OCS Study

MMS 2001-091

Deepwater Program:

Northern Gulf of Mexico Continental

Slope Habitats and Benthic Ecology

Year I: Interim Report

MMS U.S. Department of the Interior

Minerals Management Service

Gulf of Mexico OCS Region
OCS Study

MMS 2001-091

Deepwater Program:

Northern Gulf of Mexico Continental

Slope Habitats and Benthic Ecology

Year I: Interim Report

Authors

Gilbert T. Rowe

Mahlon C. Kennicutt II

Prepared under MMS Contract

1435-01-99-CT-30991

by

Texas A&M University

Texas Engineering Experiment Station

College Station, Texas 77843-3146

Published by

U.S. Department of the Interior

Minerals Management Service

Gulf of Mexico OCS Region

New Orleans

October 2001
iii

DISCLAIMER

This report was prepared under contract between the Minerals Management Service (MMS) and

Texas A&M University. This report has been technically reviewed by the MMS and approved

for publication. Approval does not signify that the contents necessarily reflect the views and

policies of the Service, nor does mention of trade names of commercial products constitute

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

with MMS editorial standards.

REPORT AVAILABILITY

Extra copies of the report may be obtained from the Public Information Office (Mail Stop 5034)

at the following address:

U.S. Department of the Interior

Minerals Management Service

Gulf of Mexico OCS Region

Public Information Office (MS 5034)

1201 Elmwood Park Boulevard

New Orleans, Louisiana 70123-2394

Telephone Number: (504) 736-2519

1-800-200-GULF

CITATION

Suggested Citation:

Rowe, G.T. and M.C. Kennicutt II. 2001. Deepwater Program: Northern Gulf of Mexico

Continental Slope Habitat and Benthic Ecology. Year I Interim Report. OCS Study MMS

2001-091. U.S. Department of the Interior, Minerals Management Service, Gulf of

Mexico OCS Region, New Orleans, Louisiana. 166 pp.
v

TABLE OF CONTENTS

PAGE

List of Figures............................................................................................................ ix

List of Tables ............................................................................................................. xi

Executive Summary................................................................................................... 1

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

1.1 Program Objectives........................................................................................ 1-3

1.2 The Program................................................................................................... 1-5

2.0 State of the Knowledge.............................................................................................. 2-1

2.1 General Deep-Sea Ecology............................................................................ 2-1

2.2 The Deep-Sea GOM - Geologic Setting ........................................................ 2-4

2.3 The Geochemistry of Deep-Sea Sediments ................................................... 2-5

2.4 Physical Oceanography of the GOM ............................................................. 2-6

2.5 Deep-Sea Ecology of the GOM ..................................................................... 2-8

3.0 A Conceptual Model of the Deep-Sea ....................................................................... 3-1

3.1 Biotic Variables ............................................................................................. 3-3

3.2 Community Structure..................................................................................... 3-5

3.3 Community Function ..................................................................................... 3-6

3.4 Sediment Properties ....................................................................................... 3-7

3.5 Water Column Properties............................................................................... 3-10

3.6 Community “Health” ..................................................................................... 3-10

4.0 Sampling Design........................................................................................................ 4-1

4.1 General Design Considerations ..................................................................... 4-1

4.2 Working Hypotheses and Station Selection................................................... 4-2

4.3 Dependent and Independent Variables .......................................................... 4-10

4.4 Statistical Analyses........................................................................................ 4-11

4.4.1 Univariate Analyses........................................................................... 4-11

4.4.2 Power Analysis .................................................................................. 4-16

4.4.3 Multivariate Analyses........................................................................ 4-16

4.5 Revision of Taxonomic Level of Analysis .................................................... 4-17

5.0 The Field Program ..................................................................................................... 5-1

5.1 The Ship......................................................................................................... 5-1
vi

5.2 Cruise I - Survey ............................................................................................ 5-2

5.3 Cruise II - Processes ...................................................................................... 5-2

5.4 Third Year Field Activities............................................................................ 5-6

6.0 Field Methods ............................................................................................................ 6-1

6.1 Standard Sampling Techniques ..................................................................... 6-1

6.1.1 Boxcoring........................................................................................... 6-1

6.1.2 Trawling............................................................................................. 6-1

6.1.3 Photo-Apparatus ................................................................................ 6-3

6.1.4 Water Column Profiles ...................................................................... 6-3

6.2 Community Structure..................................................................................... 6-5

6.2.1 Bacteria .............................................................................................. 6-5

6.2.2 Protozoa (Foraminifera)..................................................................... 6-5

6.2.3 Meiofauna .......................................................................................... 6-5

6.2.4 Macrofauna ........................................................................................ 6-8

6.2.5 Megafauna and Fishes ....................................................................... 6-8

6.2.5.1 Trawl Samples .................................................................... 6-8

6.2.5.2 Photosurveys....................................................................... 6-8

6.3 Community Function ..................................................................................... 6-9

6.3.1 Microbial Metabolism........................................................................ 6-9

6.3.2 Sediment Community Oxygen Demand ............................................ 6-10

6.3.3 Foodweb Studies - Stable Isotopes .................................................... 6-11

6.4 Sediment Properties ....................................................................................... 6-11

6.5 Chemical Contaminants................................................................................. 6-11

6.6 Geochemistry ................................................................................................. 6-11

7.0 Laboratory Methods................................................................................................... 7-1

7.1 Taxonomy ...................................................................................................... 7-1

7.2 Community Structure..................................................................................... 7-3

7.2.1 Bacteria .............................................................................................. 7-3

7.2.2 Foraminifera....................................................................................... 7-4

7.2.3 Meiofauna .......................................................................................... 7-4

7.2.4 Macrofauna ........................................................................................ 7-5

7.2.5 Megafauna and Fishes ....................................................................... 7-5

7.3 Community Function (Process Studies) ........................................................ 7-5

7.3.1 Bacterial Metabolism......................................................................... 7-6
vii

7.3.2 Meiofaunal Feeding Rates ................................................................. 7-6

7.3.3 Sediment Community Respiration..................................................... 7-6

7.3.4 Foodweb Analyses - Stable Isotopes ................................................. 7-6

7.4 Sediment Properties ....................................................................................... 7-7

7.4.1 Grain Size .......................................................................................... 7-7

7.4.2 Geotechnical Properties ..................................................................... 7-7

7.4.3 Total Organic and Inorganic Carbon ................................................. 7-7

7.5 Chemical Contaminants................................................................................. 7-8

7.5.1 Hydrocarbons..................................................................................... 7-8

7.5.2 Trace Metals ...................................................................................... 7-8

7.6 Geochemical Properties ................................................................................. 7-9

7.7 Water Column Profiles .................................................................................. 7-12

7.8 Archival of Specimens................................................................................... 7-12

8.0 Status of DGoMB Program........................................................................................ 8-1

8.1 Task 1 - Re-Examination of Previous Studies ............................................... 8-1

8.2 Task 2 - Field Sampling................................................................................. 8-1

8.3 Task 3 - Sample Data Processing and Analysis............................................. 8-2

8.3.1 Physical Oceanography...................................................................... 8-2

8.3.2 Geology.............................................................................................. 8-3

8.3.3 Geochemistry and Contaminants ....................................................... 8-11

8.3.4 Biological Studies .............................................................................. 8-12

8.4 Task 4 - Data Interpretation, Synthesis, and Reporting................................. 8-13

8.4.1 Community Structure......................................................................... 8-13

8.4.2 Community Function ......................................................................... 8-16

8.4.3 Sediment Properties ........................................................................... 8-16

8.4.4 Water Column Chemistry and Oceanography ................................... 8-18

8.4.5 Ecosystem “Health”........................................................................... 8-18

8.4.6 Data Fusion and GIS.......................................................................... 8-19

8.5 Data Management .......................................................................................... 8-20

8.6 Meetings, Interpretation, and Reporting........................................................ 8-20

8.6.1 Planning ............................................................................................. 8-22

8.6.2 Field Program, R/V Gyre, June 1-20, 2001........................................ 8-23

9.0 Literature Cited.......................................................................................................... 9-1

Appendix I - Cruise I Report ..................................................................................... AI-1
viii

Appendix II - “The Edge of the Gulf Cruise, 16-31 October 2000” ......................... AII-1
ix

LIST OF FIGURES

PAGE

Figure 1. A general model of a sediment-associated food-web ....................................... 3

Figure 3.1 Preliminary conceptual model of the deep-sea Gulf of Mexico ....................... 3-2

Figure 3.2 Macrofauna submodel of system carbon food chain model ............................. 3-3

Figure 3.3 Sediment submodel of functional bacterial groups as defined by

utilization of different terminal electron acceptors........................................... 3-9

Figure 4.1 Benthic survey stations in the northwestern GOM........................................... 4-4

Figure 4.2 Benthic survey stations across the Florida Escarpment.................................... 4-5

Figure 4.3 Benthic stations along the Mississippi Trough................................................. 4-6

Figure 4.4 Physiographic settings for benthic survey stations in the Central GOM.......... 4-7

Figure 5.1 Benthic survey stations for Cruise I, May and June, 2000 ............................... 5-3

Figure 5.2 Sampling sites during Cruise II, the first “processes” cruise,

June 1-19, 2001................................................................................................. 5-5

Figure 5.3 Proposed locations for two remaining cruises into the Mexican EEZ, June

and August 2002 ............................................................................................... 5-7

Figure 6.1 Schematic of quantitative boxcore station activities and sampling

protocols............................................................................................................ 6-2

Figure 6.2 Schematic of trawl station activities and sampling protocols........................... 6-4

Figure 6.3 Vertical distribution of meiofauna taxa for Cruise I......................................... 6-7

Figure 6.4 Benthic lander ................................................................................................... 6-10

Figure 8.1 Frozen versus fresh nutrient concentrations from station 32 on

NEGOM cruise N8 ........................................................................................... 8-5

Figure 8.2 Frozen versus fresh nutrient concentrations from station 33 on

NEGOM cruise N8 ........................................................................................... 8-6

Figure 8.3 Sea surface height field for 14 May 2000 based on analyzed height

anomaly of TOPEX and ERS-2 altimeter data added to mean sea

surface height field............................................................................................ 8-7
x

Figure 8.4 Broad-band 150 kHz ADCP current vectors at average depth of 12.4 m

on DGoMB leg 1 Cruise, 3-23 May 2000 ........................................................ 8-8

Figure 8.5 Sea surface height field for 10 June 2000 based on analyzed height

anomaly of TOPEX and ERS-2 altimeter data added to mean sea

surface height field............................................................................................ 8-9

Figure 8.6 Narrow-band 150 kHz ADCP current vectors at average depth

of 11.6 m on DGoMB leg 2 Cruise, 21 May - 21 June 2000............................ 8-10

Figure 8.7 Negative sulfate anomaly as a function of water depth in the pore of the

top 5 cm of a core from each sampling site ...................................................... 8-11
xi

LIST OF TABLES

PAGE

Table 1.1 Program Team - Key Personnel........................................................................ 1-4

Table 2.1 GOM water masses with associated property extrema and potential

densities ............................................................................................................ 2-7

Table 4.1 Summary of benthic survey experimental design: null hypotheses,

station selection criteria, number (No.) of stations (sta.), and number

samples.............................................................................................................. 4-9

Table 4.2 Independent variables fixed by the sampling plan design ................................ 4-12

Table 4.3 Dependent variables to be measured ................................................................ 4-12

Table 4.4 Ancillary variables to be measured at Survey and Experimental

Stations.............................................................................................................. 4-13

Table 5.1 Summary of sampling conducted during Cruise I ............................................ 5-4

Table 6.1 Effect of core tubes size (inner diameter) on meiofauna counts and

average density ................................................................................................. 6-6

Table 7.1 Taxonomists involved in the analysis of macrofauna and corresponding

taxonomists working on UNAM Mexican national collections ....................... 7-2

Table 7.2 Summary of parameters to be analyzed and the methods to be used................ 7-10

Table 7.3 Chemical parameters to be analyzed ................................................................ 7-10

Table 8.1 Sample inventory for Cruise I (survey) ............................................................ 8-4

Table 8.2 Data collection summary and tracking ............................................................. 8-21

Table 8.3 General biological field collection form........................................................... 8-22
1

EXECUTIVE SUMMARY

A research program has been initiated by the Minerals Management Service (Contract

No. 1435-01-99-CT-30991) to gain better knowledge of the benthic communities of the deep

Gulf of Mexico entitled “The Deepwater Program: Northern Gulf of Mexico Continental Slope

Habitat and Benthic Ecology.” This report describes the program and provides a summary of the

progress to date at the end of the first year of the program. At this early stage in the program,

sample analyses are still in progress with little or no data finalized. The program is on schedule

and planning has been completed for the second year’s field program.

Increasing exploration and exploitation of fossil hydrocarbon resources in the deep-sea

prompted the Minerals Management Service of the U.S. Department of the Interior to support an

investigation of the structure and function of the assemblages of organisms that live in

association with the sea floor in the deep-sea. The program, Deep Gulf of Mexico Benthos or

DGoMB, is studying the northern Gulf of Mexico (GOM) continental slope from water depths of

300 meters on the upper continental slope out to greater than 3,000 meters water depth seaward

of the base of the Sigsbee and Florida Escarpments. The study is focused on areas that are the

most likely targets of future resource exploration and exploitation. However, to develop a Gulfwide perspective of deep-sea communities, sampling in areas beyond those thought to be

potential areas for exploration has been included in the study design.

The program is designed to gain a better ability to predict variations in the structure and

function of animal assemblages in relation to water depth, geographic location, time and

overlying water mass. Biological studies are integrated with measurements of physical and

chemical hydrographic parameters, sediment geochemical properties and geological

characteristics that are known to influence benthic community distributions and dynamics. Eight

(8) hypotheses are being tested on the basis of measures of benthic community structure. It is

hypothesized that community structure varies as a function of:

1) water depth,

2) geographic location (east vs. west),

3) association with canyons,

4) association with mid-slope basins,

5) sea surface primary productivity,

6) proximity to hydrocarbon seeps,

7) time (seasonal and interannual scales), and

8) association with the base of escarpments.

Measures of community structure used to test the hypotheses are variations in diversity,

similarities in assemblage composition (at the species level), variations in biomass and

abundance, and the mean size of individuals within specific size categories.

The underlying premise of the hypotheses to be tested is that deep-sea communities are

food limited. This premise leads to the hypothesis that variations in community structure in time

and space are a function of the input of food to the seafloor. In other words, community

dynamics and structure are dependent on the availability and quality of food resources. Corollary

hypotheses test the possibility that each independent variable is related in some way to how

organic matter from a variety of potential sources is utilized by the benthic community.
2

After defining community structure, the next set of objectives use this information to

infer the flux of organic carbon into and through the ecosystem. The conceptual model assumes

that community structure and function are tightly coupled. Presently there is little reason to reject

this generalization, but direct evidence for it in the deep-sea is at best fragmentary.

The conceptual model represents each of the principal size categories of the living

components as standing stocks at each study site in the survey. The model includes demersal

fishes, megafauna, scavengers, macrofauna, meiofauna, and heterotrophic bacteria. This model

(Figure 1), of a sediment-associated food web, can be coupled with a model of fossil

hydrocarbon utilization by chemoautotrophic organisms including large invertebrates that house

endosymbionts. This linkage is yet to be explicitly established and is the basis for one of the

hypotheses being tested. The boxes in the model represent standing stocks which have units of

biomass (organic carbon per unit area) whereas the arrows represent flux between boxes and

hence have units of organic carbon per unit area per unit time. For consistency, the units are mg

C m-2 and mg C m-2 day-1. Data from the survey portion of the program quantifies standing

stocks across the survey area. Respiration rates are estimated on the basis of organism size and

temperature from established relationships in the published literature. The fluxes represent

transfers between components and are calculated by difference to balance respiratory losses at

steady state. Burial loss of carbon is organic carbon (detrital) concentration times sediment

accumulation rate. Input to the bottom is assumed to be equal to the sum of the respiration and

burial losses at steady state.

The second phase of the project is designed to test the model. Direct measurements will

be made of fluxes. This will be carried out by two field programs in June of 2001 and 2002.

Total sediment community respiration will be determined using a benthic lander and incubation

chambers. Total respiration will be partitioned by measuring bacterial activity in pressure

chamber incubations at in situ temperatures. Uptake and respiration will be determined using

mixed amino acids labeled with radiocarbon. Sulfate reduction will be measured using radiolabeled sulfate incubation of samples from sediment cores. Lander/chamber fluxes that are to be

measured include oxygen, dissolved inorganic carbon, inorganic nitrogen, phosphate, and

silicate. Scavenger domains of occupation will be estimated using baited traps, time-lapse

cameras and an ADCP to estimate vertical and horizontal eddy mixing and mean current

direction. Stable isotopes of carbon and nitrogen will be used to determine the food chain’s

structure and linkages. Physical and biological mixing will be estimated using a suite of natural

radionuclides characterized by an appropriate range of decay rates. Data from the second field

year will be used to adjust model parameters. The location of the experimental sites will be

evaluated according to the model, sampling results, and on-going testing of programmatic

hypotheses. Experiments during the third field year will be designed to further validate the

revised model rates and parameters. Sampling sites will be selected as needed to improve the

resolution of the models and advance the testing of the hypotheses.
3































































































DEADFALLS RAIN OF POC

SARGASSUM

ADVECTED POC

CARCASSES SEDIMENT 

ORGANICS

FISH SCAVENGERS

HETEROTROPHIC 

MICROBIOTA

MEGAFAUNA

MEIOFAUNA

MACROFAUNA

SEEP FAUNA 

AND 

SYMBIONTS

CHEMOTROPHS

FOSSIL 

HYDROCARBONS

METHANE

SULFIDE

METHANE

? ?

Figure 1. A general model of a sediment-associated food-web.
1-1

1.0 INTRODUCTION

The topography, geology, geophysics, currents, hydrography, chemistry and biota of the

continental slope are much less well known than those of the continental shelf. The earliest

information on the deep-sea biota of the Gulf of Mexico come from studies that used benthic

trawling and photography (TerEco 1976, 1983). The largest study, The Northern Gulf of Mexico

Continental Slope Study (NGOMCS), concentrated on geologic features, water circulation,

chemistry, and biological communities (LGL and TAMU 1988). New scientific findings in the

area, including chemosynthetic communities and a better understanding of the geological

complexity of the region, have significantly altered our view of the northern GOM deep-sea

(MacDonald 1998; MacDonald et al. 1996). Rapid expansion of energy industry activities into

the deep-sea has occurred over the past decade. It is expected that this trend will continue and

that deep-sea regions of the northern GOM will be the site of energy exploration and

development activities for decades to come.

An MMS workshop report on the deepwater GOM concluded that there was a need for

additional information on the composition and structure of benthic communities, the associated

biogeochemical processes, habitat heterogeneity and physiography, trophic interactions, and the

biological “health” of the region (Carney 1998). The deep-sea is a setting within which benthic

communities survive and propagate in the northern GOM. The deep-sea is characterized by total

darkness, low temperature, nearly featureless mud, sparse food resources, predictable biomass

patterns, unusual diversity patterns, and poorly defined couplings to topography,

biogeochemistry, and currents.

The DGoMB program will provide a better understanding of:

1) the present condition of biological communities in the study area,

2) the distribution patterns of deep-sea biota,

3) the biological and physical processes that control the environmental setting, and

4) the effects that these processes have on the character of benthic and

benthopelagic communities.

The program emphasizes understanding the make-up and variability of soft-bottom

biological communities with a secondary effort to characterize the important biological and

abiotic processes that sustain or change the observed patterns. The study will:

1) detail the composition and structure of slope biological communities,

2) infer the relationship between these communities and local conditions and

forcing factors,

3) characterize the “health” and functioning of deep-sea communities, and

4) compare and contrast the GOM region with similar oceanic basins.

The DGoMB program design was developed based on historical knowledge of deep-sea

communities in the GOM. The interdisciplinary nature of the scientific objectives was

recognized and the study design balances the benthic survey aspects of the program with

experimental (or “process”) oriented studies needed to understand the deep-sea community’s

structure and function. A careful analysis of previous information was used to focus the study on
1-2

the most relevant areas and those areas which will provide the greatest likelihood of establishing

generalities about the structure and function of deep-sea benthic communities. The program will

provide a predictive capability for areas not directly sampled or observed. This predictive

capability is a framework for ascertaining the potential for, and the most likely impact from,

fossil fuel exploration and exploitation in the deep-sea.

Each work element is nested in an integrated design that links data collection to a

coherent framework that provides maximum complementary information based on a detailed

model of the system. Survey station results were used to choose experimental stations.

Experimental stations will be a subset of reoccupied survey stations tightly linking all

observations and data in space and time. Each measurement is taken to provide quantitative

estimates of unknown elements of the model, to improve the quantitative accuracy of the

elements of the models, and/or to test and refine the underlying assumptions of the model.

A review of previous studies, particularly the NGOMCS slope study provided valuable

insights for designing the new study (LGL and TAMU 1988). The program design incorporated

the following strategic conclusions:

1. An equal sampling effort must be concentrated at different water

depths to determine if “zones” exist. Site selection emphasized equally

spaced depth intervals and replication at the treatment level (sites that are

mostly similar except for depth) recognizing that gradients in ecosystem

properties are more likely than “zones”.

2. Depth dependence in community structure and composition must be

evaluated in the context of other recently recognized confounding

factors such as seafloor topography, and currents.

3. Sampling sites must be chosen based on characteristics believed to be

important in establishing biological patterns such as detrital flux to the

seafloor as influenced by near surface patterns of primary productivity.

4. Proximity to the Mississippi River and Fan is an important spatial

consideration.

5. Benthic communities are nestled in different topographic and

sedimentologic settings that are influenced by slope failure and varying

inputs of terrigenous materials.

6. Sampling sites must be selected to compare benthic communities

associated with known physical features such as the thermohalocline, the

oxygen minimum, and high current regimes.

7. The program is designed to provide flexibility by revising and

rethinking the underlying strategy and design on a regular basis in

response to collection of new data and re-evaluation of historical data.
1-3

8. Temporal variations in community structure and composition are

important and can be quantified by reoccupying historical sites and

visiting a subset of sites during each of the three planned field

programs.

9. An improved understanding of community structure and composition

requires better and more refined measurements of biomass for input

into the conceptual model.

10. Improved estimates of the megafaunal role in the ecosystem are

important and include a three pronged approach to surveys: trawling (with

improved quantitative methodologies), photosurveys, and baited traps.

11. The number of sites sampled and the intensity of sampling must be

increased over the previous studies.

12. Replication and the size of the sample must be increased over the

previous studies to ensure that the total number of animals collected

adequately samples the diversity of the communities being studied.

13. The data must be meticulously managed so that it will be readily

available for future reassessment as our understanding of the deep-sea

evolves (this includes the use of standard and accepted methods in all

aspects of the program and placement of data in a GIS framework).

The program will receive added value by its close linkages with previous and on-going

MMS efforts in the GOM. Many members of the Team are participating in ongoing programs

such as the deep water literature survey and review, the northeastern GOM hydrography and

chemical oceanography program, the deep water physical oceanography re-analysis program, the

Mississippi-Alabama pinnacles program, and chemosynthetic community studies (Table 1.1).

The methods and approaches adopted for this program are the same, or compatible with, the

methods of these other corollary programs allowing for seamless integration of new results with

the results of other programs in the final synthesis. This will result in a holistic evaluation of the

GOM deep-sea benthos and the linkages between abiotic and biotic processes that control the

complex ecological patterns of the deep-sea benthos.

1.1 Program Objectives

The structure and function of deep-sea benthic communities is the end-result of complex

interactions between and among the biota and the topography, geology, currents, hydrography,

chemistry, and physical setting. The NGOMCS study was an attempt to describe the geology,

water circulation, chemistry, and biologic communities on the vast northern GOM continental

slope region (LGL and TAMU 1988). The current project is intended to build on, improve, and

supplement this pioneering study. A reassessment of continental slope ecosystems, in the context

of intensive oil and gas exploration and exploitation in the region, is considered essential for the

management and protection of biological resources in the deep-sea.
1-4

Table 1.1 Program Team - Key Personnel*

Name Discipline Role Institution

• Gilbert T. Rowe • Deep-sea Benthic

Ecology

• Project Manager • Texas A&M University

• Principal Scientist

• Chief Scientist

• Group Leader-Deep-sea

Ecology

• Mahlon C. Kennicutt II • Environmental • Deputy Program Manager • Texas A&M University

Chemist Contaminant Chemist

• Gary A. Wolff • Data Management • Data Manager • Texas A&M University

• Jody Deming • Microbiology • Co-PI Ecology • University of Washington

• Paul Montagna • Benthic Ecologist • Co-PI Ecology • University of Texas

• Study Design

• Richard Haedrich • Bottom Fishes • Co-PI Ecology • Memorial University

• Megafauna • Data Analysis

• Richard Heard • Macrofauna Taxonomy • Co-PI Ecology • University of Southern

Mississippi

• John Morse • Inorganic • Geochemistry • Texas A&M University

Geochemist Group Leader

• William Bryant • Geological • Geology • Texas A&M University

Oceanographer Group Leader

• Worth Nowlin • Physical • Oceanography • Texas A&M University

Oceanography Group Leader

• Joan Bernhardt • Foraminifera • University of South

Carolina

• Norman Guinasso • Physical Oceanography

Field Program

• Texas A&M University

• Bob J. Presley • Metal Contaminants • Texas A&M University

• Terry L. Wade • Organic Contaminants • Texas A&M University

• Steven DiMarco • Physical Oceanography • Texas A&M University

• Michael Rex • Community Structure • Science Review Board • University of

Massachusetts-Boston

• Kenneth L. Smith, Jr. • Community Dynamics • Science Review Board • Scripps Institution of

Oceanography

• William W. Schroeder • Gulf of Mexico Ecology • Science Review Board • Dauphin Island Marine

Laboratory, University of

Alabama

*Does not include taxonomists.

The overarching goals of DGoMB are to:

• determine in greater detail the composition and structure of slope bottom

biological communities and to infer relationships between biological patterns

and major controlling processes and

• characterize the area as to its present “health” and function and compare and

contrast the region with similar oceanic regions.

Specific DGoMB objectives are to:

• improve the conceptual model that serves as the guide for the design and overall

conduct of the study and to test specific hypotheses related to the models;
1-5

• compile and synthesize data from existing databases and on-going programs to

interpret new results;

• conduct field collections to describe the distribution and structure of benthic

communities on the continental slope of the GOM and to elucidate the functional

interactions among them in known environmental settings;

• characterize the hydrographic structure and measure the dissolved and

particulate water column nutrient concentrations, primary productivity, and

chlorophyll a at the study sites;

• characterize the sediments at the study sites including grain size and

hydrocarbon, metal, carbonate, and organic carbon concentrations;

• characterize the basic attributes of the benthic microbiota and biomass at the

study sites;

• characterize the soft-bottom macro- and megafauna at the study sites;

• relate variations in benthic biota patterns to sedimentary processes and to the

chemical and physical setting;

• define basic levels of animal and bacterial activity and production and describe

interactions between and among benthic biota, the several ecological/biological

compartments, and the abiotic environment; and

• compare and contrast the GOM benthic marine environment and communities

with those in other basins of similar depth ranges and oceanic settings.

The program is to be conducted over a 48-month period of performance. Major

oceanographic cruises are to be conducted, one in each of the first three years of the program.

The final year of the program will be dedicated to completing sample analyses begun in the first

three years, data management and interpretation, model refinement, and production of the

Synthesis Report. The field surveys will document the biota, the abiotic character of the slope

and the important biotic and abiotic forcing factors. Station selection criteria included

consideration of anticipated zonation, water depth, distance from shore, abiotic variables,

physiography and topography, geochemical environment, anthropogenic effects, and present and

future leasing trends.

1.2 The Program

The program consists of four tasks:

TASK 1 - Re-examination of Existing Data and Field Study Design

All available scientific records and databases have been identified, collected, and reexamined. Previous studies of particular importance are the TerEco Corporation synthesis (1976

and 1983), the MMS NGOMCS (LGL and TAMU 1988), and chemosynthetic ecosystem studies
1-6

(MacDonald 1998 and MacDonald et al. 1996). Industry data, MMS leasing history and

production data, USGS Gloria data, NODC data, governmental holdings of results of various

MMS physical oceanography programs (LATEX, NEGOM Deepwater), and other information

will be integrated into the new findings. These data formed the basis for final recommendation of

study sites to the Contracting Officer Technical Representative (COTR) and the Scientific

Review Board (SRB). This information was used to describe the study sites, how each site

contributed to the overall program design and verification of important features of the conceptual

model.

TASK 2 - Field Sampling

The R/V Gyre was used to conduct Cruises I and II. Conventional sampling

methodologies were used for the community structure survey and innovative experimental

approaches are being used for process studies. Year II and III cruises are sampling those sites

selected on the basis of information produced in Year I and II, respectively. The goal of the

sampling program is to describe the benthic communities in distinct and identifiable settings in

the study area in time and space. A phased-in approach concentrated the benthic survey portion

of the work in Year I allowing ample time to process samples and analyze data. Year II and III

are a mix of infilling of survey stations based on programmatic results. Experimental stations are

addressing key questions related to processes and forcing factors during cruises in years two and

three. Experimental stations have been chosen based on existing knowledge and Cruise I results.

The experimental stations are a subset of survey stations providing for a close integration of all

data collected. Water column sampling provides descriptive hydrography and water column

chemistry (designed similar to the NEGOM program) at all sites. Seafloor sampling of sediments

for benthic and benthopelagic fauna (design similar to the GOOMEX program) is the main

activity at the survey stations. Basic ecological processes such as microbial activity; sources and

fates of nutrients and detrital material; feeding habits; the relative importance of feeding guilds

and taxa; and the presence of potential contaminants are provided at experimental stations.

TASK 3 - Sample and Data Processing and Analysis

All samples and data are being processed as specified in Chapters 7 and 8. The quality of

data and samples is ensured by a comprehensive data management plan (i.e., the Program

Management Plan). Chain-of-custody and sample tracking activities guarantee the integrity and

quality of the samples and data from shipboard collection to final synthesis. All parameters that

can be reasonably measured onboard the ship (nutrients, salinity, oxygen, etc.) are measured

using standard protocols. Sample and data processing include descriptive hydrography and water

chemistry; sediment properties, chemical contaminants, and sediment geochemical properties;

benthic microbiota, meiofauna, macrofauna, megafauna, and fishes; and measurements of basic

ecological processes. Experimental stations being studied in Year II and III are being planned in

consultation with the COTR and the SRB.
1-7

TASK 4 - Data Interpretation, Synthesis and Reporting

Two (2) narrative Interim Reports and a Synthesis Report will be produced. This report is

the first interim report. The reports will contain an assessment of historic information, the data

collected, descriptions of methods and analyses, interpretations of the analyzed information, and

the results and discussions of the findings. Models will be refined and recast as warranted in

light of new information. The present “health” of the area will be assessed. These reports will

contain appropriate charts, maps, or schematics that portray faunal and habitat variability and the

major forcing factors related to community structure and function in the deep-sea GOM as data

becomes available. Topics to be covered in these reports include relevant historical information;

the hydrography and oceanography of the region; the biological, chemical, geological, and

physical processes and interactions in the water column and at the sediment-water interface; the

effects of biotic and abiotic forcing factors on slope biota; concentrations and sources of

hydrocarbon and metal contaminants in the area including an assessment of potential biological

effects; and the likely effects of OCS petroleum exploration and development and other human

activities on biotic resources in the study area. The COTR, CO, and SRB are informed of

progress in the program by monthly status reports.
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2.0 STATE OF THE KNOWLEDGE

A comprehensive review of the state of the knowledge of the deep-sea is beyond the

scope of this report. However, a brief review of the salient features of deep-sea ecology in

general provides a context for the DGoMB program. This short review then focuses on the

northern GOM. The review concentrates on the ecological and biological aspects of the deep-sea

GOM with brief reviews of the chemistry, geology, sedimentology, and physical oceanography.

References to more detailed discussions are provided.

2.1 General Deep-Sea Ecology

The biota of the deep-sea has been sampled for more than a century. An age of

exploration, utilizing mostly rather simple qualitative gear (trawls and dredges), continued up

until the middle of the 20th century. Quantitative sampling developed for fisheries research in

shallow waters began finding wide use in the deep-sea shortly after World War II. Many of the

early qualitative and quantitative studies resulted in global generalizations about the “community

structure” of the deep benthos (Menzies et al. 1973). Benthic metazoans have been subdivided

into meiofauna, macrofauna, and megafauna, and these categories are further defined on the

basis of size or major taxa. Near-bottom or demersal fishes are often lumped with the

megafauna. Microbiota include heterotrophic protists such as ciliates, flagellates and forams and

a suite of functional groups of bacteria. All the size groups listed, decline markedly in biomass

and abundance as water depth increases although some decline at faster rates than others. A

similar decline in abundance was correlated with distance from shore and surface seawater

productivity (Rowe 1971). Most species, it was concluded, exhibit “zonation” with depth (Rowe

and Menzies 1969) although this is more accentuated in some groups than others. A number of

authors have generated elaborate schemes of “zones” based on the occurrence of faunal groups.

Although the deepest parts of the ocean are thought of as “deserts”, in terms of biomass, the

diversity of the fauna is high compared to shallow water depth (Hessler and Sanders 1967).

Many genera appear to be cosmopolitan, but in fact, a great many species are endemic to specific

oceanic basins or subsets of basins. In general, Menzies et al. (1973) supported the argument that

the “oldest” forms, on geologic time scales, are found at intermediate depth (slope depths) rather

than at the greatest depths. The deeper living forms tend to be more specialized and hence

“younger” in a geologic sense.

The summary of Menzies et al. (1973) marked a significant turning point in deep-sea

biology from studies of community structure to a recognition and inclusion of studies of the

dynamic aspects of the biota. These studies have been summarized in a number of articles over

the years. A decade after Menzies et al. (1973), a series of papers on deep-sea community

structure and function was published (Rowe 1983). Gage and Tyler (1991) review community

structure including an extensive natural history of the different functional, taxonomic and size

groups of organisms. The review is most lucid in its description of animal growth rates. It is

pointed out that many animals spawn in a seasonal manner, most likely in response to seasonal

inputs of particulate organic carbon. The deep-sea is the ultimate sink for detrital particulate

carbon (Rowe and Pariente 1991).

Recent investigations of “community function” were made possible by new observational

capabilities such as deep submersibles, the most important being the Deep Submergence Vessel
2-2

(DSV) Alvin, and moorings and landers that operate remotely on the sea floor without

attachments to a mother ship. Reviews have documented measurements of sediment community

respiration (Smith and Teal 1973); time series studies of the rapid destruction of wood by deepsea boring organisms (Turner 1973); baited traps to attract large scavengers that rapidly consume

carcasses (Hessler et al. 1978); measurement of the slow rain of particulate matter to the deep

ocean and its seasonality (Deuser and Ross 1980); and the seemingly slow deterioration of

organic matter enclosed in DSV Alvin when it descended unintentionally to the sea floor. The

reviews imply that low biomass, low rates of metabolic processes, and low growth rates (Gage

and Tyler 1991) are a result of the minimal input of photoic zone organic carbon (Rowe and

Gardner 1978). However, some taxonomically narrow groups of organisms can rapidly consume

allocthonous organic matter (scavengers and wood borers, for example).

The decade of the 70’s ended with a pivotal biological discovery in the deep-sea:

extensive biological communities supported by reduced inorganic chemicals at hydrothermal

vents (Hessler 1981). The spreading centers between the plates of the earth's crust are often

characterized by fluids rich in sulfides. Symbiotic bacteria, living in the tissues of large

invertebrates, oxidize the sulfide and the energy gained is used to synthesize organic matter for

both the symbionts and the host. Numerous vents around the world are now known to support a

wide variety of unusual but locally abundant organisms (Tunnicliffe et al. 1998). The latter

review also notes that similar faunas occur near dead whales and petroleum seeps, including

those in the GOM (Kennicutt et al. 1985). MMS has sponsored two programs to study GOM

seep communities (MacDonald 1998; MacDonald et al. 1996) and no further discussion of seeps

or vents is provided, except related to the potential effects of seeps on non-seep communities.

Contemporary studies of deep-sea benthic communities continue to address a series of

long-standing questions. To a large degree, these studies are designed to explore the

relationships between the structure and function of deep-sea communities. The consensus

appears to be that biomass and animal abundance decline at log-normal rates with increasing

water depth in many of the ocean’s basins. However, meiofauna and bacteria decline less rapidly

than macrofauna, creating an increase in the relative importance of these taxa as depth increases

(Rowe et al. 1991). This has been assumed to reflect a decline in the reactivity of detrital organic

matter that requires a bacterial recycling loop at the base of the food web (Richardson and

Young 1987).

The reasons for variations in diversity remain elusive. Most new ideas are variations on

Sander's original stability-time hypothesis (reviewed in Gage and Tyler 1991). Rex (1983) has

pointed out that a monotonic increase in diversity does not exist in the deep-sea . To the

contrary, Rex found that diversity indices peak between 2 to 3 km. Further work by others

recently confirmed this pattern exists in many oceanic basins (Levin and Gage 1998). The idea

that “a temporal and spatial mosaic” of physical and chemical variability enhances or preserves

diversity has been tested by emplacement of sediment trays on the sea floor followed by

harvesting of organisms after various deployment times. Snelgrove et al. (1996), for example,

suggest that aged patches of Sargassum promote high diversity by providing fauna with a series

of micro-habitats in time and space. However, the numbers of “expected species” in such

experiments are lowest in the trays with added organic matter, leading to the possibility that

competitive exclusion occurs in response to enrichment. However, this is only speculation.
2-3

Some progress has been made in allocating food resources to various size or functional

groups (stocks) in the deep-sea. It has been suggested for example that among the suite of

organisms living within the sediments, the bacteria consume approximately 30% of the available

organic matter at some locations (Rowe and Deming 1985). In the benthic boundary layer above

the sea floor, organic detritus is parceled among a wide variety of epibenthic holothuroids,

benthopelagic crustacea and migrating fishes, but most of the total organic matter flux, according

to Smith's carbon budget, is consumed by sedimentary organisms (Smith 1992). Another

consensus is that the rain of pelagic detrital organic carbon is tightly coupled to water column

processes. Although it has been proposed that the lateral transport of detrital organic carbon is

important, in the deep Pacific there appears to be a long-term imbalance between the input of

organic matter and its remineralization (Jahnke et al. 1990; Smith and Kaufman 1999).

A growing body of information suggests that the flux of organic matter to the seabottom

has considerable control over both the structure and the dynamics of benthic communities. The

basic structure of the living components of the near-bottom ecosystem have been identified in

terms of functional groups (Rowe 1981). Information is mounting on the relative importance of

some taxa in carbon cycling and energy flow (Rowe 1983; Smith 1986a; Deming and Baross

1993; Smith 1992). Using biomass spectra to estimate production, Haedrich and Merrett (1991)

suggested that a number of characteristics of community energy or carbon flow among the fishes

can be inferred. While fish densities drop markedly over the slope, biomass is relatively constant

to depths of almost 2600 m, suggesting that mean size per fish increases with depth over the

slope. Hence, it is inferred that the relative importance of fishes increases compared to other size

and functional groups with increasing water depth to 2600 m. At greater water depths, fish

biomass precipitously declines.

