OCS Study 

BOEMRE 2010-05 

Multi-Agency Rocky Intertidal Network 

(MARINe) Study of Rocky Intertidal 

Communities Adjacent to OCS 

Activities – Final report (2007-2010) 

Final Technical Summary 

Final Study Report 

U.S. Department of the Interior 

BOEMRE Bureau of Ocean Energy Management, Regulation and Enforcement 

Pacific OCS Region 

 
OCS Study 

BOEMRE 2010-05 

Multi-Agency Rocky Intertidal Network 

(MARINe) Study of Rocky Intertidal 

Communities Adjacent to OCS 

Activities – Final report (2007-2010) 

Final Technical Summary 

Final Study Report 

Project Manager 

Peter T. Raimondi 

Principal Investigators 

Richard Ambrose 

Jack Engle 

Steve Murray 

Jayson Smith 

Study design, oversight, and funding were provided by the U.S. 

Department of the Interior, Bureau of Ocean Energy Management, 

Regulation and Enforcement, Environmental Studies Program, 

Washington, DC under Agreement Number M07AC12503 

by 

Center for Ocean Health 

Long Marine Laboratory 

University of California 

Santa Cruz, CA 93106 

 
Disclaimer 

This report has been reviewed by the Pacific Outer Continental Shelf Region, Bureau of 

Ocean Energy Management, Regulation and Enforcement, U.S. Department of the 

Interior and approved for publication. The opinions, findings, conclusions, and 

recommendations in this report are those of the authors, and do not necessarily reflect the 

views and policies of the Bureau of Ocean Energy Management, Regulation and 

Enforcement. Mention of trade names or commercial products does not constitute an 

endorsement or recommendation for use. This report has not been edited for conformity 

with Bureau of Ocean Energy Management, Regulation and Enforcement editorial 

standards. 

Availability of Report 

Extra copies of the report may be obtained from: 

U.S. Dept. of the Interior 

Bureau of Ocean Energy Management, Regulation and Enforcement 

Pacific OCS Region 

770 Paseo Camarillo 

Camarillo, CA 93010 

Phone: 805-389-7621 

Suggested Citation 

The suggested citation for this report is: 

Raimondi, P.T. and R.N. Gaddam. Multi-Agency Rocky Intertidal Network (MARINe) 

Study of Rocky Intertidal Communities Adjacent to OCS Activities – Final report (2007-

2010). BOEMRE OCS Study 2010-005. Center for Ocean Health, Long Marine 

Laboratory, University of California, Santa Cruz, California. BOEMRE Cooperative 

Agreement Number M07AC12503. 38 pages (plus appendix). 

 
 

PROJECT ORGANIZATION 

Project Technical Officer: 

Mary Elaine Helix, Bureau of Ocean Energy Management, Regulation and Enforcement 

(BOEMRE)

Report Authors: 

Peter T. Raimondi, University of California, Santa Cruz 

Rani N. Gaddam, University of California, Santa Cruz 

Key Project Personnel: 

Principal Investigators: Peter T. Raimondi 

Richard F. Ambrose 

John M. Engle 

Steven N. Murray 

Jayson R. Smith 

Project Staff: Stevie Adams 

Karah Ammann 

Laura Anderson 

Christy Bell 

Sean Bergquist 

Lisa Gilbane 

Galen Holt 

Steven Lee 

Dan Martin 

Melissa Miner 

Carla Navarro 

Melissa Redfield 

Rafe Sagarin 

Sean Vogt 

Stephen Whitaker 
Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

TABLE OF CONTENTS 

PROJECT ORGANIZATION ..................................................................................... 4

LIST OF FIGURES..................................................................................................... 2

LIST OF TABLES ....................................................................................................... 2

FINAL TECHNICAL SUMMARY ............................................................................. 3

FINAL STUDY REPORT............................................................................................ 7

PART I: INTRODUCTION, OBJECTIVES, AND APPROACH................................. 7

1.1 Introduction.............................................................................................................................. 7

Central and Southern California Rocky Intertidal Habitats ...................................................... 8

San Luis Obispo and Northern Santa Barbara Counties (north of Point Conception) .............. 9

Southern Santa Barbara, Ventura, Los Angeles and Orange Counties (south of Pt. Conception)

........................................................................................................................................................ 10

1.2 Objectives .............................................................................................................................. 10

1.3 Approach................................................................................................................................ 10

Target Species Monitoring...................................................................................................... 10

Coordination—Internal and with MARINe ............................................................................ 16

Data management.................................................................................................................... 17

Project management................................................................................................................ 17

1.4 Significant Conclusions ......................................................................................................... 18

1.5 Study Results ......................................................................................................................... 18

1.6 Study Product(s) .................................................................................................................... 18

Presentations (2007-2010) ...................................................................................................... 19

Publications (2007-2010)........................................................................................................ 26

Reports (2007-2010) ............................................................................................................... 28

Sample Data Requests (2010) ................................................................................................. 30

ACKNOWLEDGEMENTS ............................................................................................. 31

LITERATURE CITED .................................................................................................... 32

APPENDIX ....................................................................................................................... 34

Selected Publications (attached) ............................................................................................. 34

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

LIST OF FIGURES 

Figure 1: Location of Sampling Sites........................................................................................... 12 

LIST OF TABLES 

Table 1: Extent of rocky and sandy shores for central/southern California. (Mainland 

data from Littler and Littler, 1979. Island data from Littler and Littler 

1980) ........................................................................................................................... 8 

Table 2: Sites sampled from north to south, group and Principle Investigator (PI) 

responsible for sampling and the seasons that were sampled during the 

contractual period. .................................................................................................... 11 

Table 3: Target species sampled (X) at each of the 24 sample sites............................................. 14 

Table 4: Target species plots in which motile organisms were sampled...................................... 15 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

FINAL TECHNICAL SUMMARY 

STUDY TITLE: “Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky 

Intertidal Communities Adjacent to OCS Activities” 

REPORT TITLE: Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky 

Intertidal Communities Adjacent to OCS Activities - Final report (2007-2010)” 

CONTRACT NUMBER: Cooperative Agreement Number M07AC12503 

SPONSORING OCS REGION: Pacific 

APPLICABLE PLANNING AREA(S): Southern California 

FISCAL YEAR(S) OF PROJECT FUNDING: FY 2007- FY2010 

COMPLETION DATE OF REPORT: December 31, 2010 

COSTS: FY2007 $325,237; FY 2008 $305,849; FY 2009 $320,414 

PROJECT MANAGER(S): Dr. Peter Raimondi 

AFFILIATION: Long Marine Laboratory, University of California, Santa Cruz (UCSC) 

ADDRESS: UC Santa Cruz Office of Sponsored Projects, 1156 High Street, Santa Cruz, 

California 

PRINCIPAL INVESTIGATOR(S): Dr. Pete Raimondi, University of California, Santa 

Cruz (UCSC); Dr. Richard Ambrose, University of California, Los Angeles (UCLA); Dr. 

Jack Engle, University of California, Santa Barbara (UCSB); Dr. Steve Murray, 

California State University, Fullerton (CSUF); Dr. Jayson Smith, California State 

University, Fullerton (CSUF) 

KEY WORDS: rocky intertidal, monitoring, black abalone, 

BACKGROUND 

Oil and gas activities, especially the tankering of oil along the California coast and the 

extraction of oil from OCS activities, raise the possibility of an oil spill or other impact to 

coastal resources. Population monitoring of coastal biota in central and southern 

California provide baseline information in case an event such as a spill damaged these 

resources. BOEMRE initiated the formation of a long-term monitoring program, the 

Multi-Agency Rocky Intertidal Network, MARINe, in 1997, which now has 32 Federal, 

State and local agency, University and private partners and monitors 120 rocky shore 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

sites. Through this study, BOEMRE funds biannual monitoring at 24 established rocky 

intertidal sites along the California mainland adjacent to OCS operations. The study also 

funds operation and maintenance of the shared MARINe database, and coordination of 

the MARINe committees. 

OBJECTIVES 

The primary objective for this research is to contribute to the ongoing monitoring 

program that provides a basis for determining if change in rocky shoreline communities 

adjacent to producing OCS facilities can be attributed to producing operations or 

accidents from OCS facilities. The second objective is to provide an ecological context 

through monitoring so as to understand the natural and anthropogenic changes to these 

communities that have occurred in the Southern California Bight since the OCS program 

was initiated. This latter objective is based on a collaboration between MARINe and 

other groups (especially the Partnership for Interdisciplinary Study of Coastal Oceans 

(PISCO)) and includes the collection of additional biodiversity data and comparison to 

comparable historic data (using matching funds). Additional objectives included 

oversight of a concurrent database process and publication of metadata for the BOEMREfunded long-term data set. 

DESCRIPTION: 

The work completed in the period 2007-2010 employed methodologies consistent with 

the previous MARINe projects in order to maximize comparability among project results. 

The methodological details for these projects can be found in Engle (2005 and 

www.marine.gov), and are summarized below. 

To accomplish the first objective, target species at 24 established rocky intertidal sites 

along the mainland coast of Southern and Central California adjacent to producing 

platforms were monitored spring and fall. 

Target species include: mussels (Mytilus californianus), barnacles (Chthamalus spp., 

Balanus glandula and Pollicipes polymerus), anemones (Anthopleura elegantissima), 

algal species including Endocladia muricata, Hesperophycus harveyanus, Silvetia 

compressa, Mazzaella spp., Mastocarpus papillatus, surfgrass (Phyllospadix 

scouleri/torreyi), motile invertebrates such as owl limpets (Lottia gigantea), black 

abalone (Haliotis cracherodii) and sea stars (Pisaster ochraceus). Mussels, barnacles, 

anenomes and algal species were photographed in fixed rectangular plots and scored in 

the lab or field (barnacles at some sites) by scoring species under 100 points on each 

slide. Five replicate plots per target species were photographed at each site where the 

plots occurred. Surfgrass cover was estimated using a point contact method along 10 m 

transects. Owl limpets were measured and counted in 5 replicate, 1-meter circular plots at 

each site where the plots occurred. Abalone were counted and measured in 3 replicate 

irregular plots. Sea stars were counted, measured and classed by color in either 2 meter 

wide, 10 m long band transects or irregular plots, depending on the habitat. In many of 

the target species plots we also sampled the associated motile species. To optimize future 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

environmental impact assessments, sites have been established systematically over a 

broad geographic range and each species is monitored at several sites within that range. 

This study also included overall coordination of MARINe, including facilitating meetings 

with the MARINe Steering Committee, Data Panel, and Science Panel and coordinating 

use of the data in collaborative projects. A large MARINe database is also populated and 

maintained for the entire network through this Cooperative Agreement. 

Dr. Pete Raimondi, the Project Manager, coordinated the study, and specifically oversaw 

monitoring in San Luis Obispo and northern Santa Barbara County sites. Dr. Steve 

Murray and Dr. Jayson Smith at California State University, Fullerton conducted the 

monitoring in Orange County. Dr. Rich Ambrose at UCLA conducted companion 

monitoring for southern Santa Barbara and Los Angeles Counties. Dr. Jack Engle at the 

UC Santa Barbara coordinated MARINe efforts, particularly with regards to protocol 

standardization and documentation. In addition, the BOEMRE Pacific Regional 

Intertidal Survey and Monitoring (PRISM) Team participated in the sampling, and other 

program functions to assure continued coordination with BOEMRE was maintained. 

SIGNIFICANT CONCLUSIONS: 

Ongoing monitoring of the black abalone documented the continuing decline of the 

species in much of its range. Additional studies coupled to the MARINe monitoring were 

carried out to determine the extent of the critical habitat for the species. These two data 

sets were combined to estimate the population size of Black abalone. These results were 

critical to the listing of the species as endangered. 

MARINe monitoring data was used by the State of California to aid in the Marine Life 

Protection Act design of the Marine Protected Area (MPA) network for southern 

California. Intertidal datasets were used to delineate the biogeographic regions and 

optimal sizes of intertidal MPA’s were also calculated based on MARINe datasets. 

MARINe datasets were the foundation of the assessment of potential impacts to the State 

designated Areas of Special Biological Significance. 

STUDY RESULTS: 

During the course of the performance period for this contract all 24 sites were sampled, 

usually twice per year (Table 2). Both sessile and motile species were sampled and 

sampling was generally uneventful. Fourteen target species were sampled across the 

project sites and in many of these plots, motile species were also sampled. During this 

period no additional sites were set up using direct BOEMRE funding, but 38 sites were 

set up using co-funding from the State of California (MPA and ASBS funding) and the 

U.S. Fish and Wildlife Service. 

During this period MARINe protocols were accepted as the first approved monitoring 

protocol for the U.S. National Park Service monitoring program (for Redwoods National 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

Park), and these protocols are now being used as the basis of monitoring programs in 

Park Service areas on the east coast. 

In terms of the biological communities sampled, the major result is the continued decline 

in the black abalone. The decline during this period was more muted than in the past, but 

still present. Importantly recruitment of new individuals still has not occurred at sites 

affected severely by the withering disease. Other species were dynamic but the changes 

in populations were not outside natural dynamics. We continued to monitor invasive 

species, but did not note any additional invasions. A full data report covering all 

MARINe sites will be finished in 2011. This report will be a comprehensive assessment 

of the entire MARINe region and cover species dynamics at spatial scales from 1000’s to 

10’s of kilometers and temporal scales from seasons to decades. This will be the most 

comprehensive assessment of a marine ecosystem (rocky intertidal throughout much of 

the California Current region) ever done. 

STUDY PRODUCT(S): Products include annual update of the MARINe database, 

collection and archival of photos and specimens, 135 conference presentations, 39 peer 

reviewed papers and posters, and 25 reports. See report and www.MARINe.gov for full 

listing. 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

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FINAL STUDY REPORT 

PART I: INTRODUCTION, OBJECTIVES, AND APPROACH 

1.1 Introduction 

The central/southern California mainland and Channel Islands seacoasts possess an 

exceptional diversity of valuable rocky intertidal resources. Major factors contributing to 

the richness of coastal marine life in this region include their location along the boundary 

of two major biogeographic provinces (cold-temperate Oregonian and warm-temperate 

Californian), their high diversity of habitat types, and their exposure to varying local 

oceanographic conditions. In addition, these rocky intertidal resources are heavily 

utilized (Thompson et al. 1993), with large human populations concentrated on the 

coastlines of San Diego, Orange and Los Angeles Counties. Oil and gas activities, 

especially the tankering of oil along the California coast and the extraction of oil from 

Outer Continental Shelf (OCS) activities, raise the possibility of an oil spill or other 

impact to coastal resources. Population monitoring of coastal biota in central and 

southern California would provide baseline information in case an event such as a spill 

damaged these resources. This baseline information would be essential for (1) scientific 

studies investigating the short- and long-term effects of the spill, and (2) natural resource 

damage assessment. In addition, the monitoring studies would yield important data on 

population dynamics on a local and regional scale, which could be utilized for more 

effective resource management as well as provide fundamental ecological knowledge 

about the dynamics of the systems. 

Federal, state and local agencies have recognized the importance of baseline information 

on coastal ecological resources by funding the establishment of a network of monitoring 

stations noted above. Of the over 120 established MARINe sites, over half are funded by 

Federal agencies, (e.g., BOEMRE, The National Park Service), and the balance are 

funded by private, State, and non-governmental entities. The biological information 

acquired during these surveys also is incorporated into resource databases hosted by the 

Multi-Agency Rocky Intertidal Network (MARINe) and Partnership for Interdisciplinary 

Study of Coastal Oceans (PISCO). This innovative monitoring program was initiated by 

the Channel Islands National Park in the early 1980’s (Davis 1985; Richards and Davis 

1988). In 1990, the Cabrillo National Monument in San Diego County began long-term 

rocky intertidal monitoring (Davis and Engle 1991). Monitoring in Santa Barbara 

County began in 1992 with a project funded jointly by the Bureau of Ocean Energy 

Management (BOEMRE), formerly the Minerals Management Service (MMS), which 

funded monitoring of intertidal and subtidal resources (Ambrose et al. 1992a, b), and the 

County of Santa Barbara, which funded monitoring of wetland resources (Ambrose et al. 

1993). In 1994, it was expanded by the California Coastal Commission (CCC) to include 

the northern Channel Islands (particularly Santa Cruz Island) and Ventura and Los 

Angeles Counties (Engle et al. 1994). The CCC projects include monitoring of subtidal, 

rocky and sandy intertidal and, for Los Angeles/Ventura Counties, wetland resources. 

Although the monitoring network is principally motivated by oil and gas activities, the 

information it generates provides valuable information about the status and trends of the 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

biological resources of the region, similar to the Environmental Protection Agency 

(EPA)’s Environmental Monitoring & Assessment Program (EMAP) but on a finer 

spatial scale. The National Research Council has also emphasized the value of 

coordinated regional monitoring such as proposed here (NRC 1990a, b). 

Nearshore coastal resources can be divided into three general habitat types: intertidal, 

subtidal, and coastal wetland. All three habitat types could be impacted by an oil spill. 

Numerous studies have documented major oil spill impacts on rocky intertidal regions 

(see Foster et al. 1986 for review). Impacts to subtidal habitats are likely to be less (and 

would certainly be less conspicuous). Coastal wetlands are particularly susceptible to 

damage from spilled oil; however, many wetlands along the southern California coast are 

isolated from the open sea during part of the year, or could be protected by booming or 

diking should a spill occur. 

Central and Southern California Rocky Intertidal Habitats 

The extent of rocky shoreline varies substantially in central and southern California 

(Ambrose et al. 1989). The northern section of the region and the Channel Islands are 

predominantly rocky (Table 1). San Luis Obispo County has the most extensive stretch 

of rocky shores (54 mi, or 58% of its coastline) in the region, except for the Channel 

Islands. Ventura and Orange Counties have the least rocky shoreline, each with 3 miles 

or 7% of the coastline. 

Location Coastline 

Length (mi) 

Miles Rocky Miles Sandy % Rocky % 

Sandy 

San Luis 

Obispo Co. 

93 54 39 58 42 

Santa Barbara 

Co.* 

110 26 84 24 76 

Ventura Co.* 41 3 38 7 93 

Los Angeles 

Co.*^ 

77 26 51 34 66 

Orange Co. 41 3 38 7 93 

San Diego Co. 76 11 65 14 86 

Channel Islands 273 211 62 77 23 

* excludes Channel Islands ^ includes harbor breakwaters 

Table 1: Extent of rocky and sandy shores for central/southern California. (Mainland data from 

Littler and Littler, 1979. Island data from Littler and Littler 1980) 

The biological communities of the mainland from San Luis Obispo County in the north to 

Orange County in the south are distinctly different north and south of Point Conception. 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

San Luis Obispo and Northern Santa Barbara Counties (north of Point 

Conception) 

Rocky intertidal communities to the north of Pt. Conception are well-known for their 

diverse and relatively pristine biota. The majority of the coast is either privately-owned, 

owned by the military, or inaccessible and is undeveloped. The natural beauty and 

coastal resources of this area make it a popular tourist destination, as evidenced by more 

than 10 State and County Parks and Beaches. A majority of the shore consists of rugged 

rocky reefs fully or partially exposed to prevailing oceanic swells. Situated at the 

northern end of the transition zone between southern (Californian) and northern 

(Oregonian) biota, these intertidal habitats contain a unique mix of species, with warmtemperate species declining and cold-temperate forms increasing in abundance compared 

with counties to the south. For example, warm-water sea palms (Eisenia arborea), 

rockweed (Hesperophycus harveyanus), barnacles (Tetraclita rubescens, Chthamalus 

fissus), and horse mussels (Brachidontes adamsianus) are rare or absent, while coldwater sea palms (Postelsia palmaeformis), rockweed (Fucus distichus, Pelvetiopsis 

limitata), barnacles (Balanus glandula, Chthamalus dalli), and horse mussels (Septifer 

bifurcata) appear or increase in abundance in SLO county. Black abalone (Haliotis 

cracherodii) populations have crashed due to disease, during the period of MARINe 

monitoring. 

The rich marine communities of this region are vulnerable to oil spills or other oil and gas 

operations impacts, primarily from major coastal tanker traffic, but also from terminal 

operations at Estero Bay, onshore pipeline breaks, and possible future oil exploration 

leases. Spills from OCS platforms also pose a threat. The Torch Platform Irene pipeline 

oil spill in 1997 landed on shores in this region. In addition, other anthropogenic impacts 

are vastly increasing, particularly those related to increases human access to shores that 

were until recently only reachable via private ranches. We have noted huge increases in 

public presence at sites throughout the region, accompanied by harvest and trampling. 

Only ongoing monitoring is effective at separating such impacts from those that could be 

linked to oil operations. 

Rocky coast flora and fauna in this region remain largely unstudied except for MARINe 

studies, those done by the PISCO program, impact surveys associated with the Diablo 

Canyon Nuclear Power Plant located north of Avila Beach (North et al. 1989, Tenera 

Environmental 1988a, b, 1994) and research on seasonal and successional variation in 

intertidal community structure conducted at 2 sites (Point Sierra Nevada and Diablo 

Canyon) (Kinnetic, 1992). The ongoing Diablo Canyon surveys, initiated in the 1970’s, 

represent an excellent time series for this one area. The seasonal and successional studies 

at Point Sierra Nevada and Diablo Canyon were funded by BOEMRE, formerly the 

Minerals Management Service (MMS), during 1985-1991, and currently one of the 

MARINe sites is at Point Sierra Nevada, thus extending the period of sampling to 2010. 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

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Southern Santa Barbara, Ventura, Los Angeles and Orange Counties (south 

of Pt. Conception) 

This region is prominent in the distribution of rocky intertidal organisms because it is 

bordered by Point Conception, an important biogeographical transition area. Although 

there is considerable overlap, there are distinct differences between the organisms north 

and south of Point Conception (Murray and Littler 1981, Ambrose et al., 1992a, b). For 

example, seaweed communities north of Point Conception are characterized by species 

such as Laminaria, lean brown algae and large, fleshy red algae, and by greater biomass, 

whereas communities south of the Point are characterized by fucalean brown algae and 

shorter, more densely branched red algae (Abbott and Hollenberg 1976). 

Concerns about the impact of oil spills in this region stem from transport by offshore 

tanker and onshore pipeline, production platforms, and terminal operations. Natural oil 

seeps are prominent features, especially at Point Conception. Previous studies in the 

region include work by PISCO, Littler and colleagues at Coal Oil Point and Government 

Point (Littler 1979), funded by BOEMRE, and Kinnetics at Government Point. 

1.2 Objectives 

The primary objective for this research was to contribute to the ongoing monitoring 

program that provides a basis for determining if change in rocky shoreline communities 

adjacent to producing OCS facilities can be attributed to producing operations or 

accidents from OCS facilities. The second objective was to provide an ecological context 

through monitoring so as to understand the natural and anthropogenic changes to these 

communities that have occurred in the Southern California Bight since the OCS program 

was initiated. This latter objective is based on collaboration between MARINe and other 

groups (especially PISCO) and includes the collection of additional biodiversity data and 

comparison to comparable historic data (using matching funds). Additional objectives 

included oversight of a concurrent database process and publication of metadata for the 

BOEMRE-funded long term data set. 

1.3 Approach 

The work completed in the period 2007-2010 employed methodologies consistent with 

the previous MARINe projects in order to maximize comparability among project results. 

The methodological details for these projects can be found in Engle (2005 and 

www.marine.gov), and are summarized below. 

Target Species Monitoring 

To accomplish the first objective, target species at 24 established rocky intertidal sites 

along the mainland coast of Southern and Central California adjacent to producing 

platforms were monitored spring and fall (Table 2, Figure 1). 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

Site Name SiteID

North/South 

Order Group 

Principal 

Investigator Seasons Sampled

Point Sierra Nevada PSN 1 UCSC Pete Raimondi 2007 Spring to 2010 Fall

Piedras Blancas Lighthouse PBL 2 UCSC Pete Raimondi 2007 Spring to 2010 Fall

Rancho Marino Reserve RMR 3 UCSC Pete Raimondi 2007 Spring to 2010 Fall

Cayucos CAY 4 UCSC Pete Raimondi 2007 Spring to 2010 Fall

Hazards HAZ 5 UCSC Pete Raimondi 2007 Spring to 2010 Fall

Shell Beach SHB 6 UCSC Pete Raimondi 2007 Spring to 2010 Fall

Occulto OCC 7 UCSC Pete Raimondi 2007 Spring to 2010 Fall

Purisima PUR 8 UCSC Pete Raimondi 2007 Spring to 2010 Fall

Stairs STA 9 UCSC Pete Raimondi 2007 Spring to 2010 Fall

Boathouse BOA 10 UCSC Pete Raimondi 2007 Spring to 2010 Fall

Government Point GPT 11 UCSC Pete Raimondi 2007 Spring

Alegria ALEG 12 UCLA Rich Ambrose 2007 Spring to 2010 Fall

Arroyo Hondo ARHO 13 UCLA Rich Ambrose 2007 Spring to 2010 Fall

Coal Oil Point COPT 14 UCLA Rich Ambrose 2007 Spring to 2010 Fall

Carpinteria CARP 15 UCLA Rich Ambrose 2007 Spring to 2010 Fall

Mussel Shoals MUSH 16 UCLA Rich Ambrose 2007 Spring to 2010 Fall

Old Stairs OLDS 17 UCLA Rich Ambrose 2007 Spring to 2010 Fall

Paradise Cove PCOV 18 UCLA Rich Ambrose 2007 Spring to 2010 Fall

Whites Point WHPT 19 UCLA Rich Ambrose 2007 Spring to 2010 Fall

Point Fermin PTFM 20 UCLA Rich Ambrose 2007 Spring to 2010 Fall

Crystal Cove CRCO 21 CSUF Steve Murray 2007 Spring to 2010 Fall

Shaws Cove SHCO 22 CSUF Steve Murray 2007 Spring to 2010 Fall

Treasure Island TRIS 23 CSUF Steve Murray 2007 Spring to 2010 Fall

Dana Point DAPT 24 CSUF Steve Murray 2007 Spring to 2010 Fall

Table 2: Sites sampled from north to south, group and Principle Investigator (PI) responsible for 

sampling and the seasons that were sampled during the contractual period. 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

Figure 1: Locations of sampling sites 

Location of sampling sites

Figure 1: Location of Sampling Sites 

Target species include: mussels (Mytilus californianus), barnacles (Chthamalus spp., 

Balanus glandula and Pollicipes polymerus), anenomes (Anthopleura elegantissima), 

algal species including Endocladia muricata, Hesperophycus harveyanus, Silvetia 

compressa, Mazzaella spp., Mastocarpus papillatus, surfgrass (Phyllospadix 

scouleri/torreyi), motile invertebrates such as owl limpets (Lottia gigantea), black 

abalone (Haliotis cracherodii) and sea stars (Pisaster ochraceus). Table 3 shows the 

target species at each of the sites sampled. Table 4 shows the plots in which motile 

species were also sampled. Analysis following the 167 bbl. “Torch spill”, an OCS 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

pipeline spill from the Platform Irene pipeline, showed that it was possible to detect 

change in percent cover of barnacles and mussels as small as 8-15% using this fixed plot 

sampling protocol. Importantly, it was also possible to differentiate between natural 

changes such as the El Nino storms and the effects of the oil spill (Raimondi et. al, 1999). 

