3

Gammaropsis thompsoni 3

Jassa slatteryi 3

Leucothoe alata 3

Megabalanus californicus 3

Modiolus capax 3

Mytilus spp 3

Obelia dichotoma 3

GA-A1-M-34: Balanus trigonus 1

Chama arcana 1

Elasmopus hologurus 1

Metridium senile 1

Ophiothrix spiculata 1

Spirobranchus spinosus 1

Caprella equilibra 2

Gammaropsis thompsoni 2

Halosydna brevisetosa 2

Haplosclerida nr. Haliclona sp 2

Hiatella arctica 2

Jassa slatteryi 2

Lithophaga plumula 2

Metridium exilis 2

Ophiactis simplex 2

Aplousobranchia (Diplosoma) 3

Ericthonius brasiliensis 3

Lineus rubescens 3

Megabalanus californicus 3

Monocorophium sp 3

Mytilus spp 3

Obelia dichotoma 3

Paraxanthias taylori 3

Phascolosoma agassizi 3

Syllidae 3

GA-A1-M-35 Balanus trigonus 1

Chama arcana 1

Elasmopus hologurus 1

Ophiothrix spiculata 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Spirobranchus spinosus 1

Antithamnion hubbsii Dawson 2

Caprella equilibra 2

Gammaropsis thompsoni 2

Hiatella arctica 2

Jassa slatteryi 2

D-63
PLATFORM GAIL - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

GA-A1-M-35 Kellia suborbicularis 2

(continued) Lithophaga plumula 2

Nereis mendocinana 2

Ophiactis simplex 2

Phyllodoce medipapillata 2

Polysiphonia scopulorum var. villosum (J. Ag.) Hol 2

Tetraclita rubescens 2

Amphissa reticulata (dead) 3

Balanus nubilus 3

Ceramium camouii Dawson 3

Harmothoe ? hirsuta 3

Leucothoe alata 3

Monocorophium sp 3

Mytilus spp 3

Pachygrapsus crassipes 3

Phyllochaetopterus prolifica 3

Procerarea sp. 3

Syllis gracilis 3

GA-A1+A796-M-3 Balanus trigonus 1

Chama arcana 1

Diadumene cincta 1

Elasmopus hologurus 1

Metridium exilis 1

Metridium senile 1

Ophiothrix spiculata 1

Spirobranchus spinosus 1

Haplosclerida nr. Haliclona sp 2

Hiatella arctica 2

Leucothoe alata 2

Lithophaga plumula 2

Megabalanus californicus 2

Nereis mendocinana 2

Ophiactis simplex 2

Phyllodoce medipapillata 2

Pododesmus cepio 2

Halosydna brevisetosa 3

Mytilus spp 3

Paleonotus bellis 3

GA-B1-B/S-5 Aplidium sp 1

Balanus trigonus 1

Chama arcana 1

Metridium senile 1

Ophiothrix spiculata 1

Haplosclerida nr. Haliclona sp 2

Hiatella arctica 2

Lithophaga plumula 2

Metridium exilis 2

Ophiactis simplex 2

D-64
PLATFORM GAIL - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

Ostrea conchaphila 2

Balanus nubilus 3

Elasmopus hologurus 3

Gammaropsis thompsoni 3

Kellia suborbicularis 3

Leucothoe alata 3

Mytilus spp 3

Pachygrapsus crassipes 3

Paraxanthias taylori 3

Phascolosoma agassizi 3

GA-B1-B/S-6 Aplidium sp 1

Balanus trigonus 1

Chama arcana 1

Diadumene cincta 1

Elasmopus hologurus 1

Metridium exilis 1

Ophiothrix spiculata 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Spirobranchus spinosus 1

