U.S. Department of the Interior 

Minerals Management Service 

Gulf of Mexico OCS Region 

OCS Study 

MMS 2003-030 

Workshop on Deepwater Environmental 

Studies Strategy: A Five-Year Follow-Up 

and Planning for the Future 

May 29-31, 2002 

Editors 

William W. Schroeder 

Carolyn F. Wood 

Prepared under MMS Contract 

1435-01-02-CA-85035 

by 

The University of Alabama 

Dauphin Island Sea Lab/MESC 

Dauphin Island, Alabama 

Published by 

New Orleans

May 2003 
iii 

DISCLAIMER 

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

University of Alabama, and the Dauphin Island Sea Lab. This report has been technically 

reviewed by the MMS, and it has been approved for publication. Approval does not signify that 

the contents necessarily reflect the views and policies of the MMS, nor does mention of trade 

names or commercial products constitute endorsement or recommendation for use. It is, 

however, exempt from review and compliance with the MMS editorial standards. 

REPORT AVAILABILITY 

Extra copies of this 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 Numbers: 1-504-736-2519 

 1-800-200-GULF 

CITATION 

Suggested citation: 

Schroeder, W.W. and C.F. Wood, eds. 2003. Workshop on Deepwater Environmental Studies 

Strategy: A Five-Year Follow-Up and Planning for the Future, May 29-31, 2002. U.S. 

Dept. of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New 

Orleans, LA. OCS Study MMS 2003-030. 135 pp. 

ABOUT THE COVER 

The graphic depicts the dramatic increase in the production of both natural gas and oil in the 

deeper waters of the Gulf. In 1985, less than 10 percent of the oil and natural gas production in 

the Gulf was attributed to the deep waters of the Gulf. That number has dramatically increased 

to nearly 60 percent in 2001. Estimates are that the percentage will continue to increase into the 

future. 
v

Workshop on Deepwater Environmental Studies Strategy: 

A Five-Year Follow-up and Planning for the Future 

May 29-31, 2002 

New Orleans Airport Hilton 

New Orleans, Louisiana 

Workshops sponsored by the Minerals Management Service (MMS) promote the dissemination 

and exchange of information about topics of concern relative to planned or potential Outer 

Continental Shelf (OCS) activities. In April 1997 MMS sponsored a workshop on environmental 

issues surrounding deepwater oil and gas development in the Gulf of Mexico. This workshop 

brought together experts from other government agencies, academia, and industry that were 

tasked with identifying information needs in the physical, biological/ecological, and 

social/economic sciences as they related to industry’s recent and rapid advancement into the 

deeper waters of the Gulf. These discussions were then used as guidance in designing the MMS 

Deepwater Strategic Studies Plan, composed of a series of deepwater studies. 

With increased development of the deep waters of the Gulf of Mexico for oil and gas, MMS 

must consider possible impacts to both the natural and human socioeconomic environment. As 

industry gains more experience in deep waters of the Gulf and studies better explain the 

deepwater environment, MMS seeks to gather experts from academia, industry, and government 

sources for a Deepwater Workshop. A similar workshop held in April 1997 provided guidance 

to the MMS for deepwater issues, which led to focused environmental studies to fill much 

needed data gaps. 

OBJECTIVE 

The purpose of the workshop was to 1) review the current status of industry activity in 

deepwater; 2) discuss any new environmental and/or social issues that have come to light since 

the first workshop; and 3) to examine information syntheses and data gaps identified during 

objectives one and two. 
vii

ACKNOWLEDGMENTS 

This meeting was a joint effort between the University of Alabama (UA), the Dauphin Island Sea 

Lab (DISL) and the U.S. Department of the Interior’s Minerals Management Service (MMS). 

The success of this workshop was due to the individuals below. The professional dedication and 

skills contributed on behalf of this effort before, during, and after the meeting deserve a special 

note of thanks and appreciation. 

Gary Goeke, Mary Boatman, James Ray – Program Co-Chairs 

Bill Bryant, Mike Rex, Steve Murdock – Session Chairs 

Robert Avent, Harry Luton, Sarah Tsoflias – MMS Session Co-Chairs 

David Walker, Paul Siegele, Dan Allen – Industry Session Co-Chairs 

Jeff Childs – Sub-Group Chair 

Anne Jochens, Gil Rowe, Randy Edwards – Invited Technical Overview Speakers 

Carolyn Wood, Randy Schlude, Jonathan Martin – UA/DISL Support Staff 

Debbie Vigil – Exhibit Coordinator 

Wayne Plaisance – Exhibit Production 

Margaret Metcalf, T. J. Broussard, Connie Landry – MMS Workshop Support Staff 

The Staff of the New Orleans Airport Hilton, Kenner, Louisiana 

____________________ 

William W. Schroeder 

Program Manager 
ix

TABLE OF CONTENTS 

List of Figures............................................................................................................................ viii 

List of Tables ............................................................................................................................... ix 

List of PowerPoint Presentations Presented at Workshop.............................................................x 

 I. Background - Workshop on Deepwater Environmental Studies Strategy: A Five-Year 

Follow-up and Planning for the Future 

 Robert Avent, Greg Boland, Alexis Lugo Fernandez, Gary Goeke, 

 Harry Luton and Sarah Tsoflias.....................................................................................1 

 II. Industry Perspectives .........................................................................................................11 

 Going Beyond, 

 David Walker, BP America, Inc. ...........................................................................11 

 Workshop on Deepwater Environmental Studies Strategy: Industry Perspective, 

 Paul Siegele, ChevronTexaco ................................................................................16 

 III. DeepSpill Experiment, 

 Dan Allen, Chevron USA Production Co. ..................................................................18 

 IV. Technical Overviews .........................................................................................................23 

 Overview of the Physical Oceanography of the Deep Gulf of Mexico, 

 Ann E. Jochens, Steven F. DiMarco, Matthew K. Howard, 

 Worth D. Nowlin, Jr., and Robert O. Reid, Texas A&M University ....................23 

 Overview of the Geology/Geohazards of the Continental Slope of the Northwest 

 Gulf of Mexico, 

 William Bryant, Texas A&M University...............................................................32 

 Overview of Knowledge of the Benthos of the Deep Gulf of Mexico, 

 Gilbert Rowe, Texas A&M University..................................................................39 

 Overview of Fisheries of the Deep Gulf of Mexico, 

 Randy Edwards and Kenneth J. Sulak, USGS Biological Resources 

 Division..................................................................................................................56 

 Overview of the Current Status of the Socioeconomic Studies in the MMS Gulf 

 of Mexico Region, 

 Steve Murdock, Texas A&M University...............................................................64 

 V. Breakout Group Summaries...............................................................................................67 

 Ecology Breakout Group 

 Michael Rex, University of Massachusetts 

 Robert Avent, Minerals Management Service 

 James P. Ray, Shell Global Solutions (US) Inc. 

 Jeff Childs, Minerals Management Service 

 Margaret Metcalf, Minerals Management Service ................................................67 
x

 Pelagic Systems: Ecology Breakout Subgroup 

 Jeff Childs, Minerals Management Service...........................................................76 

 Geology/Geohazards Breakout Group 

 Bill Bryant, Texas A&M University 

 Sarah Tsoflias, Minerals Management Service 

 Jim Niemann, ChevronTexaco 

 T. J. Broussard, Minerals Management Service ....................................................80 

 Socioeconomics Breakout Group 

 Steve Murdock, Texas A&M University 

 Harry Luton, Minerals Management Service 

 Connie Landry, Minerals Management Service ....................................................92 

VI. Appendices.........................................................................................................................96 

 Appendix 1. Deepwater Workshop Agenda ..............................................................96 

 Appendix 2. Working Group Participants ..................................................................98 

 Appendix 3. Workshop Attendees and Addresses....................................................101 
xi

LIST OF FIGURES 

Section III. DeepSpill Experiment 

 Figure 1. Diagrammatic of the deployed equipment for the experimental hydrocarbon 

release. .................................................................................................................20 

 Figure 2. Relationship of experimental hydrocarbon release site to the 

 Norwegian coastline.............................................................................................20 

 Figure 3. Surface slick that developed after a hydrocarbon test release. ............................21 

 Figure 4. Underwater gas release from the subsea manifold. .............................................21 

Section IV. Technical Overviews 

Overview of the Physical Oceanography of the Deep Gulf of Mexico 

 Figure 1. Sea surface height field for 20 September 1999 (top) showing extension of 

 Loop Current into the northeastern Gulf and formation of Loop Current Eddy 

 Juggernaut and for 14 November 1999 (bottom) showing westward migration 

 of LCE Juggernaut as well as the Loop Current in the southeastern Gulf and 

 an older anticylone in the western Gulf. ..............................................................25 

 Figure 2. Current vectors (40-hr low-passed; north directed upward) from SAIC 

 mooring G located in 3200 m water depth at 25.60N, 85.50W off the southern 

 West Florida Shelf. In December 1984, currents above 1000 m are affected 

 by the Loop Current in a surface-intensified manner, while currents below are 

 not affected. During April-June 1985, during an eddy separation, the current 

 appear to be coherent throughout the water column, with some indication of 

 bottom intensification. .........................................................................................27 

Overview of the Geology/Geohazards of the Continental Slope of the Northwest Gulf 

 of Mexico

 Figure 1. Bathymetry map of the northern Gulf of Mexico. ...............................................33 

 Figure 2. 3D surface extraction showing the physiography of Green Knoll. 