It is vital that the monitoring protocol is in sufficient detail to address these low-level 

changes. 

Mussels, barnacles, anenomes and algal species were photographed in fixed rectangular 

plots and scored in the lab or field (barnacles at some sites) by scoring species under 100 

points on each slide. Five replicate plots per target species were photographed at each 

site where the plots occurred. Surfgrass cover was estimated using a point contact method 

along 10-meter long transects. Owl limpets were measured and counted in five replicate, 

1-meter circular plots at each site where the plots occurred. Abalone were counted and 

measured in three replicate irregular plots. Sea stars were counted, measured and classed 

by color in either 2-meter wide, 10-meter long band transects or irregular plots, 

depending on the habitat. In many of the target species plots, we also sampled the 

associated motile species (Table 4). To optimize future environmental impact 

assessments, sites have been established systematically over a broad geographic range 

and each species is monitored at several sites within that range. 

Monitoring of the long-term sites was usually done in Fall and Spring each year, although 

the motile species in target species plots were sometimes sampled only once per year (see 

Table 4). There can be considerable seasonal changes in the rocky intertidal community, 

especially after stormy winters and hot summers. Two samples per year adequately track 

these communities. October or November is usually the first period after summer with 

low tides during the daytime (which greatly improve efficiency of sampling and safety), 

and is appropriate for determining the post-summer community. March or April is an 

appropriate time to determine the post-winter community, and there are once again low 

tides during the daytime. 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

Site Name

anthopleurachthamalus/balanusendocladiahaliotishesperophycuslottiamastocarpusmazzaellamytiluspisasterpollicipespostelsiarecoverysilvetia

Point Sierra Nevada X XX XXXX X X

Piedras Blancas Lighthouse X X X XX X

Rancho Marino Reserve X X

Cayucos XXXXX X X X

Hazards X X X XXX X

Shell Beach X X X XX X

Occulto X X X X

Purisima X

Stairs XXX X X X X X

Boathouse XXXX X X X X

Government Point XXX X XXX X

Alegria X X X XXX

Arroyo Hondo X X X

Coal Oil Point X X

Carpinteria X X X XXX

Mussel Shoals X X X X X

Old Stairs XXX X X X

Paradise Cove X X X X X

Whites Point X X X X X

Point Fermin X XX X

Crystal Cove X XX X

Shaws Cove X X X X X X

Treasure Island X X X

Dana Point X XX X

Tar

X

X

X

X

X

get Species

Table 3: Target species sampled (X) at each of the 24 sample sites. 

14 
Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

Site Name

chthamalus / balanusendocladiahesperophycusmastocarpusmytiluspollicipesrecoverysilvetia

Motile Sampling 

Notes

Crystal Cove X XX

Dana Point X XX

Shaws Cove X X X X

Treasure Island X XX

Piedras Blancas Lighthouse X X X X Spring sampl

Alegria X X X Spring sampling only

Arroyo Hondo X X Spring sampling only

Carpinteria X X X Spring sampling only

Coal Oil Point X Spring sampling only

Mussel Shoals X X Spring sampling only

Old Stairs X X X Spring sampling only

Paradise Cove X X X Spring sampling only

Point Fermin X X X Spring sampling only

Whites Point X X X Spring sampling only

Boathouse X X X X

Cayucos XXX X X

Government Point X X X X

Hazards X X X X

Occulto X X X No Fall 2007 sampling

Point Sierra Nevada XXX X

Shell Beach XX XX X

Stairs X X X X X No Fall 2007 sampling

Tar

ing only

get Species

Table 4: Target species plots in which motile organisms were sampled 

15 
Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

Depending on the size of the site and the number of target species being monitored, one 

pair to three pairs of biologists was needed to collect the field data. The majority of sites 

needed four to five trained biologists to complete the work on a given tide. Pacific 

Region Intertidal Survey and Monitoring (PRISM) Team, formerly MMS Intertidal Team 

(MINT) biologists assisted in the collection of the field data at as many as 20 of the sites 

depending on tidal cycles. Travel to and from sites benefited from cost sharing since 

several sites can be surveyed during one tide cycle. 

Protocols used to collect the data were standardized, coordinated with other members of 

MARINe, and were not altered without prior approval of BOEMRE. A base protocol 

was standardized across the Bight among MARINe members and was maintained at each 

site; additional protocols needed to address site specific problems or answer speciesspecific questions were sometimes added with BOEMRE approval. Additional protocols 

which did not add field costs overall were accommodated in order to address these 

important research questions, so long as this was coordinated properly with MARINe 

members. 

This collection of field data was carried out by the University of California, Santa Cruz 

(UCSC), University of California, Los Angeles (UCLA), and California State University, 

Fullerton (CSUF) (see Table 2). 

Coordination—Internal and with MARINe 

Since several teams of biologists were needed to collect data at over 120 established sites 

(including the 24 covered in this grant proposal), coordination among field teams was 

essential to ensure that the data collected was of the highest quality and is comparable 

across sites. Therefore, strong coordination was needed between the Principal 

Investigators (PI)’s to ensure continuity since the tasks were inherently integrated 

between Universities. This coordination included regular meetings, email, phone calls 

and joint participation in the field. This ensured that individual PI’s are not inadvertently 

making changes in protocols or data processing which affect the other PI’s. 

Strong coordination was also needed between BOEMRE and MARINe to ensure that 

BOEMRE was providing data in a timely fashion to MARINe and that MARINe products 

directly met the needs of the scientists, including the BOEMRE PI’s. BOEMRE 

committed to providing a MARINe coordinator to that end. The duties of the coordinator 

included: 

1. Facilitating the development of the database by: 

a. Acting as a liaison between the database consultant and MARINE 

researchers in developing timely responses to database questions. 

b. Coordinating with the BOEMRE researchers in particular and MARINE 

researchers in general to ensure their data and metadata inputs are 

complete and timely. 

16 
Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

c. Providing a broad range of knowledge regarding the MARINE sites and 

technical issues to the database consultant to ensure that the database will 

be useful to researchers when it is completed. 

2. Organizing and moderating biannual Steering Committee, Science Panel and 

Database Panel meetings for MARINe. 

3. Providing ongoing coordination with the MARINe committee representatives and 

organizations outside MARINe to facilitate continued long-term funding of 

MARINe sites. 

4. Working with MARINe to develop automated standardized field datasheets. 

5. Working with MARINe to reach agreement and develop procedures which 

promote timely release of data to the public. 

These tasks were done at all campuses but the responsibility for coordination was 

centered at the University of California, Santa Barbara (UCSB). 

Data management 

Data management was overseen at UCSC. Duties included administering data in the 

MARINe (access) database. All campuses were responsible for uploading data using 

data forms, but no alterations to the database were be made without approval from the 

data administrator. Data were accessible via the Microsoft Access relational database 

management system interface, and revisions were made approximately twice per year. 

Data are available to all agencies and interested parties that make specific requests. 

Project management 

The UCSC portion of the program was managed by the Principal Investigator, Dr. Pete 

Raimondi. Dr. Raimondi has been a Principal Investigator of the BOEMRE-funded 

rocky intertidal inventory project since its inception and has been responsible for data 

analysis of the project for the past ten years. Dr. Raimondi was responsible for 

overseeing financial aspects of the project, and in particular was responsible for ensuring 

completion of project objectives and deliverables. This was done, in part, through 

coordination meetings and conference calls. However the main means of ensuring 

performance was through the yearly workshops where all PI’s get together along with 

staff to review the status of the project. 

Because this proposal is part of an overall coordinated monitoring program, the work was 

closely coordinated with other aspects of that program. Overall coordination was led by 

Dr. Steve Murray and Jayson Smith at CSUF, who conducted similar monitoring in 

Orange County. Dr. Rich Ambrose at UCLA conducted companion monitoring for 

southern Santa Barbara and Los Angeles Counties. Dr. Jack Engle at the UCSB 

coordinated MARINe efforts, particularly with regards to protocol standardization and 

documentation. In addition, the BOEMRE PRISM Team participated in the sampling, 

and other program functions to assure continued coordination with BOEMRE was 

maintained. 

17 
Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

1.4 Significant Conclusions 

Ongoing monitoring of the black abalone documented the continuing decline of the 

species in much of its range. Additional studies coupled to the MARINe monitoring were 

carried out to determine the extent of the critical habitat for the species. These two data 

sets were combined to estimate the population size of black abalone. These results were 

critical to the listing of the species as endangered. 

MARINe monitoring data was used by the State of California to aid in the Marine Life 

Protection Act design of the Marine Protected Area (MPA) network for southern 

California. Intertidal datasets were used to delineate the biogeographic regions and 

optimal sizes of intertidal MPA’s were also calculated based on MARINe datasets. 

MARINe datasets were the foundation of the assessment of potential impacts to the State 

designated Areas of Special Biological Significance (ASBS). 

1.5 Study Results 

During the course of the performance period for this contract all 24 sites were sampled, 

usually twice per year (Table 2). Both sessile and motile species were sampled and 

sampling was generally uneventful. Fourteen target species were sampled across the 

project sites and in many of these plots, motile species were also sampled. During this 

period no additional sites were set up using direct BOEMRE funding, but 38 sites were 

set up using co-funding from the State of California (MPA and ASBS funding) and the 

U.S. Fish and Wildlife Service. 

During this period MARINe protocols were accepted as the first approved monitoring 

protocol for the U.S. National Park Service monitoring program (for Redwoods National 

Park), and these protocols are now being used as the basis of monitoring programs in 

Park Service areas on the east coast. 

In terms of the biological communities sampled, the major result is the continued decline 

in the black abalone. The decline during this period was more muted than in the past, but 

still present. Importantly, recruitment of new individuals still has not occurred at sites 

affected severely by the withering disease. Other species were dynamic but the changes 

in populations were not outside natural dynamics. We continued to monitor invasive 

species, but did not note any additional invasions. A full data analysis report covering all 

MARINe sites will be finished in 2011. This report will be a comprehensive assessment 

of the entire MARINe region and cover species dynamics at spatial scales from 1000’s to 

10’s of kilometers and temporal scales from seasons to decades. This will be the most 

comprehensive assessment of a marine ecosystem (rocky intertidal throughout much of 

the California Current region) ever done. 

1.6 Study Product(s) 

Products include the following: continual enhancements to the MARINe Database; 

launch of a completely revamped public MARINe website, (which includes current news 

18 
Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

and research); restructuring of the private website (in progress); online availability of all 

MARINe data on www.piscoweb.org, (including data not previously included in the 

Access Database); the update of the MARINe Handbook, including updated tables and 

protocol enhancements; archival of photos and specimens; conference presentations, peer 

reviewed papers and posters, and reports; and organization and recording of data and info 

requests. Listed below are products of MARINe during this period; starred items were 

produced either using BOEMRE funding, using data collected at BOEMRE funded sites, 

or presented at a BOEMRE funded workshop. 

Presentations (2007-2010) 

*Ambrose, R. 2007. Oil spill rapid response protocols. MARINe Annual Workshop, San Francisco, CA. 

*Ambrose, R. 2007. Public access versus resource protection. MARINe Annual Workshop, San Francisco, 

CA. 

Ammann, K.N. 2010. Long-term rocky intertidal monitoring of Redwood National and State Parks. 

Presentation for National Park Service Klamath Network Inventory and Monitoring Program-Three 

Year Program Review. 

*Ammann, K.N., C.A. Bell. M.K. George, and P.T. Raimondi. 2009. An overview of the biological 

sampling used to assess the central California coast marine protected areas – with emphasis on rocky 

intertidal habitats. Western Society of Naturalists Annual Meeting, Monterey, CA. 

*Anderson, D. 2009. Survey team monitoring summary: Northern CA/Oregon. MARINe Annual 

Workshop, San Francisco, CA. 

*Anderson, L. 2009. Survey team monitoring summary: Santa Barbara/San Luis Obispo Counties. 

MARINe Annual Workshop, San Francisco, CA. 

Augyte, S. and F.J. Shaughnessy. 2010. A preliminary floristic analysis of marine intertidal algae from 

Cape Mendocino, CA to Cape Blanco, OR. Western Society of Naturalists Annual Meeting, San 

Diego, CA.

*Bell, C. 2007. Digital photo archive - where are we now and where are we headed? MARINe Annual 

Workshop, San Francisco, CA. 

*Bell, C. 2008. Go-kit protocol demonstration and what we learned from the Cosco Busan Oil Spill. 

MARINe Annual Workshop, San Pedro, CA. 

*Bell, C. 2008. Optional protocols revisited. MARINe Annual Workshop, San Pedro, CA. 

*Bell, C.A., K.N. Ammann, M.K. George, and P.T. Raimondi. 2009. Assessing the amount of suitable 

habitat and the population size of black abalone (Haliotis cracherodii) from Half Moon Bay to Point 

Conception. Western Society of Naturalists Annual Meeting, Monterey, CA; Black Abalone Critical 

Habitat Meeting, Ventura, CA; and MARINe Annual Workshop, San Francisco, CA. 

*Bell, C.A., K.N. Ammann, M.K. George, and P.T. Raimondi. 2010. Assessing suitable habitat and the 

population size of black abalone (Haliotis cracherodii) for critical habitat designation. Poster at 

Western Society of Naturalists Annual Meeting, San Diego, CA.

Bell, Christy. 2007. The importance of community structure and biodiversity surveys to establish baseline 

data for Marine Reserves. COBI Fishing CO-OP meeting, Isla Natividad, Baja California Sur, 

Mexico. 

*Blanchette, C. 2009. Biodiversity survey overview. MARINe Annual Workshop, San Francisco, CA. 

19 
Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

Blanchette, C.A. 2007. Intertidal communities of the CA Channel Islands: ecology and natural history. 

Western Society of Naturalists Annual Meeting, Ventura, CA. 

Blanchette, C.A., P.T. Raimondi, and B. R. Broitman. 2008. Spatial patterns of intertidal community 

structure across the California Channel Islands and links to ocean temperature. 7th California Islands 

Symposium, Oxnard, CA. 

*Conway-Cranos, L. 2007. Geographic patterns of recovery in intertidal communities. Partnership for 

Interdisciplinary Studies of Coastal Oceans (PISCO) Scientific Symposium. Corvallis, OR. 

*Conway-Cranos, L. 2007. Prediction and understanding the recovery of communities: An example from 

the rocky intertidal. Pacific Ecology and Evolution Conference. Seattle, WA; and Ecological Society 

of America Annual Conference. San Jose, CA. 

*Conway-Cranos, L. 2010. An investigation of the relative importance of mechanisms driving variation in 

the recovery of mussel beds. Western Society of Naturalists Annual Meeting, San Diego, CA.

*Conway-Cranos, L. 2010. Recovery dynamics in rocky intertidal communities: An experimental 

evaluation of resilience. Seminar at Friday Harbor Marine Laboratory, University of Washington, 

WA. 

*Conway-Cranos, L.. 2009. Recovery dynamics in rocky intertidal communities: Patterns, mechanisms and 

simulations. Ecological Society of America Annual Conference, Albuquerque, NM and Bodega 

Marine Laboratory Seminar. 

*Conway-Cranos, L.L. 2008. Facultative interactions as a potential driver for spatial variation in recovery 

patterns in the California rocky intertidal. Western Society of Naturalists Annual Meeting, Vancouver, 

BC. 

*Conway-Cranos, L.L. 2008. Recovery of intertidal communities: Perspectives from a broad-scale 

manipulation. MARINe Annual Workshop, San Pedro, CA. 

*Cox, K. 2007. MARINe regional sampling update: Northern California. MARINe Annual Workshop, San 

Francisco, CA. 

*Dalkey, A. and B. Allen. 2008. Palos Verdes Peninsula: research and education opportunities. MARINe 

Annual Workshop, San Pedro, CA. 

*Douros, W. 2007. MARINe, marine sanctuaries and more. MARINe Annual Workshop, San Francisco, 

CA. 

*Eernisse, D. 2008. Common chitons and limpets of southern California rocky intertidal. MARINe Annual 

Workshop, San Pedro, CA. 

Elsberry, L.A. and J.L. Burnaford. 2010. The effects of low-tide exposure on the high intertidal alga 

Endocladia muricata in two geographic regions. Poster at Western Society of Naturalists Annual 

Meeting, San Diego, CA.

*Engle, J. 2007. Multi-Agency Rocky Intertidal Network status. MARINe Annual Workshop, San 

Francisco, CA. 

*Engle, J. 2007. The Light and Smith Manual: invertebrate name changes. MARINe Annual Workshop, 

San Francisco, CA. 

*Engle, J. 2008. MARINe aids NOAA Mussel Watch expansion in southern California. MARINe Annual 

Workshop, San Pedro, CA. 

*Engle, J. 2008. Multi-Agency Rocky Intertidal Network status. MARINe Annual Workshop, San Pedro, 

CA. 

*Engle, J. 2009. Multi-Agency Rocky Intertidal Network status. MARINe Annual Workshop, San 

Francisco, CA. 

20 
Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

Fenberg, P.B. and K. Roy. 2007. The ecological consequences of size-selective harvesting: the owl limpet 

(Lottia gigantea) as a case study. Western Society of Naturalists Annual Meeting, Ventura, CA. 

Flectcher, N.C., P.T. Raimondi, C.M. DaCosta, M.A. Redfield, and S.E. Worden. 2010. Poster at Western 

Society of Naturalists Annual Meeting, San Diego, CA.

*Fong, D. 2009. MARINe sites on Alcatraz. MARINe Annual Workshop, San Francisco, CA. 

*Gaddam, R. 2008. Biodiversity surveys and PISCO updates. MARINe Annual Workshop, San Pedro, CA. 

*Gaddam, R. 2009. Accessing MARINe data through the online PISCO data catalog. MARINe Annual 

Workshop, San Francisco, CA. 

Garza, M.M. 2010. Relationship between habitat complexity and ochre sea star (Pisaster ochraceus) 

abundance. Poster at Western Society of Naturalists Annual Meeting, San Diego, CA.

*George, Maya, Christy Bell, Karah Ammann and Peter Raimondi. 2009. Assessing the amount of suitable 

habitat and the population size of black abalone from Half Moon Bay to Point Conception. Poster at 

Monterey National Marine Sanctuary Symposium, Monterey, CA. 

*Gilbane, L. and J. Smith. 2008. MARINe training video. MARINe Annual Workshop, San Pedro, CA. 

*Gilbane, L. and S. Kimura. 2009. Mapping: quest for the perfect map. MARINe Annual Workshop, San 

Francisco, CA. 

*Gray, H. 2008. Common shorebirds of southern California rocky shores. MARINe Annual Workshop, San 

Pedro, CA. 

*Gregorio, D. 2007. Areas of Special Biological Significance and MARINe. MARINe Annual Workshop, 

San Francisco, CA. 

*Gregorio, D. and K. Schiff. 2008. California Areas of Special Biological Significance. MARINe Annual 

Workshop, San Pedro, CA. 

Hays, CG. 2008. Genetic and maternal variation across a species’ distribution: consequences for emersion 

tolerance in an intertidal alga. Seminars at California State University Sacramento; Sacramento, CA; 

and California State University San Jose; San Jose, CA. 

Hays, CG. 2010. Genetic and maternal variation across a species’ distribution: consequences for emersion 

tolerance in an intertidal alga. Seminar at Moss Landing Marine Lab, Moss Landing, CA. 

*Helix, M.E. 2007. Overview of Multi-Agency Rocky Intertidal Network. MARINe Annual Workshop, 

San Francisco, CA. 

*Helix, M.E. 2007. Rocky Intertidal Monitoring Network and the Southern California Coastal Ocean 

Observing System. SCCOOS Board of Governors Meeting June 13, 2007. 

*Helix, M.E. 2008. Overview of Multi-Agency Rocky Intertidal Network. MARINe Annual Workshop, 

San Pedro, CA. 

*Helix, M.E. 2009. Overview of Multi-Agency Rocky Intertidal Network. MARINe Annual Workshop, 

San Francisco, CA. 

*Helix, M.E. 2010. Long-term monitoring program challenges – MARINe, the Multi-Agency Rocky 

Intertidal Network. Southern California Academy of Sciences Annual Meeting, Los Angeles, CA. 

*Helix, M.E., P. Raimondi, R. Ambrose, J. Engle, and S. Murray. 2007. MARINe: examining the health of 

rocky shores along the Pacific Coast. Monterey Bay National Marine Sanctuary Currents Symposium, 

Monterey, CA. 

*Helix, M.E., R.F. Ambrose, J.M. Engle, S.N. Murray, and P.T. Raimondi. 2007. Examining the health of 

rocky shores along the Pacific Coast – can local government and citizen’s help? Coastal Zone 2007, 

Portland, OR. 

21 
Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

Hewson, W.E. and D.J. Eernisse. 2007. A common southern California limpet is a new species that 

overlaps with its sister species in northern Baja California. Western Society of Naturalists Annual 

Meeting, Ventura, CA. 

*Joab, B. and J. Cubit. 2008. MARINe and NRDA’s: increasing the effectiveness of the combination. 

MARINe Annual Workshop, San Pedro, CA. 

*Jones, A.M. and D.P. Lohse. 2009. A regional comparison of Mytilus californianus growth rates along the 

central coast of California. Western Society of Naturalists Annual Meeting, Monterey, CA. 

*Kimura, S. 2007. GIS maps of the California coastline. MARINe Annual Workshop, San Francisco, CA. 

*Kinyon, J. 2009. Habitat mapping in Golden Gate National Recreation Area. MARINe Annual Workshop, 

San Francisco, CA. 

*Lawrenz-Miller, S. 2008. Long term intertidal population surveys on the Palos Verdes Peninsula. 

MARINe Annual Workshop, San Pedro, CA. 

*Lee, S. 2008. MARINe site at Point Fermin. MARINe Annual Workshop, San Pedro, CA. 

*Lee, S. 2008. Multi-Agency Rocky Intertidal Network. Teacher Training Workshop for Center for Ocean 

Sciences Education Excellence (COSEE-West), San Pedro, CA. 

*Lee, S. 2009. Survey team monitoring summary: LA/Ventura Counties. MARINe Annual Workshop, San 

Francisco, CA. 

*Livingston, H. 2009. Species ranges: climate change implications. MARINe Annual Workshop, San 

Francisco, CA. 

*Long, J. 2007. MARINe on the East Coast. MARINe Annual Workshop, San Francisco, CA. 

*Long, J. 2008. MARINe on the East Coast. MARINe Annual Workshop, San Pedro, CA. 

*Long, J. 2009. Survey team monitoring summary: East Coast. MARINe Annual Workshop, San 

Francisco, CA. 

*Lonhart, S. 2007. MARINe regional sampling update: Central California. MARINe Annual Workshop, 

San Francisco, CA. 

*Maloney, E. 2008. California Introduced Species Surveys: who’s on our turf? MARINe Annual 

Workshop, San Pedro, CA. 

Maloney, E.R., W.R. Fairey, A.A. Lyman, Z.A. Walton, S.F. Foss, and S.N. Shiba. 2008. Surveys for 

introduced marine species on the outer coast of California: who’s on our turf? Western Society of 

Naturalists Annual Meeting, Vancouver, BC. 

*Miller, K.A. 2009. Invasive species status. MARINe Annual Workshop, San Francisco, CA. 

Miller, K.A. 2010. California’s non-native seaweeds: a case study. XX International Seaweed Symposium, 

Ensenada, Baja California, Mexico. 

*Miner, C.M. 2008. MARINe database structure. MARINe Meeting, Seattle, WA 

*Miner, C.M. 2008. MARINe Rocky Intertidal Monitoring Program, Northwest Straits Initiative Meeting, 

Bellingham, WA 

*Miner, M. 2007. Multi-Agency Rocky Intertidal Network database update. MARINe Annual Workshop, 

San Francisco, CA. 

*Miner, M. 2008. Multi-Agency Rocky Intertidal Network database update. MARINe Annual Workshop, 

San Pedro, CA. 

*Miner, M. 2009. Survey team monitoring summary: Washington State. MARINe Annual Workshop, San 

Francisco, CA. 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

Monaco, C.J. 2010. Size-dependent intertidal distribution and foraging behavior in Pisaster ochraceus. 

Poster at Western Society of Naturalists Annual Meeting, San Diego, CA.

*Murray, S. 2007. Science, politics, the public and protecting California’s coastal ecosystems. Southern 

California Academy of Sciences Annual Meeting, Fullerton, CA. 

*Murray, S. 2008. Changes in rocky intertidal communities on the Channel Islands and the southern 

California mainland since the 1970’s. 7th California Islands Symposium, Oxnard, CA. 

*Murray, S., R.F. Ambrose, J. Engle, P. Raimondi, and S. Weisberg. 2010. Developing indicators for 

monitoring the status of rocky shores. California and the World Ocean 2010 Conference, San 

Francisco, CA. 

*Murray, S.N., C.A. Navarro, S.C. Vogt, and J.R. Smith. 2010. Feeding responses of native macroinvertebrates to non-indigenous seaweeds. XX International Seaweed Symposium, Ensenada, Baja 

California, Mexico. 

*Murray, S.N., J. R. Smith, A. Bullard, and L. Gilbane. 2009. Changes in Coastal Seaweed Populations 

over time in Urban Settings and the Ecological Implications (Plenary Lecture). Novos Bioativos de 

Macroalgas Workshop, Ilhabela – São Paulo, Brazil. 

*Murray. S. N. 2008. Seaweed Introductions: An Overview. Control of Invasive Marine Seaweeds 

Workshop, Asilomar, CA. 

*Navarro, C. 2007. MARINe regional sampling update: Southern California. MARINe Annual Workshop, 

San Francisco, CA. 

*Navarro, C.N., J.R. Smith, and S.N. Murray. 2007. Feeding rates of native consumers on introduced and 

native seaweeds on urban southern California shores. Southern California Academy of Sciences 

Annual Meeting, Fullerton, CA. 

*Neuman, M.J. and G.R. VanBlaricom. 2008. Status of black abalone populations at the California Channel 

Islands: implications for long-term viability throughout the range of the species. 7th California Islands 

Symposium, Oxnard, CA. 

Orr, D., P. Raimondi, C. Bell, T. Conway-Cranos, M. George, D. Lohse, and S. Worden. 2010. Assessment 

of effect and predictions of recovery dynamics when baseline data are scarce: a case study of the 

Cosco Busan oil spill. Western Society of Naturalists Annual Meeting, San Diego, CA.