Sediment-dwelling organisms appear to respond directly to fresh inputs of organic

matter. Working at 200 to 500 m depths in the sub-Arctic Atlantic Ocean, Rowe et al. (1997)

were able to construct a budget that balances carbon input into sediment traps with total

community respiration and sediment burial. A model of the functional components responsible

for the cycling of carbon was then constructed. Evidence that little of the carbon was channeled

through the bacteria supports the suggestion of others, that bacteria are less important at high

latitudes. The dependence of the cycling of energy and carbon on input rates has also been

demonstrated in comparisons of deep sub-oxic environments with oxic counterparts (Eldridge

and Jackson 1991). Deep-sea sediment biomass, in general, appears to be enhanced by the fresh

input of organic matter (Rowe et al. 1997). The latter work modified and simplified the

conceptual benthic boundary layer model of Smith (1992), and conducted numerical simulations

to determine how biomass and respiration were redistributed within a “fertilized” system. This

model, validated independently by work at Deepwater Dump site #106 in the northwest Atlantic,

implies that it might be possible to predict “bioenhancement” (of biomass) in response to new

carbon. This does not mean that diversity would increase. To the contrary, some models suggest

that diversity would actually decrease initially due to competitive exclusion, in agreement with

data presented in Snelgrove et al. (1996). The rates at which new “steady states” are reached

might be much slower than in shallow water at higher temperatures.

The deep-sea is seemingly benign, rather than stressful. However some exceptions should

be noted. Low oxygen zones occur in isolated basins, near large rivers and in eastern tropical

areas affected by upwelling (Levin and Gage 1997). Stress from low oxygen in the eastern

Pacific for example causes a decrease in macrofauna and megafauna (Menzies et al. 1973; Rowe
2-4

and Deming 1985) and diminished diversity and tight zonation perpendicular to the oxygen

gradient (Levin and Gage 1998). Likewise, hydrocarbon seeps are now known to occur widely

around the world on continental margins. Some have unique communities that utilize petroleum

as a source of carbon and energy, but the effects of the communities to either enhance or degrade

the surrounding benthos is unclear (Montagna et al. 1989). Another natural potential “stress”

studied in the deep-sea is high current velocities (Thistle et al. 1991). Recent observations have

confirmed the occurrence of episodic strong currents at the base of the Sigsbee escarpment

(Bryant and Nowlin, pers. comm.).

2.2 The Deep-Sea GOM - Geologic Setting

The GOM Basin is a study in physiographic contrasts. The simple topography of the

West Florida and Campeche continental slope, the Mississippi and Bryant submarine fans and

the extremely flat Sigsbee Abyssal Plain give way to the complex slump structure of the East

Mexican Slope and the extremely complex topography of the Texas/Louisiana continental slope.

The continental slope off Texas, Louisiana, and portions of Mississippi is geologically and

physiographically the most complex in the world. Over ninety basins and seven submarine

canyons dissect the continental margin of the northwestern GOM. The halokinesis of

allochthonous salt is the main mechanism of interslope interlobal and interslope superlobal basin

creation in mid- to lower-slope areas. Most slope basins are filled with turbidites and debris flow

deposits overlain by a Holocene hemipelagic sediment cover that varies from 2 to 10 meters

thick except in areas of active slumping such as the Beaumont Basin. The supralobal basins of

the lower slope are probably formed by the downbuilding of salt withdrawal under the influence

of turbidite sands. The termination of the slope, the Sigsbee Escarpment, is the southern most

extent of a salt nappe that extends from the mid- to lower-slope. The salt nappe can prevent the

migration of thermogenic gas and oil into overlying sediments. Major portions of the middle and

lower slope appear to be devoid of gas seeps; thus, gas hydrate and chemosynthetic communities

are not expected to be present except at the edge of the nappe (Sigsbee Escarpment) and in saltfree basins. In contrast, the upper slope contains numerous salt diapiric structures such as mud

and gas mounds, fluid expulsion features, hard-grounds, erosional gullies, and numerous gas

seeps and gas hydrate deposits.

Superimposed, and eroded into the complex topography of the Texas/Louisiana slope, are

four major canyon systems: the Mississippi, Keathley, Bryant, and Alaminos Canyon. The

Mississippi Canyon is a Pleistocene feature resulting from slumping processes, debris flows, and

turbidity current flows that were most active during the Wisconsinian. Alaminos, Keathley, and

Bryant Canyon were created by a combination of coalescing salt canopies and turbidity current

and debris flow erosional events. Three smaller canyons, Farnella, Green, and Cortez breach the

escarpment and were formed by mass flow events. Smaller upper- and mid-slope canyons that do

not extend to the escarpment are common features related to mass flow processes.

Since the late Pleistocene; Alaminos, Bryant, and Keathley Canyon have undergone

extensive alteration due to infilling of the canyons by the upward migration of salt. As much as

800 meters of infill has taken place within the Bryant Canyon system over the last 12,000 years.

This equates to an average vertical salt movement of 6 cm/year. It is unknown if the upward

motion of salt is continuous or episiodic. Recent seafloor faulting indicates that salt migration is

ongoing today.
2-5

An unusual form of density flow resulting in extensive bedforms on the seafloor was

recently found associated with Vaca Basin, a supralobal basin due east of Bryant Canyon. The

salt infill of Bryant Canyon has resulted in brine eroding vast fields of gullies on the slopes of

Vaca Basin and adjacent areas. Recent studies indicate that other large bed forms, seafloor

furrows, occupy an area 15 km wide southward of the base of the Sigsbee Escarpment. These

furrows are current induced structures and extensive erosion is taking place at the present time.

The geologic setting in the northern GOM is diverse, heterogeneous on several spatial

scales, and actively changing within timeframes that might be expected to effect biological

communities living in and on the sediments. This temporal and spatial heterogeneity of substrate

in the deep-sea GOM has been fully appreciated only in recent years. This realization has lead a

new perspective on how biological communities might be interacting with geological processes.

2.3 The Geochemistry of Deep-Sea Sediments

The two variables generally considered most important to the geochemistry of deepsea sediments overlain by oxic seawater are the rate of sediment accumulation and the relative

proportion of biogenic material to detrital minerals (e.g., Berner 1980). Both factors are closely

related to the extent to which biologically driven reactions occur. Sediment accumulation rate

controls the speed with which material is buried away from the sediment-water interface

increasingly insulated from the overlying oxic waters. Consequently, the degree to which

metabolizable organic matter is decomposed, at or very near the sediment-water interface,

depends on sediment accumulation rate. If accumulation rates are low, little metabolizable

organic matter is buried and the sediments may only reach suboxic conditions, whereas at

higher accumulation rates sulfidic conditions can be reached. Related to these conditions is the

second major variable, the relative input rate of the particulate organic carbon. Sediments on

continental margins and beneath highly productive open ocean waters can have a much higher

rate of carbon input than those beneath oligotrophic waters. Both of these factors combine to

control how far down the redox “ladder” (e.g., Stumm and Morgan 1996) reactions will

progress for electron acceptors associated with organic matter remineralization and the depth

spacing between the various “rungs” on the redox ladder.

An important overall general concept that is basic to this program is that physical,

chemical and biologic processes are intimately intertwined. It is also particularly germane that it

is the availability of metabolizable organic matter that will largely control benthic

biogeochemistry and community structure. This is not simply related to the total organic matter

content of sediments (e.g., Morse and Emeis 1990, 1992; Boudreau 1996). It is, therefore,

necessary to look at the consumption of electron acceptors (e.g., oxygen, nitrate, manganese and

iron oxides, sulfate) and the production of reaction products (e.g., carbon dioxide, ammonium,

hydrogen sulfide) to understand the rates and extents to which heterotrophic activity is

occurring on and beneath the seafloor.

Although there are of course many complicating factors leading to exceptions, the very

general rule is that sediments tend to have lower accumulation rates and hence become less

reducing with increasing water depth. This also reflects decreasing biologic activity with

increasing water depth. The geochemistry of GOM sediments have been investigated over much
2-6

of the study area and adjacent regions (e.g., Lin and Morse 1991; Rowe et al. 1990; Morse and

Rowe 1999) to a water depth of ~2000 m. A primary indicator of biologic activity is the

integrated rate of sulfate reduction. This generally decreases with increasing water depth.

However the rates are about three times higher at a given depth on the slope near the Mississippi

River than at GOM slope far from the river. A distinct secondary maximum in sulfate reduction

rate has been observed at ~500 m water depth. These results suggest that deep-sea biological

community structure in the GOM is not simply related to depth, but may be influenced by factors

such as down slope transport of sediments and organic matter. Further confounding simple

relationships between structure and geochemical forcing factors, is the presence of hydrocarbon

seeps. The MMS chemosynthetic community studies on the Louisiana slope, have documented

integrated sulfate rates near seeps that exceed those in surrounding sediments by over a factor of

fifty (Morse, unpublished data).

2.4 Physical Oceanography of the GOM

The GOM is a semi-closed basin with both broad and narrow continental shelves

surrounding a deep abyss reaching 3600 m. At the boundary in the southwestern GOM, the

energetic Loop Current intrudes northward into the GOM and exits east through the Straits of

Florida. The Loop Current is a permanent feature of the circulation and virtually dominates the

circulation in the eastern GOM and its influence is felt throughout the GOM as anticylonic rings

and topographic Rossby waves spawned by the Loop Current translate west and south. GOM

tides are modest. The world’s third largest river, the Mississippi River, and dozens of lessor

rivers discharge tremendous volumes of fresh water into the GOM affecting stratification over

large areas and enhancing wind-driven coastal jets along frontal boundaries. Wind driven

upwelling occurs with regularity along the western and northeastern GOM and along the

Yucatan Peninsula. Winter cyclones and summer hurricanes are not uncommon events.

The open waters of the GOM can be divided into two regimes: the eastern GOM with the

anticyclonic Loop Current and the western GOM with the anticyclonic Loop Current eddies and

associated cyclones. Approximately every nine months (on average, but with considerable

variability), it sheds anticyclonic, mesoscale current eddies with average lifetimes longer than

one year (Elliott 1982). These eddies typically migrate to the western GOM, often decaying

away in the northwest corner of the GOM. The eddies can spawn cyclonic rings during

interaction with one another or the continental slope. The Loop Current eddies have

characteristic diameters of 200-400 km when newly detached, decreasing by 45% within 150

days and 70% within 300 days (Vukovich and Crissman 1986). The eddies translate westward

with an average speed of about 5 km·d-1 and a range of 1-14 km·d-1. Currents associated with the

Loop Current and its eddies extend to depths near slightly greater than the sill depth of The

Florida Straits (800 m). The currents may have surface speeds of 150-200 cm·s-1 or more; speeds

of 10 cm·s-1 are not uncommon at 500 m (Cooper et al. 1990). Because of their longevity, the

effects of the Loop Current eddies can persist at one location for weeks or even months.

Anticyclonic Loop Current eddies interact with one another and with the continental

slope resulting in their decay. In the process of the interactions, and of the interaction of the

Loop Current with topography, many cyclonic eddies are generated within the GOM. Some

evidence exists that anticyclonic eddies may also be formed by ring-ring interactions, but they

would not have the high salinity core characteristic of Loop Current eddies. Below 1000 m,
2-7

strong current events have been observed (e.g., SAIC 1989). The Loop Current and Loop

Current eddies may influence the dynamics to the deepest portions of the GOM (~3500 m; Smith

1986b; Hamilton 1990) through the generation of phenomena such as barotrophic Rossby

Waves. Likewise strong, episodic atmospheric events (e.g., hurricanes or cyclones) can generate

currents that extend to depths of 1000 m or more. Speeds up to 50 cm•s

-1 have been observed

associated with these classes of deep currents. Deep currents are the main interest of the MMSsponsored inventory and synthesis of physical oceanographic data in the deepwater GOM.

Characteristic relationships of physical and chemical water properties (e.g., temperature,

salinity, dissolved oxygen, and nutrients) can be used to identify water masses and their sources.

Surface waters of the GOM are greatly modified by heat and freshwater exchanges through the

surface, river discharges, and wind mixing, but no subsurface water of consequence is thought to

be locally formed. Waters from the global ocean enter the GOM only through the Yucatan

Channel from the Yucatan Basin of the Caribbean Sea. Seawater properties can be used to

identify the five water masses that enter the GOM (Table 2.1). Source regions for these waters

are discussed in Morrison and Nowlin (1982). Morrison and Nowlin (1977) described the water

masses found in the Loop Current of the eastern GOM, and Morrison et al. (1983) described the

water masses and properties found offshore in the western GOM. As the waters of the Loop

Current enter the GOM, those along its western boundary are vertically mixed by the interaction

of the current with bathymetry, resulting in an averaging of properties (Nowlin 1972). Moreover,

after separation, Loop Current eddies eventually spin down in the GOM. That process entails

mixing, which likewise lessens property extrema. Below the Yucatan Channel sill depth of about

2000 m, the potential temperature, salinity, and dissolved oxygen concentrations show no

measurable horizontal variation throughout the GOM (Nowlin 1972).

Table 2.1. GOM water masses with associated property extrema and potential densities.

Water Mass ~ Depth Range

(m)

Identifying Feature(s) Sigma-theta (mg

cm-3)

Subtropical Underwater 50-250 salinity maximum 25.40

18°C Sargasso Sea Water 150-250 oxygen maximum (weak in west) 26.50

Tropical Atlantic Central Water 250-500 oxygen minimum 27.15

Antarctic Intermediate Water 500-1000 salinity minimum; nitrate, phosphate, and

silicate maxima

27.30-27.50

Upper North Atlantic Deep Water > 1000 silicate maximum ≥ 27.70

The earliest attempt at a comprehensive synthesis of the physical oceanography of the

GOM is found in Capurro and Reid (1970). Since then, and particularly in the last 15 years, the

study of the physical oceanography of the GOM has greatly accelerated. Much, if not most, of

this increased study has been funded by the MMS acting in response to intense energy

exploration and production activities on the shelf, slope, and rise. The first such study, initiated

in 1982, was a five-year program implemented as a series of regional studies. These studies

included field work in the west, central, and eastern portions of the northern GOM. The results,

detailed in a final report, emphasize eddy variability. MMS also sponsored a synthesis of GOM

meteorology and climatology data during this same period (Florida A&M University 1988). A

major MMS-funded physical oceanography study was the Texas-Louisiana Shelf circulation and

Transport Process Study (LATEX) program which surveyed and maintained current moorings
2-8

between 1992-1994 along the Texas-Louisiana shelf from the 10 m isobath to the shelf break

from Brownsville to 90.5oW. The LATEX program was a joint effort accomplished by TAMU,

Louisiana State University, and SAIC. Other study units sponsored by MMS, but not strictly part

of LATEX, generated significant amounts of related collateral data during the same time period.

Taken collectively, this study was the largest and most comprehensive shelf study ever

conducted. Following LATEX, a new series of programs similar in scope to LATEX but

organized differently, were initiated in the northeastern GOM. The most significant circulation

studies include a large (>350 drifters) program conducted by Peter Niiler of Scripps Institute of

Oceanography and Walter Johnson of MMS between February 1996 and February 1997, a

moored array and hydrography program conducted by SAIC in DeSoto Canyon from March

1997 to March 1999, and an ongoing hydrography and water chemistry program over the shelf

and slope between the Mississippi River and Tampa, Florida from November 1997 to August

2000. In 1998, a data synthesis study of the physical oceanography of the deep water GOM was

begun by TAMU under MMS sponsorship. The results of this study, due in December 2000, will

include a complete database of all available information and the design for a deep mooring array.

2.5 Deep-Sea Ecology of the GOM

The earliest studies of the deep GOM biota were by Alexander Agassiz (1888) but his

voyages never penetrated the western Gulf. The National Marine Fisheries Service has long

maintained an exploratory fishing fleet in Pascagoula, MS and information is available from

extensive trawling on the continental slopes of the GOM and the Caribbean. In the mid-1960s

studies on the biota of the deep GOM were initiated (Pequegnat et al. 1990). A wide range of

investigations of the deep water ensued, including the first quantitative samples with a Campbell

grab coupled with a camera (Rowe 1966). Several bottom contact and automatic cameras were

used and camera lowerings were dispersed more or less evenly around the GOM margin,

including the Gulf of Campeche near Veracruz, Mexico. A benthic “skimmer” was built to catch

larger forms and it was outfitted with an odometer to determine bottom distance traveled. These

samplings included the Caribbean, as well as the GOM. Faunal groups studied from the deep

GOM included squids, crustaceans (Firth 1971; Pequegnat 1970), echinoderms (Carney 1971),

molluscs, and fishes (Bright 1968) among others. Assemblages of both the megafauna and the

macrofauna were also studied. Fish feeding habits were intended to link the two. Photographs of

an “iron stone bottom” north of the Yucatan Strait suggested deep bottom currents sweep some

areas free of sediments (Pequegnat 1972). Some taxa displayed remarkable “zonation” by

species, such as the bivalve molluscs (James 1972) and the asteroid echinoderms. The

macrofauna appeared to be grouped into assemblages, based on measures of similarity, that were

distributed within “zones” down the slope and onto the abyssal plain, but no justification was

found for separating deep-living fauna into zoogeographic provinces by latitude or longitude

(Kennedy 1976).

In 1968, semi-quantitative samples were taken across the Sigsbee Abyssal Plain and then

in 1972, quantitative samples were obtained from the lower slope up onto the continental shelf

on two transects seaward of Galveston and Pascagoula. These quantitative data suggested that

the deep biomass of the GOM was depauperate in numbers and biomass, and that the mean size

of the macrofauna was in general smaller than that in the Atlantic at similar depths (Rowe 1971,

Rowe and Menzel 1971, Rowe et al. 1974). Later studies, such as the NGOMCS, used the

conversion factors from numbers and size to estimate biomass. The log-normal relationship
2-9

between biomass and depth has now been confirmed for numerous ocean basins (Rowe 1983),

but the slope of the line for the GOM is steeper than that in most basins. It has been suggested

that this is due to the low primary production in the GOM.

The most extensive sampling of the sediment biota of the northern GOM was the

NGOMCS study supported by the MMS in the 1980's. This consisted of paired GOMEX (not to

be confused with GOOMEX) boxcores (Boland and Rowe 1991), bottom survey camera

lowerings and trawl samples. The stations studied included three transects down the slope in the

western, the central and the eastern GOM with a line along the upper slope connecting the west

and central transects along isobaths. A series of reports were written describing the work but the

most concise summary is a paper by Pequegnat et al. (1990). In the descriptions of the

characteristics of the three dominant size classes (the meiofauna, the macrofauna and the

megafauna) the meiofauna appeared to dominate the biomass, a feature that would be odd for

shallow water but a relationship that is becoming increasingly apparent at deep-sea stations when

size groups are compared (Rowe et al. 1991). It was also suggested that the fauna were

distributed in “zones” along isobaths on the upper slope, but less so on the lower slope. As is

true for most deep ocean basins, the meiofauna were dominated by nematodes, the macrofauna

by polychaetes and the megafauna by echinoderms. Lesser numbers in each size category were

also quite predictably encountered in taxa such as the molluscs and crustaceans. Similarity

indices suggested that the eastern GOM, east of the DeSoto Canyon, was not similar to that in

the northwestern GOM at similar depths. “Zonation” with some groups was modest, at best. This

was true of the polychaete annelids (Hubbard 1996). Within this group, no species was

encountered below the sill depth of about 2 km that was not encountered at lesser depths as well.

An important discovery made during earlier slope studies were communities of large

organisms associated with petroleum hydrocarbon seeps (MacDonald et al. 1996). Such

communities, bearing a resemblance in both taxa and function to those associated with

hydrothermal vents, have now been documented at numerous locations on the continental slope

of the northwestern GOM in areas where fossil hydrocarbons make their way to the sediment

surface. Bubbling or seeping gas appears as “wipeout zones” in acoustic surveys of the bottom.

These communities are the subject of ongoing studies supported by MMS and other agencies and

will not be described in detail here (see MacDonald et al. 1998). Cold seeps supported by

hydrogen sulfide in “ground water” appears to support communities of large invertebrates, again

being somewhat similar to those at hydrothermal vents, on the lower reaches of the Florida

Escarpment (Paull et al. 1984).

The Instituto Ciencias del Mar y Limnologia of the Universidad Nationale Autonoma de

Mexico (UNAM) has conducted extensive studies in the southern GOM. Early studies of

megafauna on the shelf were expanded down slope into the “salt diapir zone” just west of the

Campeche Bank. These studies were extended into the Sigsbee Abyssal Plain close to the EEZ

between the U.S. and Mexico (26oN. Lat.) as well. Pathways of carbon and nitrogen in the

benthic foodweb were inferred by stable isotopic analysis (Soto and Escobar 1995). In deep

water studies across the Cordilleras Mexicanas or “Mexican Ridges” of the upper continental

rise out onto the Sigsbee Abyssal Plain regions that contain enhanced biomass have been

identified under water masses that have high rates of primary production (Escobar-Briones et al.

1999). Polychaetes dominated the infauna and a mid-slope maximum in abundance similar to

that encountered in the northern GOM has been documented (Pequegnat et al. 1990). The fauna

could be partitioned into three groups within depth intervals of >3 km, between 1.5 and 3 km,
2-10

and <1.5 km. This contrasts with the view of Pequegnat et al. (1990) that five faunal groups can

be divided into recurrent “zones”.

Several studies currently being conducted in the GOM are also important. Studies in the

Bay of Campeche in the northwestern GOM are producing important findings (TAMU/UNAM).

In 1997, at a station in 3.6 km water depth (25o15' N. Lat. x 93o26' W. Long.) on the northern

Sigsbee Abyssal Plain, the first sediment oxygen consumption measurements in the deep western

GOM were made. The sediment oxygen consumption was equivalent to 3.8 mg carbon/m2-day.

Quantitative analysis of samples of the benthic community on the Sigsbee Abyssal Plain confirm

that benthic biota are extremely sparse. Baited bottom traps in the area attracted deep-sea

scavenging amphipods. The diversity of polychaetes was not appreciably different from that

measured in the NGOMCS study (LGL and TAMU 1988).

Another important investigation is a study of mollusc shell “taphonomy” which measures

preferential preservation of material in the fossil record. Ongoing, in situ experiments at about a

dozen semi-permanent sites within the MMS study area have been established. The strategy is to

set out shell material and assess diagenetic changes over time frames of years. Bottom chamber

measures of sediment oxygen consumption and quantitative faunal samples at each site have also

been collected. The hypothesis being tested is that the chemical dissolution of carbonate is

accentuated in areas of high oxygen consumption. These sites stretch from the brine pool at the

Flower Gardens down to ~1000 m depth. Oxygen consumption measurements have been taken at

a number of locations in the study area.
3-1

3.0 A CONCEPTUAL MODEL OF THE DEEP-SEA

A conceptual model of the deep-sea, its living and non-living components, has been

constructed to represent the interacting stocks of organisms that make-up a typical benthic

boundary layer community (Figure 3.1). A biological boundary layer is defined as approximately

1 m deep into the sediments, extending up through the mixed layer of the water column to

approximately 100 m above bottom. This biological boundary layer thus conforms to that

previously used to describe the principal interacting components of a deep-sea benthic

community (Smith 1992). This conceptual model has been drawn in software called STELLA II.

The software allows flexibility in reformulating the structure and internal relationships within

the system. The formulation presented is a modification of the model used by Smith (1992) and

represents a deep-sea food chain. The modifications consist of defining every stock variable,

living or non-living, as a “box” and every process, such as predation or respiration, as an

“arrow”. Thus all interactions between the biota and the sources and sinks of organic matter are

explicit either as “boxes” or “arrows”. On the other hand, “physical” processes are not explicitly

represented. These implicit factors affect the “arrows” between the “boxes”. Each “box” has a

“size” in terms of concentration, biomass or abundance that is the sum of the “arrows” entering

the “box” minus the “arrows” leaving the “box”. At steady-state, each “box” does not change

with time, and thus the inputs equal the outputs or losses. An important process, respiration, has

been omitted in this conceptual food chain. Each stock can be taken separately in a submodel

(Figure 3.2). Macrofaunal biomass, for example, is a function of what it consumes, what

consumes it, respiration, and feces production. The contents of each stock can be expressed as a

differential equation. The set of differential equations of all the stocks can be used to simulate

the behavior of the entire food chain over time. The problem with doing this in the deep-sea is

that data to quantify the stocks and processes are sparse at best. While considerable information

exists on the stocks in a few locations and a few data exist on the rates of processes in others, the

locations where both stocks and fluxes are known, even in the most minimal sense, are quite

limited. One exception is a study of the central North Pacific, but even this study treated the

sediment dwelling biota as one functional group due to a lack of detailed information on the

foodweb (Smith 1992; Smith and Kaufmann 1999).

An advantage of this model is that with adequate data it can be used to simulate how the

ecosystem will function under different conditions. Previously this approach has been used in an

oligotrophic upper continental slope environment off eastern Greenland (Rowe et al. 1997).

Boxcore standing stocks of the components represented were coupled with measures of

community respiration (using a bottom lander with benthic chambers) and laboratory measures

of bacterial activity to simulate the variations in biomass over time in response to a single

seasonal pulse of organic matter related to a short ice-free period. In a purely hypothetical

situation, the bioenhancement of infauna due to the disposal of organic rich material, such as

sewage sludge or dredge spoils, was modeled, based on a simplified rendition of the Smith

(1992) model (Rowe 1998). By adding organic matter in a pulse, the community “shifted up” to

higher biomass and higher respiration and the alteration predicted by the model was validated by

actual data at Deepwater Dumpsite 106 on the continental rise in the northwest Atlantic Ocean.

This feature of “shifting” up or down in response to different input terms will be an important

tool for interpreting the response of community structure and function in the deep-sea GOM in

reaction to inputs from oil and gas exploration and production activities. The two most relevant

inputs at platforms are organic enrichment due to a “reef” effect and the introduction of
3-2

contaminants.
3-3

CARCASSES

SEDIMENT ORGANICS

DISSOLVED ORGANICS

MICROBIOTA

MEIOFAUNA

CHEMOTROPHS

HIGH MOLECULAR WEIGHT HYDROCARBONS

MACROFAUNA

MEGAFAUNA

FISHES

Scavenging1

Deadfalls

Scavenging2

Predation3

Predation2

Deposit Feeding3

Deposit Feeding2

Bactivory3

Bactivory1

Assimilation1

Lysis & Dissimilation

Advected Organic Detritus

Deposit Feeding1

Bactivory2

Predation1

Chemotrophy

Seeps of HMWHC

Vertical Rain of POC

Figure 3.1. Preliminary conceptual model of the deep-sea Gulf of Mexico.

= fluxes

= standing stocks of the state variables

= losses from and inputs to the system

Key
3-4

Figure 3.2. Macrofauna submodel of system carbon food chain model.

3.1 Biotic Variables

The details of the conceptual model can be described as a number of biotic (living and

non-living) and abiotic variables. In addition, the model is described in terms of various derived

variables related to community structure and function. In-the-end, an understanding of the model

components and their interactions are used to select the set of variables to be quantified that best

describe the functioning of the system being studied. These inferences are then ground-truthed

by in-the-field observations and the model is revised as needed. The biotic variables include the

microbiota, meiofauna, macrofauna, megafauna, and fishes. These groups of biota make up the

overall stocks of the system which are estimated through conventional quantitative sampling as

described in Sections 6.0 and 7.0.

Microbiota. The microbiota are the “bottom” of the food chain. Microbiota are

represented by the bacteria and protists, including benthic foraminifera. Their principal food

source is thought to be dissolved organic matter, although particulate material can be directly

utilized if the biota can produce exoenzymes to mobilize particles. The protists can engulf and

assimilate particulate material as well. The bacteria generally have a density of about 109 per mL

of wet sediment, measure about a micrometer in size, and can have very short turnover rates in

the presence of reactive organic substrates. The protists can be much larger and occur in far

MACROFAUNA

Deposit Feeding

Bactivory

Predation on Meiofauna

Predation

Respiration

Feces

(see Key in Figure 3.1.)
3-5

fewer numbers than the bacteria. Protists are thought to be important components of ecosystems

in areas of reduced oxygen. With the exception of the forams, microbiota have rarely been

evaluated in the deep-sea.

Bacteria that are specially adapted to utilizing methane and sulfide are common in areas

characterized by petroleum seeps (MacDonald et al. 1996; MacDonald 1998). Many of these are

symbiotic, living in the tissues of large invertebrates. While these specialized associations are

explicit in this model, they are presumed to be confined to “seep” areas.

Foraminifera are shelled protozoans. Foraminfera are large, often the size of metazoan

meiofauna. Few studies have compared foraminiferal biomass to other benthos in the deep-sea,

but biomass can exceed the meiofauna (Coull et al. 1977) and abundances commonly exceed the

meiofauna plus the macrofauna (Snider et al. 1984; Gooday 1986). Although little is known

regarding foraminiferal energetics, it has been shown that foraminiferal metabolism is markedly

increased by organic enrichment (Linke 1992). Therefore, accurate deep-sea carbon and energy

budgets should include the foraminifera.

Meiofauna. In this model, meiofauna are defined as metazoans that are retained on a 63

micron sieve. Meiofauna include nematode worms, harpacticoid copepods, and several other

taxa. In some studies benthic forams are also included, but in this model, forams are considered

part of the microbiota because they are single-celled organisms, rather than metazoans. Most

meiofauna feed on small particles consisting of detritus, bacteria, other meiofauna, and small

protozoa such as ciliates and flagellates. Turnover rates for meiofauna can be as short as a few

days when temperatures are high and food is plentiful. No reliable generalizations can be made

about their turnover times or growth rates in the deep-sea, but it is assumed that both are

substantially slower than in shallow water due to food limitation and cold water temperatures. In

shallow waters meiofauna biomass is less than that of the macrofauna, but in the deep-sea this

appears to be reversed.

The finding that meiofauna biomass is higher than macrofauna biomass in the northern

GOM (Pequegnat et al. 1990) indicates that meiofauna may be responsible for much of the

organic matter metabolism in deep-sea sediments. Therefore, a survey of meiofauna community

density and biomass is needed to characterize this energetically important group. In shallow

coastal systems, meiofauna remove bacteria at a rate that equals sediment bacterial production

(Montagna 1995). This indicates meiofauna are most likely responsible for maintaining bacterial

populations in log-phase growth cycles and are therefore indirectly responsible for maintaining

rates of nutrient recycling. Despite the apparent importance of meiofauna in deep-sea energetics,

there is no knowledge of the rates at which these processes occur. Therefore, process studies are

needed to assess meiofaunal consumption rates. Techniques to measure meiofaunal bacterial

feeding rates on bacteria have only been used in shallow water (Montagna 1995).

Macrofauna. Macrofauna, in this model, are the invertebrates retained on a 300 micron

sieve. The principal organisms are polychaete worms (≈50%), bivalve molluscs, and crustaceans

in the groups Isopoda, Amphipoda, and Tanaidacea. The production to biomass ratio of the

macrofauna in shallow water communities is often assumed to be unity, but this can vary widely.

In the deep-sea, it is assumed the ratio is much lower but there is little evidence for this one way

or the other. Biomass and densities decline sharply with depth in most ocean basins. Macrofauna
3-6

consume microbiota, meiofauna and organic detritus. Macrofauna are preyed upon by megafauna

and fishes.

Megafauna. The megafauna are organisms that are routinely sampled by trawls with 2.5

cm stretch mesh or organisms that can be seen easily in bottom photographs, usually about 1 cm

or so in diameter. They are composed for the most part of decapod crustaceans and echinoderms.

Cnidaria, such as sea pens, soft corals and anemones, are also common in the megafauna.

Megafauna can be suspension feeders, predators, scavengers or deposit feeders. For the purpose

of the model, the swimming scavengers that consume carcasses, such as the large amphipod

Eurythenes grillus, are included in this group. Megafauna have been extensively observed with

photographic techniques.

Fishes. Demersal fishes are defined as those species that live on or near the bottom.

Fishes are both predators and feed on dead falls, megafauna and macrofauna.

3.2 Community Structure

Community structure, in the context of this model, has two interpretations. It is

represented explicitly in the conceptual model as the standing stocks of the living components of

the ecosystem as discussed above, and as such it represents the relative and absolute importance

of the stocks in terms of biomass and rates of processes in the model. Secondly, community

structure refers to the parameters that quantify the living stocks, as described below.

Biomass. A measure of the standing stock in some currency of mass per unit area of

seabottom is biomass. Wet weight is a common measure. It can also be measured as dry weight,

ash-free dry weight or carbon. The model currency is carbon, so the ideal measure is in terms of

carbon. Biomass tends to be inversely related to depth, in a log-normal fashion. Within the entire

community, the highest biomasses are found in the total bacterial counts, both in shallow and

deep water. All the size fractions in the deep-sea have biomass values that are somewhat lower

that 1 g C/m2. In shallow water, each fraction can have biomasses of 10's of g C/m2 in unusually

fertile conditions. This is not expected in the deep-sea.

Abundances. A surrogate for biomass, that is often measured in ecosystem studies, is

animal abundance or density. However, mean sizes can vary. In the GOM, mean size seems to

decrease with depth. Common abundances for the organismal groups in the model are bacteria,

109

/mL wet sed.; meiofauna, 0.25 to 1.5 x 106/m2; macrofauna, 102 to 104/m2; megafauna and

fishes, several hundred to a thousand per hectare. The abundances of each group are

hypothesized to be a function of the input of carbon and energy to the stock. If the relationship of

numbers to biomass is known, these abundances can be used in the model. The NGOMCS

studies used conversion factors from the studies of Rowe (1971) to calculate biomass from

densities.

Diversity. Measurements of the numbers of different species are expressed as diversity

values. Diversity has been assessed on macrofauna, megafauna, and fishes. Diversity indices

attempt to lessen the effects of sample size, to aid comparisons between regions of differing

animal densities. Common indices of diversity are Sanders Rarefaction, Hurlburt's expected

species number and the information function H'(s). The GOM appears to be somewhat different
3-7

from large ocean basins in that maximum diversity is not found on the deep slope or upper rise,

but rather on the upper slope or outer shelf. Thus it is similar to other isolated “mediterranean”

basins where diversity declines with depth down the slope. It is expected that intense inputs of

organic matter will decrease diversity due to competitive exclusion. Diversity is not calculated

by the model.

Zonation. The degree to which individual species and groups of species are isolated

across isobaths (zonation), between geographic regions, or any other physico-chemical gradient

is referred to as zonation. Zonation by groups of species as a function of depth has been

measured by “rates of species change” across depth intervals or measures of percent similarity

between depths. These can be measured on meiofauna, macrofauna, megafauna, and fishes.

Groups of species appear to occur in zones, but considerable overlap has been observed as well,

with few distinct, immutable boundaries. On the other hand, some individual species of

megafauna tend to have a shallow water boundary that is sharp and severe and a deeper water

boundary that is a slow decline in numbers with depth. Zonation down slope is hypothesized to

be a function of competition along a gradient of declining food supplies. Zonation is not

calculated by the model but can be addressed through hypothesis testing.

3.3 Community Function

The processes, or arrows, in the model encompass a wide range of interactions amongst

the model’s components.

Microbial activity. The respiration and the assimilation of organic substrates by the

microbiota are dependent on inputs of organic matter and temperature. In the model this can be

either sedimenting POC or hydrocarbons. The sedimenting POC can be derived from several

sources, as indicated above. A basic assumption is that, in general, smaller organisms are

consumed by larger organisms because it is more energy efficient. If the organic matter is

reactive, the food web will compete for the organic matter. If the organic matter is highly

refractory then it is assumed that a food chain will dominate in which the bacteria remobilize the

organics in order to make it available to metazoans. Predation is represented as arrows between

the living components of the model as indicated. It is assumed that large organisms will

preferentially take large prey rather than small prey because it is more energy efficient.

Macrofauna are assumed to be deposit feeders. Heterotrophic bacteria are assumed to consume

sediment organic matter. Scavengers consume carcasses and are included in the megafauna.

Fishes consume megafauna and carcasses. Respiration is one of the most important measures for

each organismal group because it dominates the carbon cycle. However, respiration is not

explicit in the conceptual model. Most carbon that is consumed (50 to 90%) is recycled to

metabolic carbon dioxide. Respiration is estimated from animal size and temperature for the

larger organisms based on literature values.

Growth, reproduction and recruitment. The rates of growth, reproduction, and

recruitment are poorly known in deep-sea organisms. The model can calculate growth by

fundamental or size group. Reproduction and recruitment are not well known. It is assumed that

growth, reproduction and recruitment can be seasonal in some species but this kind of

information for the GOM slope is inferential at best. It should be noted that in the NGOMCS

study’s central transect, it did appear that there were about 1.5 times as many macrofauna
3-8

individuals on the upper slope in the spring than in other sampling periods, suggesting that some

type of growth, reproduction, and/or recruitment had occurred, but the mechanism that gave rise

to this observation is unclear.

3.4 Sediment Properties

Non-living model variables include the “fuel” for the system and those processes that

supply carbon and energy to the ecosystem. Inputs of carbon are critical to the functioning of the

ecosystem and are often present in limiting amounts in the deep-sea. On the GOM slope, labile

organic matter is transported to the communities from primary productivity (either directly

settling to the site or being laterally advected), fossil sources of carbon (oil and gas to support

chemosynthesis), and potentially from large animal carcasses and sinking Sargassum.

Sedimentary organic matter includes a suite of natural organic compounds found in deepsea sediments. Organic matter is derived mostly from the slow rain of particulate organic matter

(POM) originating from dead cells, crustacean molts, and fecal pellets produced by plankton in

the overlying photic zone. Some POM sinks very slowly but aggregates and pellets can rapidly

reach the seafloor. The composition of organic matter that reaches the sediment is largely

unreactive and poorly characterized. POM is extensively reworked in the water column either

being remineralized or transformed to dissolved organic matter (DOM). The amount of POM

that reaches the sediment, its ultimate repository, is affected by many factors but, in particular,

the water depth. POM concentrations in the sediments of the deep-sea are low. Relatively

refractory terrigenous-sourced organic matter is an increased percentage of the POM close to

shore and river discharge points. POM is usually inversely proportional to grain size, but does

not correlate well with the biomass of the living components. In spite of its meager reactivity, it

is assumed to be the basis of the deep-sea food chain except at hydrocarbon seep sites.

Three sources of sediment organic matter are possible in the deep-sea and two are

explicit in the model: vertical transport from the photic zone and lateral export from the

continental margin. The third source is slumping of material from organic matter-rich areas upslope and its importance is unknown.

The discovery of chemosynthetic communities with large megafaunal communities

dependent, through their symbionts, on methane and sulfide derived from natural seeps has

highlighted a non-photosynthetic source of carbon and energy for deep-sea GOM organisms.

Hydrocarbons migrate to near-surface sediments from deep subsurface reservoirs of oil and gas.

The hydrocarbons can then serve as substrates for communities of organisms adapted to methane

and sulfide utilization. “Seeps” support high biomass but its influence on biota outside of the

immediate vicinity of the seeps is largely unknown. Recent chemical evidence indicates that the

biogeochemical influences of seeps in sediments tend to be localized (John Morse, pers. comm.).

The oil and gas is often degraded by bacteria inducing anoxic conditions in the adjacent

sediments producing sulfidic environments.

A poorly quantified input of organics to the deep-sea are falls of carcasses that die or are

killed in the water column, usually near the surface. Carcasses can range in size from a few

centimeters to a whale of several tons. The relative importance of this source of organic matter is

not well established. It is known that scavengers exist that can take advantage of such sources, if
3-9

and when they are available. Similarly, Sargassum, Thallasia, wood, etc. has been observed on

the bottom as well.