 The collapsed top of the knoll is the result of seawater leaching the knoll’s 

 salt core. (WesternGeco 3D data). .......................................................................35 

 Figure 3. Mego-furrows on the continental rise South of Green Knoll. 

 (WesternGeco 3D data)........................................................................................36 

 Figure 4. Map illustrating the location of mega-furrows along the continental rise 

 seaward of the Sigsbee Escarpment, Northwest Gulf of Mexico. .......................36 

Overview of Knowledge of the Benthos of the Deep Gulf of Mexico 

 Figure 1. Station locations in the MMS-supported investigation referred to as the North 

Gulf of Mexico Continental Slope Study (NGOMCS), conducted by LGL 

Environmental, Inc. Log transformations of polychaete densities (/m2

) in the 

northern Gulf of Mexico (Hubbard 1995). ..........................................................41 

 Figure 2. Density of macrofauna in the Gulf of Mexico (Rowe et al. 1974). .....................43 

 Figure 3. Biomass of macrofauna in the Gulf of Mexico (Rowe et al. 1974).....................44 

 Figure 4. Comparison of polychaete densities at two different time periods on the 

 upper slope of the northern Gulf of Mexico. (Data from Hubbard 1995). .........46 
xii

LIST OF TABLES 

Section I. Background - Workshop on Deepwater Environmental Studies Strategy: A 

Five-Year Follow-up and Planning for the Future 

Table 1. Completed and Ongoing Studies Funded in Response to the 1997 Deepwater 

Workshop...............................................................................................................3 

Section III. DeepSpill Experiment 

 Table 1. Summary of the four experimental discharges. ...................................................19 

Section IV. Technical Overviews

Overview of the Geology/Geohazards of the Continental Slope of the Northwest Gulf 

 of Mexico

 Table 1. Engineering constraints and possible geohazards of intraslope basins, canyons and 

escarpments ......................................................................................................................37 
xiii

LIST OF POWERPOINT PRESENTATIONS 

PRESENTED AT THE WORKSHOP

(Click on the title to view the presentation.) 

Going Beyond 

 David Walker, BP America Inc., Houston, Texas .................................................................15 

Workshop on Deepwater Environmental Studies Strategy: Industry Perspective 

 Paul Siegele, ChevronTexaco, New Orleans, Louisiana .......................................................17 

DeepSpill 

 Dan Allen, Chevron USA Production Co., New Orleans, Louisiana ....................................22 

Overview of the Physical Oceanography of the Deep Gulf of Mexico 

 Ann E. Jochens, Texas A&M University, College Station, Texas ........................................31 

The Benthos of the Deep Gulf of Mexico 

 Gilbert T. Rowe, Texas A&M University, College Station, Texas .......................................55 

Deep Gulf Fisheries 

 Randy E. Edwards, USGS, Gainesville, Florida and Kenneth J. Sulak, University of 

 South Florida, St. Petersburg, Florida................................................................................63 

An Examination of Selected Recent MMS Socioeconomic Studies and Assessments in the 

Gulf of Mexico 

 Steve H. Murdock, Texas A&M University; F. Larry Leistritz, North Dakota 

 State University; and Stan Albrecht, Utah State University..............................................66 

Workshop on Deepwater Environmental Studies Strategy: Ecology Breakout Group 

 Robert Avent, Michael Rex, James P. Ray, Jeff Childs, and 

 Margaret Metcalf ...............................................................................................................75 

Workshop on Deepwater Environmental Studies Strategy: Geology/Geohazards Breakout 

Group 

 Bill Bryant, Sarah Tsoflias, Jim Niemann, and T. J. Broussard ............................................91 

Workshop on Deepwater Environmental Studies Strategy: Socioeconomic Breakout Group 

 Harry Luton, Steve Murdock, and Connie Landry ................................................................95 
1 

I. Background

Workshop on Deepwater Environmental Studies Strategy: A Five-Year 

Follow-up and Planning for the Future 

Robert Avent, Greg Boland, Alexis Lugo Fernandez, 

Gary Goeke, Harry Luton and Sarah Tsoflias

U.S. Department of the Interior, Minerals Management Service 

Over the last decade significant deepwater oil and natural gas discoveries transformed the Gulf 

of Mexico (GOM) from a declining oil and gas province to one of world-class stature. The move 

in the early 80's away from targeting specific groups of outer continental shelf (OCS) blocks to 

be offered for lease to more open access, or what the U.S. calls area-wide leasing, set the stage 

for innovative companies to begin to test the new deepwater frontier. Having broad access also 

promotes economies of scale because an expanding infrastructure over time lowers the size of 

what constitutes an economic field by allowing smaller, otherwise marginal fields, to be 

produced in conjunction with existing development. 

Rapidly improving deep drilling and exploration technologies, and discoveries of very large 

reservoirs has justified the higher costs of deep exploration and development. With this 

accelerating interest, leasing in waters deeper than 400 meters has proceeded at an unprecedented 

rate, with exploration and production following closely behind. Interest in deep waters has also 

been heightened by the passage of the Deepwater Royalty Relief Act in 1995 and the 

development of technologies that allow for cost-effective development beyond the continental 

shelf. In recent years, the oil and gas industry has leased tracts in depths greater than 3,000 m 

and has drilled wells in water depths greater than 2,000 m. The challenge to the Minerals 

Management Service (MMS) is to insure that the environmental information base is adequate to 

address management issues needed in the deep Gulf. 

Industry’s offshore trend has been paralleled by MMS-sponsored research of the deep sea in 

general and chemosynthetic communities and marine mammals in particular. Still by 1997, there 

clearly was a myriad of issues not yet addressed. Recognizing the magnitude of this task, MMS 

and Louisiana State University hosted a workshop on Environmental Issues Surrounding 

Deepwater Oil and Gas Development in the spring of 1997 (Carney 1998). Concurrently, the 

Deepwater Subcommittee of the OCS Advisory Board's Scientific Committee assisted MMS in 

identifying and prioritizing its deepwater information needs. 

The following topics were identified as critical environmental issues: 

• Socioeconomic effects of deepwater activity on ports and coastal support facilities; 

• Storage, handling and discharge of chemicals and drilling muds; 

• Location and avoidance of deepwater benthic communities; 

• Potential of gas hydrates to cause problems in operations; and 

• Characterization of fates and effects of deepwater blowouts or pipeline leaks. 
2 

A research strategy was developed to address these issues, with an ongoing commitment to 

continue to work with all stakeholders as the research program evolved. It was recognized early 

on that new issues would emerge and that collaborative efforts with industry and other 

governments would be necessary because MMS on its own could not entirely fund the necessary 

research and would benefit from the views and input of others. The MMS led an international 

effort with Norway and 23 oil and gas companies to learn more about the behavior of oil/gas 

spills at great water depths. A successful field experiment, known as "DeepSpill", was held in 

June 2000 off the coast of Norway, in which a deep spill was observed and characterized. This 

information will be most useful in calibrating and validating deep spill models presently under 

development that will be used in spill contingency planning and response. Concerning disposal 

of synthetic based muds, MMS is currently participating in a jointly funded study, with industry 

and the U.S. Department of Energy, to evaluate the effects on the seabed from the discharge of 

cuttings from drilling with synthetic based drilling fluids. The U.S. Environmental Protection 

Agency will use the information gathered in their general discharge permits. 

Before the 1997 Deepwater Workshop 

Prior to 1997, the MMS had funded studies to collect information about the ecology of the deep 

Gulf. Based primarily on accumulated trawl data and bottom photographs collected with the R/V 

Alaminos from the 1960’s through about 1980, a synthesis report was prepared (Pequegnat 

1983). However, the MMS still lacked systematic faunal data except for the megafauna, and this 

was only semiquantitative at best. The Northern Gulf of Mexico Continental Slope Study

(Gallaway 1988) was a descriptive field study designed largely to test or confirm the depth 

zonation scheme suggested by Pequegnat. The ongoing continental shelf studies were conducted 

as a series of regional efforts based on regional physiological and zoogeographic character. But 

because the Gulf was believed to change monotonously with depth in the 1970’s, it was believed 

that one large descriptive study with stations placed on transects and using consistent methods, 

would work for the deep-sea. (We did not yet appreciate the Gulf’s geochemical and 

physiographic complexity.) Consisting ultimately of stations on a few shallow-to-deep and E-W 

transects, the study concentrated on benthic and benthopelagic sampling. Included were 

sediment characteristics; meio-, macro-, and megafauna; contaminants; and hydrography; with 

the usual comparisons of the non-biological variables and community structure. 