Antithamnion hubbsii Dawson 2

Caprella equilibra 2

Ericthonius brasiliensis 2

Gammaropsis thompsoni 2

Halosydna brevisetosa 2

Haplosclerida nr. Haliclona sp 2

Nereis mendocinana 2

Ophiactis simplex 2

Phyllodoce medipapillata 2

Branchioglossum bipinnatifidum (Mont.) Wynne 3

Callophyllis sp. 3

Ceramium camouii Dawson 3

Crisia sp 3

Dulichiella appendiculata 3

Filicrisia sp 3

Leucothoe alata 3

Modiolus capax 3

Ophiopteris papillosa 3

Phascolosoma agassizi 3

Phyllochaetopterus prolifica 3

Pilumnus spinohirsutus 3

Pycnogonida , juv 3

Quadrimaera reishi 3

Stenothoe estacola 3

Syllidae 3

Syllis gracilis 3

Trypanosyllis sp. 3

D-65
PLATFORM GAIL - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

GA-B1-I-1 Elasmopus hologurus 1

Megabalanus californicus 1

Metridium exilis 1

Mytilus spp 1

Ophiactis simplex 1

Spirobranchus spinosus 1

Tetraclita rubescens 1

Caprella equilibra 2

Nereis mendocinana 2

Ophiothrix spiculata 2

Pachygrapsus crassipes 2

Aplousobranchia (Diplosoma) 3

Arabella iricolor 3

Balanus trigonus 3

Halosydna brevisetosa 3

Haplosclerida nr. Haliclona sp 3

Leucothoe alata 3

Obelia geniculata 3

Ostrea conchaphila 3

Trypanosyllis sp. 3

GA-B1-I-2 Chama arcana 1

Elasmopus hologurus 1

Jassa slatteryi 1

Megabalanus californicus 1

Metridium exilis 1

Mytilus spp 1

Ophiactis simplex 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Spirobranchus spinosus 1

Tetraclita rubescens 1

Caprella equilibra 2

Halosydna brevisetosa 2

Ostrea conchaphila 2

Pachygrapsus crassipes 2

Phyllodoce medipapillata 2

Balanus trigonus 3

Parapleutes pugettensis 3

Phyllochaetopterus prolifica 3

Stenothoe estacola 3

GA-B1-I-3 Balanus trigonus 1

Elasmopus hologurus 1

Megabalanus californicus 1

Metridium exilis 1

Mytilus spp 1

Ophiothrix spiculata 1

Spirobranchus spinosus 1

Tetraclita rubescens 1

Caprella equilibra 2

D-66
PLATFORM GAIL - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

GA-B1-I-3 Chama arcana 2

(continued) Jassa slatteryi 2

Nereis mendocinana 2

Ophiactis simplex 2

Aplousobranchia (Diplosoma) 3

Halosydna brevisetosa 3

Ostrea conchaphila 3

Pachygrapsus crassipes 3

Parapleutes pugettensis 3

Pododesmus cepio 3

Stenothoe estacola 3

GA-B1-M-9 Elasmopus hologurus 1

Hiatella arctica 1

Metridium exilis 1

Metridium senile 1

Ophiothrix spiculata 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Balanus trigonus 2

Caprella equilibra 2

Jassa slatteryi 2

Mytilus spp 2

Ophiactis simplex 2

Aplousobranchia (Diplosoma) 3

Crisia sp 3

Halosydna brevisetosa 3

Haplosclerida nr. Haliclona sp 3

Lithophaga plumula 3

Megabalanus californicus 3

Phascolosoma agassizi 3

Spirobranchus spinosus 3

GA-B1-M-12 Balanus trigonus 1

Caprella equilibra 1

Elasmopus hologurus 1

Hiatella arctica 1

Jassa slatteryi 1

Lithophaga plumula 1

Metridium exilis 1

Metridium senile 1

Mytilus spp 1

Ophiothrix spiculata 1

Spirobranchus spinosus 1

Gammaropsis thompsoni 2

Haplosclerida nr. Haliclona sp 2

Kellia suborbicularis 2

Monocorophium sp 2

Nereis mendocinana 2

Ophiactis simplex 2

Phascolosoma agassizi 2

D-67
PLATFORM GAIL - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

GA-B1-M-12 Phyllodoce medipapillata 2

(continued) Chama arcana 3

Filicrisia sp 3

Halosydna brevisetosa 3

Harmothoe ? hirsuta 3

Leucothoe alata 3

Modiolus capax 3

Paraxanthias taylori 3

Syllis gracilis 3

Trypanosyllis sp. 3

GA-B1-M-18 Balanus trigonus 1

Caprella equilibra 1

Chama arcana 1

Elasmopus hologurus 1

Lithophaga plumula 1

Metridium exilis 1

Ophiothrix spiculata 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Spirobranchus spinosus 1