There are a range of abiotic variables that have been shown to influence biotic patterns in

marine environments. One type are those related to the physical texture of the sediment and

include properties such as grain size, permeability, porosity, and organic and inorganic carbon

content. As the substrate that supports the benthos, variations in these physical properties are

important in understanding biotic patterns. In addition, it is known that influxes of organic matter

and contaminants can cause changes in community structure and abundance. Introductions of

labile carbon will cause opportunistic animals to flourish and others to do less well. Organic

matter enhancement also leads to anoxic conditions that produce a range of toxic chemicals such

as sulfides. Organisms are also known to be selectively sensitive to chemical contamination from

hydrocarbons and trace metals. Some animals can tolerate exposure better than others causing

shifts in populations when communities are exposed to pollution. In addition, hydrocarbons,

particularly aliphatics can be metabolized by microbes and may actually enhance sedimentary

microbial populations rather than exert a toxic effect, though as mentioned above, oxygen and

sulfate consumption can produce toxic chemicals.

Explicit in the model is microbial biomass but functional groups of bacteria are not

defined. All of the bacteria and protists are assumed to be heterotrophs, as opposed to possible

chemoautotrophs in the “chemotrophs” stock. However, the terminal electron acceptors

(oxidants) of heterotrophs can differ. In the oligotrophic central gyre areas of the deep-sea where

sediments are oxic, all the bacteria are assumed to be aerobes. In sediments on continental

margins, this is probably not true. Below the sediment-seawater interface the functional bacterial

groups are defined by the terminal electron acceptor (TEA) they use (Figure 3.3). Few

comparisons of the importance of the different TEA's (oxidants) have been made, but in rapidly

accumulating sediments near the Mississippi delta, oxygen and sulfate were of equal importance.

However, as oxygen declined and became limiting, sulfate reduction dominated heterotrophic

metabolism. These processes are measured by examination of the porewater chemistry with

depth in the sediment. These processes are important in situations where organic loading

depletes oxygen in surficial sediments, thus forcing deeper living bacterial assemblages to

depend on other oxidants. As the loading continues, the utilization of these other TEA's increases

in intensity and rises up closer and closer to the sediment water interface. Profiles of TEA's are

good indicators of organic loading to the sediment community. Ammonium is a principal

excretory product of invertebrates and bacteria. The ammonium produced by the benthic

community can be oxidized to nitrate by nitrifying chemoautotrophs, but it can then be used,

along with nitrate diffusing in from the bottom water, as a metabolic oxidant. This can be

measured with benthic chamber incubations and sediment pore water profiles of ammonium and

nitrate. The importance of this process can be significant relative to oxygen consumption.

Oxidized metals can also be used as oxidants. Comparisons with other oxidants is limited, but in

some situations this process is thought to be important. In sediments containing even modest

amounts of reactive organic compounds, sulfate reduction can become the dominant respiratory

process, even greater than oxygen. This is because sulfate is the fourth most abundant ion in

seawater, having a concentration that is 140 times that of oxygen at saturation. Lin and Morse

(1991) have made a series of cross slope transects around the GOM in which they derived
3-10

Figure 3.3. Sediment submodel of functional bacterial groups as defined by utilization of

different terminal electron acceptors.

integrated sulfate reduction rates down core. Highest rates were near the Mississippi River.

Lowest rates were in oligotrophic areas of the southern GOM. Methane can be produced as a

breakdown product of metabolism of large carbon compounds and it can be formed when carbon

dioxide is used as the oxidant. Methane can then be used as an energy source by bacteria. This

methanotrophy occurs in methane seeps near hydrocarbon seeps. Therefore, characterization of

the geochemical properties at a location is important for ascertaining the basic metabolic

processes that are important to the base of the food chain. Significant alteration of the inputs to

the system, in particular carbon, can result in large shifts in bacterial populations and metabolic

strategies. In addition, the rate of sediment accumulation and the intensity of bioturbation

DETRITAL ORGANICS

POC Input

Burial

MACROFAUNA

MEIOFAUNA

CHEMOTROPHS

Mn REDUCERS

Fe REDUCERS

SRBS

Deposit Feeding1

Deposit Feeding2

AEROBIC BACTERIA

Assimilation3

Assimilation4

Assimilation6

Predation

DIC

CaCO3

Shell Burial

Aerobic Respiration1

Aerobic Respiration2

Chemosynthesis

Sulfate Reduction

Fe Reduction

Mn Reduction

Dissolution

DIC Loss

DENITRIFIERS

Aerobic Respiration3

Denitrification

Assimilation1

Bactivory

Production

Assimilation2

(see Key in Figure 3.1.) (SRBS=Sulfate Reducing Bacterias)
3-11

(mixing) are important in establishing the sediment redox conditions and provide insight into the

reactivity of sedimentary organic matter.

3.5 Water Column Properties

The currents in the overlying water column are important when considering biotic

patterns. Near-bottom currents are in part responsible for establishing the sediment properties by

transport to the site and also winnowing/erosion of sediments. The water column is also the

media through which the overlying primary productivity is transported to the sediment. The

currents serve as a mechanism for transport of larvae and juveniles throughout the system. So

any model of the deep-sea must take into account the dynamic nature of the physical

oceanography and the hydrography of the water masses that overlie and interface with seabottom

habitats.

3.6 Community “Health”

While widely discussed, the concept of ecosystem “health” remains elusive. Due to the

complex nature of natural ecosystems an overall assessment of health is difficult to define.

Specific portions of an ecosystem can be characterized by parasite infestation, pathologies,

reproductive success, demographics (age distribution), and the presence of measurable responses

to stress (such as stress proteins and the inducement of P450 detoxification enzymes) to name

just a few potential indicators of “health”. However, a mechanism or approach to provide an

overall integrated assessment of the community “health” has yet to be agreed to. For example, in

the past it was thought that simple increases in biomass were positive for a group of organisms,

but now it is recognized that these biomass increases can be accompanied by significant changes

in community structure. Is this positive or negative for the community and is the community

“healthy”? Acute deterioration of a community, such as massive mortalities or disappearance of

species, is easily recognizable, but over longer time frames it has become clear that some of the

more intractable issues related to sublethal effects are often difficult to quantify or even

recognize in the early stages of change. For example, loss of biodiversity is seen as a

deterioration in ecosystem health, but the natural processes that also effect biodiversity are not

well understood.

Ecosystem “health” may be measured by such things as community structure, e.g., the

classic view that a healthy benthic community is one of high diversity and high productivity.

Therefore, unhealthy ecosystems share a number of properties - lessened productivity, declining

biodiversity, dominance by lower trophic levels and others. It has also been suggested that

systems degraded beyond a certain point cannot recover (Rapport and Whitford 1999; Rapport

et. al. 1998; Rowe and Haedrich 1979; Haedrich et al. 1980; Haedrich and Maunder 1985;

Snelgrove and Haedrich 1985; Haedrich and Merrett 1988; Merrett and Haedrich 1997).

Therefore “health” can be inferred from community composition, abundances, and size

frequencies. “Health” will be assessed by comparisons of the structure of similar ecosystems

world-wide that have been subjected to varying degrees and types of disturbance.

At the individual level, “health” has been inferred from physiological responses such as

disease incidence, size and condition, and reproductive state. Parasites, and the diseases they

cause, are often important determinants of population health. Measurable effects include
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mortality, decreased reproductive effort, decreased condition, and reduced or aberrant growth.

The outgrowth of these effects are increased morbidity, decreased fecundity and even effects on

predator/prey relationships.

From another point of view, “health” may be a measure of response to the stresses a

population experiences due to anthropogenic disturbances. As a first order indication of this

exposure, inventories of chemicals in sediments and biological tissues are measured. While this

is at least an indication that the potential for impact is present, simply documenting the presence

of contaminants is not sufficient to infer biological effect in most instances. However, a range of

biological effects criteria for sedimentary concentrations of contaminants have been used to infer

the possibility of effects. Once the potential for exposure has been verified, first-order biological

responses to contaminant exposure are often important variables to monitor. These include a

range of responses including production of contaminant metabolites, the induction of

detoxification enzyme systems, and molecular level indications of genetic damage, to name a

few indicators of sublethal biological response to contaminant exposure.
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4.0 SAMPLING DESIGN

The design of the sampling program involved a series of steps that relied on basic design

principles, a thorough knowledge of the current understanding of the system to be observed,

formulation of working hypotheses, application of appropriate statistical analyses (both

univariate and multivariate), linkage of findings with model revision and update, and an

objective approach to evaluate the utility of data being collected as the program acquires new

data. Taking these issues into account, the program design includes those factors believed to be

most important in characterizing the biological communities. Testable null hypotheses were

formulated and the appropriate temporal and spatial scales and locations for sampling were

chosen. All of these elements are essential for a full integration of the diverse interdisciplinary

measurement program being undertaken.

4.1 General Design Considerations

Several general principles guided the development of the overall sampling plan.

First, treatments, or in this case similar stations, were chosen that will falsify the null

hypothesis. That is, contrasts that don’t delineate differences were avoided as unproductive. Due

to resource limitations and the large geographic area to be studied, it is impossible to measure

everything, everywhere. However, it is relevant to measure what are judged to be the most

important variables at the most important sites.

Second, pseudoreplication was avoided, i.e., replication is at the treatment level. A

treatment is a factor level, or combination of factor levels, applied to a sampling unit. Sampling

units are stations or replicate samples within stations where all other variables but the variable to

be tested are as similar as possible. The generic form of all null hypotheses is that the treatment

level effect equals zero, i.e., the stations themselves are not fundamentally different by other than

the variable being tested. For example, if each treatment is only represented by a single station,

then in the end you only know that the stations are different, not why the stations are different.

Third, station locations were optimized to test more than one hypothesis. This is a cost

reduction technique. For example, stations along a transect to test for depth differences can be

paired with stations in specific habitats to test a second hypothesis.

Fourth, confounding factors were minimized. A common problem is that more than one

variable is changing at a given station. For example, two stations could differ by water depth,

distance from shore, and distance from the Mississippi River. In the end, you don’t know which

variable (or if an interaction of the variables) is causing the observed differences and thus

generalities are difficult, if not impossible, to discern. Therefore, stations are chosen where

comparisons can be based on differences in a single or related set of variables.

Fifth, balanced sampling designs were used. An uneven distribution of sampling effort

causes distortion of sample means when there is a difference in the number of observations

between the datasets being contrasted.
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Sixth, a design of appropriate power was used. Power is the ability to detect change. The

first five design considerations primarily protect at the α level against Type I errors (rejecting

the null hypothesis when it is true). But, type II errors protected at the β level must also be

considered (accepting the null hypothesis when it is false). Replication must be sufficient to

detect the amount of change that is expected given variations in the variable of interest. A large

multi-factorial design with little replication has many interactions terms that are often

significant, thus limiting the interpretation and robustness of tests for the most important effects.

In this case, previous studies suggest that a minimum of five replicate boxcores were needed at

each station to adequately sample within-station heterogeneity.

Finally, there will be a meta-analysis (or synthesis) in the end. Most programs measure

values for hundreds of dependent variables at hundreds of observational points (be they spatial,

temporal, or random replicates). When assembled in its entirety, this meta-data set contains

information that does not exist within the individual analyses. In-the-end, all of the stations and

replicates are only surrogates for the environmental factors that regulate biological processes

leading to the observed patterns of faunal composition. Therefore, measurements are made

synoptically at locations or subsamples (replicates) are taken within a location so that a metadata set can be created for the synthesis and integration of the overall study results.

4.2 Working Hypotheses and Station Selection

A sampling design is most effectively developed from a series of testable null

hypotheses. The hypotheses are derived from the conceptual model which describes the current

understanding of the system being observed (i.e., deep-sea communities). Hypotheses are then

used to select stations so that the hypotheses are testable with sufficient power to detect

differences in the dependent variables being measured (i.e., abundance, biomass, diversity,

analyte concentrations, etc.). The null hypotheses were based on the current understanding of

deep-sea benthic community structure and function and knowledge of the types of habitats that

occur in the GOM.

The following characteristics are judged to represent a significant portion of the deep-sea

GOM habitat and will be used to identify one area as being different from another:

1) water depth (transects perpendicular to isobaths);

2) geographic location - juxtaposition to the Mississippi River (east-west transects) and

distance from shore;

3) physiographic position - in a basin, in a canyon, on an escarpment, and in a low relief

area;

4) influx of organic carbon - primary productivity derived carbon, petroleum seep and

chemosynthetic derived carbon;

5) energy level of the physical environment - high versus low bottom current velocity,

juxtaposition to semi-permanent physical features (nitrocline, thermohalocline);

6) temporal changes -time series sampling; and

7) location of historical sampling sites.

The sampling design tests hypotheses rather than simply conducting a traditional

geographic survey with closely spaced stations. This approach was adopted to establish
4-3

generalities about communities in the study area and because the area to be covered is so large

that sampling everywhere is cost prohibitive. The hypothesis testing allows a prediction of when

and where particular types of communities, both in terms of structure and function, will or will

not be encountered. Hypothesis testing provides a powerful tool for either increasing or limiting

sampling intensity in time and space as new data is collected and historical data is re-interpreted.

Each hypothesis, as described below, explores mechanisms believed to explain much of the

variation in community structure and function in the deep-sea GOM. Some mechanisms are well

established, others are not.

Based on the above considerations the following kinds of contrasting environments or

habitats were sampled for comparisons:

• Depth.

- Water depth is probably the single most important gradient in determining

faunal compositions and forcing factors in the study area (Hypothesis

HO1). Comparisons were made along a series of transects.

Stations: RW1-RW6, W1-W6, C1-C12, MT1-MT6, S35-S44 (Figures 4.1-4.3)

• Nutrients (organics)

- The input of organic nutrients from Mississippi River discharge causes an

east to west gradient in faunal compositions and forcing factors

(Hypothesis HO2). Comparisons were made along isobaths at similar

distances from shore at varying distances from the Mississippi River.

Stations: RW1-RW6, C1-C12, S37-S42 (Figures 4.1-4.3)

• Basins.

- The common mesoscale basins found on the slope, unless influenced by

seeps, have the same faunal compositions and forcing factors as the

“normal” slope because the entire slope is draped in a similar Holocene

“blanket” of silt and clay within which the biological communities live

(Hypothesis HO3). Comparisons were made within and outside of basins at

comparable water depths and distances from the Mississippi River and

shore.

Stations: WC12, B1-B3, NB2-NB5 (Figure 4.4)

• Canyons.

- Faunal compositions and forcing factors are the same in or out of submarine

canyons (Hypothesis HO4). Comparisons were made between stations within

and outside of canyons at comparable depths and distances from the

Mississippi River and shore.
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Figure 4.1. Benthic survey stations in the northwestern GOM (for regional context see map in

Appendix I of survey cruise track).
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Figure 4.2. Benthic survey stations across the Florida Escarpment (for regional context see

Figure 5.1).

N
4-6

Figure 4.3. Benthic stations along the Mississippi Trough (MT1-MT6). Historical sites from the

NGOMCS study are also included (C1-C14; for regional context see Figure 5.1).
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Figure 4.4. Physiographic settings for benthic survey stations in the Central GOM. Historical

stations from the NGOMCS study are also included (W1-W6, WC-5, and WC-12;

for regional context see Figure 5.1).
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Stations: MT1-MT6, W5, W6, RW6 (Figures 4.1, 4.3, and 4.4)

• Steep Escarpments.

- Faunal compositions and forcing factors are the same on the “normal”

slope as they are at the base of the Sigsbee Escarpment (Hypothesis HO5).

Comparisons were made between stations on the slope and at the base of

the Sigsbee escarpment at similar water depths.

Stations: S39-S42 (Figure 4.2)

• Productivity.

- Cyclonic and anticyclonic features in the surface waters consistently alter

surface primary productivity and this results in differing seafloor fauna

compositions and forcing factors (Hypothesis HO6). Comparisons were

made between stations that underlie areas of historically documented

differences in sea surface primary productivity, holding other variables as

constant as possible.

Stations: RW1-RW6, S35-S36 (Figures 4.1 and 4.2)

• Hydrocarbon Seeps.

- Hydrocarbon seeps have a major effect on energy and carbon supplies

contributing to different faunal compositions and forcing factors

(Hypothesis HO7). This is tacitly true since chemosynthetic fauna are

restricted to seep sites. Rather than a direct test, inputs of chemosynthetic

carbon to the foodweb will be recognized by stable isotopic tracer studies.

Data produced from the chemosynthetic community studies will also be

contrasted with equivalent non-seep data. Explicit testing by paired

stations will not be attempted. Questions of “how close is close” are still

difficult to resolve even in studies concentrated at seep sites. The decision

to address this question in a limited way is in recognition of the fact that

the MMS is already supporting extensive studies at seep sites and that the

primary focus of this program is non-seep environments.

• Temporal Changes.

- Standing crops of benthic fauna vary with time (Hypothesis HO8).

Comparisons were made at a subset of survey stations sampled during

each of the three planned cruise activities. In addition, to provide a longer

timeframe for comparisons, historically sampled sites will be reoccupied.

The intercomparibility of data between studies will be explicitly addressed

to ensure whether inter- program comparisons are valid.
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Stations: W1-W6, WC6, C1-C12 (Figures 4.3 and 4.4)

- The above comparisons have been translated into testable null hypotheses (Table

4.1). A critically important part of program design is selection of the most

appropriate locations to conduct the measurement program to test the hypotheses.

This is especially true for this program because the area to be characterized is

large, the area contains a wide range of habitats and there are several important

forcing factors that tend to confound delineation of cause and effect relationships.

As summarized in the introductory materials, the northern GOM represents one of

the most complex geological and oceanographic settings in the world. The

challenge is to classify wide stretches of the slope into recognizable subregions

that can then be sampled to test if the extant biological communities are different

from area to area. Additional factors explicitly considered during the selection of

proposed sampling sites include the location of historical sampling (to extend

timeseries observations), the current and future trends in energy resource

exploration and exploitation, and possible anthropogenic effects related to

proximity to existing production facilities (primarily accommodated by screening

all locations for contaminants). The study stations are explicitly tied to the

hypothesis testing as listed above.

Table 4.1 Summary of benthic survey experimental design: null hypotheses, station selection

criteria, number (No.) of stations (sta.), and number samples. The number of samples

is based on five replicates per station.

Null Hypotheses Design Criteria No.

Stations

No.

Samples

HO1: Variation in benthic fauna is

explained by depth

3 Replicate transects over 7 depths;

occupy historical stations and others

21 105

HO2: Faunas exhibit an East to West

gradient

Additional transect to HO1; remove

confounding geological effects and

water mass effects

7 35

HO3: Basin faunas are different from

non-basin faunas

3 salt bottom and 3 salt surrounded

basins

6 30

HO4: Canyon fauna is different from

slope fauna

4 Canyons to be compared to noncanyon and non-basin biota from

HO1-HO3

8 40

HO5: Fauna below escarpments

different from slope

Add sta. below escarpment in

addition to HO1- HO4 in area of

furrows

7 35

HO6: Surface primary production

explains faunal differences

Add sta. to (HO1-HO2) in “hot spot”

defined by historical water column

data

7 35

HO7: Proximity to organic input

causes bioenhancement

Add sta. in proximity to

“geochemical anomalies” (hydrates,

brine pools, methane seeps)

8 40

HO8: No variation in benthic fauna

over time.

6 stations (or other elements of the

design, HO1 -HO7) over 2 years

12 60
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Survey stations were chosen to sample the broadest possible range of conditions at depths

between 300 m and 3000 m and within the EEZ boundary with Mexico (see cruise track in

Appendix I and Table 4.1). The site selection spans the range of known conditions providing the

best tests of the hypotheses posed. Thus, sampling occurs along a transect just north of the

Mexican border (RW1-RW6) over to one transect across the Florida escarpment (S37-S42; see

Figures 4.2 and 4.3). This inclusive range of conditions enables us to gain an understanding of

the whole GOM deep-sea benthos, rather than isolated parts. The smooth upper slope of the

northern Florida slope is contrasted with the heterogeneous topography off Texas. A transect

down the Mississippi Trough (MT1-MT6) provides a sampling of the effect of particulate and

nutrient input from a large river (Figure 4.4). The basins on the upper slope can be categorized

according to their structure and how they were formed, testing whether or not physiographic

setting affects the biota (WC12, B1-B3, NB2-NB5; see Figure 4.4). Two locations at the upper

end of the DeSoto Canyon (S36, S35) were chosen because one is frequented by whales and the

other is characterized by high nitrate concentrations semi-permanently in the euphotic zone (see

Figure 4.2).

Experimental, or “process” stations, will then be chosen to reflect the greatest range in

community dynamics, as inferred from the benthic survey data. The survey site selection is based

on inferences about where the greatest variations in community structure will be observed based

on the model. The next step is to place the experimental stations where the greatest ranges in

community structure are actually observed during the study. For example, a comparison of

places with high and low total biomass will be important. Observations of processes, such as

sulfate reduction or aerobic community respiration, will provide comparison of sites where

biogeochemical cycling rates are different. Potential sites at mid-depths in the Mississippi

Trough (C14, C12) are believed to experience high velocity current events below the Sigsbee

Escarpment (Figure 4.4). The central line of the earlier slope study (C1, C7, C4, C14, C12)

appears to be characterized by a seasonal signal in the biotic community (see Figure 4.4). If the

statistical tests suggest that slope basins contain enhanced biomass, then rates of metabolic

processes would be expected to be enhanced as well making a basin a candidate for an

experimental site. Experiments designed to determine the causes of bioenhancement are

considered to be important. The location of experimental stations must allow the community

structure documented during the survey, guide site selection in the context of historical data. The

type and placement of experimental stations will be carefully considered in consultation with the

COTR and the SRB.

The first interim meeting in February 2001 was used to up-date the hypotheses based on

Survey Cruise data, select sites to be repeated, add new sites to strengthen comparisons and

identify sites for process studies. The process sites selected were MT3, S36, S42, and MT6. New

sites to be added were in the furrows below Green Knoll on the top of Green Knoll, a site

between the Mississippi Trough and the DeSoto Canyon, and hear the Bush Hill seep. See

Section 5.3 for a discussion of the new sites.

4.3 Dependent and Independent Variables

Based on the various hypotheses described in the previous section, a series of dependent

and independent variables were chosen that will provide the set of observations at each station to

test the validity of the null hypotheses. Variable selection was based on a knowledge of the
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system being observed, a current understanding of how the system functions, and an estimate of

the relative importance of forcing factors as described in the conceptual model (see Section 4.0).

The set of variables measured at the survey stations are organized around the

characteristics that define the system including physiographic setting, time, water masses,

geographic location, abiotic and biotic water column properties, sediment properties, chemical

contaminants in sediments, indicators of biogeochemical processes, community structure, and

community function (Tables 4.2 to 4.4). These variables also quantify stocks and processes for

input to the model.

4.4 Statistical Analyses

Statistical analyses to test for differences among treatment means are performed using

parametric, general linear models. Prior to analysis, data are transformed, generally by natural

logarithm, to achieve homogeneity of error variance, normality of residual errors, and additivity

of effects. A data set of residual errors is created for each model and tested for normality. Both

untransformed and transformed residuals are computed, and the datasets that are normally

distributed with means of zero are used for analyses.

The models that follow describe the relationships among the independent design

variables only. The measured dependent variables are described in the methods sections. The

notation used follows conventions described by Kirk (1982).

4.4.1 Univariate Analyses

Univariate analyses will be used to test each hypothesis based on the following models.

The stations to be used to test each hypothesis are summarized in Table 4.2.

The first two hypotheses are as follows:

HO1: There is no variation in benthic fauna with depth, and

HO2: There is no difference in fauna along an east to west gradient.

The effect of depth is tested with stations along transects. Multiple transects were

necessary to replicate at the treatment level. Transects should also hold constant nuisance

variables such differences in circulation, bottom complexity, or other physical factors. The effect

of longitude is tested with stations on an east - west gradient along isobaths, so this design tests

two major hypotheses. The experiment is a two-way completely random factorial analysis of

variance (ANOVA) that is described by the following model:

Yijk = μ + αj + βk + αβjk + ∈i(jk)

where Yijk is the measurement for each individual replicate, μ is the overall sample mean, αj is

the main effect for transects and j=1-4, βk is the main effect for depths and k=1-7 (300, 750,

1200, 1650, 2100, 2550, and 3000 m), αβjk, is an interaction term, and ∈i(jk) is the random error

for each replicate measurement and i=1-5.
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Table 4.2. Independent variables fixed by the sampling plan design. 

Physiographic Characteristics

Water Depth

Basins underlain by salt

Basins surrounded by salt

Basins subjected to slumping/erosion

Basins overlain by an undisturbed drape of Holocene silt and clay

Canyons

Escarpments

Proximity to seeps

Basin slope angle

Time

Months

Years

Water Masses

Loop Current

Consistently “cool” water between eddies

Warm eddies

Geographic Location

East vs West

Distance from shore 

Table 4.3. Dependent variables to be measured.

Community Structure

Bacterial density Macrofaunal species composition

Bacterial biomass Megafaunal density

Foraminiferal biomass Megafaunal biomass

Meiofaunal density Megafaunal diversity

Meiofaunal biomass Megafaunal species composition

Meiofaunal composition to major group Fish density

Macrofaunal density Fish biomass

Macrofaunal biomass Fish diversity

Macrofaunal diversity Fish species composition

Community Function

Bacteria growth rates Fish respiration1

Bacteria respiration Fish predation on megafauna2

Bacteria response to different substrates Fish scavenging on carcasses2

Foraminiferal respiration1 Nutrient Regeneration

Foraminiferal feeding rates1 Denitrification rate

Meiofaunal respiration1 Sediment mixing rates (bioturbation)2

Meiofaunal feeding rates on bacteria Sediment accumulation rate2

Macrofaunal respiration1 Sedimentary community oxygen consumption

Macrofauna growth rates2 Sulfate reduction rate

Macrofauna predation rates2 Foodweb studies

Macrofauna predation rates on meiofauna, bacteria, and organic matter

Megafaunal respiration rates2

Megafaunal predation rate on megafauna, meiofauna, bacteria, and organic

matter2

Megafaunal scavenging on carcasses2

1-calculated based on size and temperature

2-estimated from sub-model
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Table 4.4. Ancillary variables to be measured at Survey and Experimental Stations.

Water Column Profiles Sediment Properties

• Depth • Grain Size

• Temperature • Porosity

• Salinity • Elemental composition (organic carbon,

• Oxygen nitrogen, sulfur)

• Nitrate and Nitrite • Percent inorganic carbon (TIC)

• Ammonium • Permeability

• Silicate • Shear Strength

• Phosphate • Bulk Density

• Particulate Matter (PM)

• Particulate Organic Carbon (POC) Geochemistry1

• Light

• Currents • Nutrients

• Dissolved Organic Carbon (DOC)

Biotic Water Column Profile • SO4

=

/Cl-

• Dissolved Inorganic Carbon (DIC)

• Photosynthetic Pigments • δ13C DIC

• Primary Production • Sulfate Reduction Rate

• pH

• H2S

• O2

• Reactive Fe

• Reactive Mn

Chemical Contaminants • Acid Volatile Sulfide

• Hydrocarbons

• Metals

1

Composite sample at survey station, profiles for fluxes at experimental station.

The third hypothesis is:

HO3: There is no difference between basin fauna and non-basin fauna.

Geological complexity exists in the northern GOM. One expression of this complexity is

basins. Basins may cause changes in current flow such that water masses are altered as they pass

across the mouth of the basin or impact a sill. This could affect benthos. One station within a

basin will be paired with two nearby stations already sampled for HO1 and HO2 above to test for

basin effects. Station pairing is necessary to control for distance from shore and depth. For

example, a station selected for HO1/HO2 at 1200 m may have a nearby basin at 1650 m, so stations

generally distant from shore and in the same water depth would be compared against the basin

stations. The entire experiment is replicated at 6 different sites, so each location is a blocking

effect. The experiment is a two-way completely random factorial ANOVA that is described by

the following model:

Yijk = μ + αj + βk + αβjk + ∈i(jk)

where Yijk is the measurement for each individual replicate, μ is the overall sample mean, αj is

the main effect for replicate sites and j=1-6, βk is the main effect for treatments and k=1-3 (basin,
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non-basin same distance from shore, and non-basin same depth), αβjk, is an interaction term, and

∈i(jk) is the random error for each replicate measurement and i=1-5. Differences between sites are

not of interest because they replicate the basin effect, so it doesn’t matter if that test is

significant. The main test of interest is a multiple comparison tests among treatment levels if

there is a significant difference among treatments.

The fourth hypothesis is:

HO4: There is no difference between canyon fauna and non-canyon fauna.

Another form of geological complexity in the GOM is canyons. Often sediment slumping

occurs in canyons in addition to alteration in near-bottom current patterns. One station within a

canyon will be paired with nearby stations at similar depths that are not in a canyon. The entire

experiment is replicated at four (4) different sites. The experiment is a two-way completely

random factorial ANOVA that is described by the following model:

Yijk = μ + αj + βk + αβjk + ∈i(jk)

where Yijk is the measurement for each individual replicate, μ is the overall sample mean, αj is

the main effect for replicate sites and j=1-4, βk is the main effect for treatments and k=1-2

(canyon and non-canyon), αβjk, is an interaction term, and ∈i(jk) is the random error for each

replicate measurement and i=1-5.

The fifth hypothesis is:

HO5: There is no difference between escarpment fauna and non-escarpment fauna.

Another form of geological complexity in the GOM is escarpments. These steep walls

may be different from more gently sloping areas. One station adjacent to the base of an

escarpment will be paired with nearby stations at a similar depth that are not adjacent to an

escarpment. The entire experiment is replicated at 7 different sites. The sites will be chosen

based on pairing stations with samples already taken to test HO1-HO5. The experiment is a twoway completely random factorial ANOVA that is described by the following model:

Yijk = μ + αj + βk + αβjk + ∈i(jk)

where Yijk is the measurement for each individual replicate, μ is the overall sample mean, αj is

the main effect for replicate sites and j=1-7, βk is the main effect for treatments and k=1-2

(escarpment and non-escarpment), αβjk, is an interaction term, and ∈i(jk) is the random error for

each replicate measurement and i=1-5. Depending on exact location of samples, this design may

be altered to take into account distance from shore. In that case, the same model as that used for

basins (HO3) will be used.

The sixth hypothesis is:

HO6: There are no differences in benthos in areas with different amounts of water

column primary production.
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The sites will be chosen based on pairing stations with samples already taken to test HO1-

HO5. The design is nested as a completely random hierarchical design described by the model:

Yijk= μ + αj + βk(j)+ ∈i(jk),

where: μ = overall sample mean, αj = main effect of treatments and j=1-3 (high, medium, and

low productivity), αk(j) = nested effect for replicate stations and k =1-7, and ∈i(jk) is the random

error for each replicate measurement and i=1-5. The appropriate F-test for treatments is to use

the mean square error for stations as the denominator. Another approach to analyze this design is

analysis of covariance, where actual values indicating primary production (e.g., measured values

or chlorophyll standing stock) are used as covariates.

The seventh hypothesis is:

HO7: There is no difference in benthic fauna near and far from seeps.

Another form of geological complexity in the GOM is organic and inorganic inputs in

geochemically anomalous environments, e.g., hydrocarbon or brine seeps. Eight (8) stations are

added to pair with existing non-seep stations. The station pairs will be in 4 site regions. The sites

will be chosen based on pairing stations with samples already taken to test hypotheses HO1-HO6.

The experiment is a two-way completely random factorial ANOVA that is described by the

following model:

Yijk = μ + αj + βk + αβjk + ∈i(jk)

where Yijk is the measurement for each individual replicate, μ is the overall sample mean, αj is

the main effect for replicate sites and j=1-4, αk is the main effect for treatments and k=1-4 (brine

seep, hydrocarbon seep, control for distance from shore, control for depth), αβjk, is an interaction

term, and ∈i(jk) is the random error for each replicate measurement and i=1-5. Differences

between sites are not of interest because they are replicating seep effects, so it doesn’t matter if

that test is significant. The main test of interest is a multiple comparison test among treatment

levels if there is a significant difference among treatments.

The eighth hypothesis is:

HO8: There are no differences in benthic fauna among different sampling dates.

Six of the stations sampled for HO1-HO7 will be chosen for reoccupation in years 2 and 3

so that there will be a time series for at least 3 years. In addition, attempts will be made to

include several stations that were occupied in previous studies, extending the time series to 5 or

6 sampling periods. Assuming depth and site (i.e., east-west) gradients, these two factors must be

incorporated into the design. The experiment is a three-way completely random factorial

ANOVA that can be described by the following model:

Yijkl = μ + αj + βk + αβjk + γl + αγjl + βγkl + αβγjkl + ∈i(jkl)
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where Yijkl is the measurement for each individual replicate, μ is the overall sample mean, αj is

the main effect for sampling periods and j=1-3, βk is the main effect for sites and k=1-2, γl is the

main effect term for depths and l=1-3 (shallow, mid-depth, deep), αβjk, αγjl, βγkl, and αβγjkl are

interaction terms, and ∈i(jkl) is the random error for each replicate measurement and i=1-5.

Hypotheses will be re-evaluated as data is collected and recast as needed. Year II and III

will provide the opportunity to collect additional new survey station if needed to infill the dataset

to increase the power of statistical tests.

4.4.2 Power Analysis

Power analysis is performed to determine the detectable change in the population at a

given power (1−β) and sample size (n) Power is calculated by:

X

n

2 (t t ) x SD x α + β

∆=

where ∆ is the percent change in the population, SD is the pooled standard deviation, tα and tβ

are tabled values for a two-tailed test assuming a pooled estimate of variance from a large

sample size, and X is the sample mean. Values of α=0.05, and powers of 0.95, 0.80, 0.50 were

used in the analysis.

4.4.3 Multivariate Analyses

A meta-analysis (or synthesis) will be performed at the end of the study. The goal of the

synthesis is to merge all data sets of response variables to create one large data set. All the

ANOVA’s listed above can be analyzed in multivariate mode (MANOVA) to test the null

hypothesis that the vector of population means equals zero. Without the jargon, test to find out if

all measured variables respond to the dependent variables in the design in a similar fashion. The

advantage of MANOVA is that multivariate error is controlled. That is, error rates are controlled

at α across all response variables.

Once the meta-data set is assembled other questions can be queried. It can be tested if

benthic fauna respond to abiotic environmental factors and which factors control distributions of

responses. As stated previously, all stations and replicates are simply surrogates for the

environmental factors that regulate biological processes at different scales. These scales vary

greatly from small- (replicate boxcores), meso- (across transects, basins, or nearby stations) to

large- (across the entire GOM). In addition, there is a temporal scale to the variation in all

measurements. Multivariate analysis can be used to test the meta-data set for correlation or

covariation among the independent variables that are measured. Two multivariate techniques

will be employed: a parametric method (principal components analysis, PCA), and a nonparametric methods (multidimensional scaling, MDS).

Multidimensional scaling is a non-parametric multivariate technique for examining

similarity or dissimilarity between stations, replicates, or other dependent variables in the

experimental design. First, a similarity or dissimilarity index is computed for elements of the

design (e.g., stations) and then a plot of the distance among points is created. The plot enables us

to identify unknown variables that affect the similarity or dissimilarity between stations. Because
4-17

the MDS procedure is based on non-parametric (Kruskal-Wallis like) models, it is very popular

among European benthic ecologists, but has rarely been used among American benthic

ecologists. It is most useful to summarize biotic data (e.g., community structure), but new

variables are not created, nor can one reduce the variables in a dataset.

Principal components analysis is a parametric variable reducing technique that makes a

new set of uncorrelated variables in order of decreasing variance. Analysis of abiotic variables

can be used to summarize the co-varying environmental influences on different levels of

replications, i.e., different spatial and temporal scales. Factor loading scores are generated for

abiotic summaries of observations (rows), which can be used in other analyses. For example,

during GOOMEX several hundred environmental variables were reduced with PCA and the new

PCA scores were shown to correlate with average macrofauna and meiofauna abundance and

toxic responses. This allowed us to detect subtle sub-lethal effects within 100 m of platforms that

could not be detected with univariate analysis of variance (Green and Montagna 1996). Also, the

methods demonstrated functional responses of benthic fauna to abiotic variables, while

separating confounding influences in the study related to differences in the natural background in

which platforms were located. The same approach will be used in the deep-sea study to provide

an understanding on how environmental influences regulate benthic communities.

4.5 Revision of Taxonomic Level of Analysis

Analysis of benthic infaunal communities has been widely used in environmental

assessment and monitoring studies. The use of species level data is powerful, but expensive due

to the level of expertise and labor intensive effort required. This has inspired efforts to determine

if species level data is really necessary. For both meiofauna and macrofauna, a promising

prospect is identification to only the suborder or family level. At the Group of Experts on

Effects of Pollutants (GEEP) workshop, all levels of biological organization were studied from

the molecular to the community, and all biological components from bacteria to macrofauna

were included in both mesocosm and field experiments (Bayne et al. 1988). In the GEEP field

study, diversity indices did not detect the pollution gradient, but community structure differences

were distinct and species level data gave no more information for discrimination than did

nematode suborder or harpacticoid family groupings (Heip et al. 1988). Macrofauna family

groupings also were just as good for distinguishing the pollution gradient as was species level

data (Warwick 1988). Higher level identifications were found to be just as good as species

identifications to detect pollution gradients in the Southern California Bight (Ferraro and Cole

1990). During the GOOMEX study around Gulf of Mexico production platforms, it was not

sufficient to analyze at the family level for either meiofauna or macrofauna to describe

differences among platforms or distances from platforms (Montagna and Harper 1996). LGL

data and Year I sampling data will be reanalyzed at both species and family levels to determine

if a reduction in taxonomic effort is adequate to characterize communities in different

environmental settings.
5-1

5.0 THE FIELD PROGRAM

The Field Program was designed to collect a range of discrete samples and deploy

continuous measuring sensors at a large number of stations in the northern GOM. The Field

Program includes three cruises in each of the first three years of the program. The first cruise

concentrated on the benthic survey objectives of the program and the following two cruises will

be a mixture of survey and experimental stations. The survey field effort (Cruise I) included

boxcoring, trawling, photosurveys, and hydrocasts. Experimental stations (Cruises II and III)

will include a variety of specialized sampling efforts designed to identify important processes

and forcing factors at a limited number of selected survey stations.

In brief, the cruises and their objectives for the first two field seasons are as follows:

Cruise 1: Ship - R/V Gyre; Chief Scientist - Dr. Gil Rowe; Conducted May 3 to June

21, 2000. The cruise report is attached as Appendix I.

Cruise 2: Ship - R/V Gyre; Chief Scientist - Dr. Gil Rowe; Schedule - June, 2001;

Duration 20 days; Activities - 12 survey stations (60 boxcores, 12 trawls, 12

CTD/hydrocasts, 12 photosurveys) and 4 experimental stations (20

boxcores, 4 trawls, 4 CTD/hydrocasts, 4 photosurveys, 4 ADCP casts,

microbiological process studies, 4 benthic lander deployments, 4 pore water

and solids geochemical studies, 4 stable isotope food web collections, and 4

specialized biological/ecological studies), Staffing - 23 scientists, students

and observers.

The details of the field and laboratory methods are provided in Sections 6.0 and 7.0.

5.1 The Ship

A critical factor in ensuring the successful completion of the field program is selection of

a ship of the proper size and capabilities to conduct the required sample and data collection

activities in the deep-sea. The ship must accommodate a scientific party of adequate size to

accomplish the sample collection and processing plan. In addition, adequate laboratories, deck

handling equipment and electronics and workshop facilities must be available to support the field

operations and to respond to any adverse conditions or equipment breakdowns encountered in

the field. The chosen ship, the R/V Gyre, is owned by Texas A&M University and operated by

the Department of Oceanography of Texas A&M University. The homeport of the Gyre is at the

Texas A&M University at Galveston Pelican Island campus. The shore support facility is

equipped to assist in mobilization and demobilization of cruises and includes a port

administrative staff, a dock area, and a warehouse/machine shop complex. Several forklifts and a

mobile crane are available at the water front for handling equipment.