During the latter phases of the Northern Gulf of Mexico Continental Slope Study (Gallaway 

1988) field program (late 1984) that researchers recognized chemosynthetic species in dredge 

and trawl tows from an area known to have sediments containing oil, gas hydrates, and hydrogen 

sulfide. Carbon isotopic analyses confirmed that the tubeworms and molluscs lived via a 

chemosynthetic strategy (MacDonald et al. 1995). In 1995, the MMS initiated Change and 

Stability in Gulf of Mexico Chemosynthetic Communities to expand on the first study of 

chemosynthetic communities (MacDonald et al. 1995). The MMS recognized that there were 

still few data on (1) the ecological interactions in these communities, (2) temporal stability and 

change within the communities, and (3) the physicochemical habitats that support them. The 

second study addresses both nonbiotic habitat and biotic questions to understand the conditions 

necessary for community establishment and maintenance. 
3 

In other areas of oceanography, the learning curve was just as steep. While some information 

was available regarding the physical oceanography of the surface waters of the deep Gulf (SAIC 

1989), nothing was known about the current regime near the bottom though, generally, it was 

believed to be quiescent. Only recently, through the use of 3-D seismic has the geology of the 

Gulf been more fully understood. Additionally, little was known about the socioeconomic 

impacts from offshore oil and gas activities along the Gulf coast. 

The 1997 workshop consisted of four sessions: physical oceanography, ecology, sea floor 

geology, and socioeconomics. During the course of the workshop, two ad hoc sessions were 

formed; fisheries issues and deepwater operational process. As a result of the recommendations 

from the workshop, 30 studies have been funded (Table 1). 

Table 1. 

Completed and Ongoing Studies Funded in Response to the 1997 Deepwater Workshop 

Completed Studies 

Gulf of Mexico Deepwater Information Resources Data Search and Literature Synthesis 

Deepwater Physical Oceanography Reanalysis and Synthesis of Historical Data 

Offshore Data Search and Synthesis on Highly Migratory Species in the GOM and the Effects 

of Large Fish Attracting Devices (FADS) 

Literature Review: Environmental Risks of Chemical Products Used in Deepwater Oil & Gas 

Operations 

The Fate and Effects of Synthetic-Based Drilling Fluids and Associated Cuttings Discharged 

into the Marine Environment

Ongoing Ecological Studies 

Summary of the Northern Gulf of Mexico Continental Slope Studies 

Offshore Petroleum Platforms: Functional Significance for Larval Fish Across Longitudinal 

and Latitudinal Gradients 

Assessment and Reduction of Taxonomic Error in Benthic Macrofauna Surveys: An Initial 

Program Focused on Shelf and Slope Polychaete Worms 

Development of a Deepwater Environmental Data Model 

Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology 

Bluewater Fishing and Deepwater OCS Activity: Interactions Between the Fishing and 

Petroleum Industries in Deepwaters of the Gulf of Mexico 

Effects of Oil and Gas Exploration and Development at Selected Continental Slope Sites in the 

Gulf 

Sperm Whale Seismic Study (SWSS) 
4 

Table 1. Continued 

Completed and Ongoing Studies Funded in Response to the 1997 Deepwater Workshop 

Ongoing Physical Oceanography Studies 

Observation of Deepwater Manifestation of Loop Current Rings 

Deepwater Currents at 92 W 

Study of Subsurface, High-Speed Current Jets in the Deep Water Region of the Gulf of Mexico 

Analysis and Validation of a Mechanism that Generates Strong Mid-depth Currents and a Deep 

Cyclone Gyre in the Gulf of Mexico 

Modeling and Data Analysis of Subsurface Currents on the Northern Gulf of Mexico Slope and 

Rise: Effects of Topographic Rossby Waves and Eddy-Slope Interaction 

Study of Subsurface, High-Speed Current Jets in the Deep Water Region of the Gulf of Mexico 

Exploratory Study of Deepwater Currents in the Gulf of Mexico 

Ongoing Socioeconomic Studies 

Labor Migration and the Deepwater Oil Industry in Houma 

An Analysis of the Socioeconomic Effects of OCS Activities on Ports and Surrounding Areas in 

the Gulf of Mexico Region 

Labor Migration and the Deepwater Oil Industry 

Potential Spatial and Temporal Vulnerability of Pelagic Fish Assemblages in the Gulf of Mexico 

to Surface Oil Spills Associated with Deepwater Petroleum Development 

Assessing and Monitoring Industry Labor Needs 

Benefits and Burdens of OCS Deepwater Activities on Selected Communities and Local Public 

Institutions 

OCS-Related Infrastructure in the Gulf of Mexico 

Supply Logistics of OCS Oil and Gas Development in the Gulf of Mexico -- Evaluation of 

Technological and Economic Parameters of Ports as Supply and Manufacturing Bases 

Other Ongoing Studies 

Understanding the Processes that Maintain the Oxygen Levels in the Deep Gulf of Mexico 

Joint Industry Project, "Gulf of Mexico Comprehensive Synthetic Based Muds Monitoring 

Program" 

What is Known Today 

Research over the past five years has greatly increased our understanding of the environment of 

the Gulf of Mexico. What was once thought to be a simple, monotonous system is now known 

to be complex and dynamic both above and below the seafloor. The following sections discuss 

some of what has been learned since the last workshop. More specific information was 

presented in the plenary session and the details can be found in the final reports. 
5 

Geology 

Understanding the Gulf of Mexico environment begins with the complex geologic setting, which 

creates a foundation for the life within and above. The majority of the complex geology of the 

Gulf of Mexico is due to horizontal and vertical movement of salt. The Louann Salt, which 

underlies the sedimentary provinces, was deposited in Jurassic time in the basin during repeated 

episodes of flooding and evaporation of shallow saline waters. Bathymetric maps of the 

continental slope in the northwestern Gulf of Mexico (Bryant et al. 1990; Bouma and Bryant 

1995) reveal the presence of over 105 intraslope basins with relief in excess of 150 meters. The 

southern edge of the salt mass within the northern Gulf is the Sigsbee Escarpment. The lower 

continental slope contains numerous submarine canyons that cut into the Escarpment. 

Submarine fans of various sizes extend seaward of the canyons onto the continental rise. On the 

upper continental slope, gas hydrates and underconsolidated gassy sediments are common. 

The geology of the deepwater Gulf of Mexico influences the geochemical and biological 

processes in the region. Faults act as migration conduits for subsurface fluid and gas to the 

seafloor. Interesting benthic habitats are created due to this fluid and gas seepage and 

chemosynthetic communities are common. Understanding the geology of the deepwater 

continental slope aids in understanding the deepwater biologic communities. 

Due to the interaction of halokinesis and rapid sedimentation, several geologic hazards, or 

geohazards, exist in this region. Salt movement can cause potential hazards such as seafloor 

fault scarps, slumping from steep unstable slopes, shallow gas pockets, seeps and vents, and 

rocky or hard bottom areas. Gas hydrate instability could result in the dissociation of hydrates 

and subsequent sediment slumps and slides. High sedimentation rates cause unconsolidated, 

high-water-content, and low-strength sediments. Under these conditions, the sediments can be 

unstable, and slope failure or mass transport of sediments can result. Rapid sediment deposition 

and salt movements create instabilities by over steepening slopes resulting in slumps, creep and 

debris flows. 

Physical Oceanography 

Above the seafloor, the circulation of water within the Gulf helps create communities through 

the transport of nutrients, plankton, and larvae. Currents are also important because they 

transport the discharges from oil and gas activities. As an initial step in understanding the 

deepwater physical oceanography, MMS funded a synthesis of the present “state of knowledge” 

(Nowlin et al. 2001). The data compiled in this study represents the most complete and updated 

source of information on deepwater physical oceanography of the Gulf. Examination of the 

spatial and temporal distribution of the data reveals a number of data gaps. Except in the central 

Gulf, there are few current data sets in water depths of 1000 m or more, and few stations 

available south of 25°N. 

The circulation within the Gulf of Mexico is driven principally by two sources of energy. The 

main source consists of the Yucatan Current and other circulation features that enter the Gulf 

from the Caribbean Sea through the Yucatan Channel and forms the Loop Current. The second 

major energy source is wind stress forcing. Other effects include episodic currents forced by 
6 

high frequency but strong atmospheric events including tropical cyclones, extratropical cyclones, 

cold air outbreaks, and other frontal passages. Thermohaline forcing is known to be important 

over the Gulf shelves, e.g., buoyancy forcing by river discharge affects the nearshore coastal 

currents over the shelves. However, no thermohaline forcing of consequence or significant water 

mass formation are known to occur in the deepwater Gulf. 

Ecology 

Arguably, the most recognized studies of the MMS Environmental Studies Program have been 

the “Marine Ecosystems” studies. Almost as soon as the National Environmental Policy Act 

(NEPA) was passed and there was an Environmental Studies Program (1973), the Bureau of 

Land Management (the BLM, a predecessor of the MMS) began to fund a series of ambitious 

descriptive regional field studies around the Gulf. In some cases, these continental shelf studies 

were the first truly systematic, multidisciplinary, multiyear studies of a given area. Since then, 

there have dozens of final reports on shelf ecosystems. In the late 1970’s it was already apparent 

to the BLM that the industry was moving onto the upper continental slope, and early planning 

was in order for studies of the continental slope. 

Deep-sea animals live mostly under conditions of total darkness, low temperature, nearly 

featureless mud, and sparse food resources. They are generally small and fragile and the 

structure of benthic communities is generally well known, if not satisfactorily explained, 

ecologically. Many of the same sampling and statistical methods used in shallow water apply 

well in the deep-sea environment. However the costs for sea time and sample treatments are 

usually significantly higher. The character and rarity of many deep animals, the high species 

diversity, and the relative paucity of qualified systematists add to the difficulties. 