Gammaropsis thompsoni 2

Haplosclerida nr. Haliclona sp 2

Jassa slatteryi 2

Leucothoe alata 2

Monocorophium sp 2

Mytilus spp 2

Nereis mendocinana 2

Ophiactis simplex 2

Phyllodoce medipapillata 2

Polysiphonia scopulorum var. villosum (J. Ag.) Hol 2

Aplidium sp 3

Arabella iricolor 3

Branchioglossum bipinnatifidum (Mont.) Wynne 3

Ceramium camouii Dawson 3

Doridacea 3

Filicrisia sp 3

Halosydna brevisetosa 3

Hiatella arctica 3

Holothuroidea juv unid 3

Janiropsis tridens 3

Kellia suborbicularis 3

Megabalanus californicus 3

Musculus sp damaged 3

Mysidacea frag 3

Pachygrapsus crassipes 3

Parapleutes pugettensis 3

Paraxanthias taylori 3

Phascolosoma agassizi 3

Phyllochaetopterus prolifica 3

D-68
PLATFORM GAIL - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

GA-B1-M-18 Pugettia sp juv 3

(continued) Syllis gracilis 3

Tetrastemma signifer 3

GA-B1-M-24 Elasmopus hologurus 1

Megabalanus californicus 1

Metridium exilis 1

Metridium senile 1

Mytilus spp 1

Ophiothrix spiculata 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Antithamnion hubbsii Dawson 2

Balanus trigonus 2

Caprella equilibra 2

Chama arcana 2

Halosydna brevisetosa 2

Haplosclerida nr. Haliclona sp 2

Hiatella arctica 2

Kellia suborbicularis 2

Lithophaga plumula 2

Nereis mendocinana 2

Ophiactis simplex 2

Ceramium camouii Dawson 3

Filicrisia sp 3

Gregariella coarctata 3

Jassa slatteryi 3

Monocorophium sp 3

Pachygrapsus crassipes 3

Paleonotus bellis 3

Parapleutes pugettensis 3

Syllis gracilis 3

GA-B1-M-25 Balanus trigonus 1

Chama arcana 1

Diadumene cincta 1

Elasmopus hologurus 1

Metridium exilis 1

Ophiothrix spiculata 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Spirobranchus spinosus 1

Aplidium sp 2

Halosydna brevisetosa 2

Haplosclerida nr. Haliclona sp 2

Leucothoe alata 2

Mytilus spp 2

Nereis mendocinana 2

Ophiactis simplex 2

Phyllodoce medipapillata 2

Acrosorium venulosum (Zanardini) Kylin 3

Ceramium camouii Dawson 3

D-69
PLATFORM GAIL - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

GA-B1-M-25 Harmothoe sp. 3

(continued) Megabalanus californicus 3

Paraxanthias taylori 3

Phascolosoma agassizi 3

Phyllochaetopterus prolifica 3

GA-B1-M-29 Balanus trigonus 1

Elasmopus hologurus 1

Lithophaga plumula 1

Mytilus spp 1

Ophiactis simplex 1

Ophiothrix spiculata 1

Phascolosoma agassizi 1

Spirobranchus spinosus 1

Aplidium sp 2

Caprella equilibra 2

Hiatella arctica 2

Jassa slatteryi 2

Phyllodoce medipapillata 2

Aplousobranchia (Diplosoma) 3

Balanus nubilus 3

cf. Sinocorophium sp 3

Gammaropsis thompsoni 3

Halosydna brevisetosa 3

Kellia suborbicularis 3

Leucothoe alata 3

Monocorophium sp 3

Pachycheles pubescens 3

Phyllochaetopterus prolifica 3

Seila montereyensis 3

Syllis gracilis 3

GA-B1-M-30 Elasmopus hologurus 1

Haplosclerida nr. Haliclona sp 1

Kellia suborbicularis 1

Metridium senile 1

Ophiactis simplex 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Balanus trigonus 2

Caprella equilibra 2

Gammaropsis thompsoni 2

Leucothoe alata 2

Lithophaga plumula 2

Metridium exilis 2

Monocorophium sp 2

Ophiothrix spiculata 2

Acrosorium venulosum (Zanardini) Kylin 3

Aplidium sp 3

Harmothoe ? hirsuta 3

Hiatella arctica 3

D-70
PLATFORM GAIL - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

GA-B1-M-30 Jassa slatteryi 3

(continued) Mytilus spp 3

Naineris dentritica 3

Phascolosoma agassizi 3

Phyllochaetopterus prolifica 3

GA-B1-M-33 Balanus trigonus 1

Caprella equilibra 1

Elasmopus hologurus 1

Haplosclerida nr. Haliclona sp 1

Lithophaga plumula 1

Metridium senile 1

Monocorophium sp 1

Ophiothrix spiculata 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Diadumene cincta 2