The R/V Gyre was built for the US Navy by Halter Marine Services of New Orleans, LA.

The ship was launched in mid-1973 and began research operations in early 1974. The vessel was

extensively remodeled in 1980-1984 with the addition of a new deckhouse. The Gyre is a

general-purpose, open-ocean research vessel. The deck plans and diagrams of the ship can be

accessed at the ships URL:

http://www.ocean.tamu.edu/Cruise/plns.html
5-2

5.2 Cruise I - Survey (Figure 5.1; Table 5.1)

Cruise I was devoted to a survey of deep-sea communities of the northern GOM. Each

standard survey station consisted of the following activities:

A. One (1) CTD: The CTD was deployed with the starboard hydrowinch using

conductor cable (the CTD remains attached to the conducting cable for the entire

cruise, unless problems are encountered);

B. Five (5) Boxcores: The boxcore was deployed with the hydraulic winch on the nonconducting cable. A pinger was attached to the wire above the boxcore at depths of 1

km and greater. Otherwise wire out and tension was adequate to determine bottom

contact.

C. One (1) Camera Lowering: The camera system was deployed with the nonconducting cable on the starboard hydrowinch. A pinger was attached to the frame to

determine bottom contact and distance to the bottom. The camer takes up to 50

exposures.

D. One (1) Bottom Trawl: The otter trawl was deployed with the heavy-duty winch on

the fantail.

The shipboard scientific crew operated on watches of 12 hours on and 12 hours off.

Between stations, the trawl samples were sorted to species and fixed in jars by those assigned to

trawling. The five sievers on watch fixed and bottled the material and then assisted with the

trawl sorting, displacement volume measurements (for biomass), preservation and labeling.

Shipboard marine technicians analyzed samples for oxygen, nutrients, and salinities between

stations.

Each watch was assigned a “watch chief” (Clif Nunnally and Chris Gudeman) who had

the duty of keeping records, notifying the Chief Scientist when problems arose, notifying the

watch when the ship was on station, waking the new watch at the appropriate hour, and notifying

the bridge when station activities were completed. The watch chief maintained a log in the main

laboratory on the main deck that documented each activity in chronological order. Comments on

the success or failure of the activity and inventory of all samples taken were kept. The watch

chief and assistant ensured that the station logs on the bridge agreed with those in the laboratory.

Each “watch chief” reported directly to the Chief Scientist. The “watch chief” communicated

between the bridge and scientists on the deck.

5.3 Cruise II - Processes (Figure 5.2)

Plans for the first processes cruise were made during the first interim meeting in February

2001. The plans were made on the basis of findings to date. Extremes of high and low densities

in bacteria, meio- and macrofauna were used for selection criteria. The sites chosen were MT3,

S35, S42, and MT6. High densities characterized MT3 and S36 at 1000 and 1850 m depth in the

Mississippi and DeSoto Caynons, whereas low densities were found at S42 and MT6 at 750 and

2750 m depth.
5-3

Figure 5.1. Benthic survey stations for Cruise I, May and June, 2000.
5-4

Table 5.1. Summary of sampling conducted during Cruise I.

Station Trawl Boxcore Camera CTD

RW1 1 5 1 1

RW2 1 5 1 1

RW3 0 5 1 1

RW4 0 5 1 1

RW5 0 5 1 1

RW6 1 5 0 1

AC1 0 5 1 2

W6 1 5 1 1

W5 0 5 1 1

W4 0 5 0 1

W3 1 5 1 1

W2 0 5 1 1

W1 1 5 1 1

WC5 1 5 1 1

WC12 0 5 1 1

B1 1 5 1 1

NB2 1 5 1 1

NB3 1 5 1 1

B2 3 5 1 1

NB4 1 5 0 2

B3 1 5 1 0

NB5 1 5 1 1

C12 1 4 1 1

C14 1 5 1 1

C4 1 5 1 1

C7 1 5 1 1

C1 1 5 1 1

S36 1 5 1 1

S37 1 5 1 1

S38 1 5 1 1

S35 1 5 1 1

S44 1 5 1 1

S43 1 5 1 1

S42 1 5 1 1

S41 1 5 1 1

S40 1 5 1 1

S39 1 5 1 1

MT6 1 5 1 1

MT5 1 5 1 1

MT4 1 5 1 1

MT3 1 5 1 1

MT2 1 5 1 1

MT1 1 5 1 1
5-5

98 W 97 W 96 W 95 W 94 W 93W 92 W 91 W 90 W 89W 88W 87 W 

25 N

26 N27 N28 N29 N30 N31 N

GALVESTON

MT1

MT3

HiPro

S42

S41

S36

MT6 GK(Furrow)

GK(Top)

C7 Bush_Hill

GALVESTON

DGoMB Cruise Track 01-19 June 2001 

Contours shown are 200, 1000, 2000, an

Figure 5.2. Sampling sites during Cruise II, the first “processes” cruise, June 1-19, 2001. Sites MT3, S36, 

designated as experimental sits.
5-6

Other sites chosen for repeating were MT1 (Ho4-canyon), C7 (Ho8-time), and S41 (Ho5-

escarpments). New sites added were “HIPRO” (Ho6-surface productivity), “furrows” (Ho9-

effects of furrows), “Green Knoll” (Ho10-positive topographic anomalies), “Bush Hill” (Ho7-

seeps), and “Fe Stone” (Ho11-iron crust).

Eleven sites were occupied during Cruise 2 (Processes; Figure 5.2). The lander was used

successfully at S42 and MT3, providing estimates of total community respiration rates measured

in situ. Shipboard incubations were made of total community oxygen uptake, sulfate reduction,

thymidine incorporation into bacteria and bacteria grazing by meiofauna at four sites: MT3, S36,

S42, and MT6. The experiments and the survey samples are being worked up at this time. Some

of the preliminary findings will be presented at the annual Information Transfer Meeting (ITM),

the Second Team Planning Meeting, and the Second Interim Report.

5.4 Third Year Field Activities

After the initial draft of this report, the original field work plan was altered. The original

plan called for a single cruise of 20 days in June 2002. The new plan calls for two principal trips

of 15 days each in June and August 2002. These will be into the Mexican EEZ on the Sigsbee

Deep abyssal plain at depths of 3400 to 3650 m. The locations have been chosen on the basis of

negotiation with collaborating Mexican scientists (Figure 5.3).

The first of the two will emphasize processes with use of the lander, ADCP mooring, and

baited trap/camera array. Although the usual survey site sampling will be conducted to

supplement and fill in the sampling, the survey activities will be emphasized on the August trip.

Likewise, if any of the process or experimental measurements were missed, due to equpiment

failture, weather, etc., they they will have the opportunity to be inserted into the latter field

program. Both these trips will work principally in deep water.

In addition to this deep work, two short shallow trips will be made on transits from other

work in the eastern gulf back to Galveston. These will allow sampling at those sites that have

particularly rich biological communities. Placing them earlier in the overall schedule enhances

our ability to stay on schedule. This allows us to take winter/spring samples of locations that are

suspected to vary seasonally. The opportunity will also be taken to make up a lander site missed

on Cruise II (site S36).
5-7

98 ̊W 97 ̊W 96 ̊W 95 ̊W 94 ̊W 93 ̊W 92 ̊W 91 ̊W 90 ̊W 89 ̊W 88 ̊W 87 ̊W 8

23 ̊N24 ̊N25 ̊N26 ̊N27 ̊N28 ̊N29 ̊N30 ̊N31 ̊N

GALVESTON

Low_Currents_1Sigsbee

Low_Currents_2

Iron_Stone

High_Currents

MT6

C7

GALVESTON

DGoMB Proposed Modification 3 (est. 15.6 days)

DGOMB 05-20 June Time Frame, Today is 02-Aug-01

Figure 5.3. Proposed locations for two remaining cruises into the Mexican EEZ, June and Augus
6-1

6.0 FIELD METHODS

The Field Program is designed to collect a range of observations at survey and

experimental stations. Survey stations are characterized by measuring a set of biological,

chemical, sedimentological, hydrographic, and oceanographic variables. Samples and data are

collected from the sediments, at the sediment-water interface, and in the overlying water column.

At experimental sites, all standard survey variables are measured but in addition, fluxes are being

measured to provide information about rates of metabolic processes.

6.1 Standard Sampling Techniques

As mentioned above several standard techniques such as coring, trawling, photosurveys,

and hydrocasts are the techniques of choice to collect various types of samples and data.

6.1.1 Boxcoring

A 0.2 m2

 GOMEX or Gray-O’Hara boxcore (Boland and Rowe 1991) was used for the

sampling on the Survey Cruise. Original plans called for the use of a USNEL Spade Corer

outfitted with “vegematic” inserts. A comparison of sampling effiency prompted the boxcoring

team to switch devices. Instead of the vegematic inserts, the boxcore was equipped with a cross

bar onto which core liners of various diameters and lengths could be attached conveniently with

hose clamps. Routinely the boxcoring team attached six (6) such subcores to the cross member.

On return to the surface, caps were placed on the tops of the core liners to prevent

contamination. Surface water was siphoned off through a 300 micron sieve. Then the surface 15

cm of sediment was removed for sieving for macrofauna. Once this surficial 15 cm was

removed, the individual subcores were capped on the bottom, the hose clamps were opened, and

the core liners were removed. Excess mud on the liners was washed through the 300 micron

sieves to prevent loss of macrofauna.

The six subcores were used for meiofauna, bacteria, geology, geochemistry, and

contaminants. All six subcores were taken on all five boxcore replicates at each station. The

original proposal called for mixing these into a single sample for analysis of each of the

variables. It was decided not to mix the samples but to initially analyze a single replicate and to

archive the other cores. In that way, if odd or interesting values are observed in the single

replicate, the whole suite of replicates from the other cores at each site are available for further

measurements (Figure 6.1).

6.1.2 Trawling

Megafaunal invertebrates and fishes sampled were with bottom trawling, and bottom

photography. Trawling was conducted using a 40' otter trawl with 2.5” stretch mesh. These types

of trawls have been extensively employed during similar studies (Haedrich and Rowe 1977;

Haedrich et al. 1975, 1980). Steel doors or conventional 7’ x 14’ wooden doors were used on a

single warp (shrimp trawlers use a double warp with two wires). The trawl is lowered at a rate of

25 m of wire/minute. When the trawl is on the bottom, the vessel increases speed parallel to the

isobaths (or into the wind or surface current, if this is required to control the vessel's position

relative to the wire and its angle with the surface) up to a speed of approximately three to four
6-2

Arrive on Station

Record Station

Parameters

Water Column

Sampling

CTD

Niskin

Rosette

Quantitative

Boxcore

Sediment

Properties

Contaminant

Chemistry

Geochemical

Properties

Relocate

Evaluate

Acceptability Reject

Accept

Quantitative

Subcores

Enter Sample

Information

Biotic Samples

Ship to

Laboratories

Figure 6.1. Schematic of quantitative boxcore station activities and sampling protocols.

Foraminifera

Ship to

Laboratories

Process

and Store

Process

and Store

Process

and Store

Process

Process

Enter Sample Information &

Siever’s ID

Meiofauna

Sievin Macrofauna

Process

and Store

Water

Chemistry

Microbiota
6-3

knots. A DGPS fix is made at this point. As the trawl is pulled, the wire is gradually paid out

until the "wire out" is approximately 1.5 to 2 times the water depth. Steaming continues until the

total bottom time is equal to 30 minutes per 1000 m of water depth. That is, at 3000 m the

bottom time would be 1.5 hours. At the end of the bottom time, another DGPS fix is taken to

give over-ground distance traveled by the trawl. The trawl is then retrieved at speeds less than 50

m/minute. Samples retrieved by trawling were processed for standard survey work elements

(Figure 6.2).

6.1.3 Photo-Apparatus

A Benthos digital camera, with a strobe, was utilized to take up to 50 photographs of the

seafloor. The camera was actuated by a bottom contact switch in order to assure that the same

area of sea bottom was photographed with each exposure at each station.

6.1.4 Water Column Profiles

CTD/rosettes casts were taken at all survey and all experimental stations (Figures 5.1 and

5.2). At each station, the CTD/rosette collects continuous vertical profiles of seawater

conductivity/salinity, temperature, pressure, light transmission, light penetration, optical

backscatter and fluorescence and trip Niskin-bottles are tripped to collect discrete water samples

for dissolved oxygen, nutrients, particulate organic carbon, suspended particulate matter, and

phytoplankton pigments. Salinity was measured on discreet bottle samples at selected depths to

calibrate the conductivity sensor. Sampling is from the surface layer to as close to the bottom as

can be safely accomplished with the CTD/rosette package and an acoustic pinger to determine

depth off the bottom. A 24-bottle rosette was used. Bottle samples were closely spaced near the

sediment/water interface as well as near the sea-surface.

All sampling was conducted to the same standards and using the same types of

equipment and personnel as employed on the MMS-sponsored programs LATEX-A and

NEGOM. A SeaBird Model 911plus CTD and a General Oceanics rosette with Niskin bottles

were the equipment of choice. An altimeter allowed safe lowering of the package to within a few

meters of the bottom. In vivo fluorescence was measured by a submersible fluorometer. Light

penetration was measured as downwelling irradiance with a Biospherical Instruments, Inc.

Model QSP-200L irradiance profiling sensor. Light transmission was measured with a SeaTech

25 cm transmissometer. Additionally a D&A Instruments and Engineering optical backscatter

sensor provided continuous profiles of particle scattering. The CTD equipment and a complete

back-up system was onboard.

In addition, a downward-looking Acoustic Doppler Current profiler (ADCP) was

deployed to the seabottom at the beginning of each experimental station. The ADCP recorded

bottom currents for the duration of each experimental station. The equipment of choice is a 300

kHzWorkhorse ADCP from RDI, model 300S Sentinal rated to 6000 m. The ADCP measures

horizontal currents at 0.5 to 2.0 m intervals in the lower 50-90 m of the water column to define

short-term variability in bottom currents. The instrument was equipped with a syntactic foam

collar for floatation, weighted with expendable anchor material, and released using two Benthos

acoustic releases. The backscatter data from the bottom-mounted ADCP will be used to
6-4

Arrive on Station

Record Station

Parameters

Benthic Trawl

Relocate

Evaluate

Acceptability Reject

Accept

Rough Sort

Enter Sample Information

& Sorters ID

Vertebrate

Samples

Biomass and Numbers Determined to

Lowest Possible Taxon

Invertebrate

Samples

Laboratories &

Data Management

Figure 6.2. Schematic of trawl station activities and sampling protocols

Label, Fix,

and Store

Label, Fix,

and Store

Refuse

Count, Identify,

and Photograph
6-5

quantify the temporal variability of the bottom nepheloid layer during experimental stations. The

boundary layer advection and dispersion (mixing) rates will be used in a model of the “domain

of occupation” of scavengers caught in baited traps (see below).

6.2 Community Structure

A wide variety of community structure measurements were made at the survey stations

(Table 4.2) In order to provide quantitative information for the conceptual model, all important

taxa were sampled including the microbiota, meiofauna, macrofauna, megafauna, and fishes.

Each type of assemblage was sampled by different techniques that provide the best chance to

quantitative sampling of the community. In some cases, multiple techniques are being employed

as a cross-check (e.g., trawling, photosurveys and trap baiting for megafauna) and to provide

complementary data from the same community. Each type of sample has specific field collection

and processing techniques that are widely used and accepted as standard protocols. These

protocols are described below.

6.2.1 Bacteria

Immediately upon boxcore retrieval shipboard, the temperature of the overlying seawater

and the sediments was determined with a metal thermometer inserted in the sediment.

Determining the temperature is important in evaluating the integrity and utility of the recovered

sediment for measuring microbial activity under simulated in situ conditions.

For bacterial counts, the sediment subcores were extruded and sliced, using aseptic

techniques, at predetermined depth intervals. The subsamples were fixed in a final concentration

of 2% formaldehyde, prepared in a sterile, particle-free (0.2 um filtered) solution of artificial

seawater (ASW) and stored (and shipped) in the dark at 4oC for shore-based analysis.

6.2.2 Protozoa (Foraminifera)

Five replicate subcores were obtained from the boxcorer at each experimental station to

measure foraminifera biomass. The cores were vertically sectioned at 0-1 cm, 5-6 cm, and 10-11

cm for analysis. Foraminifera densities at depths greater than ~10 cm were low and thereby

precluded analysis in deeper sections. When feasible, individual organisms were sorted on shipboard, so the samples did not need to be preserved.

6.2.3 Meiofauna

Two core samples were taken from each boxcore sample, and stored for meiofaunal

community analysis. Meiofauna were collected by a core tube (5.1 cm i.d.) that was mounted

inside the boxcore. A mounted corer within a box will ensure that meiofauna are collected from

an undisturbed surface. Insertion of a core tube after the sample has already been sloshed around

the deck of the ship is known to create artifacts including loss of organisms. Surface disturbance

can occur when the boxcore is placed on the ship’s deck. Taking the sample from an inner

subcore reduces edge effects (Eckman and Thistle 1988). The bow waves of sampling devices in

deep water can have an impact on estimates of surface dwelling meiofauna (Hulings and Gray

1971).
6-6

The two critical sampling issues for meiofauna were core size and sampling depth. A 1.9

cm diameter core tube (2.8 cm2) was used during previous MMS projects, e.g., Santa Barbara

seeps (Montagna et al. 1989), CAMP (Montagna 1991), and GOOMEX (Montagna and Harper

1996) sampling programs. A 3.5 cm i.d. core was used to collect meiofauna in the NGOMCS

study (Pequegnat et al. 1990). Densities in the deep-sea Gulf of Mexico are low (Table 1), so a

large core must be used. About 80% of the meiofauna were in the top 4 cm of sediment. A

sampling depth between 2 and 6 cm was used in seven of nine deep-sea studies reviewed by

Thistle et al. (1991). The NGOMCS study (Pequagnat et al. 1990) sampled to a depth of 5 cm.

To resolve these two issues, a study was performed during the shakedown cruise (16-18

February 2000) to determine the most appropriate core size and vertical sampling depth for

meiofauna in the current study area. To compare sizes, four cores ranging from 2.2 to 6.7 cm

inner diameter (i.d.) were used to collect the top 1 cm of sediment, and five replicates were

taken. To exam the vertical distribution of meiofauna, a 5.1 cm core tube was used. Samples

were taken at 1 cm intervals down to 20 cm, and five replicates were taken. All samples were

taken at station W-2 in water depths of about 661 m.

More organisms were found in progressively larger cores (Table 6.1). But, there was no

statistically significant differences for abundances of total meiofauna, nematodes, harpacticoids

and other taxa among different core sizes. Although total abundance in the smallest core was

about half that found in the three larger cores, it was not statistically different. Because each core

yielded the same abundance estimate, total counts per core were used to choose the appropriate

core size. For statistical purposes, it is imperative to obtain > 30 organisms in a taxon per

sample. Therefore, the 5.1 cm core was chosen for the benthic survey.

Table 6.1. Effect of core tubes size (inner diameter) on meiofauna counts and average density.

Based on five replicates taken at station W-2. Abundance is detransformed from ln,

so taxa averages do not sum to the total average.

Counts (n/core) Abundance (n/10 cm2)

Core Size (cm i.d.) 2.2 3.1 5.1 6.7 2.2 3.1 5.1 6.7

Taxa

Nematodes 20.2 64.8 161.0 219.0 31.3 59.4 50.5 54.3

Harpacticoids 5.4 30.8 74.2 99.4 2.3 26.1 20.8 24.4

Nauplii 7.2 38.6 72.2 85.6 0.2 29.2 22.9 19.0

Others 12.2 14.0 27.8 45.8 3.6 14.5 8.5 10.6

Total 45.0 148.2 335.2 449.8 54.0 135.7 111.3 112.2

There were no meiofauna found below 13 cm sediment depth, so just the top 13 cm are

plotted (Figure 6.3). Most organisms were found in the top 3 cm. A total of 87% of total

meiofauna were in the top 3 cm, and 97% of the harpacticoids. In addition, 77% of the

harpacticoids were found in the top 1 cm. Because the distribution is so skewed to the surface, it

was decided to sample the top 3 cm only during the benthic community survey cruise. Because

harpacticoids were so restricted to the top 1 cm, the core was split into 2 sections: 0-1 cm and 1-

3 cm.
6-7

Total Meiofauna (n/section)

0 100 200 300 400

Section Depth (cm)

0

2

4

6

8

10

12

14

Nematoda (n/section)

0 50 100 150 200

Section Depth (cm)

0

2

4

6

8

10

12

14

Harpacticoida (n/section)

0 20 40 60 80 100

Section Depth (cm)

0

2

4

6

8

10

12

14

Figure 6.3. Vertical distribution of meiofauna taxa for Cruise I. Average of 5 replicates.
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After the sections were collected, the meiofauna were relaxed in 7% MgCl2 and

preserved in an equal volume of 10% buffered formalin (yielding a final concentration of 5%

formalin) (Hulings and Gray 1971). The buffered formalin was made up with seawater that was

filtered through a 0.042 mm mesh to exclude plankton. Rose bengal was added to the

preservative to distinguish cytoplasm-containing foraminifera from empty foraminiferal tests

(shells).

6.2.4 Macrofauna

Macrofauna were sampled from five (5) replicate boxcores per station. Sieve size was

300 microns. Sieving, a critical stage in macrofauna analysis, was conducted using the gentle

floatation method developed by Howard Sanders of the Woods Hole Oceanographic Institution

(WHOI). A set of five (5) sieving stations were constructed, one for each replicate boxcore

sample. Sievers were limited to experienced biologists. One was assigned to each core. The top

15 cm of each boxcore surface was copped out and deposited into a 50 gallon plastic trash can.

Sea water, filtered with an in-line water filter to remove surface water organisms and particulate

matter, was allowed to flow by hose into the bottom of the can with the sample. The trash cans

are mounted in an adjustable frame, referred to as the “tipper” constructed of marine-grade

plywood. The water flows into the trash can, through the sample at the bottom of the can, and out

a 20 cm long, 3 cm diameter spout 20 cm from the top of the can. On exiting the spout goes

immediately into a sieve, which is held in place by an adjustable sieve holder also constructed of

marine grade plywood. This process floats the animals out of the sediments and onto the sieve

with the least possible trauma. This is a critical step because severe losses of animals can occur.

Each siever signed the boxcoring deck log and entered comments in the margin on sample

quality at the end of the sieving process. The samples were fixed in 10% formalin with sea water

that was filtered as above. Rose Bengal was added to aid in rough sorting in the laboratory. On

return to the laboratory, the formalin-Rose Bengal solution was changed to a 70% EtOH

solution. At this point, the samples are more or less permanently preserved.

6.2.5 Megafauna and Fishes

6.2.5.1 Trawl Samples

Once onboard, the trawl sample was removed from the net and placed in large plastic

tubs (Figure 6.2). Organisms were then sorted to species to the best of sorters' abilities. Each

species was counted, its displacement volume determined, and each individual’s length was

measured and recorded. The samples, sorted by species, were placed in ziplock bags or small

plastic jars, labeled with indelible solvent proof labels, and preserved in 10% formalin and

seawater solution. All species were stored together in five gallon plastic containers covered with

tight plastic lids. For fishes, the body cavity of the larger individuals were opened to enhance

fixation. Trash was separated out and stored in separate five gallon plastic containers. Larger

items were photographed and discarded or saved for disposal on land.

6.2.5.2 Photosurveys

The purpose of the camera lowerings was to quantify the megafauna. This is important

because the megafauna are an explicit component of the conceptual model of the ecosystem. If

the biota are abundant, then good estimates can be made with few exposures. For example, it has
6-9

been demonstrated that from the upper slope down to the lower slope, on the order of 30 or so

exposures, each covering an area of six square meters, is adequate to quantify the dominant

megafauna (Rowe and Menzies, 1969; Grassle et al. 1975). At lower densities, more exposures

are required. During the NGOMCS study, approximately 48,000 photographs were taken, but

only 25% of them were ultimately analyzed. A digital camera was used so that the images could

be easily scanned upon system retrieval. The images are also easily electronically transmitted

and archived on CD ROMs.

6.3 Community Function

In addition to the standard set of analyses performed at all survey and experimental

stations, a series of specialized studies are being conducted at experimental stations to develop a

better understanding of important forcing factors and transfer functions at the sites being studied.

These studies will be conducted on samples provided by the standard set of techniques and

equipment, specialized sampling protocols, and gear lowerings. These methods have been used

during Cruise II and will be employed during all future field work.

6.3.1 Microbial Metabolism

For microbial activity measurements, subsamples from three sediment depths per boxcore

(per station) will be diluted in artificial seawater to prepare sediment slurries for homogeneous

amendment with the desired radiolabeled substrates. Separate aliquots, in duplicate, will then be

incubated and sacrificed at each of five time intervals to develop rate measurements of substrate

respiration and incorporation into biomass. Such sediment slurries provide an upper bound on

microbial activity due to the oxygenation and disruption of microniches caused by sample

retrieval. Cross-site comparisons will be important.

6.3.2 Sediment Community Oxygen Demand

A key component of the experimental studies is the measurement of total sediment

community oxygen demand using the benthic lander and in situ chambers (Figure 6.4). The

GOMEX (for Gulf of Mexico) lander is designed to estimate fluxes of oxygen and metabolites

into or out of the sediments by incubating the bottom water and sediment surface in enclosed,

stirred chambers. Thorough descriptions of the GOMEX lander have been published in Pomeroy

et al. (1991), Rowe et al. (1994), and Miller-Way et al. (1994).

The GOMEX lander, as used in this study, consists of a square aluminum-pipe frame

measuring 2 m on a side. This frame holds 1) two acrylic incubation chambers, 2) a multifunction electronic timed release system, with “burn wire” release mechanisms, 3) a deep-sea

multishot camera and strobe system, 4) two disposable anchor weights, and 5) glass floatation

balls. The two chambers each contain an oxygen sensor and thermistor, a submersible pump, an

additional stirring motor, and three 60 cc hypodermic syringes. Each chamber encloses a

sediment surface area of 906 cm2

 under a volume of seven liters of bottom water. A stirring bar

inside the chamber is driven by a magnet attached to an electric motor in an oil-filled water-tight

case outside the chamber. The camera and strobe are attached to the frame opposite the chambers

to monitor proper contact with the sediments and syringes. Two disposable anchors (totaling 200

lbs) composed of cylinders of lead are dropped under the control of the electronic
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Figure 6.4. Benthic lander.
6-11

timed release, with corrosive links of variable duration as a backup. Relocation on the surface is

aided by a flag, two radio direction finders and a strobe flasher. The chambers remain on the

bottom for periods of 8 to 36 hours.

The sequence of events for this “free vehicle” involves floating to the bottom and then

undergoing a series of programmed mechanical operations that are controlled by an electronic

timer that burns release wires on command. The chambers incubate bottom water from which

metabolic substrates are consumed and into which metabolic by-products are produced. The

fluxes are calculated as:

area x time

(Change inConc.) x Vol. Flux =

6.3.3 Foodweb Studies - Stable Isotopes

Organism tissues are being selected by the biologists for stable isotope analysis for the

foodweb studies. The tissue is excised or the organism is frozen whole at -4oC.

6.4 Sediment Properties

Subcores for sediment properties were taken from each of the five replicate boxcores.

These were not pooled but are separately stored. The top two centimeters were sampled using a

spatula or scoop. Shear strength is being measured in the shorebased laboratory.

6.5 Chemical Contaminants

Subcores for trace metals and hydrocarbons were taken from each of the five replicate

boxcores. The subcores are extruded and the upper 2 cm of the sediment is sectioned with a

teflon-coated spatula. Total organic and inorganic carbon are being measured on the

hydrocarbon sample. Hydrocarbon subsamples were immediately placed into precleaned

(combusted at 425°C) 1/2-pint glass jars with teflon-lined lids (~150 g). Trace metal samples

were immediately placed into pre-cleaned plastic jars (~150 g). All sediment samples for

contaminant chemistry are stored frozen (-20°C).

6.6 Geochemistry

At each survey site, near surface (about 0 to 2 cm) samples from each of the five (5)

replicate samples were frozen but analytical work is being completed at shore-based laboratories

on only one sample. The other five have been archived frozen.
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7.0 LABORATORY METHODS

Once samples and data are collected on the various cruises, extensive shore-based

laboratory analyses are performed. Wherever feasible, analyses are completed onboard the ship.

In addition, other samples and data were processed to the fullest extent possible aboard the ship

and properly and uniquely identified, labeled, and stored in appropriate facilities and media. The

samples are preserved for storage onboard the ship to ensure their integrity during transport to

the various PI's laboratories. The methods employ standard techniques widely used for similar

programs ensuring that comparisons with historical studies are valid. This data compatibility is

important to provide the greatest value in the final synthesis. The laboratory methods are

described in detail below.

7.1 Taxonomy

Taxonomy is a vital component of the GOM slope study. Many of the hypotheses will be

tested at the species level and therefore the taxonomists must be the best available. A team of

taxonomists was selected on the basis of their international reputations, their familiarity with the

GOM, and the management team's experience with them as productive scientists (Table 7.1).

The first step is getting good samples and that is assured by the described shipboard sampling

and processing protocols. The next step is accurate and thorough sorting of the samples to major

group. That is accomplished by graduate students and experienced professional invertebrate

zoologists.

The sorting laboratory sorts Rose Bengal-stained invertebrates and separates them to

major taxonomic group: polychaetes, oligochaetes, molluscs, crustaceans, and others. QA/QC is

performed by re-sorting the “waste” materials prior to storage. All materials collected during the

program is stored until the program is complete so that it can be reviewed as needed. Poorly

sorted samples discovered during resorting are sorted again. The initial sorter is identified and

retrained to ensure proper sorting.

Taxa that are routinely considered meiofauna but are retained on the 300 micron sieve are

separated and quantified. The numbers and biomass of these larger animals are added to the data

from the meiofauna component. Most of these taxa are nematodes, harpacticoid copepods, and

forams.

Determination of biomass as wet weight is accomplished at the group level prior to

distribution to the taxonomists. For larger organisms, this is done by weighing the organisms in

their alcohol preservative as a group (Rowe 1983). For smaller organisms, this is done by

measuring them, calculating their displacement volumes, and assuming a density of 1.2 g/mL.

The major groups are sent to the appropriate lead taxonomist. The polychaete taxonomist

is Dr. Fuinn Fain Hubbard (TAMU), an expert on deepwater polychaetes of the GOM.

Dr. Christer Erseus (Swedish National Museum of Natural History) is the oligochaete

taxonomist. These make up about 5% of the fauna by number and are important in the GOM. Dr.

Erseus has published extensively on the oligochaetes of the deep GOM.
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Table 7.1. Taxonomists involved in the analysis of the macrofauna and corresponding

taxonomists working on UNAM Mexican national collections. The last column lists

alternatives or taxa for which no specialist has been identified (those listed are

potential collaborators but have not yet been approached about the availability of the

samples).

TAXON DGoMBS UNAM Other

Fishes John McEachran (TAMU) Luis Zambrano

Amphipoda Richard Heard (USM) Fernando Alvarez

Aplacophora Amely Scheltema (WHOI)

Ascidiacea Claude Monniot(U.Paris)

Asteroidea Gordon Hendler (LA Co. Mus.) Alfredo Laguarda, Francisco Solis

Bivalvia Anders Waren(N. Mus. Sweden)

Brachiopoda Mary Wicksten (TAMU)

Bryozoa Nielsen

Cumacea Heard Alvarez

Decapoda Wicksten Alvarez

Echinoidea Hendler Laguarda, F. Solis

Echiura Eibye-Jacobsen

Gastropoda Waren/Rex/Davenport Garcia Cuba(Conus & Terebra)

Harpacticoida H. Lee (Montagna) Alvarez

Holothuroidea Hendler Laguarda, F. Solis

Hydrozoa

Isopoda Geo. Wilson(Aust. Nat. Mus.) Alvarez

Kinorhyncha Rhinehard Kristensen (Danish Mus.)

Mysidacea Heard Alvarez

Nematoda N.A.

Nemertini Jon Norenburg(USNM)

Oligochaeta Christer Erseus(Nat. Mus. Sweden)

Ophiuroidea Hendler Laguarda, F. Solis

Ostracoda L. Kornicker(USNM) Gío Argaez

Polychaeta G. Fain Hubbard Vivien Solis

Porifera Patricia Gomez

Priapulida

Pycnogonida Allen Child

Scaphopoda Waren

Scyphozoa

Sipunculida Mary Rice(USNM)

Tanaidacea Heard Alvarez

Turbellaria

Anthozoa Daphne Fautin (U.Kansas)

Copepoda Lee (Montagna)

Chaetognatha Gerald McLellan (USM)

Halacaridae Anna Hoffman-Mendizabel

Crinoidea Chas. Messing (FAU) Laguarda, F. Solis

Cladocera
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Dr. Anders Waren (S.N.M.N.H) is the molluscan taxonomist. He is a widely known

taxonomist. Dr. Waren will be assisted by Mr. Roe Davenport. Mr. Davenport will assist Dr.

Waren with provincial taxonomic issues.

Dr. Richard Heard (University of Southern Mississippi) is the crustacean taxonomist. He

is a well know taxonomist who worked on the NGOMCS study. Dr. Heard will distribute the

crustacea among his group and other outside experts for identification including Dr. B. Wilson

for isopods.

Dr. Gordon Hendler (L.A. County Museum), is the echinoderm taxonomist. While most

of the adult echini will be taken in the trawl samples, juveniles may be frequently encountered in

the boxcores.

Each lead taxonomist is responsible for identifications to the species level. Any

misidentifications by the sorters that may be encountered in the bulk group samples are returned

to the sorting laboratory for redirection. Species lists are regularly reviewed. The Data Manager

archives and distributes species lists to the PIs and the taxonomists on a regular basis.

Sampling of benthic infauna is concentrated in the first two years of the program.

7.2 Community Structure

A wide range of taxa will be quantitatively assessed at each station for a variety of

community structure characteristics. These analyses are key for understanding the complex deepsea foodweb. The community structure analyses form the framework on which the program

depends.

7.2.1 Bacteria

Bacterial abundance in sediments are being determined using a dual staining technique

(acridine orange and DAPI stains) and standard epifluorescence microscopy for marine

sediments (Relexans et al. 1996 and Schmidt et al. 1998). This procedure does not attempt to

remove bacteria from the sediment grains prior to counting. Separating the bacteria from the

sediment inevitably results in an underestimate of abundance, since bacteria tightly bound to the

sediments are left behind. Instead, the method of choice views the bacteria directly in the

presence of the grains after treatment with Triton-X detergent and sonication (to loosen the

attached or aggregated cells). For each sediment core, a down-core profile of bacterial

abundance will be determined at ten (10) closely spaced sampling intervals from 0-15 cm with

spot checks to a depth of 30 cm. Sediment bacterial abundances are rarely examined at depths

greater than 15 cm. The deeper samples (done to 30 cm) are important in understanding bacterial

distributions in deep-sea sediments. The potentially unique nature of some of the targeted slope

sediments suggests that significant variations from typical pelagic marine sediment downcore

profiles known may be observed (Schmidt et al. 1998). Since ultimately abundance is integrated

over depth in the sediment to provide benthic bacterial mass estimates at each station for

modeling and hypothesis testing purposes, unusual abundance profiles in the deeper layers of

sediment will be important.
7-4

Bacteria are also being sized in selected samples by measuring the length and width of

photographed cells stained with acridine orange and projected onto a flat white surface (Lee and

Fuhrman 1987) to convert bacterial abundance to biomass. Bacterial sizing in sediments is not an

automated procedure. Benthic bacteria are rarely sized for biomass conversions. Researchers

have instead assumed a constant volume based upon more easily sized bacterioplankton. The

proposed method is a significant improvement in the accuracy of benthic bacterial biomass

estimates.

7.2.2 Foraminifera

Biomass of foraminifera is difficult to measure because foraminiferal assemblages

include a combination of live specimens and empty shells. Measurement of only the organic

fractions is appropriately done by measuring ATP content. Benthic foraminiferal ATP will be

measured at the experimental stations. From each sample, 50 specimens will be individually

measured for length and subsequently extracted for ATP following the procedure of Bernhard

(1989). If time and foraminiferal abundance permits, additional specimens will be extracted.

7.2.3 Meiofauna

Meiofauna are being extracted from sediment using the Ludox centrifugation technique

(deJonge and Bouwman 1977). Recent QA/QC studies have shown that the technique extracts

95-99% of organisms over all sediment grain sizes (Burgess, submitted manuscript). Samples are

then sieved and counted to major metazoan taxonomic category. Protozoan, primarily

Foraminifera and Ciliata, are enumerated if stained as well and will be reported

The term “meiobenthos” was first coined by Mare (1942) to describe benthic organisms

of intermediate size. These are metazoans that are smaller than macrofauna but generally larger

than the single-celled microbenthos (e.g., bacteria, microalgae, and protozoans). By convention,

the definition of meiofauna is those animals that pass through a 500 micron sieve but are retained

on a 63 micron sieve (Hulings and Gray 1971; Coull and Bell 1979; Giere 1993). Because deepsea organisms are small, most meiofaunal ecologists use 42 micron sieves to retain meiofauna

(eight of nine papers reviewed in Thistle et al. 1991). To conform with other studies of deep-sea

meiofauna, a 45 micron sieve was used to retain meiofauna.

Meiofauna are being identified to the major taxon level. Meiofaunal communities are

composed of two groups. Temporary meiofauna are those juveniles of the macrofauna that will

eventually grow into larger organisms. Permanent meiofauna are those groups where adults are

less than 300 microns, e.g., Nematoda, Copepoda, Gastrotricha, Turbellaria, Acarina,

Gnathostomulida, Kinoryncha, Tardigrada, Ostracoda, and some Rhyncocoela, Oligochaeta, and

Polychaeta. In 1971, Thiel suggested that the grouping of benthic organisms according to size

differences had little taxonomic or ecological justification, except convenience of sample

processing (quoted from Thiel 1975). However, ecological literature since 1971 has shown that

meiofauna are different from macrofauna and have different roles in marine ecosystems (for

reviews see: Coull and Bell 1979, Coull and Palmer 1984, Giere 1993). Even where meiofauna

share ecological properties with macrofauna the processes operate on much smaller spatial and

shorter temporal scales for the meiofauna (Bell 1980).

Meiofauna biomass are being measured or calculated (Montagna 1984; Montagna and Li

1997) for all samples. There is an extensive literature on biomass techniques. It is well known

that biomass is underestimated by 30-40% in formalin preserved samples, so biomass will be
7-5

adjusted for this loss (Frithsen et al. 1986). For small organisms (e.g., meiofauna) biomass is

calculated based on volume measurements and conversion factors. Conversion factors specific to

the deep-sea GOM do not exist, so they will be empirically determined in 10% of the samples by

direct measurements using a CHN analyzer and electrobalance (Montagna 1984). There is also

an extensive literature on how best to calculate the volume of meiofauna based on length and

width measurements. Robinson (1984) compared five methods for nematode biomass and

recommends calculating volume based on a cylinder the length of the nematode and the diameter

of the nematode’s area/length ratio. Pearre (1980) has compared five methods for copepod

biomass and recommends calculating volume based on a cylinder. Techniques and formulas for

other meiofauna are given in Duplisea and Hargrave (1996).