In 1988 when the Northern Gulf of Mexico Continental Slope Study final report was received 

(Gallaway 1988), the MMS was already aware that the classical picture of the continental slope 

was changing. Many newer scientific findings were made, among the most important being the 

discoveries of productive chemosynthetic communities in 1984, and the collection of far better 

information on geological structural complexity and related biogeochemical processes. It was 

now generally conceded that the available information on the continental slope was inadequate. 

During the 1997 workshop, the discussion group on deep-sea ecology focused on the state of 

knowledge of benthic communities, its composition and complexity, associated biogeochemical 

processes, habitat heterogeneity and trophic considerations. Several studies were funded based 

on the recommendations including Northern Gulf of Mexico Continental Slope Habitats and 

Benthic Ecology (in progress), Management Applicability of Contemporary Deep-Sea Ecology 

and Reevaluation of Gulf of Mexico Studies (Carney 2001) and Effects of Oil and Gas 

Exploration and Development at Selected Continental Slope Sites in the Gulf of Mexico (in 

progress). 

Fisheries 

Deepwater fisheries as they relate to offshore oil and gas development have only recently 

become an issue as a result of the shift of interest from the continental shelf to the deeper waters 

of the northern Gulf of Mexico. The potential for interactions between bluewater fishing and the 
7 

deepwater energy industry was raised as a concern by a fisheries subcommittee during the first 

deepwater workshop sponsored by MMS (Carney 1998). This concern provided the impetus for 

the recently completed study, Bluewater Fishing and OCS Activity, Interactions Between the 

Fishing and Petroleum Industries in Deepwaters of the Gulf of Mexico by Continental Shelf 

Associates (CSA 2002, submitted). This study addressed conflicts between pelagic longliners 

and geophysical survey vessels, longline interactions with other surface operations, and bottom 

trawl interactions with structures. A second issue raised during the workshop was the potential 

for deepwater petroleum structures (DPSs) to impact Gulf fish and fisheries by acting as fish 

aggregating devices (FADs). A recently released report prepared by the United States Geologic 

Survey Potential for Gulf of Mexico Deepwater Petroleum Structures to Function as Fish 

Aggregating Devices (FADs) – Scientific Information Summary and Bibliography (Edward and 

Sulak 2002) discusses the topic.

Socioeconomics 

The socioeconomic breakout group for the 1997 deepwater workshop (Carney 1998) faced a 

problem similar to that faced by earlier reviews and workshops; the lack of studies to review. 

Until the 1990s, the GOMR had conducted few social and economic studies; those that were 

funded addressed a narrower range of issues. By 1990, external reviews, advice from the 

agency’s Science Committee, and the traumatic 1980s oil price bust had convinced the MMS of 

the need to expand its consideration of the program’s social and economic effects and several 

new socioeconomic studies were underway. All of these addressed the consequences of the oilprice collapse; most of them had employed a “boom/bust” model to explain its social 

consequences. However, while these studies show the growing emphasis on socioeconomics, the 

MMS’s present-day approach to social and economic research for the Gulf Region developed 

later, beginning in 1992. That year the NRC reviewed the MMS studies program (NRC 1992), 

the GOMR held its socioeconomic agenda setting workshop (Gramling and Laska 1993), and the 

GOMR studies program began to incorporate their findings into its studies planning process. 

Nevertheless, five years later when the 1997 GOMR deepwater workshop was held, its members 

still confronted an almost empty slate. While the bust-related studies were complete, only two 

published studies reflected the initial MMS response to the NRC review and GOMR workshop. 

One was an expanded version of a workshop “white paper” that linked changes in offshore 

petroleum technology and business practices to social effects; the other was an assessment of 

stakeholder issues for the central Gulf. Several others were in draft or underway. The agency’s 

slow response to the NRC and workshop recommendations was due in part to the time needed to 

reshape the studies planning process. However, the Gulf also faced a budget problem. The NRC 

reviews of physical oceanography and ecology had been first out of the gate. By 1997, much 

planning had been completed but most studies funds had already been committed to addressing 

NRC suggestions in these areas. 

Now, however, the 2002 deepwater workshop does not face an empty slate. The last decade of 

MMS Gulf socioeconomic studies has been robust and varied, particularly when compared to 

earlier times. Many of these studies are now published, many others will soon conclude. 

Guidance from the 1992 NRC review (NRC 1992) and workshop (Gramling and Laska 1993) 
8 

and the 1997 deepwater workshop (Carney 1998) have substantially shaped this output—at least 

as this guidance has been interpreted and operationalized by MMS. 

The timing of the GOMR 2002 deepwater workshop is fortuitous because this is the time to 

retool for the second wave of research. Part of this task is to assess what the first wave left 

undone, what needs following up, what failed, and what did not. To facilitate this process, Drs. 

Steve Murdock, Stan Albrecht, and F. Larry Leistritz have prepared an assessment of MMS Gulf 

socioeconomic study reports completed during the last decade and MMS has prepared a 

description of the ongoing studies. The MMS is also providing a history of the MMS Gulf 

socioeconomic studies program that was prepared for its Scientific Committee. 

This workshop is intended to consider what MMS should do in light of what its research has 

accomplished. The participants may identify specific information needs and specific studies that 

would address them. However, MMS is not seeking a list of suggested study titles but, rather, 

what might best be characterized as “strategic thinking” about issue selection, methodologies, 

and research and socioeconomic assessment goals. It seeks discussion on such questions as: 

Where should the next round of study effort be concentrated and why? What areas, questions, 

and problems are most critical for an environmental assessment? What might be the most 

effective ways to research them? What obviously important questions might not be effectively 

addressed? To facilitate this discussion, MMS will provide a hypothetical research agenda that 

identifies problem areas in the current research program and the goals and methodologies of a 

series of studies that might address them. 

What’s Next? 

Five years have passed since the 1997 workshop (Carney 1998) and it is time to examine where 

the program has been and where it is going. This workshop is structured to parallel the first 

deepwater workshop with the exception of physical oceanography. A separate workshop was 

held to discuss deepwater physical oceanography in September, 2000 (McKay et al. 2001). 

Therefore, this workshop was broken into three main sessions; ecology, sea floor geology, and 

socioeconomics. One ad hoc group was formed to discuss fisheries. 

The remoteness of deepwater development has brought about consideration of several nonroutine issues. The MMS has had discussions with various companies leading efforts to 

investigate offshore support facilities for equipment and consumables, temporary housing of 

personnel, emergency landing facilities for aircraft, field hospitals, offloading terminals, central 

gathering facilities, shuttle tanker transport of produced hydrocarbons, waste management, and 

mariculture initiatives. With each new proposal, environmental and technological challenges 

emerge. The role MMS will play in these nonroutine initiatives designed to support deepwater 

development will evolve as individual projects become more certain. Also, given the unknown 

aspects of what awaits discovery in ever-deeper waters, we must be environmentally vigilant. 

The recent discoveries of chemosynthetic communities, deepwater furrows on the seabed, and 

“iceworms” living on methane hydrates may be just a preview of what is to come. It is 

incumbent on us to use emerging technology being developed, such as remotely operated 

vehicles and ever-improving sensors, to further our understanding of these deep resources. A 
9 

challenge for our future is to be ready and able to assess, protect, and possibly use these 

resources in a sustainable manner. 

References 

Bouma, A. H. and W. R. Bryant. 1995. Physiographic features on the northern Gulf of Mexico 

continental slope. Geo-Marine Letters 14:252-263. 

Bryant, W. R., J. R. Bryant, M. H. Feeley and G. S. Simmons. 1990. Physiography and 

bathymetric characteristics of the continental slope, Gulf of Mexico. Geo-Marine Letters 

10:182-199. 

Carney, R. S. 1998. Workshop on environmental issues surrounding deepwater oil and gas 

development. Final Report. U.S. Department of the Interior, Minerals Management Service, 

New Orleans, LA. OCS Study MMS 98-0022. 

Carney, R. S. 2001. Management Applicability of Contemporary Deep-Sea Ecology and 

Reevaluation of Gulf of Mexico Studies. U.S. Department of the Interior, Minerals 

Management Service, Gulf of Mexico OCS Region, New Orleans, LA. OCS Study MMS 

2001-095. 174 pp. 

Continental Shelf Associates, Inc. 2000. Deepwater Gulf of Mexico Environmental and 

Socioeconomic Data Search and Literature Synthesis. Volume I: Narrative Report. OCS 

Study MMS 2000-049. U.S. Department of the Interior, Minerals Management Service, Gulf 

of Mexico OCS Region, New Orleans, LA. 340 pp. 

Continental Shelf Associates. 2002 submitted. Deepwater Program: Bluewater fishing and OCS 

activity: Interactions between the fishing and petroleum industries in deepwaters of the Gulf 

of Mexico. Draft Final report to ). U.S. Department of the Interior, Minerals Management 

Service, contract #1435-01-99-CT-31011. 185 pp. + appen. 

Edwards R. E and K. J. Sulak. 2002. Potential for Gulf of Mexico deepwater petroleum structures 

to function as fish aggregating devices (FADs) – Scientific information summary and 

bibliography. Final Project Report, U.S. Department of Interior, Geological Survey, USGS 

BSR 2002-0005 and Minerals Management Service, Gulf of Mexico OCS Region, New 

Orleans, Ala, OCS Study MMS 2002-39. 261 pp. 