Gammaropsis thompsoni 2

Leucothoe alata 2

Metridium exilis 2

Ophiactis simplex 2

Phyllodoce medipapillata 2

Acrosorium venulosum (Zanardini) Kylin 3

Aplidium sp 3

Aplousobranchia (Diplosoma) 3

Chama arcana 3

Halosydna brevisetosa 3

Harmothoe ? hirsuta 3

Hiatella arctica 3

Kellia suborbicularis 3

Mytilus spp 3

Naineris dentritica 3

Pilumnus spinohirsutus 3

Syllis gracilis 3

GA-B1-M-34 Aplidium sp 1

Elasmopus hologurus 1

Haplosclerida nr. Haliclona sp 1

Mytilus spp 1

Ophiactis simplex 1

Pterosiphonia dendroidea (Mont.) Falk. 1

Balanus trigonus 2

Kellia suborbicularis 2

Leucothoe alata 2

Metridium exilis 2

Ophiothrix spiculata 2

Caprella equilibra 3

Halosydna brevisetosa 3

Harmothoe ? hirsuta 3

Iselica sp 3

Jassa slatteryi 3

D-71
PLATFORM GAIL - Taxa by Individual Station/Quadrat

Station/Quadrat Species or Taxon Relative 

Abundance

GA-B1-M-34 Lithophaga plumula 3

(continued) Monocorophium sp 3

Parapleutes pugettensis 3

Paraxanthias taylori 3

Phascolosoma agassizi 3

D-72
Appendix E 

Data Appendix: PointCount’99® Analysis 

E-1
Appendix E has been organized into three primary sections: 

 Table E-1 – this one-page table summarizes the dominant species or taxa identified 

during the PointCount’99® analysis and indicates which taxa were also identified 

during either quantitative slide analysis or scraping analysis. 

 Table E-2 – this four-page table summarizes the dominant taxa identified during 

PointCount’99® analysis. Summary data include mean, minimum, maximum, 

frequency of occurrence, and whether each taxon was also identified as a QSA 

dominant. 

 PointCount’99® Data Appendix, Sum of Counts – separate spreadsheets (each 

containing four to six pages) have been developed for the 10 platform legs summarizing 

the observations from the PointCount’99® analysis. Separate spreadsheets are provided 

for each platform leg. Site identifiers are located in the upper left corner of each 

spreadsheet (e.g., Platform Gail, Leg A1: Sum of Counts). Within each spreadsheet, data 

are organized by water depth (i.e., from shallowest to deepest) in the horizontal plane. 

In the vertical plane, data are organized by dominant taxa (i.e., highest average counts), 

in descending order. Summary data (i.e., average, minimum, maximum, and frequency 

of occurrence) are provided on the last page of each separate set of spreadsheets. 

E-3
Table E-1. Dominant species or taxa from the PointCount’99® analysis (31 taxa 

total) and their occurrence in quantitative slide analyses (QSA) or 

scraping samples. 

PointCount’99® Taxa Present in QSA Present in 

Scrapings 

Aglaophenia sp. N N 

Anthopleura elegantissima (rosy morph) Y Y 

Balanus spp. Y Y 

Bryozoa erect Y Y 

Cancer spp. Y Y 

Coenocyathus bowersi Y N 

Corynactis californica Y Y 

Desmophyllum dianthus Y N 

Encruster Y P 

Fan Worm Y – Sabellidae/Serpulidae 

unidentified Y 

Florometra serratissima Y N 

Galathea californiensis Y N 

Green Algae Y Y 

Macroalgae P P 

Metridium exilis Y Y 

Metridium farcimen Y N 

Metridium senile Y Y 

Mytilus spp. Y Y 

Obelia sp. Y Y 

Ophionereis sp. N N 

Ophiothrix spiculata Y Y 

Paracyathus stearnsii Y N 

Pisaster sp. Y N 

Pleurobranchaea californica Y N 

Pollicipes polymerus Y N 

Porifera Y – Sponge, [color descriptor] Y 

Porifera, erect Y – Sponge, [form descriptor] P 

Red Algae Y Y 

Rockfish Y – Sebastes spp. N 

Turf Y N 

Zoanthidea Y N 

Key: Y – yes; N – no; P – possible 

Notes: 

 Dominant taxa included above represent the top 12 taxa found on each platform 

leg (see Table 3-14). 