7.2.4 Macrofauna

The macrofauna are expected to be one of the most complex size groups to sort and

analyze. After sieving, the macrofauna are being sorted under dissecting microscopes to major

taxonomic groups. QA/QC is performed on all sorted samples. All residues are properly

preserved and retained for the duration of the project for review as needed. After sorting to major

group, wet weight biomass is determined and estimates of densities and biomass are calculated

for each major group.

Each major group is sent to the lead taxonomists as described in Section 7.1. The lead

taxonomists is responsible for sorting to species. If they find individuals that are misplaced, they

are returned to the sorting laboratory for redirection. The final samples sorted to species are

returned to TAMU for archival.

7.2.5 Megafauna and Fishes

In the field, the fishes and megafauna recovered by trawl were processed as followed: 1)

sorting of fishes and megafauna to “tentative” species (along with volume, measurements,

counts, and length by species; 2) selecting specimens for tissue samples for stable isotopic and

DNA analyses; 3) processing, labeling, and storing tissue for shore-based analysis; 4) fixation in

10% neutral buffered formalin, and 5) recording any unusual occurrences in the trawl

performance that might effect the catch. Upon return to the laboratory, tissues for stable isotopic

analysis will be delivered to the appropriate PI. The fish subsamples are soaked in water to

remove all traces of formalin and then transferred to 70% ethanol. The megafauna and fish

identifications are verified and transferred to a single jar per species per station.

7.3 Community Function (Process Studies)

At each experimental station a specialized set of process studies will provide important

information to support those data obtained at the standard survey stations during Cruises II and

III. These studies are performed using techniques and methodologies specific to each

programmatic component.
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7.3.1 Bacterial Metabolism

Bacterial productivity was estimated in sediment samples from the process stations using

the tritiated thymidine approach, as applied by Alongi (1990) to other deep-sea sediments. For

comparative purposes, we tested for activity in undiluted and diluted surface sediments and in

samples incubated at atmospheric pressure and in situ pressures, all at in situ temperature. We

ran endpoint, time-course and variable substrate concentration experiments to assess isotope

dilution and other procedural issues. Incubations were terminated shipboard using 80% ethanol.

Returned samples were processed further to assess thymidine incorporation into DNA, again

following procedures of Alongi (1990).

7.3.2 Meiofaunal Feeding Rates

Meiofaunal feeding rates on benthic bacteria were measured by incubating sediment

cores with radiolabeled thymidine (3HTdr; Montagna 1984, 1993). Flow through core tubes in

June 2002 will be fitted to the benthic lander (described below) and upon impact will fill with

sediment and close off at the top. At that point 2 uCi of 3HTdr is injected and incubated for 8 h

after which formalin is injected into the cores to stop label uptake. After retrieval of the benthic

lander, a one ml subsample will be withdrawn from the core. The subsample will be filtered onto

a 0.2 micron Millipore filter and rinsed three times with seawater to estimate uptake of 3HTdr by

bacteria. The subsample will be dispersed and suspended in five mL of distilled water and 15 mL

insta-Gel for dual label liquid scintillation counting at a shore-based facility. Meiofauna will be

separated from sediments by diluting samples with 2% formalin, swirling to suspend animals,

and decanting them and the supernate onto 63 micron Nitex screen filters. Meiofauna will then

be rinsed into jars and kept refrigerated in 2% formalin until sorting at a shore-based facility.

The labeled meiofauna collected are sorted under a dissecting microscope in a shorebased laboratory. The individual taxa are placed in one mL of water in a scintillation vial. The

meiofauna are then dried at 60oC and solubilized in 100 μL Soluene tissue solubilizer for 24 h.

Samples are ultimately counted by dual-label scintillation spectrophotometry in 15 mL of Instagel.

7.3.3 Sediment Community Respiration

The changes in the chemical concentrations of oxygen, dissolved inorganic carbon (DIC),

ammonia, nitrate, nitrite, manganese, iron, silicate, and phosphate in the benthic chambers are

being used to estimate total community respiration by organisms living within the sediments in

benthic chamber incubations. The oxygen concentrations are determined from a continuously

recording polarographic oxygen electrode, backed-up by a miniaturized Winkler method (uses

25 mL samples). The other chemicals will be measured in syringe samples from the beginning,

middle, and end of the incubations. Conventional wet chemistry is employed as described in the

geochemistry section.

7.3.4 Foodweb Analyses - Stable Isotopes

Selected organismal tissues have been sampled and preserved for stable isotope analysis.

The tissues will be analyzed for carbon and nitrogen stable isotopic compositions. Most samples
7-7

will be measured with a Finnigan MAT Delta S Elemental Analyzer-Isotope Ratio Mass

Spectrometer (EA-IRMS). If, for any reason, samples cannot be processed by EA-IRMS, they

will be measured by standard tube combustion methods similar to those described in Cifuentes et

al. (1988). Finally, the stable carbon isotope ratio of bacteria in sediments is being determined by

proxy, in phospholipid fatty acids, a biomarker of bacterial biomass (Salata 1999).

7.4 Sediment Properties

Sediments retrieved from the boxcores are preserved and returned to shore-based

laboratories for analysis (see below).

7.4.1 Grain Size

Grain size was determined by the standard Folk settling method. Fifteen to twenty grams

of sediment are treated with hydrogen peroxide for twelve hours to remove organic matter. After

washing with distilled water, the sediment is dispersed with hexametaphosphate solution and

poured over the appropriate screen. The material that passes through the screen is then subjected

to a series of prescribed settling techniques that are based on removing materials at set times.

The individual fractions that are collected are dried and weighed to provide quantitative values

for each size fraction as a percent of the total weight of sediment. Per cent gravel, sand, silt, and

clay are calculated. Duplicates are analyzed with every batch of twenty samples to estimate

precision.

7.4.2 Geotechnical Properties

All boxcore samples are examined and sampled for shear strength, bulk density, water

content, and grain size. Selected samples are being tested for permeability. Shear strength is

determined by hand held vane shear devices and is used to determine the cohesion of the

sediment at several depths and locations in a non-contaminating and non-disturbing manner

within each boxcore. Bulk density and water content is determined by standard geotechnical

techniques. Porosity was determined from the bulk density measurements. Permeability is the

capacity of the sediment to transmit fluids without impairment of the structure of the medium.

Permeability regulates the rate of flow of interstitial waters resulting from the compaction

process and is important in the transport of fluids and gases within sediments. Permeability was

determined on selected samples by pressure permeameters and a constant gradient

consolidometer. Of the above sediment physical properties, grain size is the only one for which a

large number of correlations have been made with benthic communities. It is reasonable to

presume however that they may correlate or co-correlate with animal distributions.

7.4.3 Total Organic and Inorganic Carbon

Total organic and inorganic carbon was determined by standard LECO combustion

techniques or by Carlo Erba element analyzer. A freeze-dried and homogenized sample is burned

in the presence of oxygen and accelerator to CO2 which is swept from the combustion chamber

into a detector. The detector is calibrated with rings of known carbon content and the sample

carbon content is calculated from the detector response. Inorganic carbon is determined as the

difference in carbon content between an untreated and acid-treated sediment sample.
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7.5 Chemical Contaminants

Each survey and experimental site will be screened for the presence of chemical

contaminants. Hydrocarbon and relevant metals will be measured at each site.

7.5.1 Hydrocarbons

Sediment samples are analyzed for polynuclear aromatic hydrocarbons (PAHs) using

NOAA National Status and Trends Methods (Denoux et al. 1998; Qian et al. 1998). The

proficiency and validity of this method has been established by 14 years of laboratory

intercomparisons. Briefly, deuterated PAH are added before the extraction and are used to

calculate analyte concentrations. Sediment samples are mixed with anhydrous sodium sulfate

and are extracted with methylene chloride/acetone in an Automated Solvent Extractor (ASE).

The extracts are separated from possible interfering compounds by silica/alumina columns. The

purified extracts are analyzed on a HP 5890/5970 gas chromatograph with a mass selective

detector (GC/MS) using a selected ion detection technique. The GC/MS is calibrated with known

concentrations of analytes at five different concentration levels and the average response factors

of the analytes are used for PAH concentration determination. Concentrations of PAHs are

reported as nanogram/gram (ng/g) on dry weight basis for sediment samples. Both non-alkylated

(parent PAHs) and alkylated PAHs are reported. Each sample batch of 20 samples or less

includes a procedural blank, a matrix spike, a matrix spike duplicate and a standard reference

material. These quality assurance samples ensure that the analytical results for each batch are

valid and of acceptable accuracy and precision.

7.5.2 Trace Metals

Sediment samples are analyzed for Ba, Cd, Cr, Fe, Hg, Pb, and Zn. These have been

shown to correlate with drilling and production in previous studies (e.g., Kennicutt, et al.

1996a,b) and/or are known to be toxic to organisms. The analyses follow the well-established

National Status and Trends methods. Methods include atomic absorption spectroscopy (AAS),

instrumental neutron activation analysis (INAA) and/or inductively coupled plasma spectrometry

(ICP) depending on the metal and the concentration (e.g., Taylor and Presley 1998). INAA will

be used to determine Ba, Cr and Fe. The precision and accuracy for these elements by INAA is

excellent regardless of the matrix, including pure drilling mud. A more sensitive method is used

when needed for other metals to insure accurate and precise values.

Sample preparation beings with freeze-drying a representative sediment aliquot and

grinding it to a fine powder. No further treatment is needed for INAA providing a check on the

sample dissolution techniques needed for AAS/ICP analysis. For INAA, 0.5 g aliquots of the

powdered samples is weighed directly into plastic vials and heat sealed. The samples are

irradiated for 12 hours in the 1 megawatt TRIGA reactor. After a 10 day cooling period to allow

Na, Cl, and other interfering isotopes to decay to low levels, the samples are counted using a

hyper-pure germanium detector coupled to a Nuclear Data Corp. model 9900 multichannel

analyzer integrated with a Digital VAX II/GPX graphics workstation. Concentrations are

obtained by comparing counts for each sample with those for sediment and rock reference

materials of accurately known elemental composition. Details of this method are given in Boothe

and James (1985), including information on counting geometry, reference materials, spikes,

blanks and other aspects of QA/QC.
7-9

The National Status and Trends Program methods (Lauenstein and Cantillo 1998) are

used in for AAS/ICP analysis. The method for Hg is the standard EPA sulfuric acidpermanganate digestion of a dry powdered sample followed by stannous chloride reduction to

Hg metal and detection by cold vapor AA. For other metals, 200 mg aliquots of the powdered

sediment samples are weighed into teflon “bombs” and completely dissolved in a mixture of

nitric, hydrofluoric and boric acids by prolonged exposure of the closed bombs to a temperature

of 130°C. Various dilutions are made on the clear digests to bring them into the working range of

the AAS or ICP.

A Perkin-Elmer Corp. model 3300DV (dual view) ICP is used when element

concentrations permit. When concentrations are too low for this instrument, a Perkin-Elmer

3030Z AA equipped with an HGA-600 graphite furnace and an auto sampler are used. Details of

furnace programs, matrix modifiers, blanks, spikes, reference materials and other QA/QC

information can be found in the reference given above. The proposed methods ensure that matrix

spike recovery for all elements is greater than 90% and that recoveries of certified values for

reference materials from the National Research Council of Canada are 90% or better as well.

7.6 Geochemical Properties

The geochemistry component will measure a range of relevant sedimentary properties at

both survey and experimental sites. Single replicate samples are analyzed at the survey sites and

detailed profiles will be determined at experimental sites to determine important flux rates.

Various geochemical properties are measured on pore waters and solid phases. Analyses that are

best performed immediately after sample retrieval will be conducted onboard, whereas other

analyses which require more time consuming methods can only be performed at shore-based

facilities (Tables 7.2 and 7.3). Pore water is separated from the solid phase by centrifugation or

pressure filtering.

For pore water a combination of microelectrode, titrametric, ion chromatographic and

other analyzers will be used. Dissolved pore water oxygen, hydrogen sulfide, iron (Fe+2), and

manganese (Mn+2) are measured by microelectrodes. Sulfate concentrations in pore waters will

be determined by a standard ion chromatographic technique. Total dissolved inorganic carbon in

pore waters is determined by coulometric titration. Pore water nutrients (nitrate, nitrite,

ammonia, urea, phosphate, and silicate) are determined by standard autoanalyzer techniques

much like those for water column nutrients. Dissolved organic carbon in pore waters is

determined with a high temperature combustion DOC analyzer.

The geochemistry studies at experimental stations include detailed depth profiles of

biogeochemically important parameters, measurement of sulfate reduction rates, and benthic flux

measurements in addition to survey variables. Isotopic studies are also being carried out at these

stations. In addition to the shore-based analyses described for the survey stations, the following

analytical work is being performed. Detailed near interfacial profiles of O2, H2S, Fe and Mn

were acquired by the microelectrode method of Luther et al. (1998). Sulfate reduction rates were

determined using the 35SO4

2- tracer technique in order to measure the approximate rate of

hydrogen sulfide generation within the sediment (Lin and Morse 1991). Pore waters were

extracted from sectioned cores to produce depth profiles of nutrients, pH, dissolved inorganic
7-10

Table 7.2. Summary of parameters to be analyzed and the methods to be used.

Type of Component Component Analytical Method

Pore water O2, H2S, Fe and Mn Microelectrodes

Total CO2 (DIC) Coulimetric titration

Sulfate and chloride Ion chromatograph

pH Electrodes

Nutrients Auto analyzer

Dissolved organic C (DOC) DOC analyzer

Sediment Solids C stable isotopes Extract/mass spectrometer

Porosity Wt. change on drying

CHNS Carla Erba analyzer

Reactive Fe and Mn CD extraction, FAAS

Carbonate carbon Leco C analyzer

Metals NS&T Methods

Hydrocarbons NS&T Methods

Radioisotopes Counting

Biologic SO4

2- reduction rate 35S tracer method

The following table lists the chemical parameters to be analyzed and categorizes them by

column as to which type of station, survey or experimental, they will be utilized and whether

they are field (F) or laboratory (L) measurements. Note that at the survey station combined

surficial sediment samples will be analyzed whereas at experimental stations depth profiles will

be determined for most parameters.

Table 7.3. Chemical parameters to be analyzed.

Parameter Survey Station Experimental Station

Sediment Properties

CHNS L L

Carbonate content L L

Contaminants

Metals L L

Hydrocarbons L L

Indicators of Biologic Activity L L

Nutrients L L

DOC L L

SO4

/Cl L L

DIC L

δC13 DIC L

Radioisotopes L

Reactive Fe and Mn L

Sulfate reduction rate F

pH F

H2S F

O2 F

Dissolved Fe F

Dissolved Mn F
7-11

carbon (DIC), DOC, and sulfate/chloride ratios. All of these were analyzed on shore. Carbon

stable isotopes are being determined on the DIC samples.

All solid components, except trace metals and hydrocarbons, are also being determined in

depth profiles. Reactive Fe and Mn are being measured by extraction with citrate dithionite and

analyzed by FAAS of radioisotopes.

For the solid phase, the methods for grain size, TOC, TIC, and porosity have already

been described. In addition total reduced sulfides will be determined by an extraction technique

which is followed by colorimetric detection. Sulfate reduction rates will be determined by

incubation with 35S labeled sulfate and measurement of the production of labeled sulfide. To

determine the source of organic carbon in sediments, organic carbon will be analyzed for its

stable carbon isotopic composition by standard tube combustion (Cifuentes et al. 1988). Selected

measurements of the stable carbon isotope ratio of porewater dissolved inorganic carbon will be

performed according to Salata et al. (1996).

Analysis of selected radionuclides will be used to determine sediment accumulation and

mixing (bioturbation) rates at experimental stations. Samples along a depth profile will be

gamma counted and analyzed for 210Pb and 239,240Pu by wet chemistry followed by alpha

counting. Gamma counting of samples will be carried out on a HPGe Well Detector for 210Pb (46

keV), 234TH (63 keV), 226Ra (351 keV), 7Be (575 keV), and 137Cs (661 keV).

The radionuclide analyses will:

• measure the natural 7Be and 234Th activity concentrations in the surface sediments by

gamma counting to determine short-term, near-surface mixing (bioturbation) rates,

• measure the natural 210Pbxs (210Pb-226Ra) activity concentrations in sediments from

boxcores to determine the steady-state sediment accumulation rates and 210Pb

inventories for the assessment of radionuclide and sediment focusing effects.

• measure the bomb fallout nuclide 137Cs and 239,240Pu activity concentrations in

sediments to determine sediment accumulation rates from the 1963 bomb fallout

peak. It is necessary to determine both nuclides as 137Cs can show substantial postdepositional mobility in marine sediments.

For analysis, core material is dried and homogenized. Sediment samples of about 10 g

size will be used for non-destructive gamma counting in a low-background, high-efficiency high

purity Germanium (HPGe) well detector followed by wet chemical extraction procedures and

alpha counting for individual radionuclides. Procedures are given in Santschi et al. 1999 and

references therein.

For 210Pb determinations, samples of approximately 1 g each are used for by alpha

counting for complete digestion and chemical separation. Gamma counted samples will provide

a less precise 210Pb value used as a cross-check. For 226Ra, 234Th, 137Cs, 7Be, and 137Cs samples

of 10 g each are analyzed by non-destructive gamma counting. For 239,240Pu, samples of 10 g

each are analyzed by wet chemistry and alpha counting.
7-12

7.7 Water Column Profiles

As summarized in Section 6.1.4, most water column properties are measured at sea by

standard techniques: autoanalyzer for nutrients, Winkler titration for oxygen, and salinometer for

salinity. In addition, total suspended particulate matter is determined by gravimetric analysis of

filters. Particulate organic carbon is determined by total combustion of an acidified filter sample

followed by detection of CO2. Phytoplankton pigments are determined by a high performance

chromatography (HPLC) method with quantitative UV detection. The pigment analysis

quantitatively determines chlorophylls and carotenoids used to assess the relative importance of

the various phytoplankton groups. The methods to be employed are those of NEGOM (Jochens

and Nowlin 1998).

Continuous monitoring sensors produce detailed profiles at each of the stations during the

hydrocasts (see Section 6.1.4). A “quick look'“ at the data was performed at-sea to uncover

potential problems in the data at the earliest possible opportunity. A quick-look also provides the

opportunity to scan for features and to revise sampling plans to more appropriately sample any

observed features. Data is further validated on return to shore by checking all of the metadata

(e.g., times of sampling, depths, positions, or calibration checks) against the cruise logs and the

data file format. For CTD data, pressure versus time is examined to remove ship motions. All

out-of-range, unrealistic outliers, gaps and discontinuities in the dataset are manually checked.

The continuous data is then discretized at 0.5 m intervals and written into computer files as space

delimited columns of plain ASCII text. Characteristic plots are prepared for each station.

The water column chemical measurements were done aboard with discrete water samples

collected on the upcast of the rosette sampler. A Guideline Model 8400B salinometer was used

for salinity analyses. The microWinkler technique was used for measurement of dissolved

oxygen. Nutrients (nitrate, nitrite, ammonia, urea, phosphate, and silicate are analyzed using a

Technicon Autoanalyzer and standard colorimetrc techniques. At-sea analysis ensures high

precision and accurate measurements as opposed to preservation, storage, and shipment to shorebased laboratories. In addition, water is sampled for various particulate matter parameters. Twoliter water samples were vacuum filtered through pore-weighed filters for total suspended

particulate matter (PM) analysis. Another liter of water was filtered through 25-μm

precombusted GFF filters for determination of particulate organic carbon (POC). Another liter of

water was filtered through 0.45 micron Millipore filters for analysis of the major phytoplankton

pigments. All filters were carefully placed in combusted aluminum foil or plastic bags and

properly stored for transport to shore-based laboratories for analysis.

7.8 Archival of Specimens

All the biological material in this study that is identified to species by taxonomists will be

retained for the duration of the project by the taxonomists, at the sorting lab in the Oceanography

Department, or at the Pequegnat Deep-Sea Systematics Collections. At the end of the project,

voucher specimens will be made available for archiving at the USNM of the Smithsonian

Institution as directed by the MMS. These will include the megafaunal invertebrates, the

macrofauna and the fishes. It does not include the bacteria or the meiofauna because they will

not be identified to species. In addition to the voucher specimens to be given to the Smithsonian,

regional working systematic reference collections will also be encouraged to access, curate and

catalogue voucher specimens for future research and education when such specimens are
7-13

available. This will include the LA County Museum, the Texas Cooperative Wildlife

Collections, the Pequegnat Deep-Sea Invertebrate Collections, The Australian National Museum

of Natural History, and the Swedish National Museum.
8-1

8.0 STATUS OF DGoMB PROGRAM

8.1 Task 1 - Re-Examination of Previous Studies

Several sources of information were readily available to review and assess. These can be

categorized as theses and dissertations of students of Willis E. Pequegnat; the MMS-supported

slope study overseen by LGL Ecological Research Associates, Inc. (NGOMCSS); and the peerreviewed literature. Practically all of this material has been included in a review of the deep

GoM environmental information conducted by Continental Shelf Associates under contract with

the MMS. DGoMB personnel participated in that review (G. Rowe, W. Nowlin, W. Bryant, D.

Biggs, and M.C. Kennicutt II). That report should be consulted for specific details on individual

sub-disciplinary studies.

All megafauna, macrofauna, megafauna, meiofauna and sediment raw data files were

supplied to DGoMB by LGL Ecological Associates, Inc.. These have been sorted by discipline

and restored as individual Microsoft Excel files. These files have been made available on the

internet to DGoMB principal investigators. Dr. Richard Haedrich has plotted megafauna and fish

distributions to assess the effect of depth and east-west gradients on species composition.

Macrofaunal polychaete diversity (taken from the Ph.D. dissertation of G. Fain Hubbard) using

several complementary indices has been plotted with depth by transect to consider potential

internal GoM gradients (E to W, depth, etc.) and for comparison with other ocean basins.

Several tentative conclusions can be concluded from earlier studies:

1. biomass and densities of the size groups studied decrease in general as a

function of depth down the continental slope, but with frequent exceptions to

this rule;

2. densities of macrofauna differed between sampling dates on the C transect

(for Central), with high densities in spring and low densities in the fall;

3. three depth zones can be defined tentatively, based on species composition:

the upper slope, the mid slope and deep water;

4. the continental slope in the western GoM is different in species composition

(macrofauna and megafauna) from the eastern GoM;

5. sediments contained no anomalous contaminants that would not be expected

in a typical deep-sea environment;

6. diversity maxima are encountered on the upper slope (as opposed to the lower

slope/upper rise, in other basins); and

7. biomass and densities of the different size groups studied are lower than

observed on other ocean basin margins when studied with similar approaches.

8.2 Task 2 - Field Sampling

The initial field work was a short shakedown cruise conducted on February 16-18, 2000,

to test gear and to evaluate procedures with survey participants. The main outcome of this trip

was the conclusion to change from the USNEL spade corer to the GOMEX boxcore.
8-2

A survey cruise was conducted on the R/V Gyre from May 3 to June 23, 2000. Four

different activities were carried out at each of 43 sites: CTD, box cores (5 replicates with a 0.2

m

2

 GOMEX corer), bottom camera (up to 50 exposures per site covering ca. 5 m2 area per shot)

and 40’ otter trawl (Table 8.1). In addition, two ADCPs collected information on near surface

currents continuously throughout the cruise. The boxcores were subsampled for meiofauna,

bacteria, geology, contaminants and geochemistry. Some of the results, where available, are

discussed below. A separate cruise report was developed and is available as Appendix I. The

distribution of samples collected is provided in Table 8.1 along with an estimate of when each

set of data will be available to the rest of the program. The data generated from Cruise I will be

used to choose the locations of the process study sites to be occupied in June 2001.

DSRV Alvin aboard the R/V Atlantis were at sea from October 16 to October 31

occupying a suite of continental margin sites in and amongst the DGoMB study area.

Observations were made by Drs. Ian MacDonald, William Bryant, and Joan Bernhard who were

accompanied by three DGoMB-supported graduate students. The results of their work are

reported in a separate cruise report (Appendix II). Drs. Bryant and MacDonald reported on their

observations at the December 2000 MMS Information Transfer Meeting (ITM). The Alvin cruise

was a multi-agency project and the full cruise report is included in Appendix II.

The first process cruise (Cruise II) was conducted from June 1-19, 2001. It will be

described in the Second Interim Report. The sites studied are discussed in Section 5.0 and the

sites are mapped in Figure 5.2.

8.3 Task 3 - Sample Data Processing and Analysis

Four kinds of information were collected at each observational site during the survey

cruise on Gyre, May 4 to June 23, 2000: physical and chemical properties of the water column,

geological characteristics of the sediments, geochemistry of the sediments, and kinds and

numbers of organisms present. The present status of these individual sets of data will be

separately described along with some preliminary interpretation of their significance and how the

results might affect the future direction of the program.

8.3.1 Physical Oceanography

During the first year, cruise collection of most of the physical data scheduled was

successful. This included shipboard 38 kHz ADCP measurements and 150 kHz broad- and

narrow-band ADCP measurements added as options to the original contract. Analyses and

quality control of the POC, TSPM, and pigment samples from the first year cruise are complete.

Quality control has begun on the CTD and bottle data from the first DGoMB cruise. The

possibility of freezing nutrient samples and analyzing them ashore rather than carry out

shipboard analyses was considered. To assess the potential of the stability of the preservation

technique, duplicate nutrient samples from several stations during NEGOM cruise N8 carried out

in April 2000 were frozen and analyzed onshore. The results were compared to those carried out

aboard ship. The samples for shoreside analyses were poisoned and frozen immediately after

collection.
8-3

Fresh versus frozen nutrient sample analyses for phosphate, silicate, nitrate, nitrite,

ammonium, and urea from two stations are compared in Figures 8.1 and 8.2. These stations were

in water depths of approximately 1000 m representing twelve water samples that extended

throughout the water column. Agreement is seen to be excellent for silicate and nitrate,

somewhat less for phosphate and nitrite, and poor for ammonium and urea. The poor agreement

for ammonium and urea is expected in view of the relative ease with which those nutrients are

utilized by organisms during storage.

The shipboard ADCP measurements recorded during both legs of DGoMB are of good

quality. Comparisons of the near-surface (40-60 m) currents measured simultaneously by the 38

and 150 kHz instruments are favorable. No large gaps exists in the data set; however, short gaps

due to GPS dropout and computer down time for data backups exist. The short gaps do not affect

the overall data quality.

Based on TOPEX/ERS-2 sea surface height anomaly (SSHA) plots, the Loop Current

was hammer-shaped during leg 1 of the survey cruise, intruding northward of 27°N and

westward to 89°W. The SSHA field for June 10, 2000 is shown in Figure 8.3. Thus, the Loop

Current was east of the study region during that leg. However, two Loop Current Eddies were

present in the western Gulf and their presence is seen in the ADCP vector fields. Figure 8.4

shows current vectors at a vertical bin centered at 12.4 m depth are shown in Figure 8.4. The

weaker of the two eddies was centered at 91.5°W, 24°N. The leg 1 cruise track passed through

the northern limb of this eddy at 26°N between 90°W and 91°W. The stronger eddy was centered

at 94.5°W, 26°N. The anticyclonic current field is clearly seen in the horizontal vector stick plots

along the cruise track. Particularly strong southward currents (of order 100 cm/s) are seen along

the eastern side of this eddy at around 93.5°W.

During Leg 2 of Cruise I, the stronger LCE drifted west about 0.5° of longitude. The

SSHA field for June 10 is shown in Figure 8.5. The anticyclonic structure of the stronger eddy is

again seen in the Leg 2 ADCP data. ADCP vectors for a vertical bin centered at 11.6 m during

Leg 2 are shown in Figure 8.5. The westward movement of the eddy is also seen in the data as

the strongest southward currents are located at 94°W and are reduced in amplitude about 50-70

cm/s. The cruise track of leg 2 was well north of the weak LCE, centered at that time near 92°W,

23°N.

During Leg 2 of Cruise I, the Loop Current did not intrude into the Gulf as far north as

27°N (see Figure 8.6), and thus did not influence directly the currents along the cruise track.

However, a weak LCE centered at 90°W, 26°N and a stronger cyclonic eddy centered at 87°W,

27°N are both seen in SSHA plots and in the ADCP data.

8.3.2 Geology

Sub-samples (15 to 40 cm deep cores) were taken from each of the 5 replicates at each of

the 43 sampling sites on Cruise I. These are being analyzed for a suite of physical properties by

conventional methods as described in previous chapters.
8-4

Table 8.1. Sample inventory for Cruise I (survey).

Biology Samples Water Column Samples Sediment Samples Geoch

Bacterial 201 Depth 44 Grain Size 212 Nutrients Foraminiferal 0 Temperature 44 Porosity 212 Dissolved OrganMeiofaunal 208 Salinity 44 Elemental composition (organic

carbon, nitrogen, sulfur)

212 SO4=/Cl- 

Macrofaunal 212 Oxygen 44 Percent inorganic carbon (TIC) 212 Dissolved InorgaMegafaunal 43 Nitrate and Nitrite 44 Permeability 212 δ13C DIC 

Fish 43 Ammonium 44 Shear Strength 212 Sulfate Reduction “Trash” 43 Silicate 44 Bulk Density 212 pH 

Phosphate 44 H2S 

Particulate Matter (PM) 44 Hydrocarbons 212 O2 

Particulate Organic Carbon (POC) 44 Metals 186 Reactive Fe Light 44 Reactive Mn Currents 44 Pore water 209 Acid Volatile Su

Photosynthetic Pigments 44 O2, H2S, Fe and Mn 209

Primary Production 44 Total CO2 (DIC) 209

Sulfate and chloride 209pH 209Nutrients 209Dissolved organic C (DOC)

209

Sediment Solids 209

C stable isotopes 209Porosity 209CHNS 209Reactive Fe and Mn 209Carbonate carbon 209MetalsHydrocarbons 209Biologic 209RadioisotopesSO42- reduction rate

4 bacterial aliquots (0, 5, 10, 15) per sample2 meiofaunal aliquots per samplefiltered samples (POC, pigments, and PM) at three (3) different depths (bottom, chl max or mid, and surface water)
8-5

Figure 8.1. Frozen versus fresh nutrient concentrations (micromoles) from station 32 on

NEGOM cruise N8 (April 2000). There are 12 pairs each.
8-6

Figure 8.2. Frozen versus fresh nutrient concentrations (micromoles) from station 33 on

NEGOM cruise N8 (April 2000). There are 12 pairs each.
8-7

Figure 8.3. Sea surface height field for 14 May 2000 based on analyzed height anomaly of

TOPEX and ERS-2 altimeter data added to mean sea surface height field.

Anticyclonic (cyclonic) circulation features have clockwise (counterclockwise)

currents and positive (negative) sea surface height values. Courtesy of Robert

Leben (University of Colorado).
8-8

Figure 8.4. Broad-band 150 kHz ADCP current vectors at average depth of 12.4 m on DGoMB

leg 1 Cruise, 3-23 May 2000.
8-9

Figure 8.5. Sea surface height field for 10 June 2000 based on analyzed height anomaly of

TOPEX and ERS-2 altimeter data added to mean sea surface height field.

Anticyclonic (cyclonic) circulation features have clockwise (counterclockwise)

currents and positive (negative) sea surface height values. Courtesy of Robert

Leben (University of Colorado).
8-10

Figure 8.6. Narrow-band 150 kHz ADCP current vectors at average depth of 11.6 m on DGoMB leg 2 Crui

2000.
8-11

8.3.3 Geochemistry and Contaminants

Subsamples were collected for chemical analyses during Cruise I. These samples

consisted of 5 replicate cores covering the upper 5 cm of depth in the sediment obtained from

box cores at each site. Of these 5 cores for each site, one was selected for initial analysis and the

others have been archived.

Chemical analyses are currently underway. Extracted pore waters have been analyzed for sulfate

to chloride ratio (an indicator of sulfate reduction), inorganic nutrients and dissolved organic

carbon. Because several samples indicated significant sulfate reduction, total reduced sulfur was

determined in the solid phase. Solid-phase C-H-N-S analyses are currently underway. Analytical

results produced during the first year (up to October 1, 2000) of the project are summarized in

Figure 8.7.

Figure 8.7. Negative sulfate anomaly as a function of water depth (the degree to which the ratio

of sulfate to chloride diverges from that of sea water) in the pore water of the top 5

cm of a core from each sampling site. This is an assessment of the loss of sulfate to

bacterial sulfate reduction. Note the negative values around a depth of 1 km, a

suspected depocenter.

0 1000 2000 3000 4000

-50

-40

-30

-20

-10

0

10

Water Depth (m)

Sulfate Anomaly (%)
8-12

8.3.4 Biological Studies

All size categories of the sediment-associated biota were sampled on Cruise I. These

included 1) microbiota, 2) meiofauna, 3) macrofauna, 4) megafauna and 5) demersal fishes. Each

fraction was fixed and labeled aboard ship as described above and distributed to respective PI’s

immediately after the termination of the survey. Analyses of the biological samples are in a

preliminary stage of processing and therefore no conclusions can yet be reached.

Macrofauna sample rough sorting to major taxon was initiated immediately on return of

the samples to the Benthic Sorting Laboratory in College Station. To date, six graduate students

have been trained to rough sort deep ocean invertebrate samples by Dr. Fain Hubbard.

Photographs have been printed for all bottom exposures. Pictures of a variety of

organisms encountered in the trawls and in the bottom photographs were presented at the MMS

Fisheries meeting in New Orleans in October, 2000, by G. Rowe. Mary Wicksten, Rowe and

several graduate students have assisted Dr. Benny Gallaway in identifying invertebrates

encountered in the 48,000 bottom photographs taken during the MMS NGOMCS study of the

early 1980’s. Additional photographic documentation of bottom animals is being accomplished

with the ROV Millenium on the drill ship Enterprise through a cooperative study with BP at a

drill site at 1.9 km depth (Crazy Horse 2).

Those components derived from the box cores have a maximum of 215 samples that are

on the order of 50% complete in the initial assessment of the densities of organisms within each

set of samples. The macrofauna studies required the training of a sorting team, and this was

accomplished by the end of August. The next steps with the sorted macrofauna include 1)

determination of biomass, 2) distribution to taxonomists for identification to species, and 3)

archiving voucher specimens in appropriate collections.

Trawl samples were initially spit into three components aboard ship: trash, invertebrates

and fishes. Each animal was identified to the lowest possible taxon, weighed by taxon (by

volume displacement) and preserved as appropriate in 5 gallon plastic tubs. Geographic location

of the start and end of each trawl, ship's speed and time on bottom were all recorded and thus

rough estimates can be made of the area covered by each trawl. A comparison can thus be made

of animal densities in the trawl samples. The trash was not preserved but is being stored wet

sealed in 5 gallon plastic buckets. When there was too much for one container, it was

photographed, weighed (when possible), discarded over the side (biodegradable material), or

stored aboard ship for land disposal.

The megafaunal invertebrates were delivered to Dr. Mary Wicksten (Texas A&M

University). The megafauna were then separated into major taxon and distributed to recognized

taxonomists for identification. Dr. Wicksten identified the crustaceans. Mr. Roe Davenport

identified trawl-caught molluscs.

The fish were delivered to Dr. John McEachran at Texas A&M. He has finished the

identifications.
8-13

8.4 Task 4 - Data Interpretation, Synthesis, and Reporting

While at a very preliminary stage, data interpretation, synthesis, and reporting will be

conducted by the following protocols.

8.4.1 Community Structure

As summarized in the methods sections, a wide range of taxa will be counted, identified,

and sized. The most common and useful transformation of these taxa data are to derive measures

of community density, biomass, species composition, and diversity. The following variables will

be measured - bacterial density and biomass; foraminiferal biomass; meiofauna density, biomass,

and composition by major group; macrofaunal density, biomass, diversity, and species

composition; megafaunal density, biomass, diversity, and species composition; and fish density,

biomass, diversity, and species composition.

Biomass. A key variable for interpreting the “state” of a system is biomass. It is the

currency of the carbon budget and it is the variable that changes when the model is used to

simulate the system. Therefore biomass will be measured directly or estimated for all the biotic

components: bacteria, protists, meiofauna, macrofauna, megafauna and fishes. Regression

analysis has long been used to estimate the rates of change of the total fauna with depth (Rowe

1983), so biomass is a powerful tool for assessing effects of depth or things that co-vary with

depth such as food input.

Abundance. The ratio of abundance to biomass is important in assessing the age structure

of the populations that make up the community. Thus, if and when the ratios of numbers to

weights change over time at a site, then it is known that the population is either growing or

dying. Growth and production rate are very difficult to measure and are contentious issues in the

deep-sea because it is assumed that such rates are relatively slow (Rowe 1983). However, this is

not necessarily true for the upper slope. The NGOMCS study of the slope suggested that

abundances change with time on the upper slope, with the highest numbers in the spring

(Hubbard 1995). It is not known if this was accompanied by a change in biomass. It will be

important to investigate the possibility that growth can be observed on the upper slope and then

to simulate this variation in time with the model. Similar investigations of the data and the model

can be undertaken for each functional group in the community. At this point, it is not known

which will exhibit growth responses and which will not. Alien sources of organic matter might

be expected to have a similar “shift up” effect.

Diversity. A key finding in the NGOMCS study was that the variation in diversity of the

macrofauna of the northern GOM was different from similar habitats in the Atlantic Ocean

(Pequegnat et al. 1990). The finding is at once exciting and flawed. The flaw is that the

conclusion is based on uneven sampling efforts by depths, which could lead to statistical biases.

It is exciting if true. One goal of the program is to rigorously determine the diversity of species

of the study area. Diversity can be measured by two types of indices: species independent and

species dependent. Species independent methods (e.g., the Shannon-Wiener diversity index) do

not take into account community structure. Therefore, the same values could be computed for

two communities that have no species overlap. In contrast, species dependent methods use a

multivariate approach (e.g., multidimensional scaling or principal components analysis) to
8-14

compare the species present in different communities to classify habitats. Both approaches have

inherent strengths and weaknesses, so both will be computed in the current study.

Two species independent methods will be used to assess community diversity: the

Shannon-Weiner diversity index and the Hurlbert rarefraction method. The Shannon index is the

average uncertainty per species in an infinite community made up of species with known

proportional abundances (Shannon and Weaver 1949). The Shannon index is calculated by:





 



 



 



 



 



 =− ∑

= n

n ln

n

n H' i i S

i 1

where ni is the number of individuals belonging to the ith of S species in the sample and n is the

total number of individuals in the sample. Rarefaction curves compare species numbers between

communities (Ludwig and Reynolds 1988). The model calculates the proportion of potential

interindividual encounters in a given sample (Hurlbert 1971). The expected number of species,

E(Sn), found in a sample of n individuals drawn from a population of N total individuals

distributed among S species is:



























































 −

∑ −

=

=

n

N

n

i N N

1

S

i 1

E(Sn )

where Ni is the number of individuals of the ith species. This sampling model computes the

expected number of species in a random sample of size n as the sum of the probabilities that each

species will be included in the sample (Ludwig and Reynolds 1988). A series of curves is

generated, with the steepest representing the highest diversity.

Three species-dependent multivariate approaches will be used. There is much

controversy on which approach is best. The obvious solution is to seek consensus among the

competing approaches and assume that the same trend found in all analyses is the most robust

trend. The three techniques are different, but all perform multivariate analysis: a cluster method

(NESS similarity), a parametric method (principal components analysis, PCA), and a nonparametric method (multidimensional scaling, MDS).