Gallaway, B. J. (Ed.). 1988. Northern Gulf of Mexico Continental Slope Study, Final Report: 

Year 4. Volume II: Synthesis Report. Final report submitted to the Minerals Management 

Service, New Orleans, LA. OCS Study/MMS 88-0053. 318 pp. 

Gramling, R. B. and S. B. Laska. 1993. A social science research agenda for the Minerals 

Management Service in the Gulf of Mexico. Prepared by Louisiana Universities Marine 

Consortium, University Research Initiative for the U.S. Dept. of the Interior, Minerals 

Management Service, Gulf of Mexico OCS Region, New Orleans, LA. OCS study MMS 93-

0017. May. ix, 62 pp. 
10 

MacDonald, I. R., W. W. Schroeder and J. M. Brooks. 1995. Chemosynthetic Ecosystems 

Studies, Final Report. U.S. Dept. of the Interior, Minerals Management Service, Gulf of 

Mexico OCS Region, New Orleans, LA. OCS Study MMS 95-0023. 338 pp. 

McKay, M., J. Nides, L. Atkinson, A. Lugo-Fernandez and D. Vigil. 2001. Workshop on the 

physical oceanography slope and rise of the Gulf of Mexico, September, 2000. U.S. Dept. of 

the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. 

OCS Study MMS 2001-021. 151 pp. 

National Research Council (NRC). 1992. Assessment of the U.S. outer continental shelf 

Environmental Studies Program: III. Social and economic studies. Washington, DC: 

National Academy Press, National Academy of Sciences. x,164 pp. 

Nowlin, W. D., A. E. Jochens, S. F. DiMarco, R. O. Reid and M. K. Howard. 2001. Deepwater 

Physical Oceanography Reanalysis and Synthesis of Historical Data: Synthesis Report. U.S. 

Dept. of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New 

Orleans, LA, OCS Study MMS 2001-064. 528 pp. 

Pequegnat, W. E. 1983. The Ecological Communities of the Continental Slope and Adjacent 

Regimes of the Northern Gulf of Mexico. U.S. Dept. of the Interior, Minerals Management 

Service, Gulf of Mexico OCS Region, New Orleans, LA, Contract No. AA851-CT1-12, 398 

pp. 

Science Applications International Corporation (SAIC). 1989. Gulf of Mexico Physical 

Oceanography Program, Final Report: Year 5. Volume II: Technical Report. U.S. Dept. of 

the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA, 

OCS Study MMS 89-0068. 333 pp. 
11 

II. Industry Perspectives 

Going Beyond 

David Walker 

BP America Inc., Houston Texas 

BP has a huge interest in the future of the deepwater Gulf of Mexico. Of the major operators, we 

find ourselves the clear leader in terms of resources with over 3 billion barrels of oil equivalent 

discovered to date. This makes the deepwater Gulf of Mexico the biggest single investment 

opportunity we have in our upstream portfolio. The safe and environmentally sound 

development of these resources is absolutely central to the future of BP. Your invitation to speak 

today asked for an operator’s perspective on future environmental and social issues in the 

deepwater Gulf. Before I discuss that, I’d just like to say a little bit about BP, about how it feels 

to me as an engineer working there, and how environmental concerns impact what we do. 

Three months ago I was invited to attend a two day workshop in London, addressing the subject 

of the year 2015 – specifically, what sort of company would BP be by then. It was, I think, the 

most interesting two days I have spent with the company in the past 30 years. Sixty people were 

present, 30 senior staff from BP and 30 external contributors, mainly academics from the US and 

UK. Environmental and social issues dominated the agenda. One of the most interesting talks at 

the workshop was given by an architect. He was a man whose views on society’s relationship to 

the environment could be described as radical, at least by the standards of contemporary 

American society. Before he stood up to address us, I had already decided he wasn’t from BP – 

there was something about his black suit, black shirt and large floppy black bow tie that marked 

him as ‘not one of us’. But his message was hugely powerful and totally universal. He talked 

about toxicity and questioned why we tolerate so much in our lives. He explained how a new 

approach to building design could transform the impact they have on their natural surroundings – 

and he didn’t just mean the aesthetic impact, but all aspects, including, in particular, their energy 

consumption. I found out later that his architectural partnership has been engaged by BP to 

consult on questions of design. Not just product design, but on the design of the buildings and 

platforms we construct, looked at from a radical environmental perspective. I mention this, not 

because I believe we are going to change the way we do our business overnight, but because it is 

symptomatic of the debate going on inside BP about where we want to get to as a company, in 

terms of our relationship with society and the natural environment. 

This thinking starts at the top with our leadership. John Browne, our CEO, has summed it up 

very simply with three bullet points. You must admit it is commendably simple, direct and 

unambiguous. We’re not there yet, but it clearly sets the direction for all our operations and if 

these things are important to the company leadership, then they get conveyed to staff and thus 

become a focus and there’s plenty of evidence that it’s working. Over the last 10 years our 

safety record has been transformed and now we are in the top quartile of our peers. 
12 

This is where I get the title of my talk – the sense that as a company we are not simply driven by 

regulatory compliance – but by a desire to go beyond that – to be true to our aspiration of no 

damage to the environment. For a major oil company this generates a tough paradox – how is it 

possible to be both a provider of cheap and efficient energy and a force for improving the 

environment? Let me briefly summarize where I see the debate going on inside BP. 

We are paying close attention to what various international conventions are saying about these 

increasingly important issues for the planet. Learning how to determine the right answer when 

some of these priorities come into conflict is not easy. We may for example come across a 

technology with great scope for improving water quality, but if it is hugely inefficient in terms of 

energy consumption, we may have second thoughts about deploying it. The whole question of 

how we address our holistic impact on the environment and learn to make the right trade-offs is 

the big debate inside BP today. Our style is to listen to what the world is saying and to learn by 

doing. 

I think we would all agree that, in general, the industry has a great track record in terms of 

devising financial metrics. Greenhouse gas emissions data as environmental performance 

indicators are evolving quickly. Social performance metrics are also beginning to mature. 

However if we think about an issue like biodiversity, one can argue that performance measures 

are still in their infancy. This presents a real challenge to us if we are going to incorporate 

actions to address biodiversity into the performance driven culture of our company. Okay I hear 

you say, all this is fine, but how do these high ideals translate into the real world of deepwater oil 

and gas production here in the Gulf of Mexico? Let me give you some examples. A cornerstone 

of our environmental policy is the need for measurement, transparency and continuous 

improvement. The way we have chosen to do this is via adoption of ISO 14001 certification. 

We have been running this program here in the Gulf of Mexico since December 1998 and we 

were the first operator to introduce it. Twice a year we call in an independent authority to audit 

our business units. This entails a detailed review of all our measured environmental impacts – 

emissions to air, discharges to water, waste disposal, hydrocarbon spills and environmental fines. 

This data is published annually – evidence of what I mean by transparency. The audit also 

includes interviews with key personnel to gather evidence that our performance targets are 

understood and that a rigorous system is in place for their delivery. In the same way that we 

monitor safety performance, not just within our own operations but also within those of our 

contractors, so too with ISO 14001 compliance. Since 1998, we have certified all of our drilling 

rigs under long term charter. ISO 14001 embodies the concept of continuous improvement – 

each year the target levels on environmental impact measures are reduced. What has been 

achieved is truly remarkable. 

For example, in 1998, BP announced that it would reduce greenhouse gas emissions by 10% 

from a 1990 baseline figure by 2010. This was to be accomplished against an aggressive 

production growth target for the company over this period, which effectively meant a 33% 

reduction in emissions per unit of production. This target was achieved this year – eight years 

ahead of schedule - and a new target has been announced to take us through to 2012. One of the 

important tools used by the company to meet the target was the establishment of an emission 

trading system between business units. This acted as a mechanism for identifying where in the 

company emission reductions could be achieved most economically. In comparison to other 

parts of the company our deepwater production facilities are amongst the lowest emitters of 
13 

greenhouse gas – roughly 10% of the company average, expressed in terms of tons of CO2 

emitted per 1000 barrels produced. This whole approach to greenhouse gas emissions is not just 

good environmental practice – it also makes sound business sense. A recent analysis of the value 

of the steps we had taken to reduce emissions over the past few years demonstrated a net positive 

NPV to BP of several hundred million dollars. 

All sorts of different technologies can contribute to achieving this. Last year we were the first 

company to moor a drilling rig using polyester moorings in a water depth where conventionally 

in the past we would have used dynamic positioning. This reduced fuel consumption and hence 

CO2 emissions by over 60%. Similar levels of improvement are being achieved with drilling 

fluid discharges. For many years we’ve been working in collaboration with the MMS, the EPA, 

and our industrial partners to define new standards on what is permissible. As a result of the new 

EPA western GoM discharge permit, the implementation of a program tackling discharges of 

synthetic based drilling fluids will achieve a 50% reduction. It is mandatory within the company 

that every new development project generates an environmental strategy that details how the 

company’s goals are being met. As mentioned earlier, this involves making difficult decisions to 

balance our goal of “no damage to the environment” with other important considerations such as 

safety, technical feasibility, reliability and, of course, cost. The strategy is subject to intense peer 

review and is reviewed at a senior level in the company. I hope I’ve managed to convey a sense 

of how a structured and audited process for meeting environmental targets is having a profound 

impact on our operations. It constitutes nothing less than a complete cultural change compared 

to the past. I touched on the subject of biodiversity earlier in the talk and I’d like to return to it. 