*Orr, D.W., M.A. Redfield, L.M. Anderson, K.N. Ammann. 2010. Overview of the biological sampling 

used to assess California’s Central Coast Marine Protected Areas – with an emphasis on rocky 

intertidal habitats. Poster at Monterey Bay National Marine Sanctuary Symposium, Monterey, CA. 

Parker, M.A. and K.J. Nielsen. 2007. A tale of two headlands: recruitment and reproductive output of 

Balanus glandula and Chthamalus dalli along the northern California coast. Western Society of 

Naturalists Annual Meeting, Ventura, CA. 

Pearse, J.S., D.E. Pearse, and V.B. Pearse. 2007. Rising sea level and changes in intertidal zonation: 

professor Snadrock 60 years later. Western Society of Naturalists Annual Meeting, Ventura, CA. 

Pister, B. and T. Philippi. 2010. Twenty years of rocky intertidal monitoring at Cabrillo National 

Monument: detection and analysis of long-term trends. Western Society of Naturalists Annual 

Meeting, San Diego, CA.

*Protopapadakis, L. 2008. California’s Marine Life Protection Act: laying a foundation for the future. 

MARINe Annual Workshop, San Pedro, CA. 

*Raimondi, P. 2007. MARINe and Marine Protected Areas. MARINe Annual Workshop, San Francisco, 

CA. 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

*Raimondi, P., D. Gregorio, and A. Compton. 2007. Rocky intertidal health. MARINe Annual Workshop, 

San Francisco, CA. 

*Raimondi, P.T. 2008. Go-kit protocols updated through Cosco Busan Experience. MARINe Annual 

Workshop, San Pedro, CA. 

Recchia, C., L. Whitman, P. Raimondi, A. Scholz, S. Murray, and S. Katz. 2010. Evolving MPA 

monitoring: aligning science and policy. California and the World Ocean 2010 Conference, San 

Francisco, CA. 

*Redfield, M. 2009. Survey team monitoring summary: Monterey/Marin Counties. MARINe Annual 

Workshop, San Francisco, CA. 

Redfield, M.A., P.T. Raimondi, N.C. Fletcher, and S.E. Worden. 2010. An overview of the North Central 

Coast Marine Protected Areas Baseline Program monitoring. Poster at Western Society of Naturalists 

Annual Meeting, San Diego, CA.

Reinhard, L.J., K.N. Ammann, M.T. Tinker, P.T. Raimondi, and C.A. Bell. 2009. Effects of sea otters on 

local distribution and density of black abalone. Western Society of Naturalists Annual Meeting, 

Monterey, CA. 

Richards, D. 2008. Foundations of Marine Reserves at the Channel Islands, NPS Aquatic Professionals 

Meeting, Fort Collins, CO. 

*Richards, D. 2009. Black abalone restoration/recovery plan status. MARINe Annual Workshop, San 

Francisco, CA. 

Richards, D. 2009. Marine Reserves at the Channel Islands. George Wright Society Meeting, Portland, OR. 

*Richards, D. 2009. Survey team monitoring summary: Channel Islands. MARINe Annual Workshop, San 

Francisco, CA. 

Richards, D.V. 2008. Black abalone at the Channel Islands, a brief history. 7th California Islands 

Symposium, Oxnard, CA. 

Richards, D.V. and S.G. Whitaker. 2010. Monitoring black abalone movement and aggregating behavior. 

Poster at Western Society of Naturalists Annual Meeting, San Diego, CA.

Sagarin, R.D. 2008. Size matters: loss of large coastal invertebrates and implications for ecology and 

management. Western Society of Naturalists Annual Meeting, Vancouver, BC. 

*Smith, J.R. 2007. Long-term change in macrophyte & macroinvertebrate communities on wave-exposed 

rocky intertidal shores. Seminar at California State University, Northridge, Department of Biology, 

Biology Colloquium. 

 *Smith, J.R. 2007. Seaweed communities in a heavily urbanized environment in southern California. 

Seminar at the Coastal Studies Consortium, Universidade Federal Fluminense, Niteroi, Brazil. 

*Smith, J.R. 2008. Coastal ecology in the face urbanization and environmental change. Seminars at Eastern 

Connecticut State University, and NOAA Workshop on Managing Visitor Use at Dana Point, CA. 

*Smith, J.R. 2009. Coastal urban ecology for teachers. Seminar for Centers for Ocean Sciences Education 

Excellence (COSEE) at Dana Point, CA. 

*Smith, J.R. 2009. Survey team monitoring summary: San Diego/Orange Counties. MARINe Annual 

Workshop, San Francisco, CA. 

*Smith, J.R. 2009. Urban ecology: a southern California rocky intertidal perspective. Seminars at SUNY 

Stony Brook Southampton, NY, CA State University Fullerton, and University of Alaska Southeast. 

*Smith, J.R. 2010. Urban ecology: a southern California rocky intertidal perspective. Seminars at 

California Polytechnic University, CA and University of New Haven, CT. 

24 
Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

*Smith, J.R., R.F. Ambrose, and P. Fong. 2008. Regional comparisons and decadal changes in mussel 

populations (Mytilus californianus) and mussel bed community diversity along the California coast. 

7th California Islands Symposium, Oxnard, CA. 

*Smith, J.R., S.G. Whitaker, and S.N. Murray. 2009. Experimental re-establishment of the rockweed, 

Silvetia compressa, on urban southern California shores. Western Society of Naturalists Annual 

Meeting, Monterey, CA. 

Smith, K.A. and B. Helmuth. 2007. When mussels die...an assessment of the mechanisms determining the 

upper limit of Mytilus californianus beds along the Pacific coast of North America. Western Society 

of Naturalists Annual Meeting, Ventura, CA. 

Steinbeck, J.R. 2010. Sh%t happens: how designing redundancy into a monitoring program can help 

exorcise intruding demons and increase the options for analysis and ability to detect change. . 

Southern California Academy of Sciences Annual Meeting, Los Angeles, CA. 

SWAT. 2008. Life in the tidepools and kelp forests. Seminar at Rancho del Oso Nature Center. 

*Tharratt, S. 2007. MARINe regional sampling update: offshore islands. MARINe Annual Workshop, San 

Francisco, CA. 

Thompson, S.A., K.J. Nielsen, C.A. Blanchette, B. Brockbank, and H.R. Knoll. 2007. Effects of 

commercial collection on growth and reproductive output of Postelsia palmaeformis. Ecological 

Society of America Annual Meeting, San Jose, CA. 

Thompson, S.A., K.J. Nielsen, C.A. Blanchette, B. Brockbank, and H.R. Knoll. 2007. The response of 

Postelsia palmaeformis to commercial collection across sites in California. Western Society of 

Naturalists, Ventura, CA. 

*Vogt, S., J.R. Smith, and S.N. Murray. 2010. Do native macro-invertebrates consume native over nonnative seaweeds? Northwest Algal Symposium, Whidbey Island, WA. 

*Vogt, S.C., J.R. Smith, and S.N. Murray. 2010. The consumer’s dilemma, native or non-native seaweeds. 

Western Society of Naturalists Annual Meeting, San Diego, CA. 

*Vogt, S.C., L. Gilbane, A. Bullard, J.R. Smith, and S.N. Murray. 2007. Spatial and temporal variation in 

δ13C and δ15N values of macro-algae in southern California waters. Southern California Academy of 

Sciences Annual Meeting, Fullerton, CA. 

*Walters, K. 2009. Survey team monitoring summary: Mexico/Baja California. MARINe Annual 

Workshop, San Francisco, CA. 

*Walters, K. 2009. Today’s GPS: what it can do for you – a SWAT retrospective. MARINe Annual 

Workshop, San Francisco, CA. 

Waltz, G.T., J.R. Steinbeck, S.R. Kimura, and D.E. Wendt. 2007. Simulation of human activities and 

corresponding impacts to the temperate intertidal. Western Society of Naturalists, Ventura, CA. 

Waltz, G.T., S. Kimura, J.R. Steinbeck, and D.E. Wendt. 2009. Bare space or bountiful biota: an analysis of 

human disturbance on our rocky shoreline. Western Society of Naturalists Annual Meeting, Monterey, 

CA. 

*Weisberg, S.B. 2008. The subtle benefits of cooperative regional monitoring. MARINe Annual 

Workshop, San Pedro, CA. 

Whitaker, S. 2008. Experimental re-establishment of the rockweed Silvetia compressa at Little Corona del 

Mar. MARINe Annual Workshop, San Pedro, CA. 

Whitaker, S.G. and D.V. Richards. 2010. Widespread declines in abundances of rocky intertidal ecosystem 

modifiers and associated motile invertebrate species. Poster at Western Society of Naturalists Annual 

Meeting, San Diego, CA. 

25 
Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

*Whitaker, S.G., J.R. Smith, and S.N. Murray. 2007. Experimental restoration of the rocky intertidal brown 

alga Silvetia compressa on urban southern California shores. Southern California Academy of 

Sciences Annual Meeting, Fullerton, CA. 

*Whiteside, K.E., J.R. Smith, and S.N. Murray. 2007. Distribution, habitat utilization, and reproductive 

patterns in Caulacanthus ustulatus (Caulacanthaceae, Gigartinales), a newly established seaweed on 

southern California shores. Southern California Academy of Sciences Annual Meeting, Fullerton, CA. 

*Worden, S. 2009. What is larval recruitment data telling us? MARINe Annual Workshop, San Francisco, 

CA. 

Publications (2007-2010) 

Ambrose, R.F. 2008. Habitat restoration. Pp. 260-263. In: M.W. Denny and S.D. Gaines (eds.). 

Encyclopedia of Tidepools & Rocky Shores. University of California Press, Berkeley, CA. 

Becker, B.J., L.A. Levin, F.J. Fodrie, and P.A. McMillan. 2007. Complex larval connectivity patterns 

among marine invertebrate populations. Proceedings of the National Academy of Sciences 104:3267-

3272. 

Blanchette, C.A. and S.D. Gaines. 2007. Distribution, abundance, size and recruitment of the mussel, 

Mytilus californianus, across a major oceanographic and biogeographic boundary at Point 

Conception, California, USA. Journal of Experimental Marine Biology and Ecology 340:268-279. 

Blanchette, C.A., B. Helmuth, and S.D. Gaines. 2007. Spatial patterns of growth in the mussel, Mytilus 

californianus, across a major oceanographic and biogeographic boundary at Point Conception, 

California, USA. Journal of Experimental Marine Biology and Ecology 340:126-148. 

Blanchette, C.A., C.M. Miner, P.T. Raimondi, D. Lohse, K.E.K. Heady and B. Broitman. 2008. 

Biogeographic patterns of rocky intertidal communities along the Pacific coast of North America. 

Journal of Biogeography 35:1593-1607. 

Blanchette, C.A., D.R. Schiel, E.A. Wieters, B.R. Broitman, and B.P. Kinlan. 2009. Trophic structure and 

diversity in rocky intertidal upwelling ecosystems: A comparison of community patterns across 

California, Chile, South Africa and New Zealand. Progress in Oceanography 83:107-116. 

Blanchette, C.A., P.A. Raimondi and B.R. Broitman. 2009. Spatial patterns of intertidal community 

structure across the California Channel Islands and links to ocean temperature. Pages 161-173 In: 

Damiani, C.C. and D.K. Garcelon, (eds.), Proceedings of the 7th California Islands Symposium. 

Institute for Wildlife Studies: Arcata, CA. CD-ROM. 

*Broitman, B.R., C.A. Blanchette, B.A. Menge, J. Lubchenco, C. Krenz, M. Foley, P.T. Raimondi, D. 

Lohse and S.D. Gaines. 2008. Spatial and temporal patterns of invertebrate recruitment along the west 

coast of the United States. Ecological Monographs 78:403-421. 

Broitman, B.R., L. Szathmary, K.A.S. Mislan, C.A. Blanchette, and B. Helmuth. 2009. Predator-prey 

interactions under climate change: the importance of habitat vs. body temperature Oikos 118:219-224. 

*Conway-Cranos, L. 2009. Recovery dynamics in rocky intertidal communities: patterns, mechanisms, and 

simulations. Ph.D. Dissertation. University of California, Santa Cruz. 

*Del Sontro, T.S., I. Leifer, B.P Luyendyk and B.R Broitman. 2007. Beach tar accumulation, transport 

mechanisms, and sources of variability at Coal Oil Point, CA. Marine Pollution Bulletin 54:1461-

1471. 

Dethier, M.N. 2008. Monitoring: techniques. 2008. Pp.390-393. In: M.W. Denny and S.D. Gaines (eds.). 

Encyclopedia of Tidepools & Rocky Shores. University of California Press, Berkeley, CA. 

26 
Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

Fenberg, P.B. and K. Roy. 2008. Ecological and evolutionary consequences of size-selective harvesting: 

how much do we know? Molecular Ecology 17:209-220. 

Hays, C.G. 2007. Adaptive phenotypic differentiation across the intertidal gradient in the alga Silvetia 

compressa. Ecology 88:149-157. 

*Helix, M.E., R.F. Ambrose, J.M. Engle, S.N. Murray, and P.T. Raimondi. 2007. Examining the health of 

rocky shores along the Pacific Coast – can local government and citizen’s help? Proceedings of 

Coastal Zone 2007 Symposium, Portland, OR. 

*Henkel, S. K., G. E. Hofmann, and A. C. Whitmer. 2007. Morphological and genetic variation in Egregia 

menziesii over a latitudinal gradient. Botanica Marina 50:159-170. 

*Henkel, S.K. and S.N. Murray. 2007. Reproduction and morphological variation in southern California 

populations of the lower intertidal kelp Egregia menziezii (Laminariales). Journal of Phycology 

43:242-255. 

Huff, T.M. and J.K. Jarett. 2007. Sand addition alters the invertebrate community of intertidal coralline 

turf. Marine Ecology Progress Series 345:75-82. 

Hurtado L.A., M. Mateos, C.A. Santamaria. 2010. Phylogeography of supralittoral rocky intertidal Ligia

isopods in the Pacific Region from Central California to Central Mexico. PLoS ONE 5(7): e11633. 

doi:10.1371/journal.pone.0011633. 

Lester, S.E., E.D. Tobin, and M.D. Behrens. 2007. Disease dynamics and the potential role of thermal 

stress in the sea urchin, Strongylocentrotus purpuratus. Canadian Journal of Fisheries and Aquatic 

Science 64: 314-323. 

Lester, S.E., S.D. Gaines, and B.P. Kinlan. 2007. Reproduction on the edge: large-scale patterns of 

individual performance in a marine invertebrate. Ecology 88:2229-2239. 

Lohse, D.P. and P.T. Raimondi. 2008. Barnacles. Pp. 61-64. In: M.W. Denny and S.D. Gaines (eds.). 

Encyclopedia of Tidepools & Rocky Shores. University of California Press, Berkeley, CA. 

Menge, B.A., M.M. Foley, J. Pamplin, G. Murphy, and C. Pemmington. 2010. Supply-side ecology, 

barnacle recruitment, and rocky intertidal community dynamics: Do settlement surface and limpet 

disturbance matter? Journal of Experimental Marine Biology and Ecology 392:160-175. 

Murray, S.N. 2008. Habitat alteration. Pp.256-260. In: M.W. Denny and S.D. Gaines (eds.). Encyclopedia 

of Tidepools & Rocky Shores. University of California Press, Berkeley, CA. 

Murray, S.N. 2008. Succession. Pp. 555-560. In: M.W. Denny and S.D. Gaines (eds.). Encyclopedia of 

Tidepools & Rocky Shores. University of California Press, Berkeley, CA. 

*Pfeiffer-Herbert, A.S., M.A. McManus, P.T. Raimondi, Y. Chao, and F. Chai. 2007. Dispersal of barnacle 

larvae along the central California coast: A modeling study. Limnology and Oceanography 52:1559-

1569. 

Phillips, N.E. 2007. A spatial gradient in the potential reproductive output of the sea mussel Mytilus 

californianus. Marine Biology 151:1543-1550. 

Phillips, N.E. 2007. High variability in egg size and energetic content among intertidal mussels. Biological 

Bulletin 212:12-19. 

Pister, B. 2007. Intertidal ecology of riprap jetties and breakwaters: marine communities inhabiting 

anthropogenic structures along the west coast of North America. Ph.D. Dissertation, UC San Diego. 

Raimondi, P., K. Cox, C. DaCosta, R. Gaddam, D. Lohse, C. Bell, M. George, M. Miner, and S. Worden. 

2007. Reserves in reverse. In: PISCO Coastal Connections Vol 6. Partnership for Interdisciplinary 

Studies of Coastal Oceans. 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

*Raimondi, P., R. Sagarin, R. Ambrose, C. Bell, M. George, S. F. Lee, D. Lohse, C.M. Miner, and S.N. 

Murray. 2007. Consistent frequency of color morphs in the sea star Pisaster ochraceus

(Echinodermata: Asteriidae) across open-coast habitats in the northeastern Pacific. Pacific Science 

61:201-210. 

*Reed, D.C., S.J. Holbrook, C.A. Blanchette and S. Worcester. 2009. Patterns and sources of variation in 

flowering, seed supply, and seedling recruitment in surfgrass Phyllospadix torreyi. Marine Ecology 

Progress Series 384:97-106. 

Roy, K. 2008. Ecosystem changes, natural versus anthropogenic. Pp. 201-204. In: M.W. Denny and S.D. 

Gaines (eds.). Encyclopedia of Tidepools & Rocky Shores. University of California Press, Berkeley, 

CA. 

Sagarin, R. 2008. Climate change, overview. Pp. 137-140. In: M.W. Denny and S.D. Gaines (eds.). 

Encyclopedia of Tidepools & Rocky Shores. University of California Press, Berkeley, CA. 

*Sagarin, R.D., R.F. Ambrose, B.J. Becker, J.M. Engle, J. Kido, S.F. Lee, C. M. Miner, S.N. Murray, P.T. 

Raimondi, D.V. Richards, and C. Roe. 2007. Ecological impacts on the limpet Lottia gigantea 

populations: human pressure over a broad scale on island and mainland intertidal zones. Marine 

Biology 150:399-413. 

*Smith, J.R., P. Fong and R.F. Ambrose. 2009. “Spatial patterns in recruitment and growth of the mussel 

Mytilus californianus (Conrad) in southern and northern California, USA, two regions with differing 

oceanographic conditions.” Journal of Sea Research 61: 165-173. 

*Smith, J.R., P. Fong, and R.F. Ambrose. 2008. The impacts of human visitation on mussel bed 

communities along the California coast: are regulatory marine reserves effective in protecting these 

communities? Environmental Management 41:599-612.

Thompson, S.A., H. Knoll, C.A. Blanchette and K.J. Nielsen. 2010. Population consequences of biomass 

loss due to commercial collection of the wild seaweed Postelsia palmaeformis. Marine Ecology 

Progress Series 413:17-31. 

*Whitaker, S., J.R. Smith, and S.N. Murray. 2010. Re-establishment of the southern California rocky 

intertidal brown alga, Silvetia compressa: an experimental investigation of techniques and abiotic and 

biotic factors that affect restoration success. Restoration Ecology 18:18-26.

Reports (2007-2010) 

*Ambrose, R.F. and N. Diaz. 2008. Pre-spill assessments of coastal habitat resources. Volume I: 

Development of protocols. California Department of Fish and Game Office of Spill Prevention and 

Response. 71p. 

*Ambrose, R.F. and N. Diaz. 2008. Pre-spill assessments of coastal habitat resources. Volume II: Quick 

response protocols. California Department of Fish and Game Office of Spill Prevention and Response. 

Ammann, K and P. Raimondi. 2008 Long-term monitoring protocol for rocky intertidal communities of 

Redwood National and State Parks, California. Natural Resource Report NPS/MWR/KLMN/NRR – 

2008/034. National Park Service, Fort Collins, Colorado. 

Azimi-Gaylon, S., G. Lauenstein, D. Gregorio, and E. Siegel. 2008. Northern and Central California 

regional mussel survey draft work plan 2007-09. State Water Resources Control Board. 39p. 

*Conway-Cranos, T., P.T. Raimondi and R.F. Ambrose. 2007. Spatial and temporal variation in 

recruitment to rocky shores: relationship to recovery rates of intertidal communities. MMS OCS 

Study 2006-053. Coastal Research Center, Marine Science Institute, University of California, Santa 

Barbara, California. MMS Cooperative Agreement Number 14-35-0001-31063. 38 pages. 

28 
Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

Cox, K. 2007. Abundance and distribution patterns of intertidal fishes at three sites within Redwood 

National and State Parks, 2004-2005. Thesis (M.S.)--Humboldt State University, Natural Resources: 

Fisheries Biology, 2007 

Diehl, D., K. Maruya, J. Engle, D. Gregorio, R. Fay, and G. Lauenstein. 2007. 2007-08 Southern California 

regional mussel survey workplan. 42p. 

Kinyon, J., R. Gaddam, D. Schirokauer, R. Presiado, P. Raimondi. 2009. Coastal biophysical inventory 

database: Point Reyes National Seashore & Golden Gate National Recreation Area [Computer 

software]. Pacific Coast Science and Learning Center, National Park Service, Point Reyes Station, 

CA. 

Miller, K.A. 2007. Summary of nomenclatural and taxonomic changes for California seaweeds. University 

of California, Berkeley Herbarium. 

Miller, K.A. 2008. Summary of nomenclatural and taxonomic changes for California seaweeds. University 

of California, Berkeley Herbarium. 

Miller, K.A. 2009. Summary of nomenclatural and taxonomic changes for California seaweeds. University 

of California, Berkeley Herbarium. 

*Miner, M., B. Bealer, and L. Cooper. 2007. Revised MARINe Database User Guide. U.S. Minerals 

Management Service Report. 84 pages. 

Murray, S.N. and K.A. Miller. 2010. Marine macrophytes of the open-coast, rocky intertidal habitats of the 

Cabrillo National Monument. Final Report. Coastal Marine Ecology Laboratory, California State 

University, Fullerton. 56p. 

*Murray, S.N., P. Raimondi, and S.B. Weisberg. 2010. In pursuit of bio-criteria for evaluating the 

condition of rocky intertidal communities. Report of a workshop sponsored by the University of 

Southern California Sea Grant Program. with assistance from the Bureau of Ocean Energy 

Management, Regulation and Enforcement. 11p. 

National Park Service. 2008. North Coast and Cascades Network Intertidal Monitoring Protocol. 

Nelson PA, D Behrens, J Castle, G Crawford, RN Gaddam, SC Hackett, J Largier, DP Lohse, KL Mills, PT 

Raimondi, M Robart, WJ Sydeman, SA Thompson, S Woo. 2008. Developing wave energy in coastal 

California: potential socio-economic and environmental effects. California Energy Commission, PIER 

Energy-Related Environmental Research Program & California Ocean Protection Council CEC-500-

2008-083. 

Raimondi, P. 2008. Written summary of intertidal biological data for the Duxbury Reef Area of Special 

Biological Significance (ASBS), Bolinas, CA. 

Raimondi, P., D. Orr, C. Bell, M. George, S. Worden, M. Redfield, R. Gaddam, L. Anderson, and D. 

Lohse. 2009. Determination of the extent and type of injury to rocky intertidal algae and animals one 

year after the initial spill (Cosco Busan). A report prepared for OSPR (California Department of Fish 

and Game). 

Richards, D. V. and P. J. Rich. 2009. Rocky intertidal community monitoring, 2003 Annual Report. Natural 

Resource Technical Report NPS/CHIS/NRTR—2009/263. National Park Service, Fort Collins, CO. 

Richards, D. V. and P. J. Rich. 2010. Rocky intertidal community monitoring at Channel Islands National 

Park, 2005 Annual Report. Natural Resource Data Series NPS/CHIS/NRDS—2010/XXX. National 

Park Service, Fort Collins, Colorado. 

Richards, D. V. and S. G. Whitaker. 2010. Rocky intertidal community monitoring at Channel Islands 

National Park, 2009 Annual Report. Natural Resource Data Series NPS/CHIS/NRDS—2010/XXX. 

National Park Service, Fort Collins, Colorado. 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

Richards, D. V., and P. J. Rich. 2010. Rocky intertidal community monitoring at Channel Islands National 

Park: 2004 Annual Report. Natural Resource Data Series NPS/CHIS/NRDS—2010/064. National 

Park Service, Fort Collins, Colorado. 

Richards, D. V., D. Lerma, and P. Rich. 2010. Rocky intertidal community monitoring at Channel Islands 

National Park: 2002 Annual Report. Natural Resource Technical Report NPS/MEDN/NRTR—

2010/362. National Park Service, Fort Collins, Colorado. 

USC Sea Grant. 2009. Ship to shore: linking science to policy: loving the coast to depth. Article on Steve 

Murray’s Sea Grant rocky intertidal research. Urban Mariner 1 (2): October 2009. 

*VanBlaricom, G., M. Neuman, J. Butler, A. DeVogelaere, R. Gustafson, C. Mobley, D. Richards, S. 

Rumsey, and B. Taylor. 2009. Status review report for black abalone (Haliotis cracherodii Leach, 

1814). Final report January 2009. NOAA Technical Memorandum NMFS-SWR-##. U.S. Department 

of Commerce, National Oceanic and Atmospheric Administration. National Marine Fisheries Service, 

Long Beach, CA. 

Sample Data Requests (2010) 

*CSU Monterey Bay – Clover Lee 

Project: GIS predictive habitat model for black abalone 

Data Request: Black abalone habitat assessment data from 2007-2008 

*UCSB – Stephen Gosnell

Project: Modeling sea star density and distribution along the coast 

Data Request: Pisaster and Whelk density data at MARINe sites 

UCSB – Carola Flores Fernandez 

Project: Integration of ecological, archaological, and paleoclimatic data in the study of past marine 

ecosystems 

Data Request: Shellfish abundance and mussel growth data for Channel Islands sites 

*Duke University – Cliff Cunningham 

Project: Barnacle mortality as it relates to predator abundance and temperature 

Data Request: Site temperature data and Motile data, as well as general site information (bolt to 

bolts, maps, site summaries, tidal heights). 

*MBNMS – Steve Lonhart 

Project: Determining areas where abalone may be present, for use in National Marine Sanctuary 

permitting process. 

Data Request: Lat/Longs and black abalone presence information at intertidal study sites between 

Pt Arena and Government Pt. 

*University of South Carolina – Cristian Monaco 

Project: Interaction between Pisaster ochraceus and Mytilus californianus

Data Request: All Pisaster and Mytilus density estimates, as well as Pisaster size data 

30 
Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

ACKNOWLEDGEMENTS 

This study would not have been possible without the assistance and understanding of the Project Technical 

Officer, Mary Elaine Helix. 