Similarity analyses are performed to determine which stations resemble one another in

terms of species composition. Group-averaged sorting, also know as the unweighted pair-group

method (Sneath and Sokal 1973), is used as the clustering method and the normalized expected

species shared (NESS; Grassle and Smith 1976) was used as the resemblance measure. The

results are given in dendrograms where stations are ordered into groups of increasing similarity

on a scale from 0 to 1, with 1 being the highest similarity. The NESS similarity measurement is

based on the expected number of taxa shared between random subsamples of size m drawn from
8-15

each of the two populations being compared. This similarity method is particularly useful since it

measures the contribution of rare species.

Principal components analysis is a parametric technique that makes a new set of

uncorrelated variables in order of decreasing variance. Because community data sets have many

rare species with zero occurrence at most stations, the PCA must be performed on the covariance

matrix. The usual approach is to perform the analysis on the correlation matrix, and the resultant

misleading results leading many to discount the utility of this tool. For example, two species

with zero occurrence at many stations may be highly correlated (near 1), but their covariance is

still small (near 0). Therefore, performing analyses on the covariance matrix of count data fixes

this problem. It also solves the problem of what do with rare species, they need not be deleted, as

often is erroneously recommended. The PCA also has another enormous advantage, factor

loading scores are generated for each species (columns) and observation (rows), which can be

used in other analyses. For example, during GOOMEX several hundred environmental variables

were reduced with PCA and the new PCA scores were shown to correlate with biological and

toxicological responses detecting very subtle sub-lethal effects that could not be detected with

univariate analysis of variance (Green and Montagna 1996).

Multidimensional scaling is a non-parametric multivariate technique for examining

similarity or dissimilarity between stations. First, a similarity index is computed for stations

(usually the Bray-Curtis index), then a plot of the distance among points is created. The plot

enables you to identify unknown variables that affect the similarity or dissimilarity between

stations. The MDS procedure is very popular among shallow water benthic ecologists, because

station separation is often more clear than in MDS. However, new variables are not created, nor

can one reduce the variables in a dataset.

Zonation. The degree of species isolation along or parallel to isobaths is referred to as

zonation. It is measured at the species level and at the community level. Species ranges as a

function of depth will be plotted individually. Highly zoned species have narrow depth ranges of

several hundred meters (Rowe and Menzies 1969; Grassle et al. 1975). Poorly zoned species

have much broader ranges. Zones of recurrent groups are determined using measures of

similarity or dissimilarity, discussed above. A somewhat arbitrary boundary of 50% can be used

to conclude that zones are the same or different or to identify zonal boundaries. Pequegnat et al.

(1990) suggested they could identify five zones on the northern GOM slope using the

megafauna, but Escobar et al. (1999) could discern only three in work with macrofauna. Another

way to discern group boundaries is to find depths of maximum faunal change. These are depths

with maximum numbers of first and last occurrences. Minimal faunal change occurs in the

“center” of zones. Zones are thought to occur due to competition along a gradient. In shallow

water, this can be competition for space or food, but is also affected by predator-prey

relationships. In the deep-sea, space is probably not an issue. the most plausible explanation is

competition for declining food supplies. Thus, each zone should be represented by a different

“level” of input to the model. This results in different levels of biomass in each functional group.

The model for an upper slope zone would “shift down” as one proceeds down the slope.
8-16

8.4.2 Community Function

Data produced at experimental stations will be directly incorporated into the model. The

stock values of the major groups will be determined by the survey portion of the program. The

purpose of the experimental stations will be to add rates of processes to the conceptual model.

The most important measurements in understanding rates is the respiration for each ecosystem

component. The sum of the respiration for the entire system is a first order estimate of the total

“carbon demand”. This “sum” should be equal to the sum of the input of carbon to the system.

Inequalities indicate that some set of unidentified components have been left out, or that the

system is not in steady state. Community function variables that will be measured include

bacterial growth rates and response to different substrates and meiofauna feeding rates on

bacteria. Other community function variables that are calculated from established size and

temperature relationships including foraminifera, meiofaunal and fish respiration rates, and

foraminiferal feeding rates. Predation and scavenging rates for macrofauna, megafauna, and

fishes are determined from submodels (see Section 3.0). There is not “unique solution” to the

relationships, but the model allows us to put boundaries on their values.

The total sediment community respiration in carbon units as measured by benthic

chambers is equal to the following:

SOC = RESP (macrofauna) + RESP (meiofauna) + RESP (aerobic bacteria) + CHEM OXID

(reduced end products of anaerobic metabolism)

This should equal the sum of the calculated values and the experimental rate measures.

Aerobic rates by bacteria are measured by oxygen consumption and anaerobic rates are

estimated by summing the rate at which denitrification, iron reduction, and manganese reduction

are occurring, as estimated by the changes in concentrations in the chambers and pore water

profiles of geochemical properties.

It is assumed that 0.85 moles of DIC is produced per mole of oxygen consumed

(RQ=0.85). Plus, it is assumed that the carbon to nitrogen ratio of organic matter is ~6.8 to 1.

Thus, the amount of nitrogen regeneration can be calculated from oxygen demand and dissolved

inorganic carbon (DIC) flux. If less than the predicted nitrogen is measured by a chamber

incubation, then a loss of fixed N is inferred and it is assumed this loss is denitrification. A goal

is to develop reasonable steady-state budgets of carbon fluxes at each of the experimental sites.

8.4.3 Sediment Properties

The sediment is the substrate that supports the benthic communities. The properties of

sediment directly influence ecosystem patterns. The most obvious property is grain size which is

well known to influence biotic patterns. At all stations sediments will be characterized as to

grain size, porosity, carbon content, permeability, shear strength, and bulk density. Also in the

deep-sea, carbon limiting conditions make the organic carbon in the sediment and its

“bioavailability” important issues. Though less well studied, others properties may or may not

influence biological patterns. The shear strength or cohesion of the sediment is expected to be a

factor in determining and organism's ability to move around and burrow into sediments and is

reflected in variables such as grain size, porosity, and bulk density. The permeability of a

sediment will also be important in determining or regulating movement of interstitial waters
8-17

through the sediment which is in turn important for the transport of fluids and gases in

sediments. These fundamental properties will be important to the establishment and maintenance

of geochemical gradients in the sediment column.

Hydrocarbon and metal contaminant concentrations will be used to infer the presence or

absence of previous anthropogenic disturbances at the study sites. In trying to understand

ecological systems and their functioning it is important to determine if the system has been

subjected to perturbations in the past, such as pollution, that might have already altered the

community structure and function. It is expected that areas will be relatively contaminant-free.

The contaminant data can be reduced through Principal Components Analysis (PCA) to one or

two PCs that then can be regressed against any other variable to determine if there is a

correlation or the PCs are used in multivariate statistical analyses.

The objective of the porewater and solid phase geochemical studies is to establish the

relationship between the chemistry of the sediments and the benthic biological community. The

concentrations and sources of dissolved and total organic carbon in the sediment which

represents the “fuel” for the community (source can be inferred from the stable carbon isotopic

composition), determine the near interfacial gradients of the redox reactive reactants and

products as indicators of interfacial fluxes and biological activity, determine the products of

organic matter remineralization near the sediment-water interface as a measure of biological

activity, and determine if the redox environment has reached a point where sulfate reduction is

important will be determined. The detailed down-core profiles at experimental stations will be

used to calculate sulfate reduction rates, denitrification rates, manganese reduction rates, and

iron reduction rates. Flux measurements will also be determined for cross-calibration with the

benthic chambers.

Hydrogen sulfide and carbon dioxide are important biological products. Pore water

profiles of important metabolites will be used to estimate rates of anaerobic and aerobic

metabolism. The rate at which dissolved inorganic carbon is produced will be compared with

oxygen consumption to estimate a sediment Respiratory Quotient, the oxygen utilized versus the

metabolic dissolved inorganic carbon (DIC) produced. The estimated DIC produced by all

functional groups will be summed and added to total heterotrophic metabolism. This value will

be added to the bacterial values. Iron distributions are important to fully understand the sulfide

chemistry as it actively uptakes sulfide. Nutrients and dissolved organic carbon will be used to

determine fluxes and understand the diagenesis of the sediments. Sulfate reduction, in organic

rich sediments, can be as important as oxygen consumption. In general, this is not expected to be

high in oligotrophic waters, but earlier studies suggest that it can be important in GOM

sediments on the upper slope. Integrated sulfate reduction rates will be measured and added to

the other suboxic and anaerobic processes to estimate total sediment metabolism. Sulfate

reduction tends to be accelerated in response to inputs of organic matter.

The geochemistry work element will also determine sediment accumulation rates and

rates of bioturbation at the experimental sites from radionuclide profiles. Mixing and

accumulation rates are needed to fully calculate metabolism rates. Finally, isotopic

measurements of both sedimentary organic carbon and porewater inorganic carbon will aid in

elucidating the source and fate of carbon in the system.
8-18

8.4.4 Water Column Chemistry and Oceanography

Oceanographic data will provide information on the physical setting at each station. The

upper water column will be characterized for those variables (nutrients, oxygen, particulates,

organic carbon, and phytoplankton pigments). Energetic features such as the Loop Current, Loop

Current eddies, cyclonic eddies, or bottom -intensified currents will also be identified a forcing

factor. These data provide estimates of water currents and information on the water column

chemistry. The water column work element will characterize the photic zone as to the amount,

origins, and type of particulate matter present.

The oceanographic studies will provide near-bottom flow-fields during the experimental

stations to define the physical setting at each location (ADCP studies). The dynamics and origins

of the near-bottom nepheloid layer will also be documented. This work element will also identify

any large amplitude current events during the study. Estimates of vertical measures of coherence

of currents through the bottom boundary layer will be provided. Backscatter intensity will be

used to quantify nepheloid layer occurrences, depth, thickness, and temporal variability.

In cooperation with the SeaWiFS analysis group at the University of South Florida, the

annual mean Gulf of Mexico basin-wide distribution of surface chlorophyll concentration was

calculated using SeaWiFS ocean color data from January 1998 through December 1999.

Locations of each of the DGoMB survey stations were then overlaid so that the incidence of

locally high chlorophyll concentrations in deepwater could be compared along and between

DGoMB station lines. This map was posted to the DGoMB web page; the resolution of the ocean

color annual mean is 4 km x 4 km.

In cooperation with the TOPEX/Poseidon analysis group at the University of Colorado,

the Gulf of Mexico basin-wide mean surface height anomaly (SSH) was computed for the

calendar years 1998 and 1999 using altimetry from January-December 1998 and JanuaryDecember 1999. The locations of the DGoMB stations were overlaid for comparison and this

map was also posted to the DGoMB web page.

During Year Two of DGoMB, biweekly mean (and standard deviation) chlorophyll

concentrations for a 5 x 5 pixel area (287 km2

) centered at each of the DGoMB station locations

will be extracted.

8.4.5 Ecosystem “Health”

The “health” of the ecosystem in the area to be studied will be explicitly evaluated based

on fundamental community structure variables (biomass, density, species composition, and

diversity) measured as part of the benthic survey. The northern GOM ecosystem will be

compared with other similar deep-sea settings world-wide. These comparisons will give a

perspective on what features of the GOM ecosystem are similar or dissimilar to those of other

areas. The qualitative degree of disturbance or alteration that has occurred in comparative

ecosystems will provide a perspective on the current status of disturbance, stress, and/or “health”

for the northern GOM ecosystem.
8-19

In addition, screening of the stations for chemical contaminants will provide a first-order

determination of whether significant anthropogenic influences can be recognized at the study

sites. While the levels of contaminants in the deep-sea are expected to be low, if any are

encountered the potential for biological effects will be evaluated versus various biological effects

criteria for sediment contaminant levels. By inference if no chemical contaminants are present,

the current structure is reflective of an undisturbed state as far as toxic responses would be

concerned.

As an in-the-end evaluation, the model will be capable of predicting the ecosystem

response to various types of “unnatural” inputs. In particular, organic enrichment from the

possible reef effects of offshore platforms and the possible introduction of chemical

contaminants. While these effects have been documented near production platforms, in deep

water the likely impact on the seabottom is greatly attenuated due to dispersion, dilution and

vertical transport through the long overlying water column. On the continental shelf the areal

extent of these effects around platforms are localized (within 10's of meters) and the attenuation

of surface inputs would be significant in deep water. As mentioned above, the presence of

chemical contaminants in sediments will be directly assessed. However, model predictions can

be used to develop a set of diagnostic changes or trends in community structure and function in

variables that might be expected under given “disturbance” conditions. Subsequently the

sampled areas could be re-examined for these trends to determine if the sampled communities

show any of the expected signs of disturbance or diminuation in “health”.

Other more direct measures of population and individual “health” were judged to be

beyond the scope of the current program and the available resources. However, additional

indicators of ecosystem “health” have been proposed as potential optional add-ons to the main

program.

8.4.6 Data Fusion and GIS

The complexity of the datasets being developed for this Program and the diversity of the

types of data calls for innovation in developing tools for data synthesis and reporting. It is also a

requirement of the solicitation that all data be geo-referenced in a machine-readable format

capable of being incorporated directly into ARC/INFO using ARC/INFO's default data

conversion capabilities. These requirements will be met by adopting a GIS based approach to

data management, control, utilization, and synthesis. Data management protocols are detailed in

the Program Management Plan.

Program data will be submitted to MMS for incorporation into their CORIS database.

Separate coverages for each type of data collected or a single coverage for each type of topology

will be produced. Any attributes contained in the coverage will be carried over to the SDE layer

in the CORIS database. Two INFO tables will be created for each type of data (point, line, or

poly). The ENVM_SOURCES table will hold source information about the data collected (e.g.

depth). The second INFO table is a cross-reference table that will tie the features in the

coverages to the data in the ENVM_SOURCES INFO table. ESRI software (ArcInfo, ArcMap)

will be used to generate these data products.

The proposed Program will produce a wealth of mappable data at regional and local

(station) spatial scales. This will include a wide range of data types from actual images from
8-20

benthic cameras to community structure and function, chemical, geochemical, geological and

oceanographic variables. In addition, diverse data sets from previous investigations will be

incorporated into the synthesis. In order to facilitate cross-work element and interdisciplinary

integration, the data must be readily available and in a compatible format. Standard GIS methods

will be used to fuse and disseminate data as digital and hard-copy maps using a multi-layered

data approach. Spatial statistical methods will be used to aid in the testing of hypotheses.

Interactive tools will be tailored to the Program so that the datasets are easily queried, sorted and

displayed in a geo-referenced framework. The intent is to make the Program database as user

friendly as possible and to provide state-of-the-art tools for data presentation and mapping.

8.5 Data Management

Data management plays a key role in complex environmental programs involving sample

collection, monitoring, archiving, and chemical/physical/biological analyses and it’s stated

objectives are to monitor, control and facilitate data flow, ensuring the integrity of the data

through each phase of the program.

Data management prepared a detailed summary of the planned data collection for the

program and designed sample field collection forms (Tables 8.2 and 8.3).

Information was received directly from the ship during the first cruise and posted to the

web (http://www.gerg.tamu.edu/GERG/dgomb.htm) with daily updates and weekly summaries.

Data received to date for the first cruise includes collection information which has been

incorporated into a GIS database and POC, TSPM, pigment data from three depths.

8.6 Meetings, Interpretation, and Reporting

Seven different meetings, with oral reports or formal written reports, have been

conducted as of this Interim Report. A post-award meeting was held in College Station in

October 1999, of the Principal Investigators, in the presence of the MMS personnel, to discuss

the overall plan and goals of the project. This included a time line for deliverables, future

meetings, and field work.

The Program Manager (Rowe) attended the December 1999, MMS Information Transfer

Meeting in New Orleans and presented an overview of the project. This included presentation of

the hypotheses, the conceptual model and the latest version of the complex topography over

which the stations were to be placed.

A cruise plan for the May/June survey was developed and distributed to all components

and MMS one month prior to the field work. A report of the activities on the survey was

submitted one month after the cruise was finished (Appendix I). The latter report included

critical information on each site, such as geographic positions, depths, observations, etc. It also

included an inventory of all samples in hand and to whom they are distributed.
8-21

Table 8.2. Data collection summary and tracking.

Dependent Variables to be Measured.

Community Structure Community Function

Bacterial density Bacteria growth rates

Bacterial biomass Bacteria respiration

Foraminiferal biomass Bacteria response to different substrates

Meiofaunal density

Meiofaunal biomass

Meiofaunal composition to major group

Macrofaunal density

Macrofaunal biomass

Macrofaunal diversity

Macrofaunal species composition

Megafaunal density

Megafaunal biomass

Megafaunal diversity

Megafaunal species composition Megafaunal scavenging on carcasses

Fish density

Fish biomass

Fish diversity

Fish species composition Nutrient Regeneration

Denitrification rate

Sediment mixing rates (bioturbation)

Sediment accumulation rate

Sedimentary community oxygen consumption

Sulfate reduction rate

Foodweb studies

2

-estimated from sub-model

Ancillary Variables to be Measured at Survey and Experimental Stations.

Water Column Profiles Geochemistry1

 Depth Nutrients

 Temperature Dissolved Organic Carbon (DIC)

 Salinity SO4=/Cl-

 Oxygen Dissolved Inorganic Carbon (DIC)

 Nitrate and Nitrite δ13C DIC

 Ammonium Sulfate Reduction Rate

 Silicate pH

 Phosphate H2S

 Particulate Matter (PM) O2

 Particulate Organic Carbon (POC) Reactive Fe

 Light Reactive Mn

 Currents Acid Volatile Sulfide 1

Composite sample at survey station, profiles for

fluxes at experimental station.

Sediment Properties Biotic Water Column Profile

 Grain Size Photosynthetic Pigments

 Porosity

Elemental composition (organic carbon, nitrogen, sulfur)

 Percent inorganic carbon (TIC) Chemical Contaminants

 Permeability Hydrocarbons

 Shear Strength Metals

 Bulk Density
8-22

Table 8.3. General biological field collection form.

Var Cruise Sta Sppcode Abun Biomas S_Gear Method Sampid Labsamp

Descrip. Cruise

ID

Station

ID

Species

Code

(NODC)

Abundance Biomass

(g)

Sampling Gear

(Box, Trawl)

Sed, Tis,

Wat, etc

Sample ID Lab ID

Units # g

Obs 1

Obs 2

Obs 3

Obs 4

Obs n

The Program Manager (Rowe) attended the MMS-sponsored Fisheries and Offshore

Ecology meeting in New Orleans, October 24-26, 2000. He presented an overview of the results

of the program to date. This included the hypotheses, the conceptual model, a carbon budget for

the deep Sigsbee Abyssal Plain, and photographs of typical samples taken on the Survey Cruise.

This included photographs of the wide spectrum of trash sampled with the trawl. Another paper

was presented by Dr. Douglas Biggs and Mr. Patrick Roessler on levels of surface water

productivity and potential ‘hot spots’ that might influence deep water secondary productivity and

biomass.

The Program Manager met with the Scientific Advisory Committee on November 28,

2000 to present an overview of the status of work so far and a list of overall goals of DGoMB.

Four talks were presented at the December 5-7, 2000 MMS Information Transfer

Meeting in New Orleans. The Program Manager (Rowe) presented an overview of the Survey

Cruise, results, status of the hypothesis testing, status of model runs, and potential activities on

the up-coming process-oriented field work on GYRE in June, 2001. Additional talks were given

by Drs. Ian MacDonald and William Bryant on the Alvin/Atlantis expedition in October 2000.

Dr. Elva Escobar summarized activities in deep-sea ecology by Mexico in the deep Gulf of

Mexico.

In addition to the above, the Program Manager (Rowe) presented overviews of the

DGoMB program in the weekly seminar of the Department of Oceanography at Texas A&M, at

the BP environmental science seminar series, at the Jefferson Breakfast Club in Houston, and in

the monthly seminar series of the Department of Oceanography at the University of Concepcion

in Concepcion, Chile. Dr. Rowe also provided an overview of the program to the MMS Science

Committee.

A “quick look” report required by NOAA has been written that describes the Alvin dive

results (Appendix II).

8.6.1 Planning

The Executive Committee (EC; Rowe, Kennicutt, Nowlin, Morse, and Bryant) met

during December 2000 to discuss sample analysis progress and a schedule for preliminary
8-23

interpretations for planning purposes. A preliminary draft of the June “processes” cruise plan

will be reviewed, with emphasis on sampling and observations to be conducted at each site, how

many sites to study and where the sites ought to be placed. Definite decisions on these issues will

not be made at this time because too little data are available yet, but the EC will start to set a

reasonable decision-making protocol in which priorities are defined. Top priority will be placed

on locations and activities that are important to hypothesis testing and model variables. The EC

will also discuss potential data reports that ought to be assembled. Options for data distribution

that go beyond the contract requirements will also be discussed. If necessary, DGoMB data

manager Dr. Gary Wolff was asked to attend to participate in this issue. [DGoMB would like to

develop strategies to make all data generated widely available.]

A meeting for Principal Investigators was held in February 2001 at which each PI was

asked, in the first half of the meeting (1/2 day), to bring everyone up-to-date on the status of

sample analysis, status of hypothesis testing and status of model development. The second half

of the meeting entailed discussions of the “processes” cruise on GYRE, June 1-20, 2001.

Investigators with suggestions about hypothesis testing and sampling strategies for determining

rates important to model development was asked to present their ideas. Others will be expected

to respond with constructive criticism of the ideas and suggestions presented. This meeting was

important for planning the next field work because enough data were available by this time to

give the issues serious thought ahead of time. The report from that meeting explained the

rationale for adding three new hypotheses and thre reasoning behind the choices of the four

experimental sites (MT3, S36, S42, and MT6).

8.6.2 Field Program, R/V Gyre, June 1-20, 2001

The second DGoMB Cruise was conducted on the R/V Gyre in June, 2001. Planning to

decide on sites to be studied and activities at each site was done at the Team Planning Meeting in

February, 2001. Priorities were placed on hypothesis testing and model development, as

presented in the original proposal. Significant progress is expected in the EC and PI meetings

referred to above, but this will be fine-tuned through discussions between the Program

Managers, the EC and the Principal Investigators. A final plan for the ‘processes’ field work was

available one month (on May 1, 2001) before the scheduled trip. The cruise was conducted from

June 1-19, 2001, in and out of Galveston.

Future field activities are scheduled for June and August, 2002. However, this is subject

to discussion and revision based on developing issues and new data.
9-1

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Appendix I

Deep Gulf of Mexico Benthos Program

(DGoMB)

Cruise I Report

R/V Gyre

May 3-June 21, 2000

Texas A&M University

University of Texas

etc.

MMS Contract 1435-01-99-CT-30991
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RV GYRE DGOMB SURVEY CRUISE REPORT

Background

Texas A&M University, in cooperation with a number of subcontractors (see list of

participants), is under contract to the Minerals Management Service (Contract No. 1435-01-99-

CT-30991, Deep Gulf of Mexico Benthos-DGoMB) of the US Dept. of the Interior to investigate

the structure and function of the deep ocean benthic communities in the northern Gulf of

Mexico. The program has been designed to be conducted in two phases: a census of the

composition of the communities, followed by measurements of principal biogeochemical and

eco-physiological processes that characterize the dominant populations of the communities.

Conceptual models, steady state budgets, and dynamic numerical simulations will be constructed

from the census information. The models will be tested and adjusted appropriately based on the

new data collected during the field programs in the second phase. This present report is on the

field work conducted in support of the first phase: the survey (census) of the biota.

Purpose

The purpose of the "Survey" in DGoMB was to characterize the principal components of

benthic communities over the entire northern Gulf of Mexico (GoM) from the continental shelf

break out to the southern boundary of the Exclusive Economic Zone (EEZ) at 26o

 N. Latitude.

This characterization was intended to assess the abundances and biomasses of each of the

important size classes of the communities (bacteria, meiofauna, macrofauna, megafauna and

demersal fishes). Species composition is to be determined for the macrofauna, megafauna and

fishes. The diversity and zoogeographic distribution patterns for each of these size groups will be

determined for assessments of variations within the GoM and comparisons of the deep GoM

with other continental margins. The variations in biomass within the groups and in space will be

used to construct steady state budgets of carbon flux within the study area.

Dates

May 3 to June 21, 2000, with a port stop in Port Aransas from May 22 to May 28.

Participants

Leg One Participants

1) Rowe, Gilbert T., Chief Scientist, TAMU, Prof., Oceanogr., DGoMB Pgm. Mgr.,

2) Kalke, Richard, UT-MSI Res. Assoc.,

3) Gilbert, Marianne, UT-MSI, graduate student,

4) Lee, Wonchoel, UT-MSI, postdoctoral investigator

5) Loughy, Lindsey, TAMU, Bio., undergrad. stu.

6) Salas Hernandez, Juan Antonio, UNAM, Mexican representative

7) Oseguera Perez, Luis Alberto, UNAM, Mexican representative

8) Ziegler, Mathew, TAMU grad. stu., Oceanography

9) Gudeman, Christopher, TAMU grad. stu., Oceanography

10) Carpenter, Shelly, U. Washington Res. Asst.

11) Debeukelaer, Sophie, TAMU Ocean. grad. student
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12) Nunnelly, Cliff, TAMU graduate student, Oceanogr.

13) Guichard, Aurelien, TAMU graduate student, Ocean. Engineering

14) Ammons, Archie, TAMU grad. stu., Biology

15) Zednai, Leslie, marine technician, TAMU, GERG

16) Clark, Paul, TAMU, GERG, winch operator, deck engineer, CTD, ADCP

17) Guffy, Dennis, TAMU, Ocean. Tech.

18) Rowe, Sherrylynn, Memorial Univ., Nfld, CA

19) Davenport, Roe, independent consultant, San Antonio, TX

Leg Two Participants

1) Rowe, Gilbert T., TAMU, Ocean., Prof. and DGoMB Pgm. Mgr., Chief Scientist

2) Goff, John, TAMU, Res. Asst., WFS

3) Wicksten, Mary, TAMU, Bio., DGoMB PI

4) Ammons, Archie, TAMU, Bio., grad. stu.

5) Ziegler, Mathew, TAMU, Ocean., grad. stu.

6) Gilbert, Marianne, UT-MSI, graduate student

7) Loughy, Lindsey, TAMU, undergraduate biol.

8) Gudeman, Christopher, TAMU, Ocean., grad. stu.

9) Jones, Brian, TAMU grad. stu., Oceanography

10) Debeukelaer, Sophie, TAMU grad. stu., Oceanography

11) Nunnelly, Cliff, TAMU Grad. stu., Ocean.

12) Walpert, John, TAMU, GERG

13) Zednai, Leslie Anne, marine technician, TAMU, GERG

14) Webb, Eddie, TAMU, Dept. of Oceanography, electronics technician

15) Lee, Wonchoel, UT-MSI, postdoctoral investigator

16) Methven, David, Memorial Univ., Nfld, CA

17) Davenport, Roe, independent consultant

Narrative (Figure 1-Site Map)

Forty-three sites were selected to determine the relationship between the biota and a

general set of environmental variables: 1) an east to west gradient, 2) a depth gradient, 3) basins

vs. non-basins, 4) canyons vs. non-canyons, 5) proximity to the Mississippi River plume, and 6)

proximity to fossil hydrocarbon seeps. These sites were placed along a series of west to east

transects. Where possible, earlier sampling sites from previous studies were re-occupied. Each

transect had approximately 6 sites ranging in depth from the shallow upper slope down to the

upper continental rise at the base of the Sigsbee (west area) and Florida (east area) escarpments.

The west sites were located along the 26o North Latitude line, which marks the border with

Mexico.

At each site the following sampling sequence was carried out: 1) CTD, 2) 5 box cores, 3)

camera lowering and 4) bottom trawl.
AI-5

CTD and Associated Hydrography:

The CTD and rosette water sampler was deployed at each site. Samples were taken to

within 2 m of the bottom to characterize the bottom water. The near bottom bottles were sampled

for particulate matter, POC, plant pigments, dissolved inorganic nutrients, oxygen and salinity.

The oxygen, temperature, salinity, in vivo fluorescence, light intensity and light transmission

were measured continuously with sensors and recorded aboard ship in real time. The oxygen and

salinity were calibrated aboard ship with samples from the bottles. The inorganic nutrients were

run with an autoanalyzer aboard ship on the first leg and frozen on the second leg for analysis in

the shore-based laboratory.

The CTD, 24 bottle rosette and associated sensors, and a bottom-finding pinger were lost

at site B2 on the first leg. For the remainder of the 1st leg the backup CTD and a 12 bottle rosette

were used. A replacement 24 bottle rosette was put aboard ship in Port Aransas and this was

utilized during the entire 2nd leg.

Profiles are now available of temperature, salinity, oxygen concentration, and light

transmission from each site. Inquiries about the hydrographic data should be directed to Dr.

Worth Nowlin (wnowlin@ocean.tamu.edu) or Dr. Norman Guinasso (norman@gerg.tamu.edu).

Box Cores (see table of sample inventory):

The GOMEX box cores were taken to provide quantitative information on macrofauna,

meiofauna, bacteria, geological properties, geochemical properties, trace metals, and trace

organic contaminants. The subsamples were taken by mounting core liners within the core box to

prevent artifacts due to redistribution of surficial sediments during recovery. The geology core

was taken from the core after recovery. This allowed the geo-sample to be taken with no

overlying water. A total of 215 0.2 m2

 box cores were taken; these covered a total of 43 square

meters of sea floor.

On recovery, the overlying water of each box core was siphoned off through a 300

micrometer sieve with the retained material added to the macrofauna sample. The subcores

(plastic core liners mounted in the box) were covered with core caps immediately to prevent

contamination. Then the surface sediment down to a depth of 15 cm was removed from around

the mounted subcores. This material was then sieved through 300 micrometer mesh sieves by

floating and elutriating the composite animal-containing sediment from 30 gallon plastic ash

cans out into the sieves, using filtered sea water to prevent contamination by plankton. The

macrofauna samples and associated sediments retained by the sieve were soaked in sea water

containing ca. 50 cc of Epsom Salts (MgSO4) for 30 minutes to narcotize and thus relax the

animals prior to fixation in 10% formalin and filtered sea water solution. The fixed animals and

associated sediments retained by the sieves were stored in 5 gallon plastic containers on deck.

The fixative solution volume was in all cases more than 2 times the volume of the sediment

retained in the sample after sieving. The containers were labeled inside and out using approved

"MMS-DGoMB" labels. They were also labeled with the sequential event or activity number

(see Appendix) on the container's top with a black permanent felt-tipped marker.
AI-6

Following the removal of the surficial 15 cm for macrofauna, the subcores were

stoppered or capped on the bottom and removed from the core box. They were extruded from the

bottom up and the top 2 cm were taken for the non-biological samples. A profile of bacteria

samples was taken at surface, 5, 10 and 15 cm depth intervals. The meiofauna cores were

subsampled at two intervals: the top 0 to 1 cm, followed by a layer that included cm's 2 and 3.

The meiofauna samples were preserved in 5% formalin sea water solution containing Rose

Bengal stain. These samples were transferred to the University of Texas Marine Science Institute

in Port Aransas. The bacteria were preserved in 2% glutaraldehyde and filtered sea water

solution and kept refrigerated until air freighted to the University of Washington at the end of the

2nd leg. The geochemical, trace metal and trace organic samples, each 2 cm thick, were frozen

aboard ship. The geology cores were stored on deck.

The GOMEX box core covers an area that measures 18" x 18". This is equivalent to

0.209 m^2. The areas covered by the subcores were 36.3 cm2 for each of the 5 larger subcores

(geology, geochemistry, bacteria, trace metals and trace organics) and 24.6 cm2 for each of the

two meiofauna cores. Thus a total of 230.8 cm2 was removed from the 2,090 cm^2 box.

Therefore, the macrofauna sample was 1860 cm2, or 0.185 m2. Although two meiofauna cores

were routinely mounted in the core, only one was retained for further study.

Bottom Camera Lowerings (see sample inventory below):

A Benthos digital still camera and strobe, housed in deep-sea housings, were used to take

multiple exposures of the sea floor. This camera system was set up on a vertical frame with a

bottom trigger switch so that each exposure would cover approximately the same area of sea

floor (ca. 5 m2). A pinger was mounted 25 m above the camera frame on the hydrographic wire.

Bottom contact, and thus the triggering of each exposure, was accomplished by lowering the

camera until it hit bottom (as evidenced by the PGR trace or deflection of the spring

accumulator) and then immediately recovering it to a height of 10 to 15 m above bottom. This

lowering and recovery was repeated every one to two minutes until 25 to 50 exposures were

made of the sea floor. On recovery back aboard ship, the digital images were downloaded onto a

PC for viewing on computer screen, printing and storage.

A total of 43 attempts were made to take photographs of the sea floor at the sites

designated in Figure 1. Three of these attempts failed: on one occasion (B1, May 6) the camera

batteries failed. At W4 and RW6 the photographs were exposed by pre-tripping in the water

column during transit to the bottom. A total of 1380 photographs were taken where the camera

was successful at taking pictures of the sea floor. The mean number was 32 good exposures per

site. These covered an approximate area of 6900 m2

.

Bottom Trawling (see sample inventory table):

The sea floor was trawled at 40 sites. Of these, two were failures in which the trawl nets,

doors and bridles were all lost (RW6 on May 19; RW4 on June 20). At another site, most of the

net was lost but the doors and bridle were recovered (W2 on May 14). After the loss on May 19

near the end of the 1st leg, the backup beam trawl was used successfully.
AI-7

The otter trawl had a 40' gape. One pair of steel doors measuring 3' x 4' was used on the

first leg. Wooden doors measuring 7' x 40 inches were used on the second leg. It is assumed that

the net spreads to an effective width of ca. 33'. Thus, the trawl, when working properly, sampled

a path that was approximately 10 m across. The area covered can be estimated by multiplying

path width times the distance over which the trawl was on bottom. In the case of the beam trawl,

it had a width of 4 meters. The net's mesh size in both trawl types (otter trawl and beam trawl)

was 1.75 inch stretched. The wire let out was approximately 1.5 to 2 times the water depth.

Bottom time was 30 min per 1000 m depth. Ship speed was 1.7 to 2.3 knots. Wire pay out was

25 m per min; recovery was 25 m per min until the trawl was off bottom. Then it was increased

to 50 m per min.

The trawl samples were sorted into three categories: invertebrates, fish and trash. The

invertebrates and the fish were then sorted to the "species" level, counted, and weighed (by

volume displacement). Types of trash were counted and stored with no preservative in 5 gallon

plastic containers with an appropriate label on the inside and out. The biological samples were

placed in 5 gallon plastic containers with 10% buffered formalin and sea water solution with

labels on the inside and outside of the containers. The lids of trawl samples were also labeled

with the activity number (see Appendix) and designated either fish, invertebrate or trash.

ADCP

Acoustic Doppler Current Profilers (ADCP) were operated on station and with the ship

underway to obtain an integrated picture of current direction and velocity in the upper 1000 m of

the water column. A 38 kHz OS-ADCP was operated for the entire cruise. A BB-ADCP

(broadband) was utilized for the first leg and then switched to the narrow band system on May

31 when direction could not be resolved with the broadband system. On inspection of the system,

a deep gash in transducer # 4 was discovered that probably occurred while the ship was tying up

in Port Aransas. Processing of the data is ongoing.

Mapping

Maps were made during the sampling at each site at scales of 10 to 50 km around each

site, with topography plotted at 50 m intervals. The locations of each sampling activity were

plotted to show the spatial relationships between each sampling device and sampling replicates.

"Make-up" Sampling

The sampling planned for leg 2 was completed ahead of schedule and so an attempt was

made to "make-up" sampling that had been unsuccessful or for some reason needed repeating.

Thus, when MT1 (the last scheduled site) was finished, we returned to MT4 for a trawl. Then we

did camera lowerings in B1, B3 and B2, in that order. This was followed by trawling at B2, an

intermediate site between W6 and RW 6, and a final trawl near RW4. All this make-up sampling

was successful, with the exception of the last trawl: the wire parted and the whole system was

lost. Most of the damage to trawl gear occurred on transects W and RW.
AI-8

Inventory of Deep Bottom Samples from DGoMB

Trawls Box Cores 

SITE Fish Invertebrates Trash Macrofauna Meiofauna Bacteria Geology Geochemistry Trace Metals T

RW1 1 1 1 5 5 5 5 5 4 RW2 1 1 1 5 5 5 5 5 3 RW3 0 0 0 5 5 5 5 5 3 RW4 0 0 0 5 5 5 5 5 3 RW5 0 0 0 5 5 5 5 5 3 RW6 1 1 1 5 5 5 5 5 5 

AC1 0 0 0 5 5 3 5 5 3 

W1 1 1 1 5 5 5 5 5 5 W2 0 0 0 5 5 5 5 5 3 W3 1 1 1 5 5 5 5 5 3 W4 0 0 0 5 5 5 5 5 3 W5 0 0 0 5 5 5 5 5 3 W6 See RW6 for trawl 5 5 4 5 5 3 

WC5 1 1 1 5 5 5 5 5 5 

WC12 0 0 0 5 5 5 5 5 5 

B1 1 1 1 5 5 5 5 5 5 B2 1 1 1 5 5 4 5 5 3 B3 1 1 1 5 5 5 5 5 5 

NB2 1 1 1 5 5 5 5 5 5 NB3 1 1 1 5 5 5 5 5 5 NB4 1 1 1 5 5 5 5 5 5 NB5 1 1 1 5 5 5 5 5 5 

C1 1 1 1 5 4 4 4 4 4 C7 1 1 1 5 5 5 5 5 5 C4 1 1 1 5 5 5 5 5 5 

C14 1 1 1 4 3 1 5 3 3 C12 1 1 1 4 4 4 4 4 4 

MT1 1 1 1 5 3 3 5 3 3 MT2 1 1 1 5 5 5 5 5 5 MT3 1 1 1 5 5 5 5 5 5 MT4 1 1 1 5 5 5 5 5 5 
AI-9

Inventory of Deep Bottom Samples from DGoMB (Cont.)

Trawls Box Cores 

SITE Fish Invertebrates Trash Macrofauna Meiofauna Bacteria Geology Geochemistry Trace Metals T

MT5 1 1 1 5 5 5 5 5 5 MT6 1 1 1 5 5 5 5 5 5 

S35 1 1 1 4 5 4 5 5 5 S36 1 1 1 5 5 5 5 5 5 S37 1 1 1 5* 5 5 5 5 5 

S38a* 1 1 1 5* 5 5 5 5 5 

S44 1 1 1 5* 4 5 5 5 5 S43 1 1 1 5 5 4 4 5 5 S42 1 1 1 5 5 5 5 5 5 S41 1 1 1 5 5 5 5 5 5 S40 1 1 1 5 5 5 5 5 5 S39 1 1 1 5 5 5 5 5 5 

* Box core leaked from some samples on recovery; see original field notes.a* Original S38 moved 5 n.mi. due west because of difficult sampling at base of Florida escarpment.
AI-10

Appendix-Event or Activity Log. UTC refers to Universal Central Time, often referred to as Greenwich Time. of the local time aboard ship. Sample types are discussed above in the text. The site names are shown on the mwater depth as read off the Precision Depth Recorder. Wire out is the amount of wire let out from the winch.