I don’t know how industry observers decide what is important to oil companies, but one simple 

way is to read their annual reports. We are certainly not the only major to address it there. I 

have a feeling that if you were to go back just a very few years, that would not have been the 

case. In September of 2000, BP, in collaboration with the University of Southampton 

Oceanography Centre, published a briefing paper on Deep-Sea Biodiversity and Hydrocarbon 

Exploration and Production. The paper acknowledges that not only is marine biodiversity 

becoming increasingly important, but that our level of understanding is very mixed. In some 

deepwater basins (and I would include the GoM in that group) we have a reasonable amount of 

data – while in other deepwater areas of interest to us we have very little. This is a huge 

challenge for us all and presents a tremendously fertile arena for collaboration between scientists 

and oil companies. Not only do our offshore facilities represent ideal sites for studies, but much 

of the technology we are developing to support our deepwater operations – such as ROV’s and 

AUV’s – is ideally suited to support such fields of scientific enquiry. We are already very active 

in this field. We have recently set up a collaborative program of scientific research in the fields 

of marine taxonomy and zoogeography at Texas A&M and Southampton Universities. The 

broad objectives are: provide support on the taxonomy of key benthic invertebrate groups; 

realize added scientific value from available BP material including samples; and provide a 

vehicle for broader international scientific collaboration. 

Our contributions in this area in 2001 totaled over $1mm. I don’t want to list all the donations, 

but let me just give you a couple of examples. We are a major supporter of the Gulf of Mexico 

Foundation which co-ordinates research on offshore platforms in conjunction with local 

universities. This included a conservation program for migratory waterfowl. We’ve dedicated 

75,000 acres of wetlands and migratory waterfowl habitat to form a new wildlife refuge at 

Whitelake in Louisiana. We’ve also made a grant to Nicholls State University to test the designs 
14 

of artificial reefs made with recycled materials. In recognition of this work, I am proud to say 

that BP was awarded the Gulf Guardian Award in 2002. 

A final comment on biodiversity. It’s not just for us a subject where we fund collaborative 

academic research. It is having a real impact on our operations. By the end of 2003, all of our 

key facilities around the world have to have biodiversity action plans in place. So once again we 

witness the company trying to “go beyond” - that is seeking to take a distinctive lead on an 

environmental issue in a practical way. One of the topics I was asked to address today concerned 

“Challenges for the Future”. I guess I could set about presenting a list of technical topics and we 

can all think of a few potentially contentious areas. But rather than do that, I thought I would 

just talk about a piece of work we have carried out here in the Gulf, which for me at least, 

captures many of the positive features that we would like to see more of in the future. 

Go back to 1997, and we found ourselves needing to know about the Sigsbee Escarpment, a 

2,500’ foot high, submerged steep slope, that marks the southern edge of the salt mass. We 

wanted to drill adjacent to the slope, and this raised a number of questions. We needed to 

understand the effect of drilling on the slope – whether for instance it might trigger any 

movements. We needed to understand the currents in the region to be able to safely moor and 

drill from our rigs. Should we make a discovery, we needed to be able to address long term 

production questions – for example – how would we route an export pipeline across this rugged 

subsea terrain? Our first problem concerned the limitations of conventional deep tow marine 

survey equipment in working over a steeply sloping, rugged deepwater escarpment. It is difficult 

to maintain the towed data recorder at a predetermined height off an undulating seabed. In 

deepwater, it is also difficult to follow a predetermined survey route, since the recorder can be 

more than a couple of miles distant from the towing vessel. It became clear that we needed to 

take a completely new approach and so in 1999, we brought over from Norway an Autonomous 

Underwater Vehicle or AUV. 

Following successful sea trials, we became the first operator to use this technology here in the 

Gulf, and it is not an exaggeration to claim that it is has revolutionized deepwater surveying. In 

fact I would argue that without this step change in surveying technology, we could never have 

gathered such high quality data about the Sigsbee, and certainly not so quickly. 

The shear volume of data coming back from the free swimming AUV presents new challenges – 

and opportunities – in terms of data processing and management. For the first time we can take 

advantage of 3D visualization techniques, to give ourselves an unprecedented perspective of 

seafloor morphology and processes and it wasn’t just interesting data about seabed morphology 

which was collected. 

I’m sure you all read about how the AUV was able to locate the wreck of a WW II submarine 

that was found in the Gulf last year. From the overlay of the images it is quite clear what we are 

looking at. But this breakthrough in seabed surveying was only one piece in a four-year program 

to improve our understanding of the escarpment. 

What soon became clear was that it required a multi-disciplined approach – a complete 

integration of several applied sciences – geology and geophysics (we wanted to understand how 

movements of the salt masses in the seabed might be affecting slope stability), oceanography, 

geotechnics and marine biology – all were of huge importance in allowing us to address the 

16 

Workshop on Deepwater Environmental Studies Strategy: 

Industry Perspective 

Paul Siegele 

ChevronTexaco, New Orleans, Louisiana 

The deep water Gulf of Mexico is one of the premier exploration plays available to the petroleum 

industry. Over 400 wildcat wells have been drilled in deep water since 1975. About 130 

discoveries have resulted from the drilling for an overall success rate of slightly less than 1:3. 

The discoveries have an estimated ultimate recovery of over 11 billion barrels of oil equivalent. 

The first offshore licensing in the Gulf of Mexico was offered by the State of Louisiana in 1936. 

Federal licensing in the shelf waters began in 1954. The move to deep water exploration started 

in 1983, and by 1991 approximately 2400 blocks were under lease. Exploratory drilling 

resulting from the early leasing activity led to the major discoveries at Mars, Ursa, Ram-Powell, 

Auger, and Brutus. The significant move to explore the ultra deep water began in 1995, and 

between the years 1995 and 1998 approximately 3200 additional blocks were awarded to 

industry at a bonus cost of $2.5 billion. 

Exploratory drilling over the late 1990s has steadily climbed, from approximately 20 rank 

wildcat wells drilled in 1995 to over 60 rank wildcat wells drilled in 2000. 

The technical challenges to be overcome, in addition to water depth, are due to the fact that 

almost the entire deep water area is covered by thick tabular salt. This salt layer creates seismic 

imaging problems as source energy has difficulty penetrating the salt and reflecting images 

located beneath the salt. The salt also creates additional challenges when converting to the 

recorded time into depth relations that can be mapped. The industry response to these imaging 

problems has been widespread acquisition of 3D datasets. In 1995 only about 30% of the deep 

water area was covered by 3D surveys. Today virtually the entire deepwater north of the abyssal 

plain is covered by speculative 3D surveys. 

Advanced processing is required to extract useful depth information from the seismic. 

Employing a technique referred to as pre-stack depth migration, geophysicists are able to account 

for the changes in velocity in the sediments above and below salt with the velocities in the salt. 

The process is iterative, time consuming and expensive, but it is the only way to obtain clear 

pictures of geologic structures beneath the salt. 

The salt also creates drilling challenges. Exploratory wells in the ultra-deepwater typically reach 

depths below 25,000’. It is difficult to predict pore pressure in the sediments beneath salt. Well 

costs can be typically between $30-40 million, and can exceed $100 million in extreme cases 

when things go wrong. The water depth and target drilling depth are the cause of drilling costs. 

Special drilling vessels capable of reaching such targets can cost $300,000 to $400,000 per day 

to operate. 

18 

III. DeepSpill Experiment

Dan Allen 

Chevron USA Production Co., New Orleans, Louisiana 

Why should the DeepSpill Joint Industry Proposal (JIP) be conducted?

Little is known about the behavior of both liquid and gaseous hydrocarbon releases under 

deepwater conditions. Several questions were postulated that focused the JIP's efforts. 

• Would hydrates be formed and how would they affect the continued release of the 

hydrocarbons? 

• Would there be any gas phase dissolution? Would gas even come to the surface of the 

sea from a release? 

• Would the released hydrocarbons eventually come to the sea surface and how far from 

the release site would this occur? 

• Would phase separation occur? 

• To what degree would entrainment of oil occur in the water column? 

• What about the size distribution of the droplet and bubble from the hydrocarbon release? 

• Would "weathering" occur on the liquid hydrocarbons in the water column? 

The behavior of the released hydrocarbons could affect potential intervention methods. The 

formation of hydrates at the release point could limit or stop the release of the hydrocarbons. 

What kind of cleanup equipment might be needed, if it were needed at all? 

Participants in the JIP wanted to optimize their spill response "toolbox." What would work for 

containment and cleanup of a deepwater spill? Could dispersants be used effectively? Tests 

were also needed on surveillance technologies to determine their applicability and effectiveness. 

Deepwater computer transport models were being developed at two universities. Data from the 

deepwater release could be used to validate the model and its outcomes. Laboratory data were 

also generated from elements within the JIP. The release could serve to calibrate these data. 

The DeepSpill JIP had some unlikely partners. The MMS contributed funding toward the JIP 

and was actively involved throughout the process. The Norwegian Pollution Control Authority 

(SFT) and the Norwegian Clean Sea Association (NOFO), a cleanup consortium, were 

participants in the JIP. Additionally, 22 oil companies rounded out the JIP partners. 