We also could not have completed the work without a large number of volunteers who helped with field 

work, including Loana Addessi, Bengt Allen, Jessie Altstatt, Mike Ambrose, Monique Ambrose, Katherine 

Anderson, Araceli Anguiano, Katie Arkema, Joe Bayes, Mike Behrens, Sean Bergquist. Anne Boettcher, 

Helena Bowman, Debbie Boylen, Chris Bungener, Charlene Burge, Jennifer Burnaford, Tyra Byers, Don 

Canestro, Miranda Canestro, Jay Carroll, Jim Castle, Sarah Chaney, Henri Chomeau, Rachel Clausen, Lisa 

Conti, Garrett Cornish, Ann Dalkey, Kristin de Nesnera, Allyson Degrassi, Christian Degrassi, Stephanie 

Diaz, Rosylnn Dunn, Ginny Eckert, Chris Ehrler, Emily Engle, Shawn Erickson, Seri Feliciano, Nate 

Fletcher, Melissa Foley, Andrew Fredell, Victor Galvan, Anthony Garcia, Maya George, Amanda Gerrard, 

Bob Gladden, Constance Gramlich, Charlotte Greene, Mike Hearne, Scottie Henderson, Dave Hinrichs, 

Scott Holtz, Sarah Horwath, Dave Hubbard, Dania Huggins, Brittany Huntington, Zach Hymanson, Angela 

Johnson, George Johnson, Korie Johnson, Llad Johnson, Juli Kalman, Catherine Kaminski, Scott Kimura, 

Leah Kosareff, Julie Lancer, Shannon Leavey, Shannon Lee, Dave Lohse, Serena Lomonico, Maille 

Lyons, Laird MacDonald, James Marquez, Dan Martin, Amy McClean, Jamie McConnel, Greg 

McMichael, Mike Mitchell, Bobette Nelson, Jennifer O'Grady, Julie O'Neill, Dan Orr, Tamsen Peeples, 

Annalise Petriano, Rachel Piltz, Meredith Raith, Andrew Rice, Dan Richards, Mark Rigby, Jeff Rosaler, 

Ivan Sanchez, John Sayers, Andy Sharifi, Glenn Sias, Loretta Slusher, Ben Smith, Linda Smith, Lindsay 

Starrett, John Steinbeck, Jeanine Stier, Brianna Tarnower, Tetsuya Tsukamoto, Jeff Tupen, Carol 

Vandenberg, Amy Wagner, Kim Walker, Natalie Wenner, Kim Whiteside, Joe Wible, Demian Willette, 

and Amy Zimmer-Faust. 

We would also like to thank Naomi Pleizier and Peter Shellenbarger for their help in the lab. 

The BOEMRE intertidal team provided tremendous assistance in the field. This team consisted of: Ann 

Bull, Lisa Gilbane, Mary Elaine Helix, Dave Panzer, Fred Piltz, Greg Sanders, and Donna Schroeder. 

We would like to thank Don and Miranda Canestro and the University of California Rancho 

Marino/Kenneth Norris Reserve for providing shelter from the elements and access to the reef. We 

gratefully acknowledge Hearst San Simeon State Park for access to Point Sierra Nevada and Vista del Mar, 

the Bureau of Land Management for access to Piedras Blancas, the Hearst Corporation for access to San 

Simeon Point, Harmony Headlands State Park for site access, Montaña de Oro State Park for access to 

Hazards, Hollister Ranch for access to Alegria, Carpinteria State Beach for site access, and Vandenberg Air 

Force Base for access to Boat House, Stairs, Purisima and Occulto. We would like to thank the Orange 

County Marine Protected Area Counsel and the Crystal Cove State Park for providing assistance and 

support for our work in Orange County; Cabrillo Marine Aquarium and the Friends of the Cabrillo Marine 

Aquarium for their support of the Point Fermin MARINe site and their support for the 2008 workshop; the 

Tatman Foundation (specifically, Jerry Chomeau, Henri Chomeau, and Chris Bungener) for their support of 

the sampling of the two Catalina Island sites (Bird Rock and Little Harbor); the Wrigley Marine Lab for 

supporting our field stays out there, and John and Robby Mazza and the Malibu Riviera Homeowner's 

Association for providing access to Paradise Cove. 

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Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

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in Santa Barbara County. Report to the Minerals Management Service, Pacific OCS Region. January 

1992. 30 pp. plus appendices. 

Ambrose, R.F., P.T. Raimondi and J.M. Engle. 1992b. Proposed site locations and sampling protocol for 

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for inventory of coastal ecological resources of the northern Channel Islands and Ventura/Los 

Angeles Counties. Report to the California Coastal Commission. September 1994. 31 p. 

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temporal patterns in rocky intertidal communities of central and northern California. Outer 

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Service, U.S. Department of the Interior. 

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Intertidal Survey Year III. Prepared by Science Applications, Inc. for the Bureau of Land 

Management, Pacific OCS Office, Los Angeles, CA. Contract No. AA551-CT7-44. 

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Pt. Loma, Prepared for the Bureau of Land Management, Pacific OCS Office, Los Angeles, CA. 

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California. J. Biogeography 8: 339-351. 

National Research Council. 1990a. Managing troubled waters: The role of marine environmental 

monitoring. National Academy Press, Washington, D.C. 

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Press, Washington, D.C. 

32 
Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

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intertidal resources along the central and southern California mainland. 3-year report for San Luis 

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Institute, University of California, Santa Barbara). 

Richards, D.V. and G.E. Davis. 1988. Rocky Intertidal Communities Monitoring Handbook. Channel 

Islands National Park, California. 15 pp. plus appendices. 

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Demonstration. Prepared for Pacific Gas & Electric. 

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Report. Prepared for Pacific Gas & Electric. 

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Power Plant. Prepared for Pacific Gas & Electric. 

Thompson, B., J. Dixon, S. Schroeter and D.J. Reish. 1993. Benthic Invertebrates. In: Dailey, M.D., D.J. 

Reish and J.W. Anderson, eds. Ecology of the Southern California Bight: A Synthesis and 

Interpretation. University of California Press, Berkeley, CA. 

33 
Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities 

Adjacent to OCS Activities – Final report (2007-2010) 

34 

APPENDIX 

Selected Publications (attached) 

Henkel, S.K. and S.N. Murray. 2007. Reproduction and morphological variation in southern California 

populations of the lower intertidal kelp Egregia menziezii (Laminariales). Journal of Phycology 

43:242-255 

Murray, S.N., P. Raimondi, and S.B. Weisberg. 2010. In pursuit of bio-criteria for evaluating the condition 

of rocky intertidal communities. Report of a workshop sponsored by the University of Southern 

California Sea Grant Program. with assistance from the Bureau of Ocean Energy Management, 

Regulation and Enforcement. 11p. 

Raimondi, P., R. Sagarin, R. Ambrose, C. Bell, M. George, S. F. Lee, D. Lohse, C.M. Miner, and S.N. 

Murray. 2007. Consistent frequency of color morphs in the sea star Pisaster ochraceus

(Echinodermata: Asteriidae) across open-coast habitats in the northeastern Pacific. Pacific Science 

61:201-210. 

Smith, J.R., P. Fong and R.F. Ambrose. 2009. “Spatial patterns in recruitment and growth of the mussel 

Mytilus californianus (Conrad) in southern and northern California, USA, two regions with differing 

oceanographic conditions.” Journal of Sea Research 61: 165-173. 
REPRODUCTION AND MORPHOLOGICAL VARIATION IN SOUTHERN CALIFORNIA

POPULATIONS OF THE LOWER INTERTIDAL KELP

EGREGIA MENZIESII (LAMINARIALES)1

Sarah K. Henkel2

Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California 93106-9610, USA

and

Steven N. Murray

Department of Biological Science, California State University, Fullerton, California 92834-6850, USA

Intertidal Egregia menziesii (Turner) Aresch. populations were studied at three Southern California

sites to determine temporal and spatial patterns of

reproduction and morphology. The timing of sporophyll production and sporophyte recruitment was

similar at all sites. Sporophyll production was much

greater during winter periods of colder seawater

temperatures and shorter day lengths. Sporophyte

recruitment occurred from spring through midsummer, ~5 months following maximal sporophyll production. Lateral blade morphologies varied in a

consistent manner, suggesting a developmental

mechanism for form variation in Egregia thalli.

Spatulate blades dominated shorter axes and the

bases of longer axes, whereas filiform laterals

became abundant toward the tips of longer axes.

Filiform laterals (9.8mg O2 . g  1 . h  1

) had higher

light-saturated net photosynthetic rates than spatulate laterals (6.8 mg O2 . g  1 . h  1

), resulting in a

12% increase in the productivity of Egregia per

meter of filiform frond.

Key index words: Egregia; herbivory; intertidal;

kelp; morphology; photosynthesis; reproduction

Kelps are conspicuous components of temperate

seaweed communities in the eastern North Pacific

(North 1971, Foster and Schiel 1985), and these large

brown algae often exhibit species-specific variations in

reproductive strategies (Reed et al. 1996) and morphology (North 1971, Hurd 2000) in relation to environmental factors. Morphological variation, however, has

been closely examined for few kelps, probably because

of their large size and relative ease of identification.

Previous research on internal and external thallus

morphology has focused mostly on the effects of

wave exposure (Parke 1948, Sundene 1962a, b, 1964,

Chapman 1973, Palmisano and Sheng 1977, Gerard

and Mann 1979, Gerard 1987, Roberson 2001) and

the effect on turbulence (Koehl and Alberte 1988,

Hurd and Stevens 1997, Hurd et al. 1997), mass transfer (Koehl and Alberte 1988, Hurd et al. 1996), and

photon capture (Koehl and Alberte 1988, Wing and

Patterson 1993, Wing et al. 1993).

Egregia menziesii is one of the most variable and

complex of the kelps (Setchell 1893, Fritsch 1945), with

an adult morphology distinct from other species. Thallus fronds can reach up to 15 m in length and consist of

basal stipes that flatten to rachi as they become lined

with lateral blades and sporophylls (Setchell 1893,

Setchell and Gardner 1925, Abbott and Hollenberg

1976). Egregia is distributed from Alaska to Punta

Eugenio, Baja California, Me ́xico, and grows intertidally to depths of at least 20 m (Abbott and Hollenberg

1976). The life history of Egregia is typical of members

of the order Laminariales, consisting of a microscopic

gametophyte and a conspicuous, perennial sporophyte. Zoospores produced in morphologically distinct

sporophylls (Setchell 1893, Setchell and Gardner 1925,

Yoon et al. 2001) settle and germinate into gametophytes, which in turn produce eggs and sperm that

upon fertilization give rise to embryonic sporophytes

(Myers 1928). Fertility of Egregia occurs from spring to

fall in British Columbia (Gordon and De Wreede 1978)

and presumably central California (Abbott and

Hollenberg 1976); sporophyte recruitment in Southern California has been observed from January to June

(Black 1974, Murray and Littler 1977, Gunnill 1980,

1985).

Egregia morphology varies considerably throughout

its range and is believed to correlate with geographic

distribution (Abbott and Hollenberg 1976, Blanchette

et al. 2002). Historically, at least two and as many as

five species and subspecies of Egregia were recognized

based largely on variations in the morphology of the

rachis and lateral blades (Setchell and Gardner 1925,

Silva 1957, Chapman 1962a). However, despite this

high degree of morphological variation, currently only

one species (E. menziesii) and no subspecies of Egregia

are recognized (Abbott and Hollenberg 1976).

The lateral blades of Egregia can range from broad,

ovate, or spatulate to highly dissected and filiform and

1

Received 21 March 2006. Accepted 8 January 2007.

2

Author for correspondence: e-mail henkel@lifesci.ucsb.edu.

242

J. Phycol. 43, 242–255 (2007)

r 2007 by the Phycological Society of America

DOI: 10.1111/j.1529-8817.2007.00330.x
vary not only among thalli separated by many kilometers but also within local populations growing on the

same or nearby shores (Chapman 1962a). Besides representing possible ecotypic variation, differences in lateral morphology may have ecological implications

(Littler 1980, Littler and Littler 1980). For example,

variations in lateral morphology may result in differences in thallus productivity (Odum et al. 1958,

Chapman 1962b, Littler and Arnold 1982) and resistance to herbivory (Littler and Littler 1980; but see

Padilla and Allen 2000).

The purpose of this study was to determine the

timing of reproduction and recruitment and to examine variations in thallus and lateral blade morphology

in Egregia populations at three Southern California

sites. Prior studies indicate that gametophyte fertility is

reduced or inhibited at temperatures exceeding 161C

(Myers 1928, Lu ̈ning and Neushul 1978). Thus, we

hypothesized that our Southern California populations

of Egregia would produce fertile sporophylls mostly

during fall and winter. Because the appearance of

young Egregia thalli has been observed from late

spring to early summer (Black 1974, Murray and

Littler 1977, Gunnill 1980, 1985), we hypothesized

that peak recruitment of juvenile sporophytes would

be related to the fall and winter periods of sporophyll

production. Morphological plasticity is widespread

among seaweeds and often reflects environmental conditions (Dixon 1970, Hay 1981, Mathieson et al. 1981,

Lewis et al. 1987, Kilar and Hanisak 1989). Thus, we

also hypothesized that Egregia morphology would vary

with differences in site conditions, such as wave exposure or herbivory, and based on prior research (Chapman 1962b, Littler and Littler 1980, Littler and Arnold

1982), we predicted that variations in Egregia lateral

morphology would result in differences in thallus productivity.

METHODS AND MATERIALS

Site descriptions. This research was conducted at three

Southern California sites: Crystal Cove (33134.30 N,

117150.30 W), Shaw’s Cove (33132.80 N, 117148.20 W), and

Dana Point (331270 N, 1171430 W), selected for their high intertidal standing stocks of Egregia at the initiation of the study

(Fig. 1). These sites were distributed along an ~15.5 km section

of southwest facing coastline, which experiences moderate

wave exposure due to protection by the Channel Islands

(Ricketts et al. 1985, Hickey 1993). The average maximum

wave force was greatest at Dana Point (5.15 0.27 m s  1

)

followed by Crystal Cove (4.89 0.08 m s  1

) and Shaw’s

Cove (4.86 0.17 m s  1

) based on data obtained in midshore

rockweed habitats during fall and winter of 1997 (Sapper and

Murray 2003). Measurements taken throughout the year indicate that the three sites exhibit little site-to-site variation in daily

sea temperature (11C) and salinity (1%). However, annual

sea temperatures in the region vary greatly by season and

ranged from 101C to 221C during the study (unpublished data

from Balboa reference station; Marine Life Research Group,

Scripps Institution of Oceanography, La Jolla, CA).

The three study sites varied in substratum topography and

herbivore pressure. At Crystal Cove, flattened and angled

benches were separated by shallow channels located between

uplifted bedding planes. The study area was frequently inundated with sand, which at times covered Egregia holdfasts and

portions of stipes. The Shaw’s Cove sampling area was located

in a surge channel; here, Egregia was observed growing on

large, stable boulders and on channel sides below mussel beds.

Granitic boulders mixed with flattened benches characterized

the Dana Point study site. Qualitative observations indicated

that grazing on Egregia was greatest at Shaw’s Cove where high

densities of purple sea urchins [Strongylocentrotus purpuratus

(Stimpson)] and kelp snails [Norrisia norrisi (Sowerby)] were

concentrated in the surge channel, where they were observed

feeding on Egregia. Strongylocentrotus purpuratus and occasionally the red sea urchin S. franciscanus (Agassiz) and N. norrisi

were present but not abundant at Dana Point. Sea urchins were

not encountered in the immediate Crystal Cove study area,

and kelp snails were rare.

Recruitment and population structure. Recruitment of young

Egregia sporophytes at each of the three sites was determined

quarterly from January 2001 to February 2002. Results from

sampling performed during 2001 supported the prediction

that Egregia sporophyte recruitment would occur during

spring; consequently, in 2002, each site was sampled monthly from March to July to more precisely determine the magnitude and timing of sporophyte recruitment. Permanent

transect lines (10–12 m in length) were placed parallel to the

shore through Egregia populations at about Mean Lower

Low Water. At Crystal Cove and Dana Point, three bands

were established perpendicular to transects during each site

visit using a random-number table. However, at Shaw’s Cove,

the three bands were fixed and located where thalli were

most dense at the initiation of the study due to high topographical heterogeneity and the patchy distribution of

Egregia in the surge channel. Each band was 1 m wide and

6 m long, resulting in six contiguous 1 m1 m plots that extended 3 m above and 3 m below the horizontal transect.

Within each plot, the number of Egregia sporophytes was recorded and all Egregia thalli were assigned to one of four

(Types I–IV) developmental stages (Fig. 2). A Type I recruit

was defined as a laminarialean juvenile with a single, short

blade. With the exception of only the smallest juvenile sporophytes (<4 cm in length), Type I Egregia recruits could be

distinguished from Eisenia arborea Aresch. recruits because

FIG. 1. Location of the three Southern California study sites:

Crystal Cove, Shaw’s Cove, and Dana Point.

EGREGIA REPRODUCTION AND MORPHOLOGY 243
Egregia juveniles had smooth blades, whereas E. arborea

juveniles had wrinkled or corrugated blades. No other kelps

were observed to recruit into intertidal habitats at our sites

during the study. Type II Egregia juveniles had a single blade

with marginal leaflets. Type III (subadult) was defined as a

short (25 cm) branching thallus with a well-developed rachis and less than three pneumatocysts. Type IV was a mature, differentiated Egregia thallus possessing more than one

axis and more than three pneumatocysts.

Morphological features of mature Egregia thalli were determined at the three sites. The nearest Type IV Egregia thallus

within a 0.5 m radius of each 1.0 m mark along each transect

was identified to generate a sample size of 12–22 individuals

per site visit. The longest axis of each thallus was measured

from holdfast to tip, and the total number of axes was counted.

The numbers of viable (with meristem) and nonviable (sans

meristem) axes also were determined.

Sporophyll production and lateral morphologies. Patterns of

Egregia sporophyll production and lateral blade morphology

at each site were determined monthly from February 2001 to

February 2002. Nine thalli growing adjacent to sampled populations were haphazardly selected, and the first axis of each

thallus with an intact meristem and a length 450 cm was excised and taken to the laboratory. Each axis was divided into

five 5 cm sections such that 5 cm located just below the meristem was sampled, 5 cm just above the base of the axis was

sampled, and the three remaining 5 cm sections were evenly

dispersed between the apical and basal sections. Vegetative

lateral blades and sporophylls were counted in each section.

Vegetative laterals were assigned to one of three morphs (filiform, spatulate, or intermediate; Fig. 3) to characterize patterns of lateral morphology; the percentage of each morph

was determined relative to axis location for each sampled

thallus.

Reproductive periodicity was determined by the density of

sporophylls along the same axis sections. To ensure that the

sporophylls counted were fertile, one axis from each site was

randomly selected each month that axes with sporophylls were

collected. Five sporophylls were then haphazardly excised and

sectioned to check microscopically for the presence of mature

sporangia. The amount of biomass allocated to sporophyll production was also estimated for each Egregia axis. Subsamples of

Type I Type II Type III Type IV

1 cm

5 cm

0.5 m

FIG. 2. Developmental stages of Egregia sporophytes. Type I: short stipe and single blade. Type II: single blade with marginal leaflets.

Type III: short branching thallus with well-developed rachi (<25 cm), <3 pneumatocysts, and terminal blades deteriorating. Type IV:

Differentiated, mature sporophyte. Scale bar, 0.5 m for stages III and IV.

244 SARAH K. HENKEL AND STEVEN N. MURRAY
sporophylls, each lateral morph, and sections of the rachis

were dried to constant weight at 601C. The percentage

of Egregia biomass allocated to sporophylls was determined

using the mean dry weights (dwt) of these subsamples

and their abundances, and the dwt to length relationship for

the rachis.

Herbivore densities. The primary benthic herbivores observed feeding on Egregia at the three sites included Strongylocentrotus spp. (urchins); N. norrisi (kelp snail); and

Notoacmaea insessa (Hinds), a limpet that lives and feeds on

the Egregia rachis (Black 1976). In order to quantify differences in herbivore abundances, and presumably grazing

pressure, among the three sites, the numbers of red and

purple urchins and kelp snails in each plot were determined,

and the number of N. insessa on each measured Type IV

Egregia thallus was recorded.

Photosynthesis experiments. Photosynthetic rates of different

parts of Egregia thalli were determined in the field at Dana

Point, California, on March 11, and April 4 and 16, 2002,

following methods similar to those described by Littler and

Arnold (1980, 1985). Spatulate blades, filiform laterals, intermediate laterals, sporophylls, and bare rachi without epiphytes were excised from freshly collected Egregia thalli and

submerged in trays for 1–2 h before incubation. Four to six

replicates of each thallus part were then incubated in filtered

(10 mm) seawater for 10.5 h (light treatments) or 20.5 h

(dark treatments) within closed 0.5 L French square glass

bottles. During incubations, bottles were kept submerged in

shallow plastic trays, which were replenished with seawater

every 10–15 min to maintain ambient seawater temperature.

Incubation bottles were thoroughly mixed every 5–10 min

using magnetic stirrers to break down diffusion barriers.

Changes in dissolved oxygen (DO) concentration were measured with Yellow Springs Instrumentst oxygen electrodes

(Yellow Springs, OH, USA) and used to calculate net

photosynthetic and dark respiration rates. Following incubations, thallus parts were returned to the laboratory and

dried to constant weight at 601C. Light (318–974 mmol photons m 2 s  1

) and temperature (15–191C) varied among

experiments; however, analyses failed to show statistically

significant differences in net photosynthetic and dark respiration rates among experiments performed on different days

and under the range of temperature and light conditions

employed. Hence, data from all sampling dates were

pooled for analysis. Photosynthetic rates are believed to

represent light-saturated values based on reports of requirements for saturating intertidal seaweeds (300–1200 mmol

photons  m 2 s  1

; Lu ̈ning 1981).

Statistical analyses. Each data set was examined for variance homogeneity using Cochran’s and Levene’s tests and

transformed if necessary to meet parametric requirements. A

one-way analysis of variance (ANOVA) was used to test the

hypothesis that photosynthetic and dark respiration rates

differed among thallus parts. Where differences were significant, Student–Newman–Keuls’ multiple comparison tests

were used to differentiate subsets of means to facilitate interpretation of ANOVA results. Two-way ANOVA models

were employed to analyze the effects of the fixed factors

site and sampling period on the numbers of sporophylls,

numbers of different lateral morphs, maximum axis length,

and the percentage of viable axes. Variance criteria were met

either by the original data or following transformation in all

analyses.

The nonparametric Spearman’s rank correlation procedure was used to determine whether a statistical relationship could be detected between seasonal patterns of sporophyll production and seawater temperatures or photoperiods.

Surface seawater temperatures (SSTs) used in this analysis

were obtained from the Balboa, Newport Beach, CA,

reference station (Marine Life Research Group, Scripps Institution of Oceanography; unpublished data), whereas hours

of daylight were calculated from sunrise and sunset data

reported in National Oceanographic and Atmospheric Association (NOAA) tide tables for outer Newport Bay (Anonymous

1998).

RESULTS

Sporophyll production. The morphology of Egregia

sporophylls varied depending on the form of the associated vegetative laterals. Sporophylls associated

with filiform laterals were thick, strongly furrowed,

and raisin-like in appearance, with filiform extensions often seen growing from sporophyll termini. In

contrast, sporophylls produced in spatulate regions

of the axis were flattened, with plump and wrinkled

basal portions (Fig. 4). Microscopic examination revealed that almost all examined sporophylls had fertile sori and that fertile sori could be detected yearround (Table 1). The greatest proportion of examined sporophylls were fertile during winter. Sporophylls with mature sporangia tended to be darker

and more wrinkled but were of similar thickness as

nonfertile sporophylls.

Sporophyll production varied greatly over time

(F11, 286 5 16.593, P<0.001) but did not vary among

sites (F2, 286 5 2.475, P 5 0.08; two-way ANOVA); a

significant interaction between time and sites was

not detected (F22, 286 5 1.528, P 5 0.06), suggesting

that the seasonal patterns of sporophyll production

were similar at the three sites (Fig. 5). Sporophyll

C. Intermediate

B. Spatulate

A. Filiform

2 cm

FIG. 3. Vegetative lateral types used in morphological analyses of Egregia axes.

EGREGIA REPRODUCTION AND MORPHOLOGY 245
production was much greater in December and

January, during periods of colder mean monthly

ocean temperatures (11–131C) and shortest daylight

hours (9.9–10.5 h), and least during the periods

of warmer sea temperatures (17–191C) and longer

days (12.5–14.5 h). Sporophyll densities exhibited

significant negative correlations with both sea temperature (r 5 0.50; P 5 0.02) and hours of daylight

(r 5 0.81; P<0.001). At all sites, densities of Egregia

sporophylls were high (3.1–3.8 cm  axis  1

) at the initiation of the study in winter 2001 and then dropped to

nearly zero by spring. The number of sporophylls varied greatly among thalli but remained low for most of

the summer before peaking again (5.0–7.9 cm  axis 1

)

the next winter between November and January. Although variable among sites, small, short-lived increases in summer sporophyll production appeared to

follow periods when ocean temperatures at the Balboa reference station dropped for a few days to 131C.

The amount of total biomass (above the holdfast) allocated to sporophyll production showed a seasonal pattern similar to sporophyll densities. The percentage of

dry biomass allocated to reproductive tissues, pooled

across sites, ranged from a low of 0.6% in July 2001 to a

high of 14.9% in January 2002, the period of greatest

sporophyll production (Fig. 5).

Sporophyte recruitment. Recruitment of juvenile

sporophytes showed similar patterns at all sites

FIG. 4. Variable sporophyll morphologies. (A) Filiform sporophylls. (B) Spatulate sporophylls.

TABLE 1. Sporophyll fertility.

2001 2002

April May June July August September October November December January February

Shaw’s Cove 5 – 2 – 3 3 4 5 5 5 5

Crystal Cove 0 3 4 – – 5 2 2 5 5 5

Dana Point – 0 5 – – 0 3 3 3 5 5

Mean (%) of fertile sporophylls 50 30 70 0 60 53 60 67 87 100 100

Reported are the monthly numbers of sporophylls with mature sporangial sori based on microscopic examination of sections of

five sporophylls from each site (n 5 5). Dashes indicate month-site combinations where no sporophylls were present on examined

Egregia axes.

Number of Sporophylls cm−1

10

9

8

7

6

5

4

3

2

1

20

18

16

14

12

10

Shaw's Cove

Crystal Cove

Dana Point

B

A

Temperature°C

Number of Daylight Hours

Temperature

Hours of Daylight

Sporophyll % of Thallus

Biomass

14

12

10

8

6

4

2

0

F

2001 2002

MAMJ J ASOND J F

C

10

14

12

16

FIG. 5. (A) Surface seawater temperatures and hours of daylight during the study period (monthly means). (B) Patterns of

sporophyll production in Egregia menziesii populations from the

three study sites. Values are monthly means (1 SE) of sporophyll numbers per cm of axis for nine replicates from each site.