 Broader taxonomic categories may have been used on occasion during point 

count analysis; corresponding taxon/descriptor used during QSA noted, as 

appropriate. 

E-4
Table E-2. Dominant taxa on the six platforms as determined by PointCount’99® analysis. 

Platform and Leg Dominant Taxa Mean Minimum Maximum Freque

Platform Gail: 

Leg A1 - 111 images 

Corynactis californica Metridium senile Desmophyllum dianthus Anthopleura elegantissima (ros

y morph) 

Red Algae Mytilus spp. Zoanthidea Metridium farcimen Turf Metridium exilis Ophiothrix spiculata Aglaophenia sp. 

31.21 18.88 15.29 14.85 14.62 12.43 11.71 10.20 

9.86 8.90 4.25 4.00 

1 1 1 1 2 1 3 1 1 1 1 4 

50 47 30 50 33 24 42 34 35 30 10 

4 

38/1167/1117/1113/1126/1114/11

7/115/11

83/1130/1188/11

1/11

Leg B1 - 110 images 

Metridium exilis Turf Corynactis californica Metridium senile Pleurobranchaea californica Desmophyllum dianthusRed Algae Metridium farcimen Mytilus spp. Porifera Ophiothrix spiculata Zoanthidea 

29.83 20.52 17.30 14.31 

9.00 8.82 8.30 8.00 7.47 5.16 3.75 3.75 

1 1 1 1 9 1 1 8 1 1 1 1 

48 46 48 34 

9 

27 25 

8 

22 16 

9 6 

63/1162/1123/1135/11

1/11

17/1120/11

1/11

17/1145/11

4/114/11

Platform Grace: 

Leg C1 – 94 images 

Corynactis californica Turf Anthopleura elegantissima (rosy morph)

Metridium farcimen Mytilus spp. Obelia sp. Red Algae Paracyathus stearnsii Ophiothrix spiculata 

Rockfish Metridium senile Ophionereis sp. 

23.69 18.32 17.30 13.50 12.37 11.83 

9.92 7.91 6.33 5.00 4.67 4.67 

1 1 1 

13 

1 1 1 1 1 5 1 1 

45 47 43 14 26 26 28 26 12 

5 

11 12 

42/981/920/9

2/94 

19/918/924/923/912/9

1/94 3/94 6/94 
Table E-2. Dominant taxa on the six platforms as determined by PointCount’99® analysis (continued). 

Platform and Leg Dominant Taxa Mean Minimum Maximum Freque

Leg C4 – 94 images 

Corynactis californica Zoanthidea Metridium senile Metridium farcimen Mytilus spp. Turf Metridium exilis Red Algae Ophiothrix spiculata Green Algae Anthopleura elegantissima (rosy morph)

Obelia sp. 

39.14 21.17 20.55 18.89 15.00 10.99 

8.00 7.37 6.93 6.50 6.23 4.50 

5 4 1 1 1 1 4 1 1 4 1 1 

50 42 45 40 29 35 14 15 20 

9 

13 11 

37/9

6/94 

38/9

9/94 

25/972/9

3/94 

19/928/9

2/94 

13/9

4/94 

Platform Harvest: 

Leg B1 - 94 images 

Metridium senile Metridium farcimen Pisaster sp. Turf Corynactis californica Mytilus spp. Porifera Red Algae Macroalgae Anthopleura elegantissima (rosy morph)

Bryozoa erect Encruster 

23.65 22.67 20.00 19.75 16.00 12.50 

7.47 5.82 5.00 4.91 4.00 3.84 

1 5 

20 

1 1 1 1 1 2 1 4 1 

48 50 20 49 48 25 34 11 

8 

11 

4 

14 

79/9

3/94 1/94 

77/9

5/94 

18/943/917/9

2/94 

11/9

1/94 

25/9

Leg B2 - 90 images 

Turf Metridium senile Mytilus spp. Porifera Corynactis californica Red Algae Encruster Porifera, erect Anthopleura elegantissima (rosy morph)