Why was Norway selected for the test release? Norway has always been a leader in "field 

testing" oil release study efforts. The Norwegian environmental authority (SFT) and the area's 

oil spill response organization (NOFO) were involved in the study efforts. Since other releases 

have been successfully conducted off Norway, less legal complications were expected. 
19 

Conducting the Experimental Underwater Hydrocarbon Release

The table below depicts a summary of the four experimental discharges to be conducted during 

the study. 

Table 1. 

Summary of the four experimental discharges. 

Experiment Duration 

(minutes) 

Gas Rate 

(Sm3/s) 

Water/Oil Rate 

(m3/hr) 

Nitrogen and dyed sea water 40 0.6 60 

Marine diesel and LNG 60 (oil) 0.6 60 

Crude oil and LNG 50 (oil) 0.7 60 

LNG and sea water 120 0.7 60 

A variety of instruments were used during the experimental release to monitor the characteristics 

and movement of the expelled fluids. Some instruments were selected to determine if they could 

accurately detect the released hydrocarbons within the water column. The following is a listing 

of some of the instruments used during the tests. 

• Echosounders at 18, 38, 120, and 200 kHz 

• Radar 

• ADCP 

• CTD, rosette sampler, PAH fluorimeter 

• ROV videos 

The following graphic shows a diagrammatic representation of the deployed equipment for the 

experimental hydrocarbon release. 

21 

The following picture shows the surface slick that developed during one of the experimental 

releases. Note the survey vessels working in the slick. 

Figure 3. Surface slick that developed after a hydrocarbon test release. 

The figure below shows an underwater gas release from the subsea manifold during one of the 

tests.

Figure 4. Underwater gas release from the subsea manifold.

23 

IV. Technical Overviews 

Overview of the Physical Oceanography of the Deep Gulf of Mexico 

Ann E. Jochens, Steven F. DiMarco, Matthew K. Howard, 

Worth D. Nowlin, Jr. and Robert O. Reid 

Department of Oceanography, Texas A&M University, College Station, Texas

The deep Gulf of Mexico is the part of the Gulf that is seaward of the shelf break, which occurs 

approximately at the 200-m isobath. In an examination of the available current measurements in 

the deep Gulf, Nowlin et al. (2001) determined the background currents by extracting the 

maximum, mean, and standard deviation for each instrument. They found: that the highest 

maximum and mean current speeds were near the sea surface with maxima reaching up to 200 

cm·s-1 in the eastern Gulf and 100 cm·s-1 in the western Gulf, that speeds decreased with depth 

tending toward a minimum near 1000 m, and that speeds increased somewhat with depth below 

that level, likely due to bottom intensification of currents. This suggests that the circulation and 

water properties within the deep Gulf can be viewed as being approximately a two-layer system 

in the vertical, divided approximately at the 1000-m depth. 

There are two principal forcing functions of the circulation in the upper 800 to 1000 m of the 

deep Gulf of Mexico: the Loop Current system, including the Loop Current itself, Loop Current 

eddies (LCEs) and other circulation phenomena derived therefrom (Figure 1), and wind stress 

(Nowlin et al. 2001; see also Continental Shelf Associates, Inc. 2000). The Loop Current system 

begins with the Yucatan Current, which enters the Gulf through the Yucatan Channel and then 

separates from the Campeche Bank, becoming the Loop Current. The Yucatan Current is 

westward intensified, with speeds in the current core of approximately 200 cm·s-1 or more and 

dropping to about 50 cm·s-1 or less within 10 km to the west of the core and 100 km to the east 

(Cochrane 1963). There can be flows southward out of the Gulf at the western and eastern edges 

of Yucatan Channel (Cochrane 1963; Ochoa et al. 2001; Nowlin et al. 2001). 

As it enters the Gulf the Yucatan Current extends to the sill depth of approximately 2000 m. Its 

continuation in the Gulf, the Loop Current, enters and exits the Gulf through the Yucatan 

Channel and the Florida Straits, respectively. It carries within it the water masses from the 

global ocean, originating mainly in the Atlantic Ocean (Morrison and Nowlin 1982). The sill 

depths of the entrance and exit are approximately 2000 and 800 m, respectively, and essentially 

control which water masses enter and leave the Gulf. Although buoyancy forcing by river 

discharge affects the nearshore coastal currents and is a form of thermohaline forcing known to 

be important over the shelves of the Gulf, no thermohaline forcing of consequence or water mass 

formation are known to occur in the deepwater region of the Gulf (Nowlin et al. 2000). 

Water masses carried into the Gulf by the Loop Current include the Subtropical Underwater, 

which is characterized by a salinity maximum at typical depths of 150-250 m in the eastern Gulf 

(Morrison and Nowlin 1977) and 0-250 m in the western Gulf (Morrison et al. 1983). Below the 

Subtropical Underwater is 18°C Sargasso Sea water, which is characterized by an oxygen 
24 

maximum of between 3.6-3.8 mL·L-1 at depths of 200-400 m in the Loop Current waters in the 

eastern Gulf (Morrison and Nowlin 1977). This water mass characteristic appears to erode away 

as the waters mix into the western Gulf. Another water mass is the Tropical Atlantic Central 

Water, which is characterized by an oxygen minimum of below 3 mL·L-1 that occurs at depths of 

450-700 m in the eastern Gulf (Morrison and Nowlin 1977) and 250-500 m in the western Gulf 

(Morrison et al. 1983). The Antarctic Intermediate Water (AAIW) occurs between 700-1000 m 

depth in the eastern Gulf and 500-1100 m in the western Gulf and is characterized by nutrient 

maxima and salinity minimum. Below the AAIW is a modified upper North Atlantic Deep 

Water found between 900-1200 m in the eastern Gulf and 1000-1100 m in the western Gulf and 

characterized by a silicate maxima (Nowlin and McLellan 1967; Morrison and Nowlin 1977; 

Morrison et al. 1983). 

Below the sill depth of the Yucatan Channel to the bottom, data suggest no clearly discernible 

horizontal variation in potential temperature, salinity, and dissolved oxygen distributions and 

only slight vertical gradients (McLellan and Nowlin 1963; Nowlin and McLellan 1967; Nowlin 

et al. 1969). The relatively uniform dissolved oxygen, potential temperature, and salinity of the 

waters below the sill depth indicate either that the deep waters have common sources or that the 

residence time is great enough to erode away gradients by exchange processes (Nowlin 1972). A 

recent modeling study, however, suggests relatively short residence times. Moreover, vertical 

variation (e.g., bottom intensification) of deep currents must be supported by density gradients. 

The Loop Current extends into the eastern Gulf and then exits through the Florida Straits. As it 

extends into the Gulf, the Loop Current may be confined to the southeastern Gulf, as shown in 

the lower panel of Figure 1, or may extend well into the northeastern or north central Gulf, as 

shown in the upper panel of Figure 1 (see also Huh et al. 1981; Paluszkiewicz et al. 1983). 

Currents associated with the Loop Current and its eddies extend in depth at least down to the sill 

depth of the Florida Straits (approximately 800 m) and have surface speeds that may exceed 200 

cm·s-1 and speeds of 10 cm·s-1 at 700 m (e.g., Hamilton 1997; Cooper et al. 1990; Molinari and 

Morrison 1988). Transport estimates of the Loop Current are approximately 25-30 Sverdrups 

(e.g., Sheinbaum et al. 2002; Ochoa et al. 2001; Maul and Vukovich 1993). 

Anticyclonic Loop Current Eddies (LCEs) separate from the Loop Current at non-periodic 

intervals ranging from 3 to 17 months, with primary peaks in frequency of separation of 6 and 11 

months and a secondary peak at 9 months (e.g., Sturges and Leben 2000; see also Sturges 1994). 

They have diameters that typically exceed 250 km when newly formed and that decrease with 

age as the LCE decays (Elliott 1982). The LCEs may remain in the eastern Gulf for some time 

after their formation and may even reattach to the Loop Current (e.g., Vukovich 1995). Most 

eventually move westward, with typical translation speeds of approximately 5 km·d-1 (Elliot 

1982, see also Hamilton et al. 1999), and reach the western edge of the Gulf of Mexico basin. 

The LCEs have current cores and water properties similar to those of Caribbean type. Thus, their 

westward migration carries those water properties into the western Gulf. These anticyclonic, 

mesoscale current rings have average lifetimes longer than one year (Elliott 1982) and may 

spawn cyclonic rings during interaction with one another or with the continental slope (e.g., 

Vidal et al. 1994). Little is known of the velocity fields within the cyclones or small 

anticyclones (e.g., see Figure 1). Hamilton (1992) reported that slope cyclones in the central 

Gulf off Louisiana were long lived and had currents of 30 to 50 cm·s-1 in the upper layers and 

extended to depths of 200 to 800 m. Berger et al. (1996) reported on the existence of smaller 

anticyclones, but not on their velocity structures. 
25 
26 

The second forcing function is wind stress, which primarily affects the upper waters of the Gulf 

of Mexico. This forcing has two main classes of phenomena. First, low frequency regional wind 

patterns may generate low frequency regional circulation patterns. Sturges (1993) suggests a 

wind-driven anticyclonic circulation occurs over the west and central Gulf with a westward 

intensified boundary current adjacent to the western slope of the Gulf. It is centered north-south 

at approximately 24°N. The volume transport and speeds in this feature have an annual cycle, 

with maximum values in July and minimum in October, in response to the wind stress curl over 

the western Gulf. The transport varies from about 2.5 to 7.5 Sverdrups; the maximum drift 

speeds in the western boundary current vary from about 5 to 30 cm·s-1. Vázquez de la Cerda 

(1993) has shown that seasonal variations in the wind fields over the Gulf generate a cyclonic 

circulation, centered near 20°N 94.5°W, over the Campeche Bay in the southwestern Gulf. This 

cyclone has an apparent annual signal with maximum transports of order 3 Sv in the summer, 

consistent with the minimum positive wind torque that occurs in that season. 