(C) Mean (þ1 SE) percentage of dry biomass allocated to

sporophylls based on pooled samples from all three sites (see

Methods and Materials for calculation).

246 SARAH K. HENKEL AND STEVEN N. MURRAY
and between years (Fig. 6), although the intensity

of recruitment varied greatly among sites and years.

Young (Type I) Egregia sporophytes showed peak

densities ~5 months following the period of greatest

sporophyll production at all sites. Type I thalli

appeared in March 2001, were found at all sites

through July or August, and then were almost

completely absent by the ensuing fall and winter.

This pattern was repeated the next year when

recruits again became abundant in March 2002

and persisted through July. During 2002, maximum Type I sporophyte recruitment occurred

at Dana Point in March (35.7 m2

) followed by Shaw’s

Cove in April (5.9 m2

) and Crystal Cove in

May (1.8 m2

).

Adult sporophyte morphology and herbivore densities. The

number of axes in field populations of Type IV

(adult) Egregia thalli varied significantly among sites

but not over time, and a significant interaction

between site and season was not detected

(Table 2). The average number of axes per Type IV

thallus was greatest at Shaw’s Cove (16.61.5) and

least at Crystal Cove (9.50.8). The percentage of

axes with viable meristems also differed significantly

among sites and seasons, and a significant interaction

between site and season was observed (Table 2). Despite having more axes per Type IV thallus, Egregia

from Shaw’s Cove had the lowest average percentage

of axes with intact meristems compared with thalli at

Dana Point or Crystal Cove. As supported by the significant interaction, the percentage of viable axes

(with meristems) increased at Shaw’s Cove from

July through December but dropped at Dana Point

during the same period.

FIG. 6. Seasonal abundances of Egregia sporophytes by developmental stage. Plotted are the mean densities (1 SE) of the four

developmental stages (Types I–IV) for the three study sites. Mean values are based on field surveys of plots (n 5 18) distributed along

transect lines.

EGREGIA REPRODUCTION AND MORPHOLOGY 247
Maximum axis lengths varied significantly among

sites and seasons, and a significant interaction was

found between these fixed factors (Table 3). Egregia

thalli were much shorter at Shaw’s Cove throughout

the year (mean 5 0.45 m0.02 m) than thalli collected

from Dana Point (mean 5 1.57 m0.07 m) and Crystal

Cove (mean 5 2.42 m0.16 m). Maximum axis lengths

were more varied at Crystal Cove and, unlike thalli at

Shaw’s Cove and Dana Point, were much shorter during October to December than previous seasons at the

conclusion of the study.

As expected, densities of N. norrisi and Strongylocentrotus spp. varied among sites (Table 4). Purple

urchin (51.8 3.9 m2

) and kelp snail (2.2 0.2 m2)

densities were much greater at Shaw’s Cove, the site

with the shortest and more-profusely branched Egregia

thalli and with the lowest percentage of viable axes.

Densities of these herbivores were much lower at Dana

Point, where purple urchins (1.50.7 m2

) and kelp

snails (<0.1<0.1 m 2

) were uncommon, and at

Crystal Cove, where kelp snails were rare

(<0.1<0.1 m2

) and urchins absent from the immediate study area. Numbers of N. insessa inhabiting Egregia thalli also varied among sites (Table 4). Much

higher numbers of N. insessa per Egregia axis, as well as

densities (number per axis cm 1

), were found at Crystal Cove compared with the other two sites.

Patterns of lateral morphology. The percentages of

spatulate laterals varied significantly by site

(F2, 285 5 109.8, P<0.001) but not by season

(F11, 285 5 1.6, P 5 0.10), and an interaction between

site and season was not detected (F22, 285 5 1.3,

TABLE 2. Number of axes and percentage of axes with viable meristems for Type IV Egregia sporophytes.

Site

Sampling period

January–February April–June July–September October–December

Number of axes

Crystal Cove 9.3 1.6 8.5 1.4 11.4 1.9 8.8 1.1

Shaw’s Cove 14.0 1.6 13.1 3.0 13.2 3.4 21.5 4.0

Dana Point 12.4 2.0 15.4 2.0 14.9 2.1 11.7 1.9

Two-way ANOVA df MS F P

Site 2 0.436 6.132 0.003**

Season 3 0.030 0.420 0.743 ns

Site  season 6 0.133 1.871 0.087 ns

% Viable axes

Crystal Cove 47.5 3.9 61.0 7.3 51.5 5.7 50.5 6.7

Shaw’s Cove 33.1 3.7 39.0 7.2 61.1 5.3 42.7 5.0

Dana Point 50.4 4.7 64.9 4.6 49.7 5.1 36.4 5.6

Two-way ANOVA df MS F P

Site 2 0.177 3.274 0.039*

Season 3 0.213 3.930 0.009**

Site  season 6 0.174 3.211 0.005**

**P<0.01; *P<0.05; ns, not significant (P0.05).

Reported are mean values (1 SE) for each of the three study sites based on 12–22 replicates for the indicated sampling periods.

Values for axis numbers were log 10 transformed before analysis of variance (ANOVA).

TABLE 3. Maximum axis lengths for Type IV Egregia sporophytes.

Site January–February April–June July–September October–December

Crystal Cove 2.53 0.35 2.76 0.35 2.72 0.26 1.34 0.19

Shaw’s Cove 0.39 0.04 0.37 0.03 0.55 0.04 0.50 0.05

Dana Point 1.43 0.15 1.42 0.14 1.92 0.23 1.58 0.13

Two-way ANOVA df MS F P

Site 2 50.020 192.376 <<0.001***

Season 3 1.532 5.891 <0.001***

Site  season 6 0.750 2.885 0.010**

***P<0.001; **P<0.01; ns, not significant (P0.05).

Reported are mean values (1 SE) based on 12–22 replicates for each of the three study sites for the indicated sampling periods.

Annual mean is calculated as the grand mean of the four period means. Analysis by two-way analysis of variance (ANOVA) with site

and season as fixed factors. Values for axis lengths were transformed using the Box-Cox procedure before ANOVA.

248 SARAH K. HENKEL AND STEVEN N. MURRAY
P 5 0.13; Fig. 7a). The percentage of filiform laterals

similarly varied significantly by site (F2, 286 5

122.8, P<0.001) and additionally varied by season

(F11, 286 5 3.6, P<0.001), declining in winter during

the period of greatest sporophyll production; again,

an interaction between site and season was

not found (F22, 286 5 1.2, P 5 0.24; Fig. 7b). Spatulate

laterals were more prevalent basally, with intermediate laterals becoming more common on longer axes.

Finally, filiform laterals became increasingly abundant with axis length and were most profuse apically.

Thus, shorter axes had predominately spatulate laterals, and longer axes bore higher numbers of intermediate and filiform laterals.

TABLE 4. Herbivore densities.

Crystal Cove Shaw’s Cove Dana Point

Strongylocentrotus pupuratus Stimpson, 1857 0 51.8 3.9 1.5 0.7

Strongylocentrotus franciscanus A. Agassiz, 1863 0 0.1 <0.1 < 0.1 <0.1

Norrisia norrisi Sowerby, 1938 < 0.1 <0.1 2.2 0.2 < 0.1 <0.1

Notoacmaea insessa Hinds, 1842 2.3 0.9 < 0.1 <0.1 0.7 0.3

Reported are mean densities (number  m 2

) 1 SE of urchins (Strongylocentrotus sp.) and kelp snails (Norrisia norrisi) for the three

study sites based on averages over all monthly site visits (n 5 9–10). Reported for Notoacmaea insessa are the number of individuals per

Egregia axis averaged over all monthly collections (n 5 90–103 per site).

FIG. 7. Monthly patterns of Egregia lateral morphology at three sites. Values are the percentage (1 SE) of spatulate (A) or filiform

(B) of the total identifiable vegetative laterals for the indicated sampling periods.

EGREGIA REPRODUCTION AND MORPHOLOGY 249
At Shaw’s Cove, where the axes collected for morphological analysis were shortest (0.66 0.02 m), thalli

almost exclusively produced spatulate laterals and generally bore only a few intermediate laterals, which

were located mostly near growing meristematic tips

(Fig. 8a). At Dana Point, where axes of intermediate

length (1.140.05 m) were collected, intermediate and

filiform laterals were found in the highest

percentages at the distal ends near the meristems;

most axes, however, possessed spatulate laterals,

particularly at their basal regions (Fig. 8b). Filiform

laterals dominated the upper (distal) half of the longer

axes (1.290.05 m) collected from Crystal Cove; but,

as was the case at both Shaw’s Cove and Dana Point,

basal portions of axes retained mostly spatulate laterals

(Fig. 8c).

Photosynthesis and respiration. Rates of net photosynthesis and dark respiration varied significantly among

Egregia thallus parts (F4, 49 5 63.8, Ppsn<0.001; F4, 49 5

16.4, Presp<0.001; Fig. 9). As hypothesized, filiform

laterals had significantly higher light-saturated net photosynthetic rates (9.8 0.1 mg O2  g  1  h  1

) than any

of the other lateral types. Intermediate (7.6

0.1 mg O2  g  1  h  1

) and spatulate (6.80.1 mg O2 

g  1  h  1

) laterals formed a subset with statistically indistinguishable rates, which were greater than the

rates exhibited by the sporophylls (2.90.1 mg O2 

g  1  h  1

). The rachis (0.8<0.1 mg O2  g  1  h  1)

had the lowest photosynthetic rate of any incubated

thallus part. Dark respiration rates also differed significantly among thallus parts (Fig. 9). Among vegetative

laterals, dark respiration rates of the filiform

(1.2 0.1 mg O2  g  1  h  1

) and intermediate (1.1 

0.1 mg O2  g  1  h  1

) laterals were highest and statistically indistinguishable. Intermediate rates of respiration

were observed for the sporophylls (0.9 0.1 mg

O2  g  1  h  1

), and the lowest rates were found for

spatulate laterals (0.50.1 mg O2  g  1  h  1

) and the

rachis (0.4<0.1 mg O2  g  1  h  1

).

DISCUSSION

Southern California populations of E. menziesii, like

many perennial macroalgae occurring outside the

tropics, exhibited a strong seasonal pattern of reproduction. These results are consistent with previous reports (Abbott and Hollenberg 1976, Gordon and

De Wreede 1978) of seasonal peaks in Egregia fertility.

Similar to Egregia from Santa Barbara (Black 1974,

1976), the Southern California Egregia populations in

this study showed greatest sporophyll production and

sorus fertility from December through February, when

monthly SSTs averaged 11–131C. Similar results were

observed for Egregia from British Columbia (Gordon

and De Wreede 1978), where summer temperatures of

10 and 151C coincided with greatest production of

gametophytes and sporophytes, and winter temperatures of 71C depressed gametophyte and sporophyte

development. Furthermore, Myers (1928) found that

the male gametophytes would not release their anFIG. 8. Lateral morphology by axis position. (A) Shaw’s Cove.

(B) Dana Point. (C) Crystal Cove. Plotted are percentages (þ1 SE)

of identifiable vegetative laterals for filiform, spatulate, and

intermediate morphs by axis location based on the indicated

number of sampled thalli. Axis positions (A–E) are defined in the

Methods and Materials and represent a gradient from the

meristem (A) to the basal (E) part of the axis.

FIG. 9. Light-saturated net photosynthesis and dark respiration rates for Egregia thallus parts. Plotted are means (þ1 SE)

based on 9–12 replicates. Letters represent statistically significant

subsets of means based of Student-Newman-Keuls’ test results.

250 SARAH K. HENKEL AND STEVEN N. MURRAY
therozooids at temperatures of 161C or greater. Other

reports (Abbott and Hollenberg 1976) indicate that in

California, Egregia produces sporophylls between April

and November. Although we observed much greater

fertile sporophyll production during winter, small

numbers of sporophylls, some of which were fertile,

were detected throughout the year, reinforcing the

suggestion (Abbott and Hollenberg 1976) that Egregia

can be reproductive year-round. We did not investigate the roles of spore production and germination

success, however, and seasonal differences in these parameters could significantly affect the reproductive

patterns derived soley from sporophyll production.

With this qualification, the reproductive pattern observed for Egregia in this study appears to be similar to

that observed for Macrocystis pyrifera (L.) C. Agardh

(Neushul 1963, Anderson and North 1967, Reed et al.

1996) and Laminaria saccharina (L.) Lamour. (Druehl

and Hsiao 1977, Lee and Brinkhuis 1986), species

which also show seasonal peaks in spore production

but can be reproductive year-round. Unlike Southern

California populations of Egregia, however, both M.

pyrifera and L. saccharina exhibit a second peak in spore

production during the year, with spore germination

success varying greatly between the two periods (Deysher and Dean 1986). The single, strong reproductive

period found in Egregia also resembles the narrow reproductive window observed in Pterygophora californica

Rupr., although this kelp produces spores only from

November through April regardless of environmental

conditions (Reed et al. 1996).

Reproductive effort can be determined by measuring the proportion of thallus biomass allocated to reproductive tissues (Chapman 1985); however, such

calculations are difficult to perform and must be interpreted with caution in kelps and other seaweeds where

many very small reproductive cells are produced in

sori (Santelices 1990). Nevertheless, the amount and

seasonal pattern of biomass allocated to reproductive

tissue in Egregia (14.9% of dwt in January to 0.6% in

July) were similar to reports (Novaczek 1984) for

Ecklonia radiata (C. Ag.) J. Ag. (17% frond surface

area covered with sori in winter to 0.2% in summer),

another member of the Alariaceae. Our values, however, are higher than those reported for M. pyrifera

(4%; Neushul 1963) and lower than reports for

Laminaria sp. (2%–30%; Kain 1971, 1975, Perez 1971,

DeWreede and Klinger 1988), Ascophyllum nodosum (L.)

Le Jol. (40%–60%; Cousens 1986), and other fucoids

(80%–90% of the deciduous fronds; Santelices 1990). It

is unlikely that the winter peak in the proportion

of reproductive biomass observed for Southern

California Egregia populations is due to winter biomass

loss (as has been reported for Macrocystis; Graham

2002, 2003) because minimum axis lengths were found

in the spring at two of the three sites, and there was no

significant difference among seasons for the number of

axes per thallus.

Maximum sporophyll production in our Egregia

populations occurred during winter conditions of

shorter days and coldest ocean temperatures (Fig. 5).

Other studies also provide support for a cold temperature requirement for successful Egregia reproduction.

Spores released from Egregia collected in northern

California in the fall and cultured under conditions

of 10–181C produced gametophytes and completed

the life history by giving rise to new sporophytes in

19–28 days (Myers 1928). In contrast, material collected in summer and cultured under warmer ambient

temperatures (16–201C) produced gametophytes but

failed to give rise to new sporophytes (Myers 1928).

Moreover, the optimum temperature for the onset of

gametophyte fertility in Southern California Egregia is

121C, and gametophyte fertility was inhibited at 201C

(Lu ̈ning and Neushul 1978).

As expected for algae (Hoffmann and Santelices

1991), especially species with distinct gametophyte and

sporophyte stages, we observed a lag between the

period of greatest fertile sporophyll production by

Egregia and the detection of new sporophyte recruits

in the spring. We measured the greatest recruitment

of juvenile Egregia sporophytes from March through

June, 5 months following the time of maximum

sporophyll and, presumably, spore production. This

peak was similar to the spring maxima in Egregia

sporophyte recruitment reported for other Southern

California sites, including La Jolla (Gunnill 1980,

1985) and San Clemente Island (Murray and Littler

1977, 1978), but later than that observed in Santa

Barbara, California, where new sporophyte generations recruited from January to March (Black 1974,

1976).

Intertidal populations of Egregia exhibit a life history strategy in Southern California that appears to be

timed to coincide with optimal conditions for reproductive success. Egregia produces sporophylls and releases its spores following the summer period of

greatest growth (Black 1974) and during stressful winter periods when the lower of the mixed semidiurnal

low tides occurs in the afternoon (Seapy and Hoppe

1973, Seapy and Littler 1982, Littler et al. 1991).

Hypothetically, the few-celled gametophytes produced

during this period are able to develop in microhabitats

protected from desiccation under the cold water

temperatures required for optimizing fertility (Myers

1928, Lu ̈ning and Neushul 1978). The spring recruitment of vulnerable juvenile sporophytes takes place

later in the year when the timing of lower tides shifts

toward the early morning, and lower shore habitats

occupied by Egregia are emersed for only brief periods

(Seapy and Hoppe 1973, Littler et al. 1991). Spring

recruits of Egregia at the three sites appeared to

reach reproductive maturity in 6–7 months, as evidenced by observations during the fall of sporophylls

present on young, newly recruited thalli <50 cm

in length. Reproduction in the first season is common

in intertidal kelps because, although they are potential

perennials, the vast majority behave as annuals

under stressful intertidal conditions (Druehl and Hsiao

1977).

EGREGIA REPRODUCTION AND MORPHOLOGY 251
The highly seasonal winter peak in sporophyll

production and spring peak in sporophyte recruitment suggest that reproductive success in intertidal

Egregia is influenced by environmental conditions

during these critical periods. For example, abnormally warm, winter ocean temperatures might reduce

Egregia sporophyll production and gametophyte fertility. Moreover, algal propagules and early postsettlement stages are known to experience high mortality

under a variety of abiotic and biotic conditions (Vadas

et al. 1992), and kelp gametophytes and microsporophytes are highly vulnerable to burial and scour by

sediments (Neushul et al. 1976, DeVinny and Volse

1978, Dayton et al. 1984) and to grazing pressure

(Kain and Jones 1966). The large discrepancy between

the high number of fertile Egregia thalli and the ensuing small number of young sporophyte recruits suggests that postsettlement survival of gametophytes and

young sporophytes is crucial to maintaining Egregia

populations at our study sites.

Our studies are the first to demonstrate that variations in lateral morphology can be related to axis

length and provide a possible mechanism for the

development of different lateral morphologies on the

same Egregia thallus. Variations in the morphology of

Egregia laterals have long been recognized (Setchell

1893) and were previously used as a basis for discriminating species and varieties within the genus

(Chapman 1962a). Lateral morphologies in Egregia

show strong geographic patterns: both broad, spatulate, and narrow, filiform laterals occur on Southern

California thalli (Abbott and Hollenberg 1976), whereas narrower and thicker spatulate laterals commonly

occur north of Point Conception, California (Blanchette et al. 2002). Results for our Southern California

Egregia populations, however, reveal a possible developmental basis for variation in lateral morphology on

the same thallus. Filiform laterals became the dominant morph on longer axes, whereas spatulate morphs

characterized young, short thalli and persisted on the

older, basal regions of more mature and longer plants.

This pattern of form variation in Egregia is unlike that

in other kelps where differentiation in stipe morphology (Mann 1971, Chapman 1973), the amount of

blade bullation (Armstrong 1987, Roberson 2001), the

length-to-width ratios and thickness of the blades

(Parke 1948, Sundene 1962a, b, 1964, Svendensen

and Kain 1971, Palmisano and Sheng 1977, Gerard

and Mann 1979, Gerard 1987, Miller and Dorr 1994,

Miller et al. 2000), or changes in the internal morphology (Burrows 1964) have been associated with environmental factors, such as growing depth, wave

exposure, or temperature gradients. However, our observations for Southern California might not apply to

Egregia populations in more northerly geographic regions where thallus and lateral morphologies can be

more variable.

Perhaps because of observations that lateral morphologies can vary on the same thallus, Chapman

(1962a) hypothesized that filiform laterals arise from

narrow leaflets that develop proliferations or that with

increasing age broader blades become eroded and

proliferated. However, we observed that filiform laterals developed directly on the distal ends of longer axes,

a finding that contradicts Chapman’s hypotheses.

Chapman (1962a) additionally reported that shallow,

wave-exposed forms of Egregia with short thalli had

axes covered with broad laterals and hypothesized that

the shorter life span of these smaller, heavily buffeted

individuals prevented complete erosion of the leaflets.

Alternatively, we attribute this dominance of broad,

spatulate laterals on shorter Egregia axes to developmental patterns and not to the absence of blade erosion.

The form of an algal thallus is known to correlate

with nutrient-uptake abilities (Odum et al. 1958), photosynthetic and respiration rates (Kanwisher 1966, Littler and Murray 1974, King and Schramm 1976,

Littler 1980, Littler and Littler 1980, Littler and

Arnold 1982), and possibly susceptibility to herbivory

(Littler and Littler 1980, but see Padilla and Allen

2000). Differences in photosynthetic and respiration

rates for different stages of development and different

parts of Egregia thalli have been reported previously.

For example, whole, young Egregia thalli had net photosynthetic rates that were ~2.5 times the rates of fully

differentiated adult thalli (Littler and Littler 1980,

Littler and Arnold 1982). Similarly, variations in

photosynthesis to respiration ratios (Clendenning

and Sargent 1958) and in net photosynthetic rates

(Druehl 1984) have been observed for different

thallus parts in Macrocystis.

The results of the photosynthesis experiments supported earlier studies conducted by Chapman (1962b)

and confirmed that net photosynthetic rates of filiform

laterals are greater than spatulate laterals. Our studies

also indicate that, per meter of axis, filiform-laden

fronds of Egregia are 12% more productive than

spatulate-covered fronds, given the higher photosynthetic rates and greater concentrations of filiform

(15.8 cm 1

) versus spatulate (6.9 cm 1) laterals on

Egregia thalli. Interestingly, this observation contradicts

results of an earlier Southern California study (Littler

and Arnold 1982) where upper thallus segments consisting of filiform laterals were 32% less productive

than basal portions with blade-like laterals of the same

thalli. However, reduced rates for upper segments

might have been caused by large numbers of lowproducing sporophylls because Littler and Arnold’s

photosynthetic experiments were performed during

October when, according to our studies, Southern California Egregia thalli show a sharp increase in sporophyll production.

Egregia menziesii is distributed across a broad latitudinal range in the eastern North Pacific where it shows

considerable variation in its vegetative and reproductive morphology (Abbott and Hollenberg 1976). Variation in the vegetative lateral blades of Egregia has long

been recognized but poorly explored. Our results indicate a developmental basis for variation in blade

252 SARAH K. HENKEL AND STEVEN N. MURRAY
morphology in Southern California populations of

Egregia; blades transitioned from lower densities of

broader, spatulate laterals to higher densities of thinner, filiform laterals with increasing axis length. These

changes increase the productivity of longer Egregia

axes and, based on additional studies by Henkel

(2003), also make the lateral blades of longer Egregia

fronds less susceptible to molluscan herbivores. Sporophylls, which in our Southern California Egregia

population ranged from furrowed, raisin-like forms

to flattened structures with wrinkled bases, were fertile

year-round but were much more abundant during

winter periods of colder ocean temperatures. Peak

sporophyte recruitment occurred in spring, about 5

months following the period of greatest sporophyll

production, suggesting a temporal link between

these events. Reproductive patterns in Egregia likely

vary, however, north of Southern California where

cooler ocean conditions occur throughout the year.

Additional studies are needed to describe morphological variation and reproductive periodicity across

the latitudinal range of Egregia and to determine the

degree to which environmental factors affect observed

patterns in this common and often abundant kelp.

This research was supported by the Sea Grant College Program

of the U.S. Department of Commerce’s National Oceanic and

Atmospheric Administration (Grant #NA66RG0477) administered by University of Southern California Sea Grant program.

S. K. H. also would like to acknowledge support from the University of Southern California (USC) Sea Grant Trainee program, which allowed her to carry out much of this research.

This project also was supported by funds supplied by the Pacific

Outer Continental Shelf Region of Minerals Management Service to S. N. M. and by the Department of Biological Science at

California State University, Fullerton; the California State University Sally Casanova Pre-Doctoral Fellowship; the Dr. and

Mrs. Donald B. Bright Environmental Scholarship; and Friends

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EGREGIA REPRODUCTION AND MORPHOLOGY 255
1

In Pursuit of Bio-Criteria for Evaluating the Condition of Rocky 

Intertidal Communities 

Report of a Workshop Sponsored by the University of Southern California Sea 

Grant Program with Assistance from the Bureau of Ocean Energy Management, 

Regulation and Enforcement

Steven N. Murray, Pete Raimondi, and Stephen B. Weisberg 

Introduction 

The ecological communities of California’s rocky coast are being altered by the 

combined impacts of coastal development, pollution, climate change, and visitor activities. 

Previous research has revealed that these rocky intertidal communities are dynamic and show 

change in response to natural (e.g., wave action, sand scour, substratum instability) and 

anthropogenic (e.g., effluent discharges, trampling) disturbance. Coastal managers are 

concerned with the status of these coastal ecological communities and are often charged with 

implementing procedures that protect and enhance species composition, diversity, and ecological 

services. They are faced with an increasing need to evaluate and monitor community change and 

performance, particularly with the current focus on Ecosystem-Based Management (EBM) and 

the implementation of the Marine Life Protection Act (MLPA). A key need is the ability to 

distinguish anthropogenic-driven changes in a coastal community from changes due to natural or 

non-anthropogenic agents. Coastal managers are seeking the metrics to determine the current 

condition or “health” of a site and trends in this condition over time, and to communicate this 

condition to the public and decision-makers in a simple manner. Ideally, this would include 

metrics that can be collected by citizen-scientists as well metrics or sets of metrics that can be 

collected by highly trained individuals. Moreover, these metrics need to be collected in a 

resource-limited environment. However, the development of simple metrics that reflect the 

condition of rocky intertidal communities has remained elusive due to the complex, dynamic, 

and heterogeneous nature of rocky shore ecosystems (Murray et al. 2006). 

Work needs to be done to determine if parameters can be identified that represent the 

status of rocky shore ecosystems so monitoring and evaluation can be focused, informative, and 

easily communicated. Biocriteria or biotic indices have long been utilized for this purpose to 

evaluate the status of aquatic and terrestrial ecosystems. These criteria or indices translate 

environmental or biotic data into an index value or a grade, thereby breaking down complex 

information into an easily understandable scoring system. For example, the Index of Biological 

Integrity (IBI) has been employed to assess ecosystem condition in streams (Karr 1991) and softbottom, benthic (Weisberg et al. 1997) habitats and, similarly, the Terrestrial Index of Ecological 

Integrity (TIEI) has played a similar role in terrestrial ecosystems (Andreasen et al. 2001). 