Ophiothrix spiculata Obelia sp. Galathea californiensis 

17.81 17.09 11.67 10.73 

8.33 7.67 7.63 7.00 6.80 6.47 5.50 3.33 

1 1 2 1 1 1 1 7 1 1 3 1 

43 38 22 32 21 19 32 

7 

15 19 

8 6 

81/976/921/937/9

6/90 9/90 

54/9

1/90 

15/915/9

2/90 3/90 
Table E-2. Dominant taxa on the six platforms as determined by PointCount’99® analysis (continued). 

Platform and Leg Dominant Taxa Mean Minimum Maximum Freque

Platform Hidalgo: 

Leg A1 - 64 images 

Metridium senile Mytilus spp. Turf Metridium farcimen Porifera Porifera, erect Corynactis californica Ophiothrix spiculata Pisaster sp. Encruster Red Algae Fan Worm 

23.85 18.23 13.57 10.33 

8.76 7.50 6.40 5.09 5.00 4.57 4.50 2.50 

1 4 1 4 1 5 2 1 2 1 3 1 

47 31 30 21 32 10 17 21 

8 

26 

6 4 

60/613/637/6

3/64 

46/6

2/64 5/64 

33/6

4/64 

35/6

2/64 2/64 

Leg B1 - 84 images 

Anthopleura elegantissima (rosy morph)

Mytilus spp. Metridium senile Turf Metridium farcimen Porifera Ophiothrix spiculata Encruster Porifera, erect Cancer sp. Florometra serratissima Pisaster sp. 

28.50 22.83 19.82 18.40 

8.50 7.93 6.11 5.97 5.50 5.00 5.00 4.50 

2 3 1 1 5 1 1 1 1 5 5 1 

45 36 47 50 12 23 19 32 10 

5 5 7 

8/84 

23/866/865/8

2/84 

44/828/838/8

2/84 1/84 1/84 4/84 

Platform Habitat: 

Leg A1 - 75 images 

Corynactis californica Zoanthidea Metridium farcimen Mytilus spp. Anthopleura elegantissima (rosy morph)

Metridium senile Turf Red Algae Rockfish Ophiothrix spiculata Coenocyathus bowersi Paracyathus stearnsii 

37.05 29.67 27.55 15.29 15.07 11.44 

7.90 6.81 4.00 3.83 3.36 3.33 

2 2 1 1 5 1 1 1 1 1 1 1 

50 50 50 35 49 39 47 24 

7 

12 

9 8 

37/7

6/75 

11/721/714/727/760/721/7

2/75 

18/711/7

9/75 
Table E-2. Dominant taxa on the six platforms as determined by PointCount’99® analysis (continued). 

Platform and Leg Dominant Taxa Mean Minimum Maximum Freque

Platform Irene: 

Leg A1 - 67 images 

Metridium senile Metridium farcimen Mytilus spp. Porifera Turf Red Algae Balanus spp. Green Algae Pollicipes polymerus Pisaster sp. Anthopleura elegantissima (rosy morph)

Cancer sp. 

28.69 21.00 14.83 

9.03 7.33 5.91 5.12 4.00 3.50 3.11 2.50 2.25 

2 

21 

1 1 1 1 1 4 1 1 1 1 

50 21 28 24 27 24 14 

4 6 6 4 3 

59/6

1/67 

40/631/648/611/617/6

1/67 2/67 9/67 6/67 4/67 
Platform Irene, Leg A1: Sum of Counts

IrA40101.jpg 

IrA40112.jpg 

IrA40119.jpg 

IrA40111.jpg 

IrA40122.jpg 

IrA40113.jpg 

IrA40120.jpg 

IrA40110.jpg 

IrA40115.jpg 

IrA40116.jpg 

IrA40117.jpg 

IrA40121.jpg 

IrA40118.jpg 

IrA40109.jpg 

IrA40114.jpg 

jpg 

0 1 1.1 2 2.1 3 3.1 4 4.1 4.2 4.3 4.4 6 8 8.1 

Voucher Shot 50Metridium senile 25 10 21 10 3 8 2 18 29 Metridium farcimen Mytilus spp 22 11 17 12 16 19 17 22 22 20 27 22 27 10 Porifera Turf 8 10 7 9 20 6 3 17 9 19 5 10 3 11 2