DATE-UTC TIME UTC LAT/MIN LONG/MIN SEQ. No. SITE

NAME

SAMPLE

TYPE

WIRE

OUT

(m)

PDR

(m)

COM

4-May-00 1241 27 46.9694N 91 46.2067W 1 WC5 CTD 329 322.3 4-May-00 1417 27 46.3012N 91 46.3146W 2 WC5 Box Core No 4-May-00 1437 27 46.2817N 91 46.1895W 3 WC5 Box Core 475 440 No 4-May-00 1525 27 46.2838N 91 45.7293W 4 WC5 Box Core 448 400 Go4-May-00 1723 27 47.1151N 91 45.8502W 5 WC5 Box Core 358 320 Go4-May-00 1857 27 46.5547N 91 45.9407W 6 WC5 Box Core 420 348 Good core 4-May-00 2018 27 46.906N 91 45.9578W 7 WC5 Box Core 405 330 Go4-May-00 2206 27 46.9893N 91 45.8800W 8 WC5 Box Core 368 325 Go5-May-00 0028 27 46.9633N 91 45.6946W 9 WC5 Camera 330 328 First h5-May-00 0037 27 46.9673N 91 45.6070W 10 WC5 Camera 330 328 Last h5-May-00 0414 27 41.8766N 91 39.4832W 11 WC5 Trawl 1755 845 Start tra5-May-00 0444 27 40.9851N 91 38.6803W 12 WC5 Trawl 1755 670 En5-May-00 0828 27 19.0946N 91 32.8177W 13 WC12 CTD 1161 1150 5-May-00 1301 27 19.3945N 91 33.3486W 14 WC12 Box Core 1168 Go5-May-00 1432 27 19.1120N 91 33.2314W 15 WC12 Box Core 1125 Go5-May-00 1549 27 19.4320N 91 33.1625W 16 WC12 Box Core 1175 Go5-May-00 1715 27 19.185N 91 33.0650W 17 WC12 Box Core 1169 Go5-May-00 1855 27 19.6198N 91 33.0871W 18 WC12 Box Core 1194 Go5-May-00 2042 27 19.6546N 91 33.0179W 19 WC12 Camera 1198 5-May-00 2125 27 20.1211N 91 33.0853W 20 WC12 Camera 1295 1300 5-May-00 2345 27 19.3666N 91 35.4967W 21 WC12 Trawl 2100 1050 Start- tra6-May-00 0016 27 19.5117N 91 36.8079W 22 WC12 Trawl 2100 1150 En6-May-00 0432 27 12.0201N 91 24.1077W 23 B1 CTD 2279 2265 CTD 6-May-00 0725 27 12.2050N 91 23.9837W 24 B1 Box Core 2206 2260 Go6-May-00 0858 27 12.1374N 91 24.1806W 25 B1 Box Core 2195 2255 No 6-May-00 1019 27 12.1853N 91 24.2407W 26 B1 Box Core 2197 2255 Go6-May-00 1208 27 12.1704N 91 24.3638W 27 B1 Box Core 2195 2253 Go6-May-00 1348 27 12.0086N 91 24.3648W 28 B1 Box Core 2196 2254 Go6-May-00 1515 27 12.1525N 91 24.3131W 29 B1 Box Core 2196 2254 Go
AI-11

Appendix-Event or Activity Log (Cont.).

DATE-UTC TIME UTC LAT/MIN LONG/MIN SEQ. No. SITE

NAME

SAMPLE

TYPE

WIRE

OUT

(m)

PDR

(m)

COM

6-May-00 1720 27 12.3258N 91 24.2320W 30 B1 Camera 2297 2260 Sta6-May-00 1815 27 12.5960N 91 24.4054W 31 B1 Camera 2194 2250 En6-May-00 2208 27 10.4993N 91 25.2956W 32 B1 Trawl 7000 2250 Start- tra6-May-00 2308 27 12.3807N 91 23.8718W 33 B1 Trawl 7000 2250 En7-May-00 0623 27 7.8630N 92 0.0356W 34 NB2 CTD 1546 1530 CTD 7-May-00 0843 27 8.0243N 91 59.9584W 35 NB2 Box Core 1490 1530 Go7-May-00 1044 27 8.2040N 91 59.9207W 36 NB2 Box Core 1490 1530 Go7-May-00 1202 27 7.9710N 92 0.0170W 37 NB2 Box Core 1490 1530 Go7-May-00 1328 27 8.1027N 91 59.9891W 38 NB2 Box Core 1495 1530 Go7-May-00 1450 27 8.2605N 92 0.0126W 39 NB2 Box Core 1528 1530 No 7-May-00 1546 27 8.0900N 92 0.0041W 40 NB2 Box Core 1490 1530 Go7-May-00 1717 27 8.4208N 92 0.1543W 41 NB2 Camera 1548 1530 Sta7-May-00 1804 27 8.6513N 91 59.8378W 42 NB2 Camera 1527 1540 End ca7-May-00 2045 27 8.8370N 92 0.4277W 43 NB2 Trawl 4000 1525 St7-May-00 2130 27 7.1924N 91 59.6843W 44 NB2 Trawl 4000 1540 En8-May-00 0309 26 33.1686N 91 49.7059W 45 NB3 CTD 1986 1875 CTD 8-May-00 0555 26 33.4820N 91 49.3530W 46 NB3 Box Core 1890 1875 Go8-May-00 0729 26 33.6122N 91 49.3738W 47 NB3 Box Core 1902 1875 No 8-May-00 0841 26 33.3912N 91 49.4683W 48 NB3 Box Core 1885 1875 Go8-May-00 1010 26 32.9725N 91 49.1853W 49 NB3 Box Core 1846 1875 Go8-May-00 1131 26 33.3039N 91 49.4705W 50 NB3 Box Core 1840 1875 Go8-May-00 1248 26 33.2733N 91 49.5132W 51 NB3 Box Core 1845 1875 Go8-May-00 1425 26 32.8549N 91 49.3671W 52 NB3 Camera 1858 1885 1st 8-May-00 1519 26 32.7164N 91 48.9535W 53 NB3 Camera 1838 1863 Last h8-May-00 1908 26 31.3028N 91 48.9448W 54 NB3 Trawl 4700 1850 Trawl on bo8-May-00 2008 26 29.0239N 91 47.8046W 55 NB3 Trawl 4700 1910 En9-May-00 0112 26 15.0457N 91 13.0378W 56 NB5 CTD 2113 2080 CTD 9-May-00 0414 26 15.1137N 91 12.6102W 57 NB5 Box Core 2085 2070 Go9-May-00 0608 26 15.0855N 91 12.7524W 58 NB5 Box Core 2040 2060 Go9-May-00 0928 26 15.0428N 91 12.7712W 59 NB5 Box Core 2040 2060 No 9-May-00 1053 26 14.8501N 91 12.7500W 60 NB5 Box Core 2025 2060 Go9-May-00 1224 26 15.2157N 91 12.6639W 61 NB5 Box Core 2025 2060 Go
AI-12

Appendix-Event or Activity Log (Cont.).

DATE-UTC TIME UTC LAT/MIN LONG/MIN SEQ. No. SITE

NAME

SAMPLE

TYPE

WIRE

OUT

(m)

PDR

(m)

COM

9-May-00 1358 26 14.7240N 91 12.5945W 62 NB5 Box Core 2055 2065 Go9-May-00 1548 26 14.6013N 91 12.2397W 63 NB5 Camera 2067 2070 1st hit on9-May-00 1739 26 14.4129N 91 11.2416W 64 NB5 Camera 2140 2150 Last h9-May-00 2111 26 14.9971N 91 12.1544W 65 NB5 Trawl 5140 2110 All 5140 9-May-00 2211 26 15.0416N 91 14.4178W 66 NB5 Trawl 5140 2100 1 hou

10-May-00 0329 26 12.2946N 91 46.0718W 67 B3 CTD 2649 2650 Ping10-May-00 0600 26 13.5570N 91 45.3033W 67 B3 CTD Tube loc10-May-00 0907 26 9.8667N 91 44.1060W 68 B3 Box Core 2545 2650 Go10-May-00 1055 26 9.7884N 91 43.9954W 69 B3 Box Core 2554 2580 Go10-May-00 1241 26 9.9750N 91 43.9772W 70 B3 Box Core 2555 2590 Go10-May-00 1442 26 9.9760N 91 44.1386W 71 B3 Box Core 2570 2610 Go10-May-00 1637 26 9.8542N 91 44.0725W 72 B3 Box Core 2545 2600 Go10-May-00 2224 26 6.4804N 91 44.5135W 73 B3 Trawl 6200 2300 St10-May-00 2354 26 10.0902N 91 44.9254W 74 B3 Trawl 6200 2620 En11-May-00 0603 26 15.2211N 92 24.0743W 75 NB4 CTD 2055 2038 CTD (backup11-May-00 0901 26 15.2711N 92 23.6978W 76 NB4 Box Core 1965 2030 Go11-May-00 1051 26 14.9693N 92 23.4731W 77 NB4 Box Core 2000 2050 Go11-May-00 1221 26 14.8748N 92 23.6513W 78 NB4 Box Core 1977 2050 No 11-May-00 1337 26 15.0096N 92 23.7449W 79 NB4 Box Core 2020 Go11-May-00 1514 26 14.9712N 92 23.5933W 80 NB4 Box Core 1990 2050 Go11-May-00 1643 26 14.8050N 92 23.5372W 81 NB4 Box Core 2004 2060 Go11-May-00 1755 26 14.9346N 92 23.6610W 82 NB4 CTD 267 250 CTD 11-May-00 2129 26 15.3007N 92 23.4718W 83 NB4 Trawl 5100 2070 All 5140 11-May-00 2229 26 16.7577N 92 25.5074W 84 NB4 Trawl 5100 1950 En12-May-00 0303 26 33.0193N 92 13.6845W 85 B2 CTD 2798 2623 CTD 12-May-00 0650 26 33.0774N 92 12.9990W 86 B2 Box Core 2615 2630 Go12-May-00 0858 26 33.3750N 92 13.4716W 87 B2 Box Core 2600 2630 Go12-May-00 1056 26 32.9491N 92 13.1357W 88 B2 Box Core 2594 2625 Go12-May-00 1247 26 32.9158N 92 13.3885W 89 B2 Box Core 2578 2625 Go12-May-00 1432 26 33.0007N 92 12.9049W 90 B2 Box Core 2661 2635 Go12-May-00 1918 26 32.1216N 92 11.7171W 91 B2 Trawl 6200 2650 6200 m 12-May-00 2048 26 34.4042N 92 14.9502W 92 B2 Trawl 6200 2450 En
AI-13

Appendix-Event or Activity Log (Cont.).

DATE-UTC TIME UTC LAT/MIN LONG/MIN SEQ. No. SITE

NAME

SAMPLE

TYPE

WIRE

OUT

(m)

PDR

(m)

COM

13-May-00 0318 26 33.7775N 92 14.1248W 93 B2 Beam trawl 2620 2610 All 13-May-00 0405 26 33.7179N 92 13.4326W 94 B2 Beam trawl 2620 263013-May-00 1939 27 34.6599N 93 33.0201W 95 W1 CTD 434 418 CTD 13-May-00 2042 27 34.7791N 93 32.8573W 96 W1 Box Core 379 375 Go13-May-00 2120 27 34.8829N 93 33.0319W 97 W1 Box Core 389 385 Go13-May-00 2217 27 34.5256N 93 33.0286W 98 W1 Box Core 412 420 Go13-May-00 2309 27 34.5441N 93 33.0153W 99 W1 Box Core 410 420 Go13-May-00 2354 27 34.6299N 93 33.0603W 100 W1 Box Core 419 415 Go14-May-00 0143 27 34.5165N 93 33.2362W 101 W1 Camera 430 441 Cam14-May-00 0244 27 34.1729N 93 33.7450W 102 W1 Camera 455 488 Last h14-May-00 0409 27 34.5799N 93 32.8831W 103 W1 Trawl 1200 400 1200 14-May-00 0439 27 33.7587N 93 32.0068W 104 W1 Trawl 1200 400 En14-May-00 0712 27 24.7201N 93 20.2936W 105 W2 CTD 646 623 CTD 14-May-00 0826 27 24.8008N 93 20.2579W 106 W2 Box Core 611 625 Go14-May-00 0919 27 24.7019N 93 20.3849W 107 W2 Box Core 620 625 Go14-May-00 1042 27 24.8517N 93 20.4010W 108 W2 Box Core 619 625 Go14-May-00 1131 27 24.8855N 93 20.4223W 109 W2 Box Core 618 625 Go14-May-00 1215 27 24.8356N 93 20.4197W 110 W2 Box Core 619 625 Go14-May-00 1317 27 24.8902N 93 20.4991W 111 W2 Camera 605 620 Cam14-May-00 1410 27 24.8822N 93 20.5403W 112 W2 Camera 610 619 Last h14-May-00 1615 27 24.4216N 93 20.5061W 113 W2 Trawl 1875 650 1875 14-May-00 1645 27 23.3197N 93 21.1637W 114 W2 Trawl 1875 675 End tr14-May-00 1853 27 10.4567N 93 19.4560W 115 W3 CTD 901 878.3 CTD 14-May-00 2021 27 10.3711N 93 19.3081W 116 W3 Box Core 852 860 Go14-May-00 2126 27 10.3840N 93 19.3315W 117 W3 Box Core 869 860 Go14-May-00 2229 27 10.4482N 93 19.4034W 118 W3 Box Core 864 875 Go14-May-00 2340 27 10.4739N 93 19.2691W 119 W3 Box Core 859 860 Go15-May-00 0027 27 10.3438N 93 19.3976W 120 W3 Box Core 859 860 Go15-May-00 0136 27 10.3525N 93 19.4711W 121 W3 Camera 867 875 Cam15-May-00 0306 27 10.5371N 93 19.4659W 122 W3 Camera 856 875 50 pic15-May-00 0540 27 9.0861N 93 18.3774W 123 W3 Trawl 2500 910 2500 15-May-00 0616 27 8.6938N 93 20.0004W 124 W3 Trawl 2500 990 En
AI-14

Appendix-Event or Activity Log (Cont.).

DATE-UTC TIME UTC LAT/MIN LONG/MIN SEQ. No. SITE

NAME

SAMPLE

TYPE

WIRE

OUT

(m)

PDR

(m)

COM

15-May-00 0948 26 43.9179N 93 19.1384W 125 W4 CTD 1507 1475 CTD 15-May-00 1143 26 43.9027N 93 19.1708W 126 W4 Box Core 1429 1420 Go15-May-00 1324 26 43.8500N 93 19.1843W 127 W4 Box Core 1435 1460 Go15-May-00 1443 26 43.8088N 93 19.2061W 128 W4 Box Core 1435 1460 Go15-May-00 1554 26 43.7675N 93 19.2508W 129 W4 Box Core 1450 1460 Go15-May-00 1656 26 43.8494N 93 19.1836W 130 W4 Box Core 1425 1460 Go15-May-00 1817 26 43.8238N 93 19.1276W 131 W4 Camera 1432 1460 Cam15-May-00 1952 26 42.8721N 93 19.2633W 132 W4 Camera 1472 1457 Last h16-May-00 0003 26 16.7711N 93 21.5289W 133 W5 CTD 2875 2745 CTD 16-May-00 0323 26 15.9654N 93 21.6653W 134 W5 Box Core 2871 2755 Go16-May-00 0545 26 16.2566N 93 21.6885W 135 W5 Box Core 2786 2750 Di16-May-00 0747 26 16.5781N 93 21.7309W 136 W5 Box Core 2665 2740 Go16-May-00 1004 26 16.1395N 93 21.7915W 137 W5 Box Core 2750 2750 Go16-May-00 1205 26 16.1871N 93 22.0669W 138 W5 Box Core 2742 2745 Go16-May-00 1450 26 16.0663N 93 19.9634W 139 W5 Box Core 2810 2775 Go16-May-00 1650 26 16.4216N 93 21.7870W 140 W5 Camera 2721 2740 Cam16-May-00 1853 26 16.1884N 93 21.7605W 141 W5 Camera 2772 2745 50 pic17-May-00 0028 26 12.7951N 93 22.6483W 142 W5 Trawl 6500 2820 All 6500 17-May-00 0158 26 8.2760N 93 23.6074W 143 W5 Trawl 6500 2950 En17-May-00 0501 25 59.9254N 93 19.2382W 144 W6 CTD 3127 3140 CTD 17-May-00 0856 26 0.2171N 93 19.6175W 145 W6 Camera 3185 3130 Cam17-May-00 1014 26 0.0288N 93 19.4049W 146 W6 Camera 3058 3120 Last h17-May-00 1148 26 0.1707N 93 19.2166W 147 W6 Box Core 3055 3140 Go17-May-00 1353 25 59.7526N 93 18.8003W 148 W6 Box Core 3100 3145 Go17-May-00 1542 25 59.7601N 93 18.5516W 149 W6 Box Core 3128 3150 Go17-May-00 1744 25 59.8101N 93 18.4085W 150 W6 Box Core 3182 3145 Go17-May-00 1800 25 59.1728N 93 18.6528W 151 W6 Box Core 3114 3150 Be18-May-00 0725 26 0.0684N 94 30.1112W 152 RW6 CTD 3033 3015 CTD 18-May-00 1200 25 59.9222N 94 29.7608W 153 RW6 Box Core 2978 3015 Go18-May-00 1438 26 0.1959N 94 29.9143W 154 RW6 Box Core 3045 3015 Di18-May-00 1643 26 0.142N 94 29.381W 155 RW6 Box Core 3000 3015 Go18-May-00 1907 25 59.9982N 94 29.5629W 156 RW6 Box Core 2941 3000 Go
AI-15

Appendix-Event or Activity Log (Cont.).

DATE-UTC TIME UTC LAT/MIN LONG/MIN SEQ. No. SITE

NAME

SAMPLE

TYPE

WIRE

OUT

(m)

PDR

(m)

COM

18-May-00 2059 25 59.8684N 94 29.9071W 157 RW6 Box Core 2976 3010 Go18-May-00 2259 25 59.8382N 94 29.7347W 158 RW6 Box Core 2972 3010 Go19-May-00 0111 25 59.5948N 94 29.6375W 159 RW6 Camera 3022 3005 Cam19-May-00 0227 25 59.0106N 94 28.9461W 160 RW6 Camera 3218 3020 Bounc19-May-00 0754 26 5.9275N 94 32.8059W 161 RW6 Trawl 7475 2850 Max ca19-May-00 0928 26 9.0176N 94 34.6319W 162 RW6 Trawl 7475 2830 Cable-sna19-May-00 1658 26 23.4249N 94 34.1794W 163 AC1 CTD 2548 2520 CTD in 19-May-00 1945 26 23.4437N 94 34.2073W 164 AC1 CTD 225 225 CTD in w19-May-00 2120 26 23.4995N 94 33.5773W 165 AC1 Box Core 2510 2505 Go19-May-00 2335 26 23.4723N 94 33.3804W 166 AC1 Box Core 2552 2480 No 20-May-00 0119 26 23.2813N 94 33.2633W 167 AC1 Box Core 2572 2450 Go20-May-00 0333 26 23.7397N 94 33.3984W 168 AC1 Box Core 2689 2485 No 20-May-00 0512 26 23.5394N 94 33.4048W 169 AC1 Box Core 2510 2480 Go20-May-00 0944 26 23.1654N 94 33.2954W 170 AC1 Box Core 2580 2440 Go20-May-00 1148 26 23.6140N 94 34.3849W 171 AC1 Box Core 2519 2580 Go20-May-00 1408 26 23.4040N 94 33.8642W 172 AC1 Camera 2695 2520 Cam20-May-00 1515 26 23.3167N 94 34.4586W 173 AC1 Camera 2560 2580 Last h21-May-00 0010 26 30.2819N 95 0.1866W 174 RW5 Box Core 1600 1620 Go21-May-00 0136 26 30.0261N 95 0.1315W 175 RW5 Box Core 1600 1620 Go21-May-00 0248 26 30.0206N 95 0.0512W 176 RW5 Box Core 1589 1620 Go21-May-00 0405 26 30.0206N 95 0.0025W 177 RW5 Box Core 1589 1620 Go21-May-00 0525 26 30.4516N 94 59.8033W 178 RW5 Box Core 1625 1620 Go21-May-00 0712 26 30.1581N 94 59.2757W 179 RW5 Camera 1618 1637 Cam21-May-00 0816 26 29.7972N 94 58.5118W 180 RW5 Camera 1719 1620 Last h21-May-00 0917 26 30.1921N 95 0.0324W 181 RW5 CTD 1652 1625 CTD ma21-May-00 1320 26 43.1654N 95 14.9221W 182 RW4 CTD 1599 1580 CTD 21-May-00 1514 26 44.8861N 95 14.7680W 183 RW4 Box Core 1599 1570 Go21-May-00 1619 26 44.9468N 95 14.6826W 184 RW4 Box Core 1542 1580 Go21-May-00 1734 26 44.9707N 95 14.9825W 185 RW4 Box Core 1539 1575 Go21-May-00 1859 26 45.1621N 95 15.0741W 186 RW4 Box Core 1539 1570 Go21-May-00 1959 26 45.0852N 95 15.0105W 187 RW4 Box Core 1537 1575 Go21-May-00 2132 26 45.0626N 95 14.9965W 188 RW4 Camera 1532 1570 Cam
AI-16

Appendix-Event or Activity Log (Cont.).

DATE-UTC TIME UTC LAT/MIN LONG/MIN SEQ. No. SITE

NAME

SAMPLE

TYPE

WIRE

OUT

(m)

PDR

(m)

COM

21-May-00 2245 26 45.0528N 95 14.9725W 189 RW4 Camera 1539 1570 End22-May-00 0150 27 0.0399N 95 30.0197W 190 RW3 CTD 1395 1326 CTD 22-May-00 0350 27 0.2983N 95 30.1920W 191 RW3 Box Core 1324 1320 Go22-May-00 0503 27 0.2956N 95 30.0541W 192 RW3 Box Core 1295 1325 Go22-May-00 0619 27 0.1881N 95 29.7639W 193 RW3 Box Core 1311 1340 Go22-May-00 0727 27 0.2706N 95 29.8642W 194 RW3 Box Core 1320 1330 Go22-May-00 0845 27 0.5014N 95 29.5417W 195 RW3 Box Core 1455 1335 Go22-May-00 1005 27 0.8138N 95 29.5962W 196 RW3 Camera 1342 1320 Cam22-May-00 1132 27 1.1573N 95 29.1856W 197 RW3 Camera 1279 1315 Last h22-May-00 1427 27 15.0391N 95 44.8585W 198 RW2 CTD 1107 950 CTD 22-May-00 1606 27 15.2435N 95 44.6186W 199 RW2 Box Core 985 950 Go22-May-00 1707 27 15.2852N 95 44.6402W 200 RW2 Box Core 1100 950 Go22-May-00 1805 27 14.9757N 95 44.8287W 201 RW2 Box Core 937 950 Go22-May-00 1904 27 15.0531N 95 45.1451W 202 RW2 Box Core 927 950 Go22-May-00 1955 27 15.2416N 95 44.8084W 203 RW2 Box Core 971 950 Go22-May-00 2132 27 15.3675N 95 44.5235W 204 RW2 Camera 986 950 Cam22-May-00 2250 27 16.1523N 95 43.6107W 205 RW2 Camera 1025 940 47 23-May-00 0053 27 16.5674N 95 44.2286W 206 RW2 Trawl 2000 920 Beam tra23-May-00 0124 27 17.0968N 95 43.9536W 207 RW2 Trawl 2000 915 En23-May-00 0417 27 30.0191N 96 0.0307W 208 RW1 CTD 211 213 CTD 23-May-00 0500 27 30.0242N 96 0.1437W 209 RW1 Box Core 211 210 Go23-May-00 0534 27 29.8191N 96 0.1854W 210 RW1 Box Core 215 213 Go23-May-00 0613 27 30.0733N 95 59.9273W 211 RW1 Box Core 215 212 Go23-May-00 0658 27 30.0550N 96 0.1154W 212 RW1 Box Core 215 212 Go23-May-00 0740 27 30.0085N 96 0.1708W 213 RW1 Box Core 219 213 Go23-May-00 0828 27 30.0345N 96 0.0243W 214 RW1 Camera 220 210 Cam23-May-00 0934 27 30.4524N 95 59.7840W 215 RW1 Camera 225 204 47 23-May-00 1023 27 30.3054N 96 0.5796W 216 RW1 Trawl 423 200 On 23-May-00 1110 27 31.3722N 96 1.8897W 217 RW1 Trawl 470 175 En30-May-00 0443 28 3.5416N 90 14.9880W 218 C1 CTD 355 344 CTD 30-May-00 0554 28 3.6046N 90 14.9329W 219 C1 Box Core 333 334 Too full, m30-May-00 0650 28 3.5783N 90 14.9483W 220 C1 Box Core 333 336 Go
AI-17

Appendix-Event or Activity Log (Cont.).

DATE-UTC TIME UTC LAT/MIN LONG/MIN SEQ. No. SITE

NAME

SAMPLE

TYPE

WIRE

OUT

(m)

PDR

(m)

COM

30-May-00 0742 28 3.5629N 90 14.9494W 221 C1 Box Core 334 336 Go30-May-00 0830 28 3.5875N 90 14.9610W 222 C1 Box Core 332 33630-May-00 0916 28 3.5903N 90 14.9950W 223 C1 Box Core 333 336 Go30-May-00 1017 28 3.4286N 90 15.1303W 224 C1 Camera 349 345 Cam30-May-00 1132 28 3.2753N 90 15.3698W 225 C1 Camera 352 356 44 30-May-00 1300 28 5.0111N 90 15.1054W 227 C1 Trawl 650 310 On 30-May-00 1329 28 3.8464N 90 15.0643W 228 C1 Trawl 656 340 En30-May-00 1706 27 43.7236N 89 58.8081W 229 C7 CTD 1113 1069 CTD 30-May-00 1853 27 43.6967 N 89 58.7782 W 230 C7 Box Core 1050 1080 Go30-May-00 2004 27 43.9713 N 89 58.6291 W 231 C7 Box Core 1047 1070 Go30-May-00 2105 27 43.8913 N 89 59.0119 W 232 C7 Box Core 1041 1066 Go30-May-00 2204 27 43.8089 N 89 59.1213 W 233 C7 Box Core 1043 1070 Go30-May-00 2302 27 43.8262N 89 58.9220W 234 C7 Box Core 1039 1072 Go31-May-00 0034 27 43.9291N 89 59.2277W 235 C7 Camera 1041 1057 Cam31-May-00 0132 27 44.0789N 89 59.9186W 236 C7 Camera 989 987 41 31-May-00 0333 27 44.9881N 89 59.4243W 237 C7 Trawl 1036 910 Traw31-May-00 0411 27 43.5643N 89 58.6686W 238 C7 Trawl 1851 1085 Net 31-May-00 0802 27 26.9570N 89 46.7507W 239 C4 CTD 1540 1468 CTD 31-May-00 1043 27 27.5640 N 89 47.1391 W 240 C4 Box Core 1465 1455 Go31-May-00 1242 27 27.6103 N 89 46.7720 W 241 C4 Box Core 1487 1452 Go31-May-00 1355 27 27.1450 N 89 46.5588 W 242 C4 Box Core 1438 1463 Go31-May-00 1504 27 27.0322 N 89 45.7167 W 243 C4 Box Core 1442 1476 Go31-May-00 1607 27 27.189N 89 45.785W 244 C4 Box Core 1447 1472 Num31-May-00 1743 27 27.5173N 89 45.9066W 245 C4 Camera 1547 1465 Cam31-May-00 1851 27 28.5639N 89 45.7584W 246 C4 Camera 1721 1426 Last hit, 31-May-00 2158 27 29.4518N 89 47.7782W 247 C4 Trawl 3050 1355 Called b31-May-00 2244 27 28.2744N 89 46.5667W 248 C4 Trawl 3506 1362 Let ou

1-Jun-00 0419 26 55.3279N 89 34.6815W 249 C14 CTD 2693 2487 CTD 1-Jun-00 0833 26 55.7737N 89 34.2830W 250 C14 Box Core 2434 2487 Only mac1-Jun-00 1116 26 55.7970N 89 34.2245W 251 C14 Box Core 2491 2487 Go1-Jun-00 1331 26 55.7900N 89 33.8676W 252 C14 Box Core 2598 2495 Go1-Jun-00 1525 26 55.7932N 89 34.2542W 253 C14 Box Core 2499 2487 Go
AI-18

Appendix-Event or Activity Log (Cont.).

DATE-UTC TIME UTC LAT/MIN LONG/MIN SEQ. No. SITE

NAME

SAMPLE

TYPE

WIRE

OUT

(m)

PDR

(m)

COM

1-Jun-00 1719 26 56.2943N 89 34.3503W 254 C14 Box Core 2487 2478 Go1-Jun-00 2000 26 56.4673N 89 33.6881W 255 C14 Camera 2867 2483 Cam1-Jun-00 2106 26 57.1821N 89 32.8457W 256 C14 Camera 2775 2506 Tota1-Jun-00 2329 26 59.0446N 89 36.8130W 257 C14 Trawl 1 2405 Net and 2-Jun-00 0506 26 53.5933N 89 31.5261W 258 C14 Trawl 1 2580 Net r2-Jun-00 0926 26 22.7693N 89 14.4295W 259 C12 CTD 2955 2915 CTD 2-Jun-00 1309 26 22.4008N 89 14.2480W 260 C12 Box Core 2900 2917 Shallow 2-Jun-00 1504 26 22.7651N 89 14.4849W 261 C12 Box Core 2848 2922 Go2-Jun-00 1707 26 22.9752N 89 14.4854W 262 C12 Box Core 2847 2920 Go2-Jun-00 1915 26 22.4978N 89 14.5836W 263 C12 Box Core 2846 2924 Only macr2-Jun-00 2130 26 22.4015N 89 14.2552W 264 C12 Box Core 2840 2918 Go3-Jun-00 008 26 22.7838N 89 14.4179W 265 C12 Box Core 2840 2920 Logged tw3-Jun-00 235 26 22.8460N 89 14.6947W 266 C12 Camera 2856 2922 Cam3-Jun-00 343 26 22.9637N 89 14.9572W 267 C12 Camera 2860 2922 Last hit, 3-Jun-00 537 26 16.4897N 89 20.9440W 268 C12 Trawl 1 3000 Net and 3-Jun-00 1308 26 30.1817N 89 9.2097W 269 C12 Trawl 1 2830 End, total 3-Jun-00 1915 27 19.8258N 88 40.2892W 270 MT5 CTD 2354 2280 CTD 3-Jun-00 2147 27 19.9308N 88 40.0690W 271 MT5 Box Core 2213 2275 Go3-Jun-00 2344 27 19.5810N 88 40.1733W 272 MT5 Box Core 2230 2290 Fish 4-Jun-00 0159 27 20.0759N 88 39.7337W 273 MT5 Box Core 2269 2267 Go4-Jun-00 0344 27 20.1910N 88 39.5716W 274 MT5 Box Core 2281 2263 Go4-Jun-00 0525 27 19.9703N 88 39.3639W 275 MT5 Box Core 2370 2280 Go4-Jun-00 0728 27 19.7201N 88 39.0161W 276 MT5 Camera 2515 2288 Cam4-Jun-00 0842 27 20.0206N 88 38.5334W 277 MT5 Camera 2501 2301 Last 4-Jun-00 1048 27 23.5939N 88 46.6155W 278 MT5 Trawl 1 2075 Net submer4-Jun-00 1613 27 15.8017N 88 33.8526W 279 MT5 Trawl 1 2410 Trawled 1 h4-Jun-00 2014 26 59.9938N 87 59.8019W 280 MT6 CTD 2790 2745 CTD 4-Jun-00 2325 27 00.0067N 87 59.8697W 281 MT6 Box Core 2673 2745 Go5-Jun-00 0129 27 0.0892N 87 59.2938W 282 MT6 Box Core 2719 2750 Go5-Jun-00 0333 26 59.7904N 87 59.9247W 283 MT6 Box Core 2673 2745 Go5-Jun-00 0541 26 59.9689N 87 59.7695W 284 MT6 Box Core 2677 2745 Go5-Jun-00 0735 27 0.0989N 87 59.9478W 285 MT6 Box Core 2676 2743 Go
AI-19

Appendix-Event or Activity Log (Cont.).

DATE-UTC TIME UTC LAT/MIN LONG/MIN SEQ. No. SITE

NAME

SAMPLE

TYPE

WIRE

OUT

(m)

PDR

(m)

COM

5-Jun-00 0949 27 0.2679N 87 59.3911W 286 MT6 Camera 2800 2748 Cam5-Jun-00 1052 26 59.8111N 87 58.9553W 287 MT6 Camera 2918 2751 Last h5-Jun-00 1350 26 59.2975N 87 58.9824W 288 MT6 Camera 3145 2755 Cam5-Jun-00 1458 26 58.8683N 87 58.1482W 289 MT6 Camera 3463 2760 Last h5-Jun-00 1703 26 55.9383N 88 08.3722W 290 MT6 Trawl 1 2680 Net down5-Jun-00 2349 27 2.2772N 87 51.6737W 291 MT6 Trawl 1 2790 Trawled 1.5 6-Jun-00 0544 27 29.9929N 87 0.0569W 292 S39 CTD 3049 3023 CTD 6-Jun-00 0924 27 29.9500N 87 0.0849W 293 S39 Box Core 2980 3007 Go6-Jun-00 1112 27 29.6965N 86 59.8982W 294 S39 Box Core 2946 3000 Go6-Jun-00 1319 27 29.2661N 87 0.0122W 295 S39 Box Core 3018 3000 Go6-Jun-00 1540 27 29.2518N 86 59.8236W 296 S39 Box Core 3008 3000 Go6-Jun-00 1738 27 29.0205N 86 59.9889W 297 S39 Box Core 3013 2998 Good core 6-Jun-00 2015 27 28.7018N 87 0.1820W 298 S39 Camera 3024 3000 Cam6-Jun-00 2119 27 28.0412N 87 0.2562W 299 S39 Camera 3102 2997 Last 6-Jun-00 2329 27 21.6638N 87 6.3576W 300 S39 Trawl 1 2937 Net submerg7-Jun-00 0621 27 31.8311N 86 59.4062W 301 S39 Trawl 1 3005 Trawl 1.5 h7-Jun-00 0913 27 49.9613N 86 44.8975W 302 S40 CTD 2999 2973 CTD 7-Jun-00 1326 27 50.3354N 86 45.1549W 303 S40 Box Core 2910 2975 Go7-Jun-00 1507 27 50.1707N 86 45.0821W 304 S40 Box Core 2907 2975 Go7-Jun-00 1651 27 50.2944N 86 45.0489W 305 S40 Box Core 2886 2972 Go7-Jun-00 1853 27 49.9965N 86 45.2125W 306 S40 Box Core 2905 2978 Go7-Jun-00 2107 27 50.3686N 86 45.0849W 307 S40 Box Core 2894 2971 Go8-Jun-00 0010 27 49.6843N 86 44.9811W 308 S40 Camera 2913 2986 Cam8-Jun-00 0124 27 49.4359N 86 44.9994W 309 S40 Camera 2938 2995 Last h8-Jun-00 0326 27 43.3428N 86 46.4221W 310 S40 Trawl 1 3050 Net submerg8-Jun-00 1040 27 59.4280N 86 43.3657W 311 S40 Trawl 1 2970 Trawl 1.5 h8-Jun-00 1436 28 00.0388N 86 34.8241W 312 S41 CTD 3174 2979 CTD 8-Jun-00 1903 28 0.8463N 86 34.5587W 313 S41 Box Core 3022 2974 Go8-Jun-00 2136 28 1.4243N 86 34.2753W 314 S41 Box Core 3006 2974 Go9-Jun-00 0017 28 0.7328N 86 34.1930W 315 S41 Box Core 2915 2978 Go9-Jun-00 0237 28 0.6970N 86 33.9732W 316 S41 Box Core 3005 2983 Go9-Jun-00 0510 28 0.8185N 86 34.4009W 317 S41 Box Core 2956 2976 Go
AI-20

Appendix-Event or Activity Log (Cont.).

DATE-UTC TIME UTC LAT/MIN LONG/MIN SEQ. No. SITE

NAME

SAMPLE

TYPE

WIRE

OUT

(m)

PDR

(m)

COM

9-Jun-00 0805 28 1.2769N 86 34.9737W 318 S41 Camera 3050 2971 Cam9-Jun-00 0922 28 2.1552N 86 35.0977W 319 S41 Camera 3124 2955 Llast 9-Jun-00 1205 27 54.2334N 86 26.0841W 320 S41 Trawl 1 3030 Net and 9-Jun-00 1858 28 4.3344N 86 40.6499W 321 S41 Trawl 1 2930 Trawl 1.5 h9-Jun-00 1136 28 30.07218N 86 4.7604W 322 S42 CTD 778 763 CTD 9-Jun-00 2320 28 15.1557N 86 25.0663W 323 S42 Box Core 750 767 Go

10-Jun-00 0011 28 15.1070N 86 25.0209W 324 S42 Box Core 753 768 Go10-Jun-00 0101 28 15.2344N 86 24.7995W 325 S42 Box Core 762 763 Go10-Jun-00 0157 28 15.1049N 86 24.8363W 326 S42 Box Core 763 766 Go10-Jun-00 0252 28 15.0602N 86 25.1562W 327 S42 Box Core 760 772 Go10-Jun-00 0359 28 15.0859N 86 24.9248W 328 S42 Camera 752 768 Cam10-Jun-00 0504 28 15.0358N 86 24.3089W 329 S42 Camera 760 764 Last 10-Jun-00 0557 28 15.9809N 86 27.8529W 330 S42 Trawl 1 800 Net and d10-Jun-00 0839 28 13.8930N 86 21.4547W 331 S42 Trawl 1 770 Trawl 0.5 h10-Jun-00 1128 28 30.0153N 86 4.7775W 332 S43 CTD 366 366 CTD 10-Jun-00 1255 28 30.1035 86 04.7983 333 S43 Box Core 358 366 Go10-Jun-00 1331 28 30.1434N 86 4.8562W 334 S43 Box Core 361 360 Go10-Jun-00 1419 28 30.0613N 86 4.8672W 335 S43 Box Core 363 362 Only mac10-Jun-00 1633 28 30.1982N 86 4.5881W 336 S43 Box Core 358 357 Go10-Jun-00 1713 28 30.1766N 86 4.6074W 337 S43 Box Core 358 358 Go10-Jun-00 1800 28 30.0545N 86 4.6404W 338 S43 Camera 356 360 Cam10-Jun-00 1902 28 30.3610N 86 4.4865W 339 S43 Camera 355 358 Last 10-Jun-00 2004 28 30.9292N 86 6.1705W 340 S43 Trawl 1 360 Net and d10-Jun-00 2130 28 28.9484N 86 3.2172W 341 S43 Trawl 1 358 Trawl 0.5 h11-Jun-00 0022 28 45.0483n 85 44.8818W 342 S44 CTD 215 215 CTD 11-Jun-00 0105 28 45.0140N 85 44.9642W 343 S44 Box Core 214 215 Go11-Jun-00 0151 28 45.0188N 85 44.9499W 344 S44 Box Core 213 213 Go11-Jun-00 0231 28 45.0632N 85 44.8807W 345 S44 Box Core 215 212 Go11-Jun-00 0309 28 45.0093N 85 44.8686W 346 S44 Box Core 215 212 Go11-Jun-00 0349 28 44.9996N 85 44.8622W 347 S44 Box Core 215 212 Go11-Jun-00 0438 28 44.9522N 85 44.6851W 348 S44 Camera 226 211 Cam11-Jun-00 0545 28 44.7038N 85 44.9938W 349 S44 Camera 225 214 Last 11-Jun-00 0641 28 45.5760N 85 45.2641W 350 S44 Trawl 1 214 Net and d11-Jun-00 0755 28 43.0225N 85 44.3370W 351 S44 Trawl 1 217 Trawl 0.5 h11-Jun-00 1712 29 19.8058N 87 3.0254W 352 S35 CTD 679 674 CTD 
AI-21

Appendix-Event or Activity Log (Cont.).