Weisberg et al. (2008) indicate that recognized European and U.S. approaches to developing 

biocriteria for assessing ecological systems include: 1) comparison to historical conditions; 2) 
2

comparison to present reference conditions; 3) models; and, 4) consensus (or best) professional 

judgment (BPJ). Rice (2003) lists the following categories of ecosystem indicators: 1) Indicator 

Species; 2) Diversity Indices; 3) Multivariate Ordination Techniques; and, 4) Aggregated 

Indicators of Ecosystem Status, and also discusses indicators that move beyond these categories 

and, with the aid of an ecological model, reflect emergent ecosystem properties. A key question 

is whether similar biocriteria or biotic indices can be developed that accurately represent the 

status of rocky shore ecosystems and that capture the degree to which rocky intertidal 

communities are disturbed by natural or anthropogenic agents. 

To address this question, a team of rocky intertidal experts was convened and a three day 

workshop held on March 5-7 2010 at the Wrigley Institute for Environmental Science on Santa 

Catalina Island, California. They were joined by coastal managers and administrators of 

agencies and programs interested in monitoring changes in rocky intertidal populations and 

communities. The workshop was sponsored by the University of Southern California Sea Grant 

program with assistance from the Bureau of Ocean Energy Management, Regulation and 

Enforcement. A list of workshop participants is provided in Table 1. 

Table 1. Workshop Participants 

--------------------------------------------------------------------------------------------------------------------- 

Rocky Intertidal Experts

Rich Ambrose University of California, Los Angeles 

Carol Blanchette University of California, Santa Barbara 

Jennifer Burnaford California State University, Fullerton 

Megan Dethier University of Washington, Friday Harbor Laboratories 

Jack Engle University of California, Santa Barbara 

Mike Foster Moss Landing Marine Lab 

Melissa Miner University of California, Santa Cruz 

Steve Murray California State University, Fullerton 

Karina Nielsen Sonoma State University 

John Pearse University of California, Santa Cruz

Pete Raimondi University of California, Santa Cruz

Dan Richards Channel Islands National Park Service 

Christy Bell University of California, Santa Cruz (Participated in Exercise but did not attend Workshop) 

Jayson Smith California State University, Fullerton 

Managers

Dominic Gregorio State Water Resources Control Board 

Mary Elaine Helix Bureau of Ocean Energy Management, Regulation and Enforcement 

Cheri Recchia Marine Monitoring Enterprise 

Steve Weisberg Southern California Coastal Water Research Project 

Elizabeth Whiteman Marine Monitoring Enterprise 

Workshop Facilitators

Phyllis Grifman University of Southern California, Sea Grant Program 

Susan Zaleski University of Southern California, Sea Grant Program 
3

The specific goals of the workshop were: 1) to determine whether there would be a high 

level of agreement among experts in identifying disturbed (natural and anthropogenic) rocky 

intertidal sites using only species abundance data and meta-data describing physical site 

characteristics; and, 2) if so, whether these experts would make their identifications using similar 

approaches. An ultimate goal of the workshop was to determine which characteristics of species 

abundance data sets were useful for distinguishing disturbance levels for rocky intertidal sites 

and whether it might be possible to use these characteristics to develop criteria or an index that 

reflect the disturbance status of rocky intertidal populations and communities. If developed, this 

index will be of great benefit to managers of California’s parks, beaches, and shoreline, as well 

as those responsible for discharges into Areas of Special Biological Significance (ASBS), who 

often face difficulties in determining benchmarks for evaluating the effectiveness of their 

management strategies. 

Prior to the workshop, a group of rocky intertidal experts was identified and asked to 

participate in an exercise to evaluate the condition of rocky intertidal sites using uniform data 

sets. This exercise was modeled after one performed for benthic infaunal communities where 

experts used their best professional judgment to assess the condition of 35 California soft bottom 

sites working only from blind data sets (Weisberg et al. 2008). In this exercise, participating 

experts ranked sites in a highly correlated way (r = 0.91) and achieved strong agreement on site 

condition. They also used similar parameters for making their assessments. In this preworkshop exercise, each rocky intertidal expert was asked to examine common data sets 

containing the abundances (% cover for macro-invertebrates and macrophytes; density for 

mobile macro-invertebrates) of intertidal species for 31 site data sets. In addition, meta-data 

(substratum type, slope, relief, wave climate, sediment influence, shore expanse, and nature of 

nearby up and down coast habitat), and calculations of total substratum cover and measures of 

diversity (numbers of taxa, H’, J’, d, and 1-) were provided for each site data collection. All 

data sets were obtained from Pete Raimondi and his U.C. Santa Cruz intertidal sampling 

program. 

Investigators were informed that each of the sites was located along a biogeographically 

uniform portion of the California coastline between Point Conception and Point Reyes. 

However, specific site locations were not provided and sites were identified only by number. 

Also unbeknown to the participants, the data included repetitive seasonal visits for five of the 

sampled sites. Thus, a total of 26 independent sites were investigated with data for 5 of these 

sites provided for two different sampling periods (Figure 1). No information describing natural 

disturbance (other than that deduced from the meta-data) and anthropogenic disturbance to sites 

was made available. 

Experts were instructed to use their best professional judgment to conduct any form of 

analysis they found useful to examine the data and arrive at their conclusions. Each expert was 

to: 

1) Assign each of the 31 site data sets to one of five condition categories – undisturbed, 

largely undisturbed, neutral, moderately disturbed, strongly disturbed – using the 

numerical codes for the five-point disturbance scale: undisturbed (1) to strongly 

disturbed (5); 
4

2) Identify the five site data sets most strongly influenced by anthropogenic 

disturbance; 

3) Describe the criteria (or attributes) used to arrive at the disturbance classifications 

together with a rating of the importance of each of these criteria; and, 

4) Describe the criteria (or attributes) used to identify the five sites most strongly 

influenced by anthropogenic disturbance. 

All expert analyses were compiled, presented to the workshop participants, and discussed 

to determine the degree of agreement in the site classifications and approaches used. 

Figure 1. Map depicting the sites and site numbers for which data sets were supplied to experts. 

Note: experts were provided two temporal data sets for sites denoted by red points on the map. 
5

Results 

Identification of the Level of Site Disturbance. There was fairly good agreement among the 

experts in identifying the sites subjected to the greatest degree of disturbance. However, much 

less agreement was evident in identifying sites subjected to moderate disturbance or that received 

little disturbance (Table 2; Figure 2). Four site data sets (7, 8, 24 and 29) received the highest 

disturbance scores, averaging > 4.00 on the 5.00 scale and for Site 24 all except for one 

investigator scored this site as “strongly disturbed”. The data sets represented two different 

temporal visits to one of these four intertidal locations (sites 8 and 29). Thus, expert consensus 

was reached on 3 of the 26 independent sites. The site identified as the next most disturbed 

based on expert consensus was Site 5, followed by Sites 1, 2, and 23. Eight sites (4, 9, 12, 17, 

21, 26, 28, and 30) fell on the undisturbed end of the scale based on expert scores. These sites 

tallied scores < 2.5. Interestingly, two of these site data sets represented sites with two seasonal 

visits where the experts scored one visit as less disturbed than the other. No site received more 

than four scores of 1 (“largely undisturbed”). 

Figure 2. Average score by experts for the 31 site data sets. Sites with two separate temporal 

visits are 8 and 29, 2 and 27, 6 and 28, 14 and 30, and 19 and 31. Note: 5 = strongly disturbed; 

4 =moderately disturbed; 3 = neutral; 2 = largely undisturbed; 1 = undisturbed. 
6

Table 2. Results of disturbance assignments of the 13 experts (A to M). Sites are arranged 

from top to bottom by average score. Sites with two seasonal visits are 8 and 29, 2 and 27, 6 and 

28, 14 and 30, and 19 and 31. Note: 5 = Strongly Disturbed; 4 =Moderately Disturbed; 3 = 

Neutral; 2 = Largely Undisturbed; 1 = Undisturbed. 

Investigator

Site

Number A B C D E F G H I J K L M Average

24 5 5 5 5 5 5 5 5 5 5 5 4 5 4.92

29 5 5 5 4 4 5 5 4 3 5 5 5 4 4.54

7 5 5 5 4 4 4 4 4 4 4 5 5 5 4.42

8 5 5 5 4 1 4 4 4 2 4 5 5 5 4.08

5 3 4 4 4 4 4 4 4 4 4 3 3 4 3.77

1 2 4 3 4 3 4 4 2 2 4 4 5 3 3.38

2 3 4 4 4 2 2 3 3 4 4 3 3 4 3.27

23 5 3 4 2 1 4 3 3 2 3 2 5 5 3.23

15 3 5 4 3 2 3 4 3 4 4 3 1 1 3.08

22 5 1 4 2 1 5 4 3 2 2 1 5 5 3.08

27 3 4 3 4 2 1 2 3 4 2 5 4 3 3.08

25 4 3 4 3 1 1 3 4 2 2 3 4 5 3.00

6 2 3 4 3 3 4 2 3 2 2 4 4 2 2.92

11 1 2 4 3 2 5 3 4 5 3 2 2 2 2.92

16 4 3 4 3 1 2 4 3 4 3 2 1 4 2.92

20 1 3 4 3 1 4 3 3 4 2 2 5 3 2.92

13 1 4 4 3 2 4 3 3 4 2 3 2 2 2.85

14 1 4 2 3 2 4 3 3 4 3 2 3 2 2.77

19 1 4 2 3 1 3 2 4 4 3 3 2 4 2.77

18 1 4 4 3 1 3 3 3 4 2 3 1 3 2.69

3 3 1 4 3 2 2 4 3 4 2 3 1 2 2.62

10 1 3 3 2 2 4 4 3 2 3 1 3 3 2.62

31 1 2 2 3 1 3 2 4 4 3 3 2 4 2.62

17 1 1 2 4 4 2 1 3 4 1 3 3 3 2.46

28 2 4 2 3 2 1 1 3 3 1 4 4 2 2.46

9 3 4 4 2 1 1 2 3 4 1 2 1 2 2.31

21 1 2 3 3 1 3 3 3 2 3 2 2 2 2.31

4 3 3 4 2 1 1 3 2 3 2 3 1 1 2.23

12 3 2 2 3 1 3 3 3 2 2 2 2 1 2.23

26 1 2 3 2 1 2 1 3 2 3 1 4 3 2.15

30 1 1 2 3 1 2 2 3 3 3 2 3 2 2.15
7

A problem identified in the score assignments during workshop discussions was that 

experts were interpreting polar ends of the disturbance scale differently, i.e., investigators 

differed in their interpretations of what was a Strongly Disturbed Site that merited a 5 score or an 

Undisturbed Site that merited a 1 score. Hence, even though investigators might similarly rank 

sites by levels of disturbance they might assign different numerical scores. 

Identification of Sites Most Strongly Influenced by Anthropogenic Disturbance. Experts 

found it difficult to distinguish anthropogenic from natural or non anthropogenic-driven 

disturbance. Nevertheless, fairly good agreement was reached among experts in the 

identification of the most anthropogenically disturbed sites (Figure 3). 

Figure 3. Frequency of identification of site data sets most influenced by anthropogenic 

disturbance by the 13 experts. Each expert Identified the 5 site data sets believed to be those 

most subjected to anthropogenic disturbance. 

The site most frequently identified by experts to be impacted by anthropogenic 

disturbance was site 24. Sites 29, 8, and 7 were also often identified as being subject to 

anthropogenic disturbance followed by sites 22 and 23. Interestingly, all but 6 sites were named 

by at least one expert as being among the five most disturbed by human influence. Of the 25 

listed sites, 16 sites were identified by only one of the 12 experts that submitted results for this 

portion of the exercise. 
8

The most frequently identified sites (29, 24, 7, 8) were also the sites considered by the 

experts to be the most disturbed regardless of whether disturbance stemmed from natural or 

anthropogenic sources. In fact, there was a strong correlation (r = 0.88) between the average 

score for a site on the five point disturbance scale and the frequency with which a site was 

identified as being disturbed by anthropogenic agents (Figure 4). 

Figure 4. Correlation between the average scores for a site based on the five-point disturbance 

scale and the frequency with which a site was identified by experts as being among the five sites 

most subjected to anthropogenic disturbance. Five of the 26 independent sites were not identified 

as being among the top five subjected to anthropogenic disturbance. 

Approaches Used by Experts to Place Sites on a Disturbance Scale. Working solely from 

the provided data, experts used a variety of approaches and criteria to identify the degree of 

disturbance, regardless of source, affecting each of the 31 site data sets. No guidance was given 

so each expert’s approach and decision-making was independent. Nevertheless, there was a high 

degree of similarity in the key criteria identified by experts in making their evaluations of site 

disturbance. The approaches and criteria used can be condensed into five categories (Table 3). 

These were consistent with the criteria and approaches used previously (see Rice 2003) to assess 

ecosystem condition and included: 1) ordination methods drawing on the full use of all biotic 

data, e.g., community-level analyses using multivariate statistics; 2) the relative cover of biota 

and bare rocky substratum; 3) the abundance profiles of specific species populations and types of 

species; 4) community diversity; and 5) the prevalence of selected physical factors. Most experts 

used multiple criteria in developing their site disturbance scores. 
9

Table 3. Summary of approaches and criteria used by experts to identify the degree of disturbance, 

regardless of source, affecting site data sets. 

Approach or Criteria Examples 

Community-Level Analyses Cluster Analysis and MDS mostly using cover data 

Overall Cover Patterns Disturbance Indicators: Low Biotic Cover; High Bare Rock 

Cover 

Diversity Disturbance Indicator: Low Diversity (Numbers of Taxa, H’, 1-

, Family Richness) 

Abundances of Species 

Groups or Selected Taxa 

Disturbance Indicators: High Cover of Opportunistic Seaweeds 

(e.g., Ulva, Filamentous, Sheet, and Tubular Algae); Low Cover 

of Rockweeds; High Abundances of Mussels, Sea Stars, 

Limpets; Low Abundances of Black Abalone, Sea Grasses, and 

Corticated Algae; Absence of Certain Species; Deviations from 

Expected Abundance Patterns 

Physical Factors Disturbance Indicator: High Sand Cover or Scour; High Wave 

Exposure; Unstable Substratum (e.g., Cobble) 

Approaches Used by Experts to Identify the Sites Most Subject to Anthropogenic 

Disturbance. Experts uniformly expressed concern about identifying the 5 sites most subject to 

anthropogenic disturbance among the 31 site data collections examined and in identifying the 

criteria used. Of principal concern was the ability to distinguish between natural and 

anthropogenic disturbance and the acknowledgement that multiple disturbance agents affect 

rocky intertidal sites so distinguishing natural from anthropogenic drivers becomes problematic. 

Two other issues arose during discussions of the identification of anthropogenically-disturbed 

sites. The first was that there appeared to be a narrow range of anthropogenic disturbance 

affecting the sites examined in the exercise. This could be addressed by including sites that 

represented a wider range of site types with respect to anthropogenic disturbance in a subsequent 

exercise. The second was that biological parameters are affected differently by different types of 

anthropogenic disturbance. Hence, it is difficult to key in on data indicators without knowing the 

type of anthropogenic disturbance. Experts agreed that addressing this topic requires more study 

and work. 

Exercise Challenges. There were two primary exercise challenges identified during the 

workshop discussions: 

1) Experts used variable definitions of “disturbance”. Some considered “natural” 

disturbance part of the natural state of a system, so a site with high levels of wave 

action, for example, was considered by some to be not very disturbed because this is 

part of its natural state. Whereas, participants, using this same information, 

categorized this type of site as highly disturbed. The definition of “natural” 

disturbance and how one categorizes this disturbance is essential for creating an index 

that represents site condition and reflects anthropogenic driven changes from the 

expected natural state. 

2) Experts variously interpreted the thresholds separating the five assessment categories 

when scoring the degree of disturbance. The scale for ranking sites from 1 to 5 was 
10

not clearly defined, so this left room for individual expert interpretation. For 

example, some experts failed to rank any site as “largely undisturbed”, whereas others 

assigned “strongly disturbed” rankings to only one site in the exercise. As a 

consequence, while good agreement was reached on the most disturbed sites, much 

less agreement was achieved in the disturbance scores for less disturbed sites and the 

inter-investigator correlation (r = 0.34) established from expert scores was relatively 

low. Participants agreed that with clearer more uniform interpretations of the five 

point disturbance scale, much better agreement would likely be realized. 

Deviations from Expected Site Conditions. Rocky intertidal habitats vary greatly from site to 

site based on biogeography and physical site features, including exposure to non-anthropogenic 

forms of natural disturbance. Experts agreed that these factors must be addressed in order to 

develop an index that describes the status of a site with respect to anthropogenic impact. In this 

exercise, sites were located within a uniform biogeographic region to eliminate geographic 

changes in biota such as between central and southern California. Physical variations in site 

features (e.g., wave exposure, sand influence, and substratum type, slope, and relief) were 

present and needed to be accounted for by experts in making their assessments. Thus, the 

challenge for making a determination of site condition and the degree to which a site was 

exposed to anthropogenic disturbance was to evaluate the suite of biological characteristics (e.g. 

species abundances, diversity, etc.) against what was believe to be the expected condition. Then, 

deviations from this expected condition could be used to assess site status. This approach would 

enable managers to identify sites that have drifted from expected conditions but would not 

determine causality. This approach requires understanding of: 

1) Normal variation expected within each site type 

2) The ends of the spectrum along the site condition scale 

3) Past or current conditions used to set the end of the spectrum where the site was free 

from anthropogenic influences. 

Future Work. Given the progress made at this workshop, the participants agreed that a 

follow-up exercise and ensuing workshop would be productive. Participants concluded that the 

ratings of a site data set were more based on differences in how an expert defined and 

categorized disturbance and determined the disturbance level on the five-point scale compared 

with the actual data-based characterization of the site. A principal purpose of a follow-up 

exercise would be to overcome interpretational differences among experts in rating sites and to 

make further progress in identifying the metrics that could best be used to describe site condition. 

This will require discussion of the expected biological characteristics of sites under different 

types and degrees of environmental “disturbance”. The follow-up exercise should be similarly 

constructed, including data from a range of sites unknown to the experts and should include 

additional, strongly disturbed site data sets to provide a wider range of conditions to evaluate. In 

addition, the disturbance scale should be more clearly defined to reduce the variation in a score 

given to a site data set viewed similarly by experts in terms of disturbance level. In this follow-
11

up exercise, experts should also be asked to rank sites from first to last on the more clearly 

defined disturbance scale. 

Summary of Consensus Outcomes. The results of the workshop were promising and several 

consensus outcomes were realized. In summary these were: 

1) Rocky intertidal habitats vary greatly from site to site based on non-anthropogenic 

environmental drivers making simple assessments of the status of these sites 

complex; 

2) There are some common characteristics and approaches that experts used to come up 

with their assessments of each site; 

3) Definitions are needed to clearly articulate what is meant by “disturbance”, including 

anthropogenic driven “disturbance”; 

4) The scale for scoring disturbance, including its end points, needs to be clarified to 

eliminate noise resulting from investigator interpretation; 

5) Once “natural” environmental characteristics are accounted for, sites would be 

expected to display a suite of biological characteristics (e.g. species abundances, 

diversity, etc.) that would represent the expected condition and then deviations from 

this expected condition could be used to describe site status; 

6) Establishing an index to capture the condition of rocky intertidal sites appears feasible 

and is worth pursuing. 

Literature Cited 

Andreasen, J. K., O’Neill, R. V. O., Noss, R., and Slosser, N. C. 2001. Considerations for the 

development of a terrestrial index of ecological integrity. Ecological Indicators 1: 21-35. 

Murray, S. N., Ambrose, R. F., and Dethier, M. N. 2006. Monitoring rocky shores. University of 

California Press, Berkeley, California. 

Karr, J. R. 1991. Biological integrity: a long-neglected aspect of water resource management. 

Ecological Applications 1: 66-84. 

Rice, J. 2003. Environmental health indicators. Ocean & Coastal Management 46: 235-259. 

Weisberg, S. B., Ranasinghe, J. A., Dauer, D. M., Schaffner, L. C., Diaz, R. J., and Frithsen, J. 

B. 1997. An estuarine benthic index of biotic integrity (B-IBI) for Chesapeake Bay. 

Estuaries 20: 149-158. 

Weisberg, S. B., Thompson, B., Ranasinghe, J. A., Montagne D. E., Cadien, D. B, Dauer, D. M., 

Diener, D., Oliver, J., Reish, D. J., Velarde, R. G., and Word, J. Q.. 2008. The level of 

agreement among experts applying best professional judgment to assess the condition of 

benthic infaunal communities. Ecological Indicators 8: 389-394. 
201

Consistent Frequency of Color Morphs in the Sea Star Pisaster ochraceus

(Echinodermata:Asteriidae) across Open-Coast Habitats in the

Northeastern Pacific1

Peter T. Raimondi,2 Raphael D. Sagarin,3,4 Richard F. Ambrose,5 Christy Bell,2 Maya George,2

Steven F. Lee,5 David Lohse,2 C. Melissa Miner,2 and Steven N. Murray6

Abstract: The sea star Pisaster ochraceus (Brandt, 1835) is among the most conspicuous members of northeastern Pacific rocky-shore fauna due to its dramatic

color variation, ranging from bright yellowish orange to brown to deep purple.

Despite a large body of ecological and developmental biology information on P.

ochraceus, few studies have rigorously examined color patterns or their causes

across its geographic range. We used thousands of observations of sea star color

and size taken from southern California to northern Oregon to show that the

frequency of orange sea stars is approximately 20% with little variation across

a broad latitudinal band. However, the frequency of orange sea stars in a population increases with the size of the animals in most populations. We consider

several alternative hypotheses for these color patterns but find that the most parsimonious explanation is that adult color is a selectively neutral genetic trait that

expresses itself ontogenetically. These novel findings point to the need for renewed study of the basic biology of this key ecological species.

One of the most immediately conspicuous

observations in northeastern Pacific tide pools

is the striking color differences in the sea star

Pisaster ochraceus (Brandt, 1835). Even at a

distance one can easily pick out orange and

purple sea stars as they line the rock walls

near intertidal mussel beds. Anecdotally, experienced intertidal biologists have observed

that about one-fourth to one-third of the

P. ochraceus in any given site along the open

Pacific coast are orange, and the remainder

are some variant of brown, rust, or purple

(E. Sanford, J. Pearse, R. Strathmann, and

C. Harley, pers. comm. to R.D.S. 2004).

Although P. ochraceus is one of the most

extensively studied intertidal invertebrates,

with many published studies, for example, on

its development (George 1999), physiology

(Vasu and Giese 1966), diet (Feder 1959,

Menge 1972), effects on prey species

(Mauzey et al. 1968), parasitism (Leighton

et al. 1991), settlement patterns (Sewell

and Watson 1993), role as a ‘‘keystone’’

species (Paine 1966, Menge et al. 2004) and

in maintaining alternate community states

(Paine and Trimble 2004), and reactions

to climatic change (Sanford 1999), remarkably little is known about the basic biological foundations of its color variants nor

the ecological conditions that support phenotypic color polymorphism in this sea star.

Most of what we know about color morphs

in P. ochraceus stems from studies done more

than half a century ago on small numbers of

individuals from just one or two locations.

Pacific Science (2007), vol. 61, no. 2:201–210

: 2007 by University of Hawai‘i Press

All rights reserved

1 This is contribution number 226 of the Partnership

for Interdisciplinary Studies of Coastal Oceans (PISCO)

funded primarily by the Gordon and Betty Moore Foundation and the David and Lucile Packard Foundation.

Manuscript accepted 9 June 2006. 2 Long Marine Laboratory, University of California,

100 Shaffer Road, Santa Cruz, California 95060. 3 Corresponding author (e-mail: rafe.sagarin@duke

.edu). 4 Nicholas Institute for Environmental Policy Solutions, Duke University, Durham, North Carolina 27708. 5 University of California, Department of Environmental Health Sciences, Los Angeles, California 90095-

1772. 6 Department of Biological Science and College of

Natural Sciences and Mathematics, California State University, Fullerton, Fullerton, California 92834-6850.
Fox and Scheer (1941) confirmed that color

in P. ochraceus is determined by two carotenoid pigments, suggesting that diet plays a

role in coloration because animals generally

do not produce carotenoids. Beyond that paper, an unpublished study of variation in

color polymorphism by Forbes (1951), and a

review by Fox and Hopkins (1966), none of

the 128 published works on P. ochraceus indexed by ISI Web of Knowledge between

1910 and 2005 nor the citations on P. ochraceus reviewed in Intertidal Invertebrates of California (Morris et al. 1980) addressed color

patterns in P. ochraceus or the mechanisms

for them.

Phenotypic color polymorphism in other

organisms has been commonly observed (Endler 1986, Galeotti et al. 2003, Wente and

Phillips 2003) and has generated numerous

evolutionary explanations for why sometimes

strikingly different colors should be maintained. In almost all studies, the null hypothesis that color polymorphism is selectively

neutral has been rejected. Although color

polymorphism without an obvious selective

mechanism is unexpected, it is not unprecedented. Oda and Ishii (2001) demonstrated

that color polymorphism in Conocephalus maculatus katydids is genetically determined but

not under environmental selection, and Finke

(1994) found no sexual, apostatic, or disruptive selective mechanisms acting on female

color dimorphism in Enallagma damselflies.

Alternative hypotheses generally can be

classified as invoking either selective mechanisms that have a persistent effect on populations or transient mechanisms that rely on

a phenotypically plastic trait. Alternative hypotheses with empirical support based on selective mechanisms include (1) nonrandom

mating due to sexual selection or signaling

to prevent inbreeding (Houde 1987, Galeotti

et al. 2003); (2) apostatic selection, in which

rare morphs are more successful in hunting

prey or avoiding predators through the disruption of search images or advertisement

of distastefulness (Allen 1988, Gillespie and

Oxford 1998, Horth 2004); (3) disruptive

selection through crypsis in heterogeneous

backgrounds or physiological adaptation to

spatially or temporally variable environments

(Nevo 1973, Hairston 1979, Etter 1988); and

(4) balancing trade-offs among these agents.

Mechanisms invoking plasticity include the

roles of (1) color plasticity in response to

environmental factors (Wente and Phillips

2003); (2) dietary differences resulting in

phenotypic differences (Tlusty and Hyland

2005); and (3) ontogenetic color change

(Booth 1990).