Red Algae 10 13 24 1 8 1 4 1Balanus spp 10 13 1 3 2 9 7 7 3 12 14 Green Algae 4Pollicipes polymerus 1 6Pisaster sp Anthopleura elegantissima 3 1Cancer sp Corynactis californica 2Fan Worm Questionable/unknown 2 1 2 1 1 1Encruster 1 1 1 1 Anthozoa 1Asterina Macroalgae Shadow Strongylocentrotus purpuratus Total 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 5

File Name and Water Depth (ft)

Taxon
Platform Irene, Leg A1: Sum of Counts

Voucher Shot Metridium senile Metridium farcimen Mytilus spp Porifera Turf Red Algae Balanus spp Green Algae Pollicipes polymerus Pisaster sp Anthopleura elegantissima Cancer sp Corynactis californica Fan Worm Questionable/unknown Encruster Anthozoa Asterina Macroalgae Shadow Strongylocentrotus purpuratus Total

Taxon

IrA40103.jpg 

IrA40102.jpg 

IRA40546.jpg

IRA40545.jpg

IRA40544.jpg

IRA40543.jpg

IRA40542.jpg

IRA40540.jpg

IRA40541.jpg

IRA40539.jpg

IRA40538.jpg

IRA40537.jpg

IRA40536.jpg

IRA40535.jpg

IRA40534.jpg

jpg

15 17 19 21 23 24 25 27 27.1 28 31 38 39 40 41 428 31 24 21 17 24 24 25 22 26 25 24 23 27 27 120 19 25 28 28 18 18 15 19 9 14 2 7 1 15 

1 8 8 7 5 2

1 3 3 6 5 4 4 6 5 11 2 111

2345263

1 424

23 

1 1 21312 11

2 1 13 

1

50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 5
Platform Irene, Leg A1: Sum of Counts

Voucher Shot Metridium senile Metridium farcimen Mytilus spp Porifera Turf Red Algae Balanus spp Green Algae Pollicipes polymerus Pisaster sp Anthopleura elegantissima Cancer sp Corynactis californica Fan Worm Questionable/unknown Encruster Anthozoa Asterina Macroalgae Shadow Strongylocentrotus purpuratus Total

Taxon

IRA40528.jpg

IRA40526.jpg

IRA40527.jpg

IRA40525.jpg

IRA40524.jpg

IRA40523.jpg

IRA40522.jpg

IRA40521.jpg

IRA40520.jpg

IRA40519.jpg

IRA40518.jpg

IRA40517.jpg

IRA40516.jpg

IRA40515.jpg

IRA40514.jpg

jpg

58 62 62.1 65 68 71 75 79 98 113 115 131 142 146 151 140 43 37 44 44 32 29 34 32 23 37 26 40 37 31 3

1 1

7 4 3 3 4 7 18 14 14 21 12 23 9 12 14 

1 7 6 2 

11 1

2 

3

2

1 1 2133 1111

311 3 1 1 2

1

50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 5
Platform Irene, Leg A1: Sum of Counts

Voucher Shot Metridium senile Metridium farcimen Mytilus spp Porifera Turf Red Algae Balanus spp Green Algae Pollicipes polymerus Pisaster sp Anthopleura elegantissima Cancer sp Corynactis californica Fan Worm Questionable/unknown Encruster Anthozoa Asterina Macroalgae Shadow Strongylocentrotus purpuratus Total

Taxon

IRA40508.jpg

IRA40507.jpg

IRA40505.jpg

IRA40506.jpg

IRA40504.jpg

IRA40503.jpg

IRA40502.jpg

avg

min

max

freq

189 201 206 206.1 215 221 232 67 images

50 50.00 50 50 2

45 47 37 50 37 28.69 2 50 59

21 21.00 21 21 1

14.83 1 28 40

1 2 9.03 1 24 314 1 11 11 27 7.33 1 27 48

5.91 1 24 115.12 1 14 174.00 4 4 13.50 1 6 23.11 1 6 92.50 1 4 62.25 1 3 42.00 2 2 12.00 2 2 1

2 2 1 1.61 1 4 36

1.50 1 3 181.00 1 1 1

1 1.00 1 1 1

1.00 1 1 11.00 1 1 31.00 1 1 1

50 50 50 50 50 50 50
REPORT DOCUMENTATION PAGE Form Approved 

OMB No. 0704-0188

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering 

and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of 

information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 

1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503. 