DATE-UTC TIME UTC LAT/MIN LONG/MIN SEQ. No. SITE

NAME

SAMPLE

TYPE

WIRE

OUT

(m)

PDR

(m)

COM

11-Jun-00 1847 29 20.0500N 87 3.3758W 353 S35 Box Core 646 658 Go11-Jun-00 1932 29 19.9897N 87 2.9021W 354 S35 Box Core 660 667 Go11-Jun-00 2025 29 19.9337N 87 3.0166W 355 S35 Box Core 664 668 Go11-Jun-00 2117 29 19.9877N 87 2.9860W 356 S35 Box Core 655 668 Go11-Jun-00 2208 29 20.1091N 87 2.7818W 357 S35 Box Core 653 666 Go11-Jun-00 2305 29 20.2815N 87 2.8106W 358 S35 Camera 688 664 Cam12-Jun-00 0009 29 20.7205N 87 2.2753W 359 S35 Camera 664 663 Last 12-Jun-00 0052 29 22.5489N 87 1.7647W 360 S35 Trawl 1 645 Net and d12-Jun-00 0250 29 18.9650N 87 2.7294W 361 S35 Trawl 1 695 Trawl 0.5 h12-Jun-00 0742 28 55.1114N 87 40.1292W 362 S36 CTD 1874 1845 CTD 12-Jun-00 1013 28 55.1647N 87 40.2232W 363 S36 Box Core 1786 1825 Go12-Jun-00 1136 28 55.0080N 87 40.0627W 364 S36 Box Core 1785 1832 Go12-Jun-00 1255 28 55.1634N 87 40.2154W 365 S36 Box Core 1777 1826 Go12-Jun-00 1359 28 55.1792N 87 40.5743W 366 S36 Box Core 1774 1827 Go12-Jun-00 1508 28 55.1108N 87 40.3290W 367 S36 Box Core 1784 1830 Go12-Jun-00 1644 28 55.1044N 87 40.4810W 368 S36 Camera 1825 1827 Cam12-Jun-00 1801 28 54.8887N 87 41.7574W 369 S36 Camera 2034 1850 Last 12-Jun-00 2010 28 57.8923N 87 33.6681W 370 S36 Trawl 1 1715 Net and d13-Jun-00 0025 28 54.0969N 87 43.7377W 371 S36 Trawl 1 1852 Trawl for 1 13-Jun-00 0307 28 33.0343N 87 46.2957W 372 S37 CTD 2418 2380 CTD 13-Jun-00 0623 28 33.4054N 87 45.7357W 373 S37 Box Core 2370 2388 Go13-Jun-00 0800 28 33.4292N 87 45.6441W 374 S37 Box Core 2349 2382 Go13-Jun-00 0917 28 33.2345N 87 45.8373W 375 S37 Box Core 2326 2382 Go13-Jun-00 1035 28 33.2196N 87 45.7768W 376 S37 Box Core 2316 2382 Go13-Jun-00 1149 28 33.2176N 87 46.0109W 377 S37 Box Core 2311 2381 Go13-Jun-00 1350 28 33.2457N 87 46.0066W 378 S37 Camera 2314 2380 Cam13-Jun-00 1502 28 33.3825N 87 45.5462W 379 S37 Camera 2339 2384 Last 13-Jun-00 1649 28 40.5318N 87 40.2689W 380 S37 Trawl 1 2365 Net and d13-Jun-00 2243 28 29.9693N 87 49.4744W 381 S37 Trawl 1 2373 Trawl 1.5 h14-Jun-00 0229 28 16.8037N 87 14.8865W 382 S38 CTD 2224 2155 CTD 14-Jun-00 0536 28 16.9406N 87 14.7745W 383 S38 Box Core 2370 2130 Poor, some 14-Jun-00 0716 28 17.0006N 87 14.6903W 384 S38 Box Core 2611 2090 N14-Jun-00 0905 28 16.8185N 87 13.9942W 385 S38 Box Core 2720 2083 N14-Jun-00 1124 28 16.4749N 87 19.9043W 386 S38 Box Core 2599 2635 Moved five n14-Jun-00 1323 28 16.3144N 87 19.5165W 387 S38 Box Core 2583 2642 Go
AI-22

Appendix-Event or Activity Log (Cont.).

DATE-UTC TIME UTC LAT/MIN LONG/MIN SEQ. No. SITE

NAME

SAMPLE

TYPE

WIRE

OUT

(m)

PDR

(m)

COM

14-Jun-00 1514 28 16.7846N 87 20.1025W 388 S38 Box Core 2596 2627 Go14-Jun-00 1703 28 16.9551N 87 20.1877W 389 S38 Box Core 2553 2627 Wa14-Jun-00 1840 28 16.7579N 87 20.2446W 390 S38 Box Core 2557 2630 Go14-Jun-00 2037 28 16.7968N 87 19.6555W 391 S38 Box Core 2577 2632 Good core14-Jun-00 2238 28 16.2454N 87 19.9944W 392 S38 Camera 2606 2647 Cam14-Jun-00 2347 28 16.2815N 87 19.8962W 393 S38 Camera 2561 2647 Last 15-Jun-00 0144 28 23.1182N 87 27.1776W 394 S38 Trawl 1 2565 Net and d15-Jun-00 0803 28 15.2889N 87 14.6914W 395 S38 Trawl 1 2650 Trawl 1.5 h15-Jun-00 2015 27 49.9268N 89 10.2049W 396 MT4 CTD 1410 1402 C15-Jun-00 2218 27 49.6198N 89 9.9526W 397 MT4 Box Core 1363 1401 Go15-Jun-00 2322 27 49.7018N 89 9.8829W 398 MT4 Box Core 1364 1401 Go16-Jun-00 0014 27 49.6810N 89 10.0723W 399 MT4 Box Core 1365 1401 Go16-Jun-00 0132 27 50.0087N 89 9.9487W 400 MT4 Box Core 1366 1402 Go16-Jun-00 0238 27 49.6563N 89 9.9687W 401 MT4 Box Core 1366 1402 Go16-Jun-00 0357 27 50.0274N 89 10.0346W 402 MT4 Camera 1373 1403 Cam16-Jun-00 0503 27 50.1708N 89 9.3478W 403 MT4 Camera 1413 1403 Last 16-Jun-00 1033 28 13.2930N 89 29.9627W 404 MT3 CTD 1014 985 CTD 16-Jun-00 1231 28 13.2246N 89 29.7679W 405 MT3 Box Core 977 983 Go16-Jun-00 1329 28 13.1533N 89 29.7860 406 MT3 Box Core 986 987 Go16-Jun-00 1422 28 13.1426N 89 29.5065W 407 MT3 Box Core 1007 990 Go16-Jun-00 1514 28 13.0561N 89 29.6289W 408 MT3 Box Core 997 988 Go16-Jun-00 1616 28 13.2906N 89 29.6427W 409 MT3 Box Core 978 985 Go16-Jun-00 1731 28 13.2712N 89 29.2921W 410 MT3 Camera 996 990 Cam16-Jun-00 1840 28 13.1632N 89 28.3526W 411 MT3 Camera 1044 1001 Last 16-Jun-00 1947 28 10.9546N 89 27.0007W 412 MT3 Trawl 1 1050 Net and d16-Jun-00 2209 28 14.7585N 89 31.0703W 413 MT3 Trawl 1 954 Trawl 0.5 h17-Jun-00 0033 28 27.0528N 89 40.1187W 414 MT2 CTD 688 681 CTD 17-Jun-00 0156 28 27.0646N 89 40.3563W 415 MT2 Box Core 660 676 Go17-Jun-00 0245 28 27.0726N 89 40.2206W 416 MT2 Box Core 660 677 Go17-Jun-00 0330 28 27.0327N 89 40.3636W 417 MT2 Box Core 660 676 Go17-Jun-00 0415 28 27.0168N 89 40.4000W 418 MT2 Box Core 662 677 Go17-Jun-00 0454 28 26.8755N 89 40.3167W 419 MT2 Box Core 662 680 Go17-Jun-00 0541 28 26.9984N 89 40.1315W 420 MT2 Camera 664 681 Cam17-Jun-00 0654 28 27.1138N 89 40.2103W 421 MT2 Camera 656 678 Last 
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Appendix-Event or Activity Log (Cont.).

DATE-UTC TIME UTC LAT/MIN LONG/MIN SEQ. No. SITE

NAME

SAMPLE

TYPE

WIRE

OUT

(m)

PDR

(m)

COM

17-Jun-00 0747 28 28.1309N 89 42.1489W 422 MT2 Trawl 1 635 Net and d17-Jun-00 1016 28 24.9338N 89 37.3878W 423 MT2 Trawl 1 737 Trawl 0.5 h17-Jun-00 1253 28 32.5092N 89 49.8284W 424 MT1 CTD 502 480 CTD 17-Jun-00 1407 28 32.5129N 89 49.7324W 425 MT1 Box Core 472 480 Go17-Jun-00 1448 28 32.3703N 89 49.7338W 426 MT1 Box Core 484 482 Go17-Jun-00 1525 28 32.4686N 89 49.6283W 427 MT1 Box Core 485 482 Go17-Jun-00 1607 28 32.4352N 89 49.7257W 428 MT1 Box Core 492 481 Go17-Jun-00 1652 28 32.4666N 89 49.5011W 429 MT1 Box Core 479 481 Go17-Jun-00 1749 28 32.7388N 89 49.4905W 430 MT1 Camera 495 475 Cam17-Jun-00 1853 28 33.1631N 89 48.9497W 431 MT1 Camera 472 473 Last 17-Jun-00 1958 28 34.3289N 89 51.7153W 432 MT1 Trawl 1 420 Net and d17-Jun-00 2139 28 31.7427N 89 48.9855W 433 MT1 Trawl 1 501 Trawl 0.5 h18-Jun-00 0331 27 53.5820N 89 17.2670W 434 MT4 Trawl 1 1340 Net and d18-Jun-00 0657 27 49.6495N 89 9.7183W 435 MT4 Trawl 1 1397 Trawl 45 mi18-Jun-00 2157 27 11.7196N 91 24.2305W 436 B1 Camera 2222 2256 Cam18-Jun-00 2300 27 11.3731N 91 23.8160W 437 B1 Camera 2236 2256 Last 19-Jun-00 0718 26 12.2787N 91 46.1872W 438 B3 Camera 2627 2651 Cam19-Jun-00 0827 26 12.8443N 91 45.9065W 439 B3 Camera 2662 2647 Last 19-Jun-00 1340 26 33.1067N 92 13.9513W 440 B2 Camera 2546 2610 Cam19-Jun-00 1457 26 32.9413N 92 13.6736W 441 B2 Camera 2574 2612 Last 19-Jun-00 1656 26 29.1157N 92 5.6651W 442 B2 Trawl 1 2320 Net and d19-Jun-00 2307 26 36.8264N 92 19.6109W 443 B2 Trawl 1 2140 Trawl 1.5 h20-Jun-00 0747 25 59.9764N 93 41.8014W 444 W6/RW6 Trawl 1 3000 Net and d20-Jun-00 1452 26 0.1963N 93 59.9278W 445 W6/RW6 Trawl 1 3150 Trawl 1.5 hou20-Jun-00 2302 26 40.9015N 95 11.1034W 446 RW4 Trawl 1 1605 Net and d21-Jun-00 0238 26 49.6196N 95 10.6836W 447 RW4 Trawl 1 1600 Lost, cable 
AI-24
AII-1

Appendix II

The Edge of the Gulf Cruise

16-31 October 2000

RV Atlantis, Cruise 3 Leg 58

DSV Alvin, Dives 3624-3637

A cruise report prepared by:

Ian R. MacDonald (Texas A&M University)

Joan Bernhard (University of South Carolina)

Barun Sen Gupta (Louisiana State University)

Cindy Lee Van Dover (College of William and Mary)
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Introduction

This is the report for RV Atlantis Cruise 3, Leg 58, which completed DSV Alvin Dives 3624-3637 at eight sites

across the northern Gulf of Mexico (Figure 1) during 16-31 October 2000. The cruise embarked in Galveston,

Texas and demobilized in Key West Florida. There was an at-sea exchange of thirteen scientific personnel on 25

October. In all, thirty six scientists and observers participated in the cruise (Table 1).

The cruise was jointly funded by National Oceanographic and Atmospheric Administration (National Undersea

Research Program), Minerals Management Service, and Dept. of Energy (National Energy Technology Laboratory).

The overall objectives of the cruise were to provide submersible and ship support for research being conducted by

four separate projects. The way the dives and ship operations were completed, there was significant overlap and

cooperation among the projects. Therefore, a single report will be submitted to all cruise sponsors. This document

provides a preliminary summary of individual project results and narrates the day to day activities. An appendix

details the observations and sample collections made dive-by-dive and day-by-day. The shipboard scientific support

program of RV Atlantis provided a series of digital data files and other records on CD ROM, with copies going to

each project investigators.

Figure 1. Dive sites and dive numbers for the 14 dives completed during 16-31 October 2000,

northern Gulf of Mexico.
AII-4

Table 1. Cruise participants, affiliations, roles, and contact information. Stage 1 of the cruise

was 16-25 October; stage 2 was 25-31 October.

Participant Stages E-Mail

Joan Bernhard, USC, Principal Investigator 1 and 2 jmbernha@sph.sc.edu

Dan Bean, TAMU, Student 1 and 2 dbean@ocean.tamu.edu

Marty Bohn, TAMU, Technician 1 and 2 marty@gerg.tamu.edu

Bill Bryant, TAMU, Principal Investigator 1 and 2 bbryant@ocean.tamu.edu

Paul Clark, TAMU, Technician 1 and 2 pclark@gerg.tamu.edu

Tom Cole, ATT Broadband Inc. Video Producer 1 and 2 tcole@broadband.att.com

Sophie DeBeukelaer, TAMU, Student 1 and 2 sophie@gerg.tamu.edu

Tim Dellapenna, TAMU-G, Investigator 1 and 2

Chris Gudeman, TAMU, Student 1 and 2 cgudeman@ocean.tamu.edu

Ian MacDonald, TAMU, Chief Scientist 1 and 2 ian@gerg.tamu.edu

Erik Scott, BHP, Inc., Observer 1 and 2

Andrew Shepard, NURP, Coordinator 1 and 2 sheparda@uncwil.edu

Evan Vetter, UNCW, Cameraman 1 and 2 evan_vetter@hotmail.com

David Volz, USC, Student 1 and 2 dcvolz@hotmail.com

Matt Zeigler, TAMU, Student 1 and 2 mziegler@ocean.tamu.edu

Paul Aharon, LSU, Investigator 1 aharon@geol.lsu.edu

Robert Avent, MMS, Observer 1 robert.avent@mms.gov

Samuel Bowser, Wadsworth Center, Investigator 1

Matt Hackworth, LSU, Student 1

Samuel Huisman, LSU, Student 1

Barun Sen Gupta, LSU, Principal Investigator 1 barun@geol.lsu.edu

Lorene Smith, LSU, Technician 1

Daniel Van Gent, LSU, Investigator 1

Sarah Fangman, NOAA, Observer 2 sarah.fangman@noaa.gov

Cheryl Jenkins, WM, Student 2 cjenk@wm.edu

Karen Jacobsen, In Situ Illustrations, Artist 2 kjnorhtherncross@aol.com

Margaret Landry, WM, Student 2 margolan@yahoo.com

John McDonough, NOS, Observer 2 john.mcdonough@noaa.gov

Zoe McKinness, Harvard, Student 2 zmckiness@oeb.harvard.edu

Thomas Mroz, DOE-NETL, Observer 2 thomas.mroz@netl.doe.gov

Joshua Osterberg, WM, Student 2 joste@wm.edu

William Sager, TAMU, Principal Investigator 2 wsager@ocean.tamu.edu

Mary Turnipseed, WM, Student 2 mturnips@hotmail.com

Cindy Lee Van Dover, WM, Principal Investigator 2 cindy_vandover@wm.edu

Megan Ward, WM, Student 2 meward@wm.edu
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General Results

Support from the crew of RV Atlantis, the Alvin team, and the Woods Hole shipboard scientific service group was

outstanding. The scientific personnel were unanimous in their praise for the thoroughly professional and unfailingly

hospitable atmosphere on board. Fourteen dives at eight separate sites were completed. None of the planned dives

were cancelled due to weather or other problems. The Atlantis/Alvin group elected not to dive at one scheduled site,

Bush Hill, because it was situated less than one mile from an energy production platform. Sites, divers, and

localities are summarized in Table 2.

Table 2. Summary of dives, sites visited, and scientific divers during cruise.

Dive # Site Depth Sci-1 Sci-2 Latitude Longitude

3624 Alaminos Canyon 2230 Paul Aharon Sam Bowser 26.35667 -94.50267

3625 Alaminos Canyon 2230 Barun Sen Gupta Joan Bernhard 26.35709 -94.48397

3626 Green Canyon 272 687 Paul Aharon Lorene Smith 27.68644 -91.53670

3627 Green Canyon 272 687 Joan Bernhard Matt Hackworth 27.68401 -91.53703

3628 Farnella Canyon 2930 Ian MacDonald Tom Cole 26.44713 -90.77330

3629 Green Knoll 2457 Bill Bryant Erik Scott 26.92353 -90.21502

3630 Miss. Canyon 853 1079 Ian MacDonald Anthony Tarantino

(PIT)

28.12663 -89.14367

3631 Miss. Canyon 853 1079 Dan Bean Tim Dellapenna 28.12640 -89.14172

3632 Atwater 425 1955 Ian MacDonald Andy Shepard 27.57516 -88.48793

3633 Atwater 425 1955 Joan Bernhard Will Sager 27.57898 -88.51056

3634 N. FL. Escarpment 2873 Ian MacDonald Sarah Fangman 28.03697 -86.55668

3635 S. Fl. Escarpment 3288 Cindy Van Dover Karen Jacobsen 26.03069 -84.91954

3636 S. Fl. Escarpment 3288 Mary Turnipseed Joshua Osterberg 26.03069 -84.91954

3637 S. Fl. Escarpment 3288 Cheryll Jenkins Anthony Tarantino

(PIT)

26.03069 -84.91954

Images taken with video and digital still cameras comprised an important part of the cruise records. Two high

resolution systems were added to Alvin's standard suite of cameras for selected dives during the cruise. These were a

high definition television (HDTV) camera provided by the Visual Data Systems and Development group at Woods

Hole Oceanographic Institution and a digital macro camera (Seapix) developed by the Geochemical and

Environmental Research Group at Texas A&M University. The standard video records and the Seapix images were

copied to principal investigators at the conclusion of the cruise. Although the right to further reproduce and

distribute these images resides with the responsible investigators, the cruise participants agreed to freely share the

images among themselves for educational purposes. HDTV images will be made available on a best-effort basis in

the months following the cruise. Table 3 summarizes the image types recorded during the dives.

Two instruments for physical oceanography were mounted on Alvin throughout the cruise. These were a 300 kHz

acoustic doppler current profiler (ADCP) manufactured by RD Instruments, Inc. and a SBE11 conductivity,

temperature, and depth recorder (CTD) manufactured by Sea Bird, Inc. Additional data recorded throughout the

cruise included multibeam bathymetry and navigation records for the ship and submarine. Additional over-the-side

sampling was conducted at most sites.

Subsequent sections provide details of the accomplishments of the individual research projects.
AII-6

Table 3. Summary of image types taken during cruise. One Hi-8mm tape series was recorded

from a 3-chip color camera mounted on the starboard manipulator arm of Alvin and

usually comprised three, two-hour tapes per dive. Additional recording of the 3-chip

camera's output was sometimes placed on beta format tapes for higher image quality.

Input from other cameras on the submarine was selectively recorded on a separate set

of three, two-hour "Alvin" tapes in Hi-8mm format. When sampling plans allowed,

high quality video records were obtained from the HDTV camera system and were

recorded on special digital tape. The Seepix camera is a Nikon Coolpix 990 digital

macro-camera, which recorded jpeg-formatted image files on internal Compact Flash

cards for subsequent copying.

Camera system: 3-Chip Alvin HDTV Seapix

Dive # 3624 x x

3625 x x

3626 x x

3627 xx x

3628 x x xx

3629 x x xx

3630 x x

3631 x x

3632 xx x

3633 xx x

3634 x x xx

3635 x x

3636 x x

3637 xx x

Louisiana State University and University of South Carolina Group:

Barun Sen Gupta and Joan Bernhard, Principal Investigators.

PROJECT DESCRIPTION

Benthic foraminifera, often the most abundant meiofaunal group in many marine habitats, respond rapidly to

environmental disturbances, and their large natural populations and well-preserved shells make them excellent

recorders of present and past marine biodiversity. These organisms are capable of inhabiting environments where

oxygen is depleted to extremely low levels, or even absent. Hydrocarbon vents provide a special window to study

the foraminifera of such dysoxic and anoxic environments. A previous NURP-supported initial study of the

foraminifera associated with Gulf of Mexico hydrocarbon vents, especially those found in or under bacterial

(Beggiatoa) mats, has indicated the existence of facultative anaerobes within this community. However, that study

was too limited in scope for an understanding of distribution patterns or physiological adaptions. The broad

objective of the present research proposal is to do a detailed study of the distributions, ultrastructures, and shell

carbon isotopes of the foraminifera occurring in Gulf of Mexico hydrocarbon vents. It involves on site retrieval of

samples from foraminiferal habitats around the vents (especially, but not exclusively, bacterial mats) and in nearby,

non vent (control) areas. The diving plan for a deeper-water submersible involves operation at different bathymetric

levels- at 600 to 700 m in Green Canyon and at 2200 m in Alaminos Canyon. The laboratory work will include a)

studies of dominance and diversity trends in both living and dead assemblages from surface and subsurface samples

of diverse habitats, and b) ultrastructural, physiological, and carbon-isotope studies of species from bacterial mats.

Foraminiferal species found in Beggiatoa mats are emphasized because of encouraging past results, including the

finding of several apparently facultative anaerobes, in this environment.

The specific objectives for this group of foraminifera will include the determination of a) horizontal and vertical

distributions of species, using stained and live individuals, b) ultrastructural characteristics of common species, c)

their physiologic responses to anoxia and dysoxia (i.e. ATP analyses), and d) whether observed ultrastructural

features of the common species reflect measured ∂13 C signals of their shells. In addition, taphonomic effects of
AII-7

shells of diverse foraminiferal species will be assessed from the subsurface distribution of empty shells in vent

cores; this information would be useful in future studies of ancient vent assemblages of benthic foraminifera.

SUMMARY OF RESULTS

Much of the work by the LSU-USC group on board was related to sampling operations on the first four dives

(3624-3627)-- two in Alaminos Canyon (water depth about 2200 m) and two in Green Canyon (Block 272, depth

680-720 m). Eighteen push cores were taken for the foraminiferal distribution study and stable-isotope analysis. In

addition, 12 push cores were taken exclusively for pore-fluid analysis related to the geochemical work; these fluids

have been extracted on board, using a new technique for sediment squeezing. Four good to excellent box cores were

also taken for the species distribution study, using NURP-designed equipment. Subcores (replicates from each box

core) were frozen, removed from their metal casings, and frozen again for laboratory analysis. Portions of a few

subcores were preserved in ethanol, to which the Rose Bengal stain had been added. For the foraminiferal

physiological studies, a suite of 11 push cores were recovered in an insulated container to minimize core warming

upon ascent (Table 4). This approach is crucial because ultrastructural and physiologic methods require live

specimen recovery. This push-core suite consists of four cores from control sites and seven from bacterial mats. The

presence of small annelids (~2 mm) and other metazoans in the Beggiatoa mats suggests the eukaryotic community

in these Gulf of Mexico seeps is similar in many respects to that of the Santa Barbara Basin. Preliminary results of

bacterial mats suggest the presence of benthic foraminifera in Beggiatoa mats although their physiologic state (e.g.,

live vs dead) remains to be determined in shore-based laboratories.

The sampling operation was highly successful, in spite of the last-minute change of one dive site (from Green

Canyon Block 185 to Block 272) because of unallowable proximity to an oil rig. We expect multiple scientific

publications to result from the laboratory data that would be based on these samples.

Table 4.Insulated cores collected for study of protozoa associated with bacterial mats. Core

types comprised controls (C), orange mats (OM), and white mats (WM).

Date Dive # Site Depth Core # Time Core Type

10/17/00 3624 Alaminos Canyon 2238 17 9:53 C

10/17/00 3624 Alaminos Canyon 2238 18 9.55 C

10/18/00 3625 Alaminos Canyon 2222 24 12:46 OM

10/18/00 3625 Alaminos Canyon 2222 23 13:01 WM

10/18/00 3625 Alaminos Canyon 2215 26 13.51 WM

10/18/00 3625 Alaminos Canyon 2215 25 13:56 WM

10/19/00 3626 Green Canyon 272 723 39 No video C

10/19/00 3626 Green Canyon 272 723 40 No video C

10/20/00 3627 Green Canyon 272 695 45 9:21 WM

10/20/00 3627 Green Canyon 272 692 46 10:19 WM

10/20/00 3627 Green Canyon 272 667 47 12:12 WM

10/20/00 3627 Green Canyon 272 700 48 14:31 WM

10/21/00 3628 Farnella Canyon 2917 62 No video C

10/21/00 3628 Farnella Canyon 2884 63 No video C

10/22/00 3629 Green Knoll 2457 67 14:34 C

10/22/00 3629 Green Knoll 2463 66 9:44 C

10/23/00 3630 Mississippi Canyon 1068 71 13:52 OM

10/23/00 3630 Mississippi Canyon 1068 72 13:52 OM
AII-8

Texas A&M University Group:

Ian MacDonald, William Sager, and William Bryant Principal Investigators

PROJECT DESCRIPTION

This program element collected otherwise unobtainable samples from the base and flanks of the Sigsbee and Florida

Escarpments. Together, the Sigsbee and Florida Escarpments extend for ~1000km and span a depth gradient of

>1000m in most regions. This topographic regime is a significant component of the benthic environment in the

northern Gulf of Mexico and may comprise a significant zoo-geographic boundary between the lower continental

slope and the abyss. With use of Alvin, however, it was possible to collect sediment samples for infaunal and

geochemical analysis. It also provided detailed photographic documentation and verbal description of the benthic

ecology and geology of the sites.

The Sigsbee Escarpment forms the southern margin of the central sampling area. Like the Florida Escarpment, its

precipitous slope poses considerable challenges to sampling from surface ships. Little is known regarding the

benthic ecology of the site. A major type of the benthic environment has recently been documented that required

reconnaissance by submersible for basic characterization. The features have been designated furrows (W. Bryant,

personal communication) and comprise deep, steep-sided gullies, which are often 10m deep and 30m wide. Furrows

tend to run parallel to the base of the escarpment and have been identified as contiguous features that extend 100km

or more. The sediment cover, and presumably the benthic communities, is entirely different between the bottom of

furrows and their upper rims. It was anticipated that in the bottom, the fine Holocene sediments will have been

eroded away, exposing coarser sediment. On the rims, the Holocene drape is still present. The origin of furrows is

unknown, but they are thought to be formed as a result of intense current events. Because of their small cross

section, furrows can only be accurately sampled with use of submersibles.

The investigators also used Alvin and the sampling capabilities of Atlantis to extend sampling and observation at

two sites where deposits of gas hydrate occurs near the seafloor. Gas hydrate generates a dynamic seafloor response,

including complex biological and geological interactions. This phenomenon is fairly well-known in the Gulf of

Mexico and has been investigated with sampling from submarines in depths of about 500 m. This is a setting where

it is possible to directly observe and sample the in-situ characteristics of the material. The two sites where these

dives were conducted are MC853 and AT425, located at depths of 1040 m and 1900 m, respectively. These sites are

being considered for an Ocean Drilling Program leg to investigate hydrate deposits in 2003.

SUMMARY OF RESULTS

Seven dives were completed as to support this project (Table 2, dive numbers 3628 through 3634). Sample

collection during the dives included push cores, and two small box cores (Table 5). Additional sediment samples

were collected with the Atlantis deck winch and large box cores (Table 6). Continual acoustic Doppler current

profile (ADCP) data were collected from Atlantis along the ship's track throughout the cruise. A second ADCP was

mounted on Alvin along with a conductivity, depth, and temperature (CTD) instrument. These instruments collected

data at the seafloor during each of the dives. Bottle cast and CTD casts were also collected with the Atlantis rosette.

Swath bathymetry data were recorded with the Sea Beam system mounted on Atlantis. These data provided detailed

bathymetric maps at each of the dive sites.

A preliminary review of dive results indicates that most of the project objective were met. The dives at Farnella

Canyon and Green Knoll (dives 3628 and 3629, respectively) confirmed that the interpretation of geophysical data

from the furrows region was essentially correct. Furrows were found to be distinct, steep-sided features arrayed in

parallel bands along the base of the escarpment. The steep angle of furrow edges and the accumulation of sorted,

coarse sediment along the bottom of furrow indicated that strong currents continue to shape furrows in the present

day. At the Green Knoll site, Alvin encounter a strong bottom current sweeping the base of the escarpment along the

length of the furrow zone. Concentrations of suspended sediments, including coarse sediments were high.

Additional sculpting and erosion of bottom sediments was evident on the slope of the escarpment above the furrow

zone.

Four of the dives targeted two potential sites for an Ocean Drilling Program leg (MC853 and At425, Table 2).

These dives performed an extensive reconnaissance of possible bore-hole locations, collected sediment samples, and

provided the first inspection of active hydrocarbon seeps in water depths of 1000 m or greater. The preliminary

results confirm that oil saturated sediments and shallow hydrate deposits occur at the MC853. Macro oil seepage

was also confirmed at AT425 and shallow hydrates were probably sighted as well. Both sites supported seep-related
AII-9

biological communities comprising seep mussels, vesicomyid clams, and extensive bacterial mats. Strikingly,

vestimentiferan tube worms, which are the ecosystem forming species at seeps in 500-600m, appeared to be

completely absent at these deeper sites. Extensive brine seepage was also noted, mostly on the flanks of topographic

highs associated with shallow hydrates.

A single dive was completed to conduct a video survey of the Florida Escarpment off the northern part of the state

(dive 3634, Table 2). The scientist encountered intense sedimentation which had produce a large accumulation of

flocculent material at the base of the escarpment. They transited approximate 700m up the vertical face of the

escarpment. The effects of ongoing sedimentation were evident in the relative paucity of sessile fauna. Corals,

sponges, crinoids, and other forms were found in abundance only where rocky overhangs protected that animals

from the settling material. The escarpment appears to be a stressed habitat over much of its surface.

These investigations are expected to produce a number of presentations and peer-review publications. Proposals for

follow-on work are also anticipated. The public response and media interest in the cruise has been very high. The

logistic arrangements offer a model for inter-agency cooperation in deep-sea science.

College of William and Mary Group

Cindy Lee Van Dover, Principal Investigator:

SUMMARY OF CRUISE RESULTS

Three Alvin dives were completed at the historic Florida Escarpment site (26 01.8’N, 84 54.9’W; 3388 m) Sixteen

quantitative mussel pots were collected, containing in total 681 mussels and occupying a total volume of 27 liters.

Fine and coarse washings from the mussels were preserved for subsequent laboratory analysis of species

identifications and abundance. Systematic sub-sampling of mussels was undertaken for measurement of condition

indices. A number of ancillary projects were also begun, including preservation of mussels for a comparative

histological analysis of pathology among Florida Escarpment seep and Mid-Atlantic Ridge vent populations (W&M

Master’s project), preservation of mussel commensal polychaetes for reproductive studies, and preparation of

mussel tissues for symbiont population studies (Harvard Ph.D. project). Tissue and blood samples were also

collected for other investigators, including Chuck Fisher and two of his students at Penn State and for Joe

Bonaventura at the Duke Marine Lab.

GENERAL SCIENTIFIC CONTRIBUTION OF THE CRUISE

The sampling program was successful, and will allow us to develop a robust, quantitative assessment of biodiversity

at the Florida Escarpment seep site. Because we used methods and standards routinely employed by my lab at vent

mussel beds, the seep data will be directly comparable and will allow insight into patterns of diversity. From these

patterns, we expect to develop hypotheses regarding processes that control biodiversity and the distribution of

species at seep and vent sites. From initial examination of the seep samples, it is immediately clear that the seep

mussel bed fauna differs from that of vents in the high abundance of echinoderms at seeps, both holothurian and

ophiuroid, and in the relative paucity of limpets and amphipods at seeps compared to vents.

SPECIFIC ADVANTAGES OF RESEARCH TO NURP

This program rigorously assesses diversity, which is one of the most fundamental descriptors in ecology. As such,

it is a direct contribution to the NURP priority of understanding the ecology of chemosynthetic systems. Seeps are

biodiversity hot spots and are thought to support a higher degree of endemicity than vent ecosystems. This

hypothesis needs to be rigorously tested by sampling other seep sites with similar efforts and methods to allow

quantitative comparisons.
AII-10

Table 5. Push cores collected from Alvin for macrofauna.

Site Name Date Core Marker Dive Number Latitude (N) Longitude (W) Depth (m) Time (CST) 

Green Knoll 10-21-00 PC-01 #2 #3629 26.56.64 90.14.2161 2457 10:58 Green Knoll 10-22-00 PC-02 #3 #3629 26.56.64 90.14.2161 2457 10:57 Green Knoll 10-22-00 PC-03 #4 #3629 26.56.64 90.14.2161 2457 10:55 Green Knoll 10-22-00 PC-04 #10 #3629 26.56.64 90.14.2161 2457 11:39 Green Knoll 10-22-00 PC-05 #11 #3629 26.56.64 90.14.2161 2457 11:48 Green Knoll 10-22-00 PC-06 #12 #3629 26.56.64 90.14.2161 2457 11:42 

MC853 10-23-00 PC-07 #3 #3630 28.12663 89.14367 1058 9:45-9:54 MC854 10-23-00 PC-08 #4 #3630 28.12663 89.14367 1058 9:45-9:54 MC855 10-23-00 PC-09 #6 #3630 28.12663 89.14367 1058 9:45-9:54 MC856 10-23-00 PC-10 #8 #3630 28.12663 89.14367 1058 9:45-9:54 MC857 10-23-00 PC-11 #7 #3630 28.12663 89.14367 1058 9:45-9:54 MC857 10-23-00 PC-12 Not available - core fell-off rack on the submersible

AT425 10-25-00 PC-13 #3 #3632 27.58122 88.50515 1943 13:30-13:40 IAT425 10-25-00 PC-14 #4 #3632 27.58122 88.50515 1943 13:30-13:40 IAT425 10-25-00 PC-15 #5 #3632 27.58122 88.50515 1943 13:30-13:40 IAT425 10-25-00 PC-16 #6 #3632 27.58122 88.50515 1943 13:30-13:40 AT425 10-25-00 PC-17 #7 #3632 27.58122 88.50515 1943 13:30-13:40 AT425 10-25-00 PC-18 #10 #3632 27.58122 88.50515 1943 13:30-13:40 

N.FL Escarp 10-27-00 PC-19 #7 #3634 28* 86.583* 2873 10:16 N.FL Escarp 10-27-00 PC-20 #8 #3634 28* 86.583* 2873 10:20 N.FL Escarp 10-27-00 PC-21 #9 #3634 28* 86.583* 2873 10:22 N.FL Escarp 10-27-00 PC-22 #10 #3634 28* 86.583* 2873 10:28 N.FL Escarp 10-27-00 PC-23 #11 #3634 28* 86.583* 2873 10:32 N.FL Escarp 10-27-00 PC-24 #12 #3634 28* 86.583* 2873 10:36 

*Approximate values - data not yet available
AII-11

Table 6. Box cores collected with use of the Atlantis winch and from Alvin.

Site Name Date Activity Marker Time Deployed Time on

Bottom

Latitude (N) Longitude (W) Depth (m) 

Farnella Canyon 102100 EB-01 Alvin Dive #3628 NA 26.269119 90.46.4224 2917 

Farnella Canyon 102100 EB-02 Alvin Dive #3628 NA 26.269119 90.46.4224 2917 

Farnella Canyon 102100 Box-01 N/A 8:00 8:45 26.26.7483 90.46.4594 2933 

Green Knoll 102200 Box-02 B1 3:46 4:32 26.55.4994 90.12.9999 2473.53 Green Knoll 102200 Box-03 B2 5:32 6:21 26.55.3007 90.12.9999 2473 Green Knoll 102200 Box-04 B3 7:17 8:01 26.55.4977 90.12.9998 2476 Green Knoll 102200 Box-05 N/A 9:02 9:49 26.55.4994 90.12.9997 2480 

MC853 102400 Box-06 B4 6:15 6:45 28.07.6064 89.08.4112 1056 MC853 102400 Box-07 B5 7:28 7:51 28.07.6064 89.08.4112 1056 MC853 102400 Box-08 N/A 8:30 8:51 28.07.6074 89.08.4100 1058 MC853 102400 Box-09 N/A 9:24 9:49 28.07.6100 89.08.4099 1058 

AT425 102500 Box-10 N/A 6:00 6:41 27.34.9303 88.30.4923 1955 AT425 102500 Box-11 N/A 7:22 7:59 27.34.9297 88.30.4304 1955 AT425 102600 Box-12 B6 2:37 3:12 27.34.9312 88.30.4285 1953 AT426 102600 Box-13 N/A 5:00 5:38 27.34.9309 88.30.4289 1949 AT426 102600 Box-14 N/A 6:32 7:11 27.34.9314 88.30.4273 1955 

S. FL Escarp 102900 Box-15 N/A 2:25 3:21 26.01.9003 84.55.1691 3307 S. FL Escarp 102900 Box-16 N/A 4:40 5:38 26.01.8996 84.55.1685 3302 S. FL Escarp 102900 Box-17 N/A 6:41 7:39 26.01.9004 84.55.1687 3303 S. FL Escarp 102900 Box-18 N/A 8:44 9:40 26.01.9002 84.55.1696 3304 
The Department of the Interior Mission

As the Nation's principal conservation agency, the Department of the Interior has responsibility 

for most of our nationally owned public lands and natural resources. This includes fostering 

sound use of our land and water resources; protecting our fish, wildlife, and biological diversity; 

preserving the environmental and cultural values of our national parks and historical places; 

and providing for the enjoyment of life through outdoor recreation. The Department assesses 

our energy and mineral resources and works to ensure that their development is in the best 

interests of all our people by encouraging stewardship and citizen participation in their care. 

The Department also has a major responsibility for American Indian reservation communities 

and for people who live in island territories under U.S. administration. 

The Minerals Management Service Mission 

As a bureau of the Department of the Interior, the Minerals Management Service's (MMS) 

primary responsibilities are to manage the mineral resources located on the Nation's Outer 

Continental Shelf (OCS), collect revenue from the Federal OCS and onshore Federal and Indian 

lands, and distribute those revenues. 

Moreover, in working to meet its responsibilities, the Offshore Minerals Management Program 

administers the OCS competitive leasing program and oversees the safe and environmentally 

sound exploration and production of our Nation's offshore natural gas, oil and other mineral 

resources. The MMS Minerals Revenue Management meets its responsibilities by ensuring the 

efficient, timely and accurate collection and disbursement of revenue from mineral leasing and 

production due to Indian tribes and allottees, States and the U.S. Treasury. 

The MMS strives to fulfill its responsibilities through the general guiding principles of: (1) being 

responsive to the public's concerns and interests by maintaining a dialogue with all potentially 

affected parties and (2) carrying out its programs with an emphasis on working to enhance the 

quality of life for all Americans by lending MMS assistance and expertise to economic 

development and environmental protection.