With so many potential mechanisms, it

may not be logistically feasible to study color

polymorphism in a species across a large

range using detailed mechanistic experiments

such as those used on smaller scales or on easily manipulated study systems (e.g., laboratory experiments with guppies). However, a

common theme to almost all alternative hypotheses is that color morphs are segregated

into different spatial, temporal, ontogenetic

or behavioral niches for which the different

color morphs are better adapted. This suggests that broad-scale observations of color

morphs taken across an environmental gradient containing many of these niches, combined with an understanding of the natural

history of an organism, can begin to eliminate the likelihood of certain hypotheses

while suggesting more-likely hypotheses that

could be addressed with specific mechanistic

studies. Here we use an unprecedented number of color and size observations obtained

over a wide latitudinal gradient to examine alternative hypotheses related to the maintenance of color polymorphism in P. ochraceus.

materials and methods

Samples of Pisaster ochraceus size and color

were taken by three different groups of investigators that share data as part of the MultiAgency Rocky Intertidal Network (MARINe)

and the Partnership for Interdisciplinary

Studies of Coastal Oceans (PISCO). Samples

were taken biannually between fall 2000 and

fall 2003 at 26 sites located between southern

California (33.71N) and northern Oregon

(45.92N) within permanent demarcated

plots in the low intertidal (Figure 1). Sizes of

the plots varied with site, ranging from 20

to 160 m2

, depending on geomorphology

and available habitat. Because our goal was

202 PACIFIC SCIENCE . April 2007
Figure 1. Map of 26 study sites along the west coast of North America.
specifically to measure and record the color

of many individuals at each site, plots were

chosen to represent a range of habitat types

(e.g., low intertidal crevices, rock walls, and

pools) where P. ochraceus of all postsettlement

life stages can be found, rather than a stratified random plot design (which would be

more appropriate if the goal was to compare

population size estimates).

Sites were sampled by MARINe researchers from University of California, Los

Angeles (UCLA), and the University of California, Santa Cruz (UCSC), and PISCO researchers from UCSC. Because our sampling

methodology is relatively simple and was conducted by experienced intertidal researchers

who frequently communicate about sampling

issues, differences due to observer bias in recording color or size across sites is unlikely.

Our study sites are wave-exposed open

coast areas that represent the most common

P. ochraceus habitat over most of its geographic range. We also used additional observations by ourselves and others from

protected-water sites in Puget Sound (Washington State) and Vancouver Island, British

Columbia, to gain insight into the open-coast

patterns we report. Along the 1,850-km

stretch of open coast from Baja California to

Oregon, and farther north, sea stars generally

occur in orange, purple, and brown color

morphs. All sampled sea stars were measured

and scored for color as either ‘‘orange’’ or

‘‘purple’’ (all brown and darker shades were

scored in the ‘‘purple’’ category because field

tests determined that brown and purple forms

are difficult to differentiate consistently). Although there is considerable color variation

among the darker forms in this species, we

use this simple orange/purple dichotomy in

our observations and analysis because it is

least likely to introduce sampling bias while

still offering the ability to evaluate the orange

color morph patterns observed in the field.

Size measurements were made with calipers or rulers from the tip of the longest arm

to the center of the aboral disk and recorded

to the nearest 10 mm. Pilot data from 438 individuals confirmed a strong correlation between this radial measurement and oral disk

radius (Pearson correlation coefficient 1⁄4

0.879, P < :001) and width of the largest

arm (Pearson correlation coefficient 1⁄4 0.904,

P < :001), indicating that maximum radius is

representative of size.

Our analysis was designed to focus on

color ratios and to avoid issues of nonindependence that might arise from repeatedly

sampling individuals in permanent quadrats.

Hence, at each site we calculated the percentage of orange individuals for each sample period and then averaged those percentages to

produce an overall site average. To examine

the percentage of orange individuals in populations of different sizes the mean number of

purple and orange individuals for each 10-

mm size bin across all sample periods was

calculated for each site. Means were then

summed for these color categories across all

sites and the percentage of orange morphs

was calculated. By aggregating our data, the

potential problem of near-zero or zero values

in the smallest and largest size categories was

avoided.

Finally, habitat use, aggregation by color,

and seasonal differences in color ratios were

tested using quantitative analyses (chi square

and analysis of variance [ANOVA]), specialized data collection efforts, and through qualitative observations made during sampling

visits.

results and discussion

The monitoring data analyzed here, incorporating 14,720 observations of Pisaster ochraceus, demonstrate both consistency of orange

color frequencies in adult sea stars over a

broad latitudinal gradient (Figure 2) and

changes in the frequency of orange morphs

from small to large sea stars at most sites

(Figure 3). The range in percentage orange

morphs for all sites was 12.6–27% (mean 1⁄4

20:0 G 4:4% SD). Regression of percentage

orange against size was positive and highly

significant (R2 1⁄4 0:74, P < :001).

Observations of 177 individuals from

Hopkins Marine Station (central California)

and Old Stairs (southern California) showed

no relationship between color and habitat

type (flat benches, vertical walls, or shaded

crevices) (Pearson chi-square 1⁄4 1.38, df 1⁄4 2,

204 PACIFIC SCIENCE . April 2007
P 1⁄4 :501). Similarly, clustering of color

morphs was not detected because 24% of

nonorange sea stars were found closest to orange individuals and 78% of orange sea stars,

mirroring the overall color frequencies, were

found closest to nonorange sea stars. These

results are in accordance with qualitative observations of the frequency of color morphs

in this species that we made during hundreds

of sampling visits. Finally, we found no evidence of consistent seasonal differences in

the percentage of P. ochraceus orange color

morphs in our sampled populations (ANOVA, F 1⁄4 1:09, df 1⁄4 45, P 1⁄4 :364).

Selective Mechanisms

The wealth of knowledge on P. ochraceus

raises doubts about hypotheses that invoke

selective mechanisms as viable explanations

for color polymorphism in this species. These

sea stars are dioecious, broadcast spawners

with little visual ability beyond sensing light

and dark (Morris et al. 1980). Hence, it is unlikely that color serves as a cue for sexual or

other forms of visually based selection. The

sea star’s main prey items are sessile and

use only size as an escape from predation,

or use their mobility to escape by responding

to chemical traces of the predator in the

water (Phillips 1975, Morris et al. 1980).

Thus, color differences would not afford any

color morph an advantage in obtaining prey.

Figure 2. Average percentage of orange sea stars (GSE) in the population at all sites, arranged from south to north.

Figure 3. Percentage of orange sea stars in increasing

size bins. The mean number of purple and orange individuals for each 10-mm size bin across all sample periods

was calculated at each site. Means were summed for each

color across all sites and percentage orange was calculated.

Patterns of Color Morphology for Pisaster ochraceus . Raimondi et al. 205
Among larger (>30-mm radius) individuals,

no P. ochraceus color morph is cryptic in intertidal habitats. Greater mortality in purple P.

ochraceus could lead to an increase in the frequency of orange sea stars in a population.

However, predation on sea stars is not commonly observed, although sea otters prey on

P. ochraceus, and seagulls are occasionally

observed pulling sea stars off intertidal rocks.

If relying on visual cues (whether color or

monochromatic), these visual predators would

likely target the more conspicuous orange sea

stars, which contrast more strongly with the

coloration patterns of intertidal habitats. Although it is plausible that experience with sea

stars or some color-specific olfactory signal

could impart a preference for purple stars if

orange stars are less palatable, to date no one

has investigated this hypothesis. However, as

Ricketts and Calvin (1939:116–117) explained,

‘‘Pisaster neither has nor seems to need protective coloration. Anything that can damage

this thoroughly tough animal, short of the

‘acts of God’ referred to in insurance policies,

deserves respectful mention.’’

Across the geographic range of our

study sites, intertidal communities experience

widely different climatic conditions, tidal regimes, and species assemblages, and yet the

ratio of orange morphs to other color variants remains similar. Moreover, the different

color morphs of P. ochraceus do not segregate

into different niches—spatially, temporally,

or behaviorally. Our observations collected

over 120 sampling visits, as well as those of

numerous intertidal ecologists, suggest that

color morphs do not separate into different

intertidal habitats, nor do they aggregate

preferentially, or show a seasonal component

to color dominance. These observations were

supported by our more-detailed scoring of

habitat use and aggregation by color at Hopkins Marine Station and Old Stairs sites, as

well as the quantitative analysis of our data

parsed by season. Finally, populations appear

to be well mixed genetically across their

range. Recent work by Harley et al. (in press)

revealed no geographic genetic population

structure across the species range, even when

comparing locations on alternate sides of

known biogeographic boundaries or known

discontinuities in larval supply. These findings suggest that genetic drift is not likely to

play a dominant role in affecting color morph

frequencies.

Nonetheless, a limited temporal and spatial perspective could mask selective pressures

affecting these populations. For example, subtidal populations, which were not sampled,

could have different overall color ratios due

to selective pressures on color. However, this

appears even less likely than in intertidal

habitats because P. ochraceus would be less affected by environmental conditions such as

heat stress while immersed and coloration

could only be affected by selective sea otter

predation at the small number of our sites

supporting otter populations. Alternately,

color polymorphisms observed at one time

may be under selection toward the dominance of one form (e.g., Stolz et al. 2003).

The samples we analyzed do not represent a

time series long enough to determine conclusively if the observed color ratios vary over

time. However, observations of color ratios

of 1,327 P. ochraceus (across all sizes) by biology student Clifford Forbes in 1951 indicated

orange frequencies of 20% in Trinidad, California (41.07N), and 25% at Hopkins

Marine Station (36.62N) (Forbes 1951),

mirroring the values we observed in our

samples.

Size-Related Plasticity

The size-related shift in the frequency of orange color morphs, which has not previously

been documented, seems to indicate phenotypic plasticity in this trait. The color shift

could arise from diet, ontogenetic differences

in mortality, or ontogenetic color change.

Adults of both color morphs were consistently observed congregating on the same

prey items (e.g., Mytilus californianus). Feder

(1959) demonstrated that regardless of geographic location or habitat, P. ochraceus overwhelmingly eats the prey it is primarily found

with, suggesting that these sea stars feed primarily on the California mussel (M. californianus) throughout its range. Nonetheless, P.

ochraceus also will feed opportunistically on

many other prey items in our study range

206 PACIFIC SCIENCE . April 2007
(E. Sanford, pers. comm. 2006). Although

it is conceivable that mussels of different

quality (e.g., reproductive individuals) might

affect color or that alternative prey items

might impart different color pigments to

their predators, it is not clear how (or why)

only one sea star color morph would consistently target one type of mussel or alternative food source. However, food sources of

juvenile P. ochraceus, which are unknown,

might ultimately affect adult color patterns.

In lobsters, for example, juvenile diet has

been shown to affect color patterns through

both genetically determined and phenotypically plastic pathways (Tlusty and Hyland

2005).

Hypothetically, P. ochraceus could change

color ontogenetically, a phenomenon that occurs in other taxa (Booth 1990). Although direct observations of color change have not

been made, support for ontogenetic color

change in P. ochraceus comes from frequent

observations of intermediate-size orange sea

stars with purple arm tips (Figure 4), and

observations of orange stars regenerating a

mostly purple arm bud. Ontogenetic color

change in limited parts of an organism’s body

has been observed in other marine invertebrates (e.g., Tlusty and Hyland 2005). The

delayed onset of orange coloration may be

related to the cryptic coloration afforded to

very small (<30 mm), nonorange-colored sea

stars on coralline algae in our study range,

where they are often found as newly settled

recruits. This is analogous to Cancer irroratus

rock crabs, where coloration is conspicuous in

Figure 4. Purple (left) and orange (right) Pisaster ochraceus photographed at low tide at Carpinteria, California, March

2004, by R.D.S. Scale bar approximately 10 cm. Note purple (dark) arm tips on the orange sea star.

Patterns of Color Morphology for Pisaster ochraceus . Raimondi et al. 207
adults but cryptic in newly settled juveniles

(Palma and Steneck 2001). Moreover, other

investigators (E. Sanford, pers. comm. 2006)

and we ourselves have noted that most small

(e.g., <30 mm) sea stars tend to be grayish

purple or grayish brown along the exposed

Pacific coast, indicating that adult purple and

brown stars also change color but perhaps not

as dramatically as orange adults. Apparently, a

different pattern is seen in some habitats in

the northeastern Pacific where small sea stars

are more commonly orange, a color that is

more cryptic on their preferred settlement

habitat there (R. Paine, pers. comm.), but

extensive observations of color ratios at different sizes have not been made for those

populations.

Differences with Protected-Water Populations

The frequencies of color morphs in P. ochraceus populations from protected waters in the

northeastern Pacific are in stark contrast to

those we observed for open-coast populations, which might shed light into the mechanisms underlying color polymorphism in this

species. First, protected-water populations are

much more variable in color ratios, and individual sites tend to be dominated by one color

morph or another. For example, on San Juan

Island (48.5N, 123W ), purple stars dominate. Of 250 individuals sampled at six sites

on San Juan Island by R.D.S. in September

2005, only 4.8% were orange. Likewise,

purple individuals dominate populations in

Georgia Strait (D. Eernisse, pers. obs.) (Harley et al. in press) and at sites along the Inside

Passage of southeastern Alaska (C. Baxter,

pers. obs.). Yet, on Orcas Island, adjacent to

San Juan Island, populations are dominated

by orange individuals (R. Strathmann, pers.

obs.). In addition, the purple stars in these

protected-water populations are far more

vivid than their open-coast counterparts,

although small numbers of brightly colored

purple stars have been observed at open-coast

sites (E. Sanford, pers. comm.). At protected

sites, orange individuals are much paler in

color, and the brown color morph seen on the

open coast is largely absent (RDS, pers. obs.).

Wave exposure, water chemistry, and

available food resources differ substantially

between protected and outer-coast sites. Local differences in wave exposure might become manifest through differences in larval

settlement patterns. In the embayments of

Puget Sound and other protected waters,

founder effects might dominate so that infrequent settlement events skewed by chance toward one color morph or another could result

in similarly skewed adult sea star populations.

This hypothesis is supported by data on the

size structures of P. ochraceus populations at

six San Juan Island sites, which showed that

sea stars <70-mm radius were absent from

250 sampled individuals compared with 27%

of all observations for the open coast. This

finding suggests that recruitment events are

more episodic in these protected waters. Salinity and pH are likely to be different in protected waters compared with open-coast sites,

but at present we do not know the effects

of water chemistry on sea star pigmentation.

Pisaster ochraceus populations in quiet water

environments also likely differ from opencoast populations in diet, because Mytilus californianus, a prominent bed-forming space occupier on much of the open Pacific coast, is

not found in great densities on San Juan Island or at other protected-water sites. Differences in diet could hypothetically result in

different color ratios and different color tones

in open- versus protected-water populations,

but dietary differences do not explain how

polymorphism is maintained with such consistency across the broad geographic range

represented by our outer-coast study sites.

Moreover, observations from protected-water

populations must be taken with caution because it has been suggested (Ricketts et al.

1985) that these populations are a subspecies

of P. ochraceus (i.e., P. ochraceus confertus).

conclusions and future directions

In 1959, Feder lamented, ‘‘Although the starfish Pisaster ochraceus is one of the most conspicuous animals to be found along the rocky

shores of the Pacific Coast . . . its natural

history is poorly known’’ (Feder 1959:721).

Nearly 50 yr later, because of Feder and

208 PACIFIC SCIENCE . April 2007
others, knowledge of the natural history

of P. ochraceus has increased, but causes of a

most obvious characteristic—its striking color

polymorphism—remains a mystery.

Several of the key questions raised by our

observations can become the focus of a renewed effort to understand patterns of color

in P. ochraceus. Elucidation of the gene(s) and

pigment complexes responsible for color is a

fundamental gap in our understanding of

color patterns. Mating experiments involving

crosses of variously colored parents might

help determine the inheritance patterns of

color, although typically high mortality in

laboratory cultures may confound interpretation of results. Basic biological questions need

to be assessed in an ecological context, considering how variation in diet, water chemistry, and biological interactions can affect

pigmentation and the occurrence and mechanisms of color change. Moreover, understanding the extent to which larval dispersal

effectively mixes populations will provide insight into the role that genetic drift could

play in skewing color ratios. Clarification of

population genetic structure and phylogeographic patterns will help to address the question of whether protected-water populations

are genetically distinct from one another and

from open-water populations. Although addressing these questions will be a challenge,

improved understanding of the mechanisms

of color variation in this common sea star

would be greatly appreciated by the many

amateur naturalists and professional biologists

who have been intrigued by this conspicuous

tide-pool animal.

acknowledgments

We thank D. Eernisse, C. Harley, B. Menge,

J. Pearse, E. Sanford, and R. Strathmann for

sharing their knowledge of Pisaster ochraceus.

J. Wible of the Miller Library at Hopkins

Marine Station provided research assistance.

Research in San Juan Island was conducted

with the Beam Reach Science and Sustainability Field School. Research by the MultiAgency Rocky Intertidal Network (MARINe)

was sponsored by the U.S. Minerals Management Service.

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210 PACIFIC SCIENCE . April 2007
Spatial patterns in recruitment and growth of the mussel Mytilus californianus

(Conrad) in southern and northern California, USA, two regions with

differing oceanographic conditions

Jayson R. Smith a,

⁎, Peggy Fong a

, Richard F. Ambrose b

a Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Dr., South, Los Angeles, CA 90095-1606, United States b Environmental Science and Engineering Program, Department of Environmental Health Sciences, University of California Los Angeles, Box 951772, Los Angeles,

CA 90095-1772, United States

article info abstract

Article history:

Received 1 August 2007

Received in revised form 6 October 2008

Accepted 16 October 2008

Available online 25 October 2008

Keywords:

Rocky shores

Recruitment rate

Growth rate

Mytilus

Mussel bed

Mussels, Mytilus californianus, and other benthic invertebrate populations on the wave-exposed intertidal

coast of the eastern North Pacific are impacted by a suite of biotic and abiotic factors on both local and larger

geographic scales. Previous surveys of mussel abundances along the California coast have revealed that

mussels, in general, are very abundant in northern California while low in southern California. Nevertheless,

mussel abundances in southern California are highly variability with a small number of sites that are

characterized as having moderately high to high abundances. To elucidate driving factors of mussel

abundances in these regions, we investigated recruitment and growth rates of mussels in 1) northern and

southern California, two regions separated by ca. 900 km and exposed to vastly different oceanographic

processes and 2) within southern California at sites with moderately high mussel abundances and at sites

with low abundances. We found that recruitment and, to a degree, growth may be important factors driving

variable abundances of mussels within southern California but could not explain patterns along the entire

California coast. Recruitment and growth rates were low in northern California even though mussels were

highly abundant. Conversely, recruitment and growth in southern California were significantly higher than

northern California and, within the region, were higher in sites characterized by moderately high

abundances. Among regions, differences in recruitment and growth are likely driven by large scale

oceanographic patterns such as upwelling affecting larval transport and temperature affecting growth.

Within southern California, local oceanographic processes likely enhanced or inhibited recruitment or

growth leading to differences in measures between closely located sites.

Published by Elsevier B.V.

1. Introduction

Macroinvertebrate communities in rocky intertidal habitats are

influenced by benthic processes, such as competition and predation,

and physical disturbance, such as that from wave activity, which can

drive patterns of abundances of adult populations (e.g. Connell, 1961;

Paine, 1966; Dayton, 1971). Equally important are oceanographic

conditions that, for example, can carry larvae on- or offshore (e.g.

Roughgarden et al., 1988) or supply coastal communities with

nutrients for primary productivity or food for benthic filter feeders

(e.g. Menge et al., 1997, 1999, 2003; Blanchette et al., 2002, 2006). For

example, adult barnacle abundances differ greatly along the eastern

North Pacific coast, with high barnacle cover in Oregon and low cover

in the northern and central portions of California, that are suggested to

be linked to the frequency of upwelling and relaxation events leading

to differing levels of larval supply (Roughgarden et al., 1988; Connolly

and Roughgarden, 1998). Furthermore, oceanographic conditions

bringing phytoplankton nearshore can drive rocky intertidal communities towards those dominated by filter feeders as opposed to macrophyte dominated communities where plankton supply is low (Menge

et al., 1997).

Along the eastern north Pacific coast, the mid rocky intertidal

zones on wave-exposed shorelines are dominated by mussels, mostly

Mytilus californianus Condrad (Ricketts et al., 1968). Mussels congregate in large clumps that can be several layers thick forming a mussel

bed that can provide space and shelter for a large number of associated

species. In addition, as filter feeders that consume large amounts of

plankton and detritus, they function as an energy link between pelagic

and benthic systems providing secondary production for a wide

number of predators. A survey of mussel abundances along three

regions of the California coast (southern, central, and northern) reveals

high variability among regions (particularly between southern and

northern California) as well as among sites within a region (Smith,

Journal of Sea Research 61 (2009) 165–173

⁎ Corresponding author. Current address: Department of Biological Science,

California State University, Fullerton, P.O. Box 6850, Fullerton, CA 92834-6850, United

States.

E-mail address: jasmith@fullerton.edu (J.R. Smith).

1385-1101/$ – see front matter. Published by Elsevier B.V.

doi:10.1016/j.seares.2008.10.009

Contents lists available at ScienceDirect

Journal of Sea Research

journal homepage: www.elsevier.com/locate/seares
2005). In general, mussel abundances are relatively low throughout

the Southern California Bight (SCB), including both the mainland and

offshore islands, and central California but are much more abundant in

northern California (Monterey Bay and north). Despite this regional

trend, there are numerous locations in the SCB that are characterized

with moderate to high mussel abundances. The driving forces behind

these patterns are unknown and likely attributed to multiple factors.

Here, we explore patterns of recruitment and growth within and

between southern and northern California, two regions with differing

oceanographic conditions, to elucidate whether these variables are

linked to adult mussel abundances.

Mussel abundances can be driven by numerous biotic and abiotic

factors on both local and large geographic scales. On a local scale,

mussels are affected, for example, by sea star predators that can

control abundances as well as the distribution of mussels into the low

intertidal zone (Paine, 1966, 1974). Desiccation and submergence time,

or the amount of time available for feeding, also have been shown

be important driving forces in mussel abundances and distributions

(Dehnel, 1956; Harger, 1970; Behrens Yamada and Dunham, 1989;

Harley and Helmuth, 2003).

Mesoscale (100s of km) oceanographic conditions are also an

important driving force for adult mussel populations. Supply of food

and mussel larvae varies greatly depending on numerous oceanographic patterns, most notably upwelling and relaxation events

(Farrell et al., 1991; Roughgarden et al., 1991; Miller and Emlet, 1997).

Because meroplanktonic larvae and other planktonic organisms are

carried by currents, recruitment and food supply patterns are heavily

influenced by movement of coastal water masses on- or offshore

(Farrell et al., 1991; Roughgarden et al., 1991, 1994; Gaines and

Bertness, 1992; Shanks et al., 2000; McCulloch and Shanks, 2003).

During periods of upwelling, plankton travel with water masses

moving offshore and accumulate at offshore frontal boundaries where

cold and saline upwelled water meets warmer and less saline water

(Roughgarden et al., 1994). This convergence zone can move,

depending on the winds, and can transport larvae or planktonic food

onshore during periods of relaxed upwelling (Farrell et al., 1991;

Roughgarden et al., 1991; Miller and Emlet, 1997).

The supply of larvae can have important implications in rocky

intertidal community structure (e.g. Underwood et al., 1983; Gaines

and Roughgarden, 1985; Connolly and Roughgarden, 1998; Connolly

et al., 2001). When larval supply is limited, the importance of benthic

processes is much reduced and adult macroinvertebrate abundances

are driven more by recruitment rates (Underwood et al., 1983; Gaines

and Roughgarden, 1985; Ebert and Russell, 1988; Roughgarden et al.,

1988; Farrell et al., 1991; Connolly et al., 2001). Furthermore, low

larval supply driven by coastal upwelling dynamics can influence

community composition by enhancing conditions whereby macroalgae dominate space (Schiel, 2004). When larval supply is not limited,

benthic interactions, such as competition and predation, are more

intense (Gaines and Roughgarden, 1985; Connolly and Roughgarden,

1998; Connolly et al., 2001).

Besides larval supply and recruitment, post-settlement processes

such as growth rates also can be important in structuring adult

populations of macroinvertebrates (Gaines and Roughgarden, 1985;

Bertness et al., 1991; Connolly and Roughgarden, 1998; Blanchette

et al., 2007). Variable growth rates may affect community structure

and population interactions (Bertness et al., 1991), and, in turn,

adult populations through alterations of susceptibility to physical

stress (Vermeij, 1971), predation (Paine, 1976; Robles et al., 1990), and

competition (Buss, 1986) and availability of free space (Gaines and

Roughgarden, 1985). In addition, growth rates impact the reproductive

potential of the population as reproductive output increases exponentially with size (Kautsky, 1982). Oceanographic regimes, mostly

temperature but also supply of food, can greatly influence growth

rates along local (among sites) and larger geographic scales (among

regions).

Recently, there have been a number of studies attempting to

elucidate the importance of larger scale oceanographic conditions on

mussel distributions (Broitman et al., 2005; Phillips, 2005; Blanchette

et al., 2006, 2007; Blanchette and Gaines, 2007). On Santa Cruz Island,

one of the southern California offshore Channel Islands (see Fig. 1),

the western side of the island experienced cold temperatures, a

higher frequency of upwelling, and low recruitment rates as compared to opposite patterns on the eastern side (Broitman et al., 2005).

Recruitment rates, abundances, and growth of mussels in this region

were positively associated with sea surface temperatures. Food

availability, as indicated by chl-a concentrations, were not related

(Blanchette et al., 2006). Additional studies have compared mussel

populations in the immediate area surrounding Point Conception, a

biogeographic break separating colder central California waters from

warmer southern California waters (see Fig. 1). Here, warmer southern

California waters with higher mussel abundances were found to have

higher growth rates that were related to temperature and wave exposure but, again, were not correlated with food availability (Phillips,

2005; Blanchette et al., 2007). Abundances north and south of Point

Conception were not driven by differential recruitment as recruitment

was low in the entire region (Blanchette and Gaines, 2007).

Despite numerous reports on oceanographic conditions and their

influence on mussel community dynamics, gaps in our knowledge still

exist. Much of the previously published work has concentrated on

areas immediately surrounding Point Conception in the northern

portion of the SCB by Santa Barbara and central California. Little work

has been conducted in the other portions of southern California (i.e..

Los Angeles and San Diego; see Fig. 1). In addition, few comparisons

have been conducted on recruitment and growth between the SCB

and northern California. The purpose of this study was to compare

recruitment and growth of mussels in two regions, southern and

northern California, subjected to different oceanographic patterns and

characterized by differing adult abundances. Recruitment and growth

of mussels were measured at several sites in southern and northern

California to determine geographic differences between the two

regions and at sites within southern California with differing adult

mussel characteristics to determine if there is a relationship with

adult mussel populations.

2. Methods

2.1. Site Selection

Nine sites were selected in two non-adjacent regions, northern and

southern California, separated by ca. 900 km of coastline (Fig. 1). The

SCB is characterized as a transition zone between temperate and

subtropical regimes with sea surface temperatures ranging yearly

from ~11 to 23 °C. Upwelling events in the region are infrequent and

often only occur in short time periods during the spring season (Littler,

1980; Hickey, 1993). Much of the southern California mainland coastline is protected from large swell events because of the orientation of

the coast and the presence of the Channel Islands that act as a barrier to

long-distance swell events. Northern California is subjected to much

colder waters ranging yearly from ~8 to 17 °C. Upwelling in northern

California is more intense and longer with few relaxation events

(Bakun and Nelson, 1991). Locations along the northern California

coastline are also seasonally exposed to large swell events.