1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 

December 2005 

3. REPORT TYPE AND DATES COVERED 

Final report 

4. TITLE AND SUBTITLE 

Survey of Invertebrate and Algal Communities on Offshore Oil and Gas 

Platforms in Southern California 

5. FUNDING NUMBERS 

C: 1435-01-98-CT-30865

6. AUTHORS 

Continental Shelf Associates, Inc. 

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 

Continental Shelf Associates, Inc. 

759 Parkway Street 

Jupiter, FL 33477 

8. PERFORMING ORGANIZATION 

REPORT NUMBER 

1665 

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 

Minerals Management Service 

Pacific OCS Region 

770 Paseo Camarillo 

Camarillo, CA 93010 

10. SPONSORING/MONITORING AGENCY 

REPORT NUMBER 

OCS Study MMS 2005-070 

11. SUPPLEMENTARY NOTES 

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE 

13. ABSTRACT (Maximum 200 words) 

The final report characterizes invertebrate and algal communities present on six oil/gas platforms and two natural 

hard bottom communities in OCS waters offshore southern California. Platforms were located at both shallow and 

deeper water sites in the Santa Barbara Channel and Santa Maria Basin. Photographic images (image area: 1/16 

square meter) and videotape data were acquired via both remotely operated vehicle and scientific divers along one or 

two platform legs, between the intertidal zone and the platform base. Limited scraping of 1/16 square meter quadrats 

was also completed at two platforms, allowing for characterization of the complex interstitial community present in 

platform mussel (Mytilus spp.) beds. The structure of platform-associated communities was determined. More than 

800 photographic images were subjected to whole slide and random point count analyses, producing both density and 

percent cover estimates. Dominant taxa were identified and depth zonation patterns were presented. Clustering and 

correspondence analyses were also completed. Wet weights and detailed enumerations of mussels were presented 

and discussed. Species diversity, dominant taxa, and depth patterns for platform-associated invertebrate and algal 

communities were summarized. Inter- and intra-platform variability was assessed, and platform taxa were compared 

to natural hard bottom communities.

15. NUMBER OF PAGES 

232 pp. + appendices 

14. SUBJECT TERMS 

Oil and gas, platforms, Santa Barbara Channel, Santa Maria Basin, California, hard 

bottom, field surveys, invertebrates, algae, dominant, density, percent cover, zonation, 

photoquadrat, random point count analysis , whole slide analysis, scraping, mussels, 

Mytilus, wet weight, interstitial, correspondence analysis, clustering analysis 

16. PRICE CODE 

17. SECURITY CLASSIFICATION 

OF REPORT 

Unclassified 

18. SECURITY CLASSIFICATION 

OF THIS PAGE 

Unclassified 

19. SECURITY CLASSIFICATION 

OF ABSTRACT 

Unclassified

20. LIMITATION OF ABSTRACT 

SAR 

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 Prescribed by ANSI Std 239-18 

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and for people who live in island territories under U.S. administration. 

The Minerals Management Service Mission 

As a bureau of the Department of the Interior, the Minerals Management Service's (MMS) 

primary responsibilities are to manage the mineral resources located on the Nation's Outer 

Continental Shelf (OCS), collect revenue from the Federal OCS and onshore Federal and Indian 

lands, and distribute those revenues. 

Moreover, in working to meet its responsibilities, the Offshore Minerals Management Program 

administers the OCS competitive leasing program and oversees the safe and environmentally 

sound exploration and production of our Nation's offshore natural gas, oil and other mineral 

resources. The MMS Minerals Revenue Management meets its responsibilities by ensuring the 

efficient, timely and accurate collection and disbursement of revenue from mineral leasing and 

production due to Indian tribes and allottees, States and the U.S. Treasury. 

The MMS strives to fulfill its responsibilities through the general guiding principles of: (1) being 

responsive to the public's concerns and interests by maintaining a dialogue with all potentially 

affected parties and (2) carrying out its programs with an emphasis on working to enhance the 

quality of life for all Americans by lending MMS assistance and expertise to economic 

development and environmental protection.