Of the nine sites selected, six sites were located in the SCB and

three sites in northern California. Six sites were chosen within

southern California, a region with variable mussel abundances, with

three locations considered to have moderate to high mussel

abundances and thick beds and three with low abundances and thin

beds. In northern California, a region characterized by consistently

high mussel abundances and very thick beds, only three locations

were chosen. The scale of mussel abundances (high to low) was based

on measures of mussel bed thickness at each of the locations. Bed

166 J.R. Smith et al. / Journal of Sea Research 61 (2009) 165–173
thickness was measured at twenty random points in five 0.5 × 0.7 m

quadrats randomly placed within the middle of established mussel

beds for a total of 100 points. At each of these points, a steel pin was

pushed through the bed until it reached the understory rock and the

length measured. Mussel bed thickness was used as a proxy for mussel

abundances as it was found to be steeply and positively related with

biomass (R2 = 0.92, pb0.001) and adult density (R2 = 0.54, pb0.001;

Smith, 2005). The areal extents of the mussel beds were not measured

but are not likely good comparisons of mussel abundances across

regions or sites as mussel bed size depends on the slope and size of the

intertidal zone which can be highly variable among locations and

between regions. Instead, measures of mussel abundances within

established beds were used as considered by others (Blanchette and

Gaines, 2007). The three SCB sites considered to have low mussel

abundances were characterized with thin, single layered beds measuring 40.9 ±2.7 (mean ± SE) mm deep while the three sites considered

to have moderate/high mussel abundances were relatively thick and

multi-layered reaching 95.4 ± 10.7 mm in depth (site specific measures

Fig. 1. Map of nine sampled sites along the wave-exposed coast of California. Also indicated are the three regions of California: southern CA separated from central CA at Point

Conception and northern CA separated from central CA at Monterey.

J.R. Smith et al. / Journal of Sea Research 61 (2009) 165–173 167
in Table 1). The northern California sites were characterized by very

thick mussel beds (145.5 ±10.9 mm; Table 1).

2.2. Recruitment

At each site, 6 or 7 recruitment collectors (Tuffy brand pot

scrubbers) were bolted to the rock within mussel beds and replaced

every month for 1 year starting March 2003. Tuffies were placed in the

middle of mussel beds to standardize effective tidal heights among

sites, since mussel bed tidal height ranges may vary due to facing

slope, wave action, and other oceanographic or geologic factors. Tuffy

scrubbers have been commonly used for mussel recruitment measures (e.g. Menge, 1992; Phillips and Gaines, 2002) as they simulate

the physical structure of filamentous algae and byssal threads in

which mussel larvae normally settle (Petersen, 1984). Collected Tuffies

were returned to the lab and frozen until further analysis.

Recruitment collectors were processed by thawing the Tuffy,

rinsing with fresh water, and collecting all solid materials in a 250 μm

sieve. Recruits were counted under a dissecting microscope. In many

cases, only 3 or 4 collectors were processed per month, as variation

within a month at a site was small. In a few cases, collectors were lost,

possibly due to wave activity or human intervention, reducing the

sample size to two collectors at sites in certain months. The mean

number of recruits per collector per month was calculated for each

site. Although Mytilus recruits were not identified to species, observations of newly recruited mussels into open patches and subsequent

aging to juvenile and adult mussels suggested that only Mytilus

californianus were recruiting to the sites. The bay mussel Mytilus

galloprovincialis Lamarck, a less common species on the open coast,

has been observed to exhibit episodic recruitment to the waveexposed rocky intertidal zone (Smith per. obs.) but are easily distinguishable as juveniles. During this study, M. galloprovincialis were not

seen in mussel cohorts observed throughout the year-long experiment

and were rare in harvested samples of already established adult

mussel populations (Smith, 2005). Furthermore, previous studies on

mussel recruitment have found that more than 90% of collected

recruits are Mytilus californianus (see Blanchette and Gaines, 2007).

2.3. Growth

At each site, 80 mussels of a range of sizes (25–80 mm, but mostly

within 40–60 mm range) were haphazardly chosen and tagged in

March of 2003. Tagged mussels were located in the middle of mussel

beds to standardize effective tidal heights. Numbered wire tags were

superglued to the surface of mussels and each mussel mapped using a

grid system. For ease of sampling and to limit damage of the mussel

bed through manual movement of mussels and weakening of their

attachment strengths, only mussels on the upper surface of the bed

were marked. Although measuring growth of surface mussels may

bias results by monitoring mussels that likely exhibit the highest

growth, similar methods were used at all sites to ensure comparability. The entire length of the mussel was measured initially. An etch

mark was then made near the posterior shell edge of each mussel, and

the length from the etch mark to the posterior lip of the mussel was

measured. Similar methods of marking mussels have been used in

other growth studies (Seed, 1976; Behrens Yamada and Peters, 1988;

Behrens Yamada and Dunham, 1989; McQuaid and Lindsay, 2000;

Steffani and Branch, 2003; Blanchette et al., 2007). Every three to four

months for 1 year, the etch mark to the lip was re-measured to

monitor growth and standardized to growth per month (30 days).

Because a portion of the mussels or tags were periodically lost, new

mussels were tagged and measured approximately every three to four

months during resampling periods in order to maintain a sufficient

sample size. Despite loss of tags, data were not compromised as we

examined growth rates for the site population for each season; we did

not attempt to measure growth for the populations at each site over a

year period. Monthly mussel growth was calculated for four seasons

throughout the year-long study. Although we attempted to use the

same range of initial sizes of mussels, the size frequency of tagged

individuals varied at sites depending on the population size frequency.

In addition, the size frequency of tagged mussels also varied seasonally due to lost tags and several remarking sampling efforts. For

presentation purposes, all data are included in the figures. However,

to account for variability in the number of replicates in the small

and large size classes, we truncated our data to include only those

individuals with an initial length between 40 and 60 mm.

2.4. Analysis

Recruitment and growth data were analyzed using the Minitab

statistical program (version 13.0). Data were tested for normality and

homogeneity of variance and transformed when necessary. To test for

spatial differences in recruitment, a Nested Two Factor ANOVA was

performed with region (southern v northern California) and month as

fixed factors and sites nested within regions. The mean number of

mussel recruits collector−1 month−1 (log transformed) was calculated

for twelve months at all sites in southern California and compared

with sites in northern California. To determine if recruitment varied

among beds in southern California with differing adult mussel populations, we calculated the mean number of mussel recruits collector−1

month− 1 for twelve months at sites with mussel populations

characterized by thick beds and compared them with recruitment at

sites with thin beds. Log transformed data were analyzed using a

Nested Two Factor ANOVA with bed thickness type (thick v thin) and

month as factors and sites nested within bed thickness type.

Growth data for each individual were converted to growth (mm)

per 30 day month (mm) and tested for normality and homogeneity of

variance. To test for regional differences in growth, a Nested Two Factor

ANCOVA was used on untransformed data with region and season as

fixed factors, sites nested within regions, and initial size as a co-variate.

To determine if growth varied among locations in southern California

with differing adult populations, untransformed growth data were

analyzed using a Nested Two Factor ANCOVA with bed thickness type

and season as fixed factors, sites nested within bed thickness type, and

initial size as a covariate. In order to present the large data set in a clear

manner, several graphs were constructed indicating the regression line

of growth per month plotted against initial size. Three graphs were

constructed showing: 1) each site individually across all seasons,

2) combined southern and northern California sites for each of the four

seasons, and 3) combined locations within southern California with

thick beds/high mussel abundances and locations with thin beds/low

abundances for each of the four seasons.

We attempted to construct von Bertalanffy growth curves and

compare these slopes to determine differences among sites. However,

growth at some sites was practically absent and, with a small degree

of measuring error, some individuals exhibited negative growth. In

Table 1

Site name, abbreviation, county, and location (latitude and longitude)

Site Site code County Location Bed thickness

(mm)

Southern California

Ocean Beach OCB San Diego 32° 44′ 38′′ 117° 15′ 19′′ 35.8 (4.0)

Carlsbad CBD San Diego 33° 06′ 45′′ 117° 20′ 41′′ 88.0 (8.6)

Treasure Island TRE Orange 33° 30′ 48′′ 117° 45′ 33′′ 42.2 (3.9)

Crystal Cove CRC Orange 33° 34′ 13′′ 117° 50′ 15′′ 106.8 (8.2)

Point Fermin PTF Los Angeles 33° 42′ 26′′ 118° 17′ 09′′ 44.8 (1.8)

Tuna Canyon TUN Los Angeles 34° 02′ 20′′ 118° 41′ 17′′ 91.4 (15.5)

Northern California

Bolinas BOL Marin 37° 54′ 13′′ 122° 43′ 34′′ 125.8 (7.4)

Bodega Head BOD Sonoma 38° 18′ 58′′ 123° 04′ 19′′ 163.5 (13.9)

Sea Ranch SEA Sonoma 38° 43′ 48′′ 123° 29′ 18′′ 147.3 (12.2)

Also reported is mean site bed thickness (±SE) for all nine sites (Smith, 2005).

168 J.R. Smith et al. / Journal of Sea Research 61 (2009) 165–173
addition, because growth was extremely low, faster rates of growth in

small mussels as compared to large mussels at some sites could not be

detected. Due to these issues, growth curves could not be satisfactorily

constructed.

3. Results

3.1. Recruitment

The mean number of recruits per artificial collector over the year

sampling period was highest at Carlsbad and Tuna Canyon in the SCB

and was lowest at Bolinas and Sea Ranch in northern California (Fig. 2).

The largest number of recruits found in one collector throughout the

study was ~1550 recruits at Carlsbad in August. Sites in northern

California had consistently low recruitment while southern California

sites were highly variable. Averaging sites within a region revealed

very low monthly recruitment rates in northern California while

recruitment rates in the SCB were an order of magnitude higher

(Fig. 2). A Nested Two Factor ANOVA revealed significant differences

between regions and among sites nested in regions while a temporal

trend was not detected. A significant interaction between region and

month was found (Table 2) with weak patterns of temporal differences in some locations in the SCB, mostly driven by high rates of

recruitment at Carlsbad in late summer/early fall.

Within the SCB, two of the three sites with thick beds/high adult

abundances had much higher recruitment rates than the three sites

with thin beds/low adult abundances (Fig. 2). Here, only 9.4 ± 1.3

(mean ± SE) recruits per month per collector were counted in thin beds

as opposed to 79.1 ± 13.7 recruits per month per collector in thick beds.

In southern California, recruitment rates were significantly higher in

the sites with thick beds than those sites with thin beds with

significant differences also found among sites nested within thick or

thin beds (Nested Two-Factor ANOVA, Table 2); temporal differences

and an interaction effect were not detected.

3.2. Growth

Growth rates were low and ranged from almost no growth to

~3 mm month−1 depending on the site and initial size of the individual (Fig. 3a). Overall, mussels at Tuna Canyon grew the fastest; the

exception was small mussels at Point Fermin, which grew slightly

faster but with the rate of growth slowing markedly with larger

individuals. The lowest growth occurred at the three northern

California sites. Most sites in southern California exhibited slightly

negative growth slopes with increasing size except Point Fermin,

which exhibited a much steeper negative slope. In northern California,

slopes varied among sites but were relatively flat due to low growth

overall. Between regions, growth was significantly higher in the SCB

than in northern California with significant differences among sites

nested within regions (Fig. 3a,b; Nested Two Factor ANCOVA, Table 2).

In addition, growth rates differed significantly among seasons

(Table 2) with relatively high growth in summer and spring for both

regions and lowest growth in winter (Fig. 3b). In fall, growth rates

Fig. 2. Mean number of mussel recruits per collector per month (±SE) for six southern California sites and three northern California sites. In southern California, sites with thick

mussel beds (high abundance) are noted by black bars while gray bars note sites with thin beds. All sites within northern California had thick beds. Mean recruitment rates (±SE) are

noted for the southern and northern California regions and for thick and thin beds within southern California.

Table 2

Summary of statistical results for Two Factor ANOVAs on recruitment and Two Factor

ANCOVA on growth data

Data Factor df MS F p value

Recruitment Region 1 26.10 59.7 b0.001

Month 1 0.361 1.3 0.250

Region ×Month 1 1.68 6.2 0.013

Site (region) 7 16.20 59.7 b0.001

Thickness 1 7.46 34.7 b0.001

Month 1 0.38 1.8 0.183

Thickness ×Month 1 0.72 3.3 0.069

Site (thickness) 4 9.68 45.0 b0.001

Growth Initial size (covariate) 1 4.99 5.43 0.020

Region 1 11.12 12.2 0.001

Season 1 4.76 5.2 0.023

Region × Season 1 10.19 11.1 0.001

Site (region) 7 11.59 12.6 0.001

Initial size (covariate) 1 7.87 5.0 0.015

Thickness 1 2.39 1.8 0.178

Season 1 0.82 0.6 0.430

Thickness × Season 1 0.76 0.6 0.446

Site (thickness) 4 6.88 5.3 b0.001

Reported are degrees of freedom (df), mean squares (MS), F stat, and p values for each of

the analyzed factors. Significant p-values are indicated in bold.

J.R. Smith et al. / Journal of Sea Research 61 (2009) 165–173 169
across all sizes were higher than any other season in southern

California. In northern California, there was a positive slope causing a

significant interaction between region and season (Table 2).

Within the SCB, overall growth was generally higher in the three

locations characterized with thick beds than locations with thin beds

(Fig. 3a,c). Sites nested within bed thickness were found to be

significantly variable but no difference was found between the thin

and thick beds (Nested Two Factor ANCOVA, Table 2). In fall, growth

ranked the highest for both bed types with a pattern of small to

medium sized mussels growing faster in thin beds than thick beds

(Fig. 3c). In thick beds, there were little differences in growth or slopes

among seasons. In thin beds, however, growth rates and growth slopes

varied with season: in summer and winter, growth slopes were flat or

slightly positive while slopes in fall and spring were negative. Growth

among seasons, however, was not found to differ significantly nor was

an interaction found between bed type and season (Table 2).

4. Discussion

Recruitment and growth were important factors affecting the

distribution of mussels within the southern California Bight (SCB) but

could not explain patterns along the entire California coast. Higher

recruitment and growth in mussel populations in the SCB characterized by low to moderately high adult abundances were contrasted

with low recruitment and growth in northern California, a region

with markedly higher adult abundances. Within the SCB, recruitment

and growth were related to the level of adult abundances as locations

with thick beds (higher adult mussel abundances) had higher

recruitment and growth rates than locations with thin beds (lower

abundances). Geographic trends in recruitment and growth across a

large geographic scale that differ oceanographically suggest that

different processes affected mussel populations within the two

regions.

Fig. 3. Slope of growth of marked mussels (mm per month) versus initial size (mm) for a) all nine sites sampled combining all seasons, b) southern California sites combined and

northern California sites combined during the four sampled seasons (F03 = Fall 2003; SU03 = Summer 2003; SP03 = Spring 2003; and W04 =Winter 2004), and c) southern California

sites with locations characterized by thick mussel beds (=high mussel abundance) combined and thin mussel beds (=low mussel abundance) combined during the four sampled

seasons. Site abbreviations are located in Table 1. Length of slopes are artificially extended or cut-off at 80 mm. The shaded region indicates the size class that was used for statistical

analyses (see Methods).

170 J.R. Smith et al. / Journal of Sea Research 61 (2009) 165–173
4.1. Recruitment

Larval transport and recruitment are known to be heavily

influenced by oceanographic processes. Coastal circulation promotes

transport of larvae to the shore in some areas, such as Oregon, while

in other areas, such as northern and central California, frequent

upwelling events transport larvae offshore (Roughgarden et al., 1988,

Connolly and Roughgarden, 1998). Recruitment at sites in northern

California was consistent with patterns produced by strong upwelling

and offshore transport of larvae. Results suggest, in accordance with

other studies (e.g. Broitman et al., 2005, 2008), that mussels are

potentially limited where upwelling is frequent. In the SCB, however,

upwelling is generally weak and sporadic (Hickey, 1993). The

oceanographic regime in the SCB may be facilitating larval transport

and higher recruitment to rocky intertidal habitats in the region. Ebert

et al. (1994) reported higher recruitment of urchins in southern

California compared to northern California and suggested that the

pattern was likely due to greater retention of water in the SCB.

Recruitment rates of Mytilus at many of our southern California

locations were similarly low to other locations in the region

(Blanchette and Gaines, 2007; Broitman et al., 2008). These locations,

although with higher recruitment rates than northern California, were

several magnitudes lower than observed in Oregon, a region with

intermittent upwelling (Broitman et al., 2008). However, contrasting

other SCB recruitment studies, we found two locations in the central

portion of the bight where recruitment was relatively high. On

occasion, recruitment rates at Carlsbad were extremely high with

levels similar to that of Oregon. This high variability in the region

denotes the need for long term recruitment monitoring studies to

include more location into the southern and central portions of the

SCB.

The factors leading to high recruitment at some sites within the

SCB need to be further investigated. It is unlikely that the adult population is regulating the number of recruits through local recruitment

from the resident population, as Mytilus californianus has exhibited no

difference in large-scale proportions of genetic types, suggesting that

gene flow occurs along the coastline and that mussel larvae disperse

long distances (Engel, 2004). Alternatively, very nearshore oceanographic processes at each of the sites may explain differences in

recruitment rates. Several processes on a local level may affect larval

supply including internal waves, surface slicks and foam lines,

and Langmuir flow (Shanks, 1983, 1995; Kingsford and Choat, 1986;

Shanks and Wright, 1987; Kingsford, 1990; Kingsford et al., 1991;

McCulloch and Shanks, 2003; Shanks et al., 2003). For example, at

sites with low recruitment, local currents may transport incoming

larvae seaward or topographically generated fronts may act as a

barrier to larvae reaching the shore (McCulloch and Shanks, 2003).

Similarly, local currents or topography may facilitate high recruitment

by transporting larvae inshore. Several studies (Shanks, 1983, 1986;

Kingsford and Choat, 1986; Kingsford et al., 1991) have reported

that some larvae of coastal invertebrates and fishes are transported

shoreward in surface slicks generated over tidally forced internal

waves. Some meroplanktonic larvae can also behaviorally utilize

vertically sheared flows to aid shoreward progression (Garland et al.,

2002). For example, offshore larvae from benthic populations can be

carried toward the coast during periods of upwelling as bottom water

flows towards the shoreline (Garland et al., 2002). Other invertebrate

larvae may be retained between the shore and an upwelling front due

to diel vertical migrations (Poulin et al., 2002). Understanding local

variations in recruitment of invertebrates with broadly dispersing

larvae and the processes affecting these variations can aid in understanding how to manage and conserve at-risk populations. This is

especially important for mussels in southern California where populations have declined over the past few decades (Smith et al., 2006).

Without knowledge of specific local oceanography at our sites, it

is difficult to ascertain reason for differing recruitment rates. Recruitment rates differed greatly at sites in close proximity (i.e.., Tuna

Canyon and Point Fermin) with no obvious geomorphological differences that could affect oceanographic patterns. However, it is

interesting to note that Carlsbad, the site with highest recruitment,

is located near the mouth of Agua Hedionda Lagoon. Here, local

oceanography may be influenced by the lagoon and may result in

larval transport onshore. Studies investigating river plume and

estuarine front dynamics suggest that buoyant coastal discharges

may induce coastal currents locally, causing a frontal circulation at the

mouth that acts as a barrier to larvae dispersal (Kingsford and Suther,

1994; Vargas et al., 2006). Here, accumulation of larvae at the front

edge may facilitate transport to some locations nearby (Eggleston

et al., 1998; Vargas et al., 2006) as the plume circles back around near

the coastline. Although flow out of Agua Hedionda is likely low, a front

may occur near the mouth where mussel larvae may accumulate and

then be transported back to shore during relaxation of estuarine

driven fronts (Eggleston et al., 1998) or when strong tidal movements

move the front shoreward.

It is clear from other work (Broitman et al., 2008) that there is some

level of year-to-year variation in recruitment rates possibly due to

temporal variation in upwelling frequency and longevity. Our study

monitored recruitment over a year period and thus did not detect

longer term temporal change. Nonetheless, the regional patterns we

detected are unlikely to change over time as geographic recruitment

patterns appear consistent over multiple years (Broitman et al., 2008).

Here, above and below normal levels of recruitment during certain

years of recruitment monitoring along the eastern north Pacific coast

appeared consistent among regions.

4.2. Growth

Growth of mussels, like recruitment, showed geographical variations with southern California exhibiting higher growth than northern

California. Geographical differences in growth rates likely reflect differences in temperature between the two regions. Phillips (2005) and

Blanchette et al. (2007) suggested that observed differences in growth

between sites north and south of Point Conception were likely

attributable to temperature differences. Within southern California,

growth rates of mussels and barnacles were found to be positively

correlated with SST (Blanchette et al., 2006) when comparing growth

at sites on a southern California offshore Channel Island subjected to a

persistent thermal gradient on opposite sides of the island. Mussels

are known to grow rapidly in temperature between 15 and 19 °C, with

decreases in growth observed in temperatures above and below that

range (Coe and Fox, 1942, 1944). At the southern California sites, mean

annual temperatures (1995–2003; Advanced Very High Resolution

Radiometer) among sites ranged from 16 to 17 °C, within the range of

highest mussel growth, while yearly mean temperatures at our

northern sites were approximately 12 °C, well below the range of

optimal growth.

Food availability can also be a factor influencing mussel growth as

filter feeders are known to exhibit higher growth in areas with higher

food availability (e.g. Duggins et al., 1989; Bertness et al., 1991;

Dahlhoff and Menge, 1996; Menge et al., 1997; Sanford and Menge,

2001). However, recent work has suggested that other factors may be

determining growth rates, either separately or in conjunction with

productivity (Sanford and Menge, 2001; Phillips, 2005; Blanchette

et al., 2006). Numerous studies have reported that growth of mussels

and other filter feeders north and south of Point Conception was

not explained by food availability or food quality (Phillips, 2005;

Blanchette et al., 2006, 2007). They suggested that temperature likely

played a more significant role in determining growth. Measures of

food availability were beyond the scope of this study thus we cannot

expand on the effects on growth at our sites.

Unlike regional differences, variation in growth in southern

California could not be attributed to temperature, since all sites

J.R. Smith et al. / Journal of Sea Research 61 (2009) 165–173 171
within the SCB fell within the temperature range of highest growth

(Coe and Fox, 1942, 1944). Furthermore, sites with low growth were in

close proximity (b50 km) to sites with high growth and thus had very

similar seawater temperatures. Although Blanchette et al. (2006)

attributed differences in growth between locations in close proximity

within southern California to temperature, they conducted work on an

offshore island subjected to quite different thermal regimes on

opposite sides of the island.

Alternative to temperature causing variability in growth rates

within southern California, potential factors such as food availability

and wave activity may be important local factors/drivers. First,

although cholorophyll a, an indicator of food availability, was consistently low throughout the SCB using satellite data from large areas

(40 ×50 km — meridional ×zonal; Smith, 2005 also supported by

nearshore measurements by Blanchette et al., 2007), local scale

dynamics may result in increased food availability at certain locations

that may not be detectable in larger scale measures of productivity.

For example, terrestrial runoff discharging into a particular site may

result in elevated nutrient levels and thus increased productivity.

Although runoff was not prominent at most sites, Carlsbad, the site

with the highest growth, is located near the Agua Hedionda Lagoon

outlet that may serve as a source of nutrients and/or food. Wave

activity may also play a role in determining growth at these sites and

has been correlated with higher growth rates at other SCB locations

(Blanchette et al., 2007). Although not directly measured, repeated

observations of wave activity at sampled sites suggest that Carlsbad is

the most wave-exposed followed by Treasure Island and Tuna Canyon;

Carlsbad and Tuna Canyon are two of three sites with high mussel

abundances and high growth. Finally, local currents may bring offshore productivity to nearshore areas leading to increased food

availability as well as an increase in larval supply leading to concurrent

high recruitment rates.

4.3. Conclusions

In the SCB, recruitment and growth were higher yet adult mussel

abundances, even at sites with thick beds, were lower than in northern

California. Differences in adult populations may be attributed to differences in mortality rates, with mussels in northern California having

higher survival rates. Previous work has found regional differences in

population size structures with a higher frequency of larger mussels

found in northern California (Smith, 2005). In conjunction with

low growth, mussels in northern California are likely much older

than those in southern California. Therefore, mussel beds in northern

California likely persist for a longer period of time. Southern California,

on the other hand, may have higher mortality and turnover rates due to

post-recruitment processes. Interestingly, the two sites with the

highest recruitment and growth, Carlsbad and Tuna Canyon, qualitatively appeared to have the highest mortality rates, as indicated by

observations of newly opened gaps during repeated visits (Smith pers.

obs.). Furthermore, tagged mussels were more frequently lost at

the sites within southern California while many tagged mussels in

northern California remained for the year-long sampling period.

However, it is unclear whether tagged mussels were lost due to

mortality or due to loss of the tags themselves.

Recruitment and growth exhibited regional differences with both

measures being important factors in driving adult populations in

southern California but not in northern California. The importance of

the linkage between recruitment and growth and adult populations is

supported by Blanchette et al. (2006) who also found that these

measures on an offshore Channel Island in the SCB were higher at sites

with higher mussel cover. Contrastingly, spatial patterns of mussel

abundances were not correlated with recruitment at a number of sites

just north and south of Point Conception. These contrasting reports

highlight the need for further studies to understand the scale of these

driving factors.

Within southern California, and sometimes in close proximity

(b50 km), recruitment and growth can be highly variable. Understanding local physical mechanisms underlying larval transport and

growth will lead to a better understanding of adult populations and

potential management of coastal species, especially those important

to fisheries and local economy.

Acknowledgements

We are thankful to the Environmental Protection Agency, the

Minerals Management Service through the Coastal Marine Institute at

the University of California, Santa Barbara, and the UCLA Ecology and

Evolutionary Biology Department for their assistance in funding this

project. We also thank several assistants in the processing of recruitment sampling including David Lin, Koosha Aghajani, Chia Lin,

Danielle Whitehead, and Vanessa Gonzalez. We are grateful to several

sources for permission and access to sites including Peter Connors and

the UC Davis Bodega Marine Lab; Linda Weinstein and the Sea Ranch

Association; Pamela Higgins and the Carlsbad State Beach; and David

Pryor and the Crystal Cove State Beach. We also thank Carol Blanchette

for the suggestions and input into the manuscript.

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