The second class of wind forcing leads to the episodic current events that are forced by 

occasional atmospheric events such as tropical cyclones, extratropical cyclones, cold air 

outbreaks, and other frontal passages. The strongest of these includes hurricanes which can 

produce currents in the mixed layer that exceed 150 cm·s-1, and when combined with wave 

currents, may exceed 300 cm·s-1 (Nowlin et al. 2000). Hurricane induced currents at 200 m have 

been observed to be approximately 100 cm·s-1 in several instances, and even at 700 m may reach 

15-20 cm·s-1 (e.g., Brooks 1983). Tropical conditions normally prevail over the Gulf from May 

or June until October or November; the nominal hurricane season is 1 June through 30 

November. From October or November until March or April the Gulf experiences intrusions of 

cold, dry continental air masses from the north that can result in cold air outbreaks and the 

formation of extratropical cyclones. These cyclogenesis events occur ~10 times per season. 

Although their main effects may be over the continental shelves, they can cause very energetic 

currents over the upper continental slopes. Speeds of 50-75 cm·s-1 in the surface layer and 

exceeding 20 cm·s-1 down to depths of 200 m have been observed. 

Mention must be given to the occasional observations of subsurface-intensified currents of short 

duration, usually lasting of the order of a day, and with vertical extents of less than 100 m 

(Nowlin et al. 2001). High-speed current cores have been reported with maxima in the depth 

range of about 100 to 400 m and with maximum speeds of 100 cm·s-1 (or perhaps greater). 

Occurrences seem confined to regions over the upper continental slope. Their causal 

mechanisms are yet unknown. 

Below about 800 m, the direction and speeds of deep currents are not well understood. Model 

output and geostrophic calculations based on reasonable choice of reference levels suggest the 

long-term mean circulation of the deep Gulf is cyclonic (Nowlin et al. 2001). This cyclonic 

circulation also seems to be intensified offshore of the steep topography of the Sigsbee 

Escarpment in the north central Gulf, the Campeche shelf, and the west Florida shelf. 

Using a sparse array of current meters and a numerical model, Hamilton (1990) and Sturges et al. 

(1993), respectively, suggested that currents below 1000 m may be strongly influenced by the 

Loop Current through excitation of energetic currents associated with topographic Rossby 
27 

waves. Hamilton (1990) inferred that low-frequency fluctuations with periods greater than 10 

days propagated from the eastern to western Gulf with group speeds near 9 km·d-1. Current 

speeds within these deep motions have been observed to be approximately 30 cm·s-1 in the 

domain beneath the Loop Current, but less than 20 cm·s-1 in the central and western Gulf. These 

currents were barotropic, being highly coherent in the vertical, and exhibited bottom 

intensification (Figure 2). Evidence suggests these deep currents may be excited by the Loop 

Current or LCE separations. 

Figure 2. Current vectors (40-hr low-passed; north directed upward) from SAIC mooring G 

located in 3,200 m water depth at 25.60 N, 85.50 W off the southern West Florida 

Shelf. In December 1984, currents above 1,000 m are affected by the Loop Current 

in a surface-intensified manner, while currents below are not affected. During AprilJune 1985, during an eddy separation, the currents appear to be coherent throughout 

the water column, with some indication of bottom intensification. 

Additional information on the currents beneath 800-1000 m comes from numerical models. 

Model studies suggest that both cyclonic and anticyclonic eddies are present, perhaps as pairs, in 

the deep basin waters (Sturges et al. 1993; Welsh and Inoue 2000; Nowlin et al. 2001). The 

eddies form in the eastern Gulf under the Loop Current or newly formed LCEs. Guided by 

topography, they then propagate into the western Gulf. Some model results suggest deep layer 

eddies form, often as a pair consisting of an anticyclone and a stronger cyclone, in a response to 

a westward moving newly formed anticyclonic LCE in the upper layer. Evidence from one 

model suggests the deep eddy pair stays coupled with the upper LCE as it migrates westward, 
28 

with the two deep rings rotating cyclonically as a pair, and with the deep anticyclone decaying 

more rapidly than the deep cyclone (Welsh and Inoue 2000; see also Nowlin et al. 2001). 

Finally, intense bottom currents may be responsible for a bed form, consisting of mega-furrows 

with depths of 5 to 10 m and widths of 10s of m eroded into Holocene deposits, discovered by 

William Bryant of Texas A&M University in early 1999 on the continental slope and rise of the 

north-central Gulf of Mexico. These furrows are spaced on the order of 100 m apart and extend 

unbroken for distances of order 100 km, generally oriented nearly along isobaths. Water depths 

range from 2000 to 3000 m. It seems likely that the processes responsible for these furrows are 

active at present. Speculation based on laboratory experiments is that near-bottom speeds of 

currents responsible for the inshore furrows might be 50 cm·s-1 or even in excess of 100 cm·s-1. 

Nearly barotropic currents fluctuating essentially along-isobath with amplitudes reaching 100 

cm·s-1 and periods of order 10 d have been observed above the bottom in the region just inshore 

from the mega-furrows. The currents associated with furrows might be sporadic or quasipermanent. They may be related to the mean circulation within the deep basin or possibly to 

topographic waves or deep eddies. 

References 

Berger, T. J., P. Hamilton, J. J. Singer, R. R. Leben, G. H. Born and C. A. Fox. 1996. 

Louisiana/Texas shelf physical oceanography program: eddy circulation study, final 

synthesis report. Volume I: Technical Report. OCS Study MMS 96-0051. U.S. Dept. of the 

Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. 

324 pp. 

Brooks, D. A. 1983. The wake of Hurricane Allen in the western Gulf of Mexico. J. Phys. 

Oceanogr. 13:117–129. 

Cochrane, J. D. 1963. Yucatan Current. Pp. 6-11, In Oceanography and Meteorology of the 

Gulf of Mexico, Annual Report, 1 May 1962 - 30 April 1963. Texas A&M University, 

Department of Oceanography, Tech. Rpt. Ref. 63-18A, College Station, TX. 

Continental Shelf Associates, Inc. 2000. Deepwater Gulf of Mexico environmental and 

socioeconomic data search and literature synthesis. Volume I: Narrative Report, OCS Study 

MMS 2000-049. Volume II: Annotated bibliography, OCS Study MMS 2000-050. U.S. 

Dept. of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New 

Orleans. 

Cooper, C., G. Z. Forristall and T. M. Joyce. 1990. Velocity and hydrographic structure of two 

Gulf of Mexico warm-core rings. J. Geophys. Res. 95(C2):1663-1679. 

Elliott, B. A. 1982. Anticyclonic rings in the Gulf of Mexico. J. Phys. Oceanogr. 12(1):292–

1,309. 

Hamilton, P. 1990. Deep currents in the Gulf of Mexico. J. Phys. Oceangr. 20:1087-1104. 
29 

Hamilton, P. 1992. Lower continental slope cyclonic eddies in the central Gulf of Mexico. J. 

Geophys. Res. 97(C2):2185-2200. 

Hamilton, P. 1997. Chapter 2 –The Physical Environment. In Northeastern Gulf of Mexico 

Coastal and Marine Ecosystem Program: Data Search and Synthesis; Synthesis Report. 

Science Applications International Corporation. U.S. Department of the Interior, U.S. 

Geological Survey, Biological Resources Division, USGS/BRD/CR-1997-0005 and Minerals 

Management Service, Gulf of Mexico OCS Region, New Orleans, LA, OCS Study MMS 96-

0014. 

Hamilton, P, G. S. Fargion and D. C. Biggs. 1999. Loop Current eddy paths in the western Gulf 

of Mexico. J. Geophys. Res. 29(6):1180-1207. 

Huh, O. K., W. J. Wiseman, Jr. and L. J. Rouse, Jr. 1981. Intrusion of Loop Current waters onto 

the west Florida continental shelf. J. Geophys. Res. 86(C5):4186–4192. 

Maul, G. A. and F. M. Vukovich. 1993. The relationship between variations in the Gulf of 

Mexico Loop Current and Straits of Florida volume transport. J. Phys. Oceangr. 23:785-796. 

McLellan, H. J. and W. D. Nowlin, Jr. 1963. Some features of the deep water in the Gulf of 

Mexico. J. Mar. Res. 21:233–245. 

Molinari, R. L. and J. Morrison. 1988. The separation of the Yucatan Current from the 

Campeche Bank and the intrusion of the Loop Current into the Gulf of Mexico. J. Geophys. 

Res. 93(C9):10645-10654. 

Morrison, J. M., and W. D. Nowlin, Jr. 1977. Repeated nutrient, oxygen, and density sections 

through the Loop Current. J. Mar. Res. 35(1):105–128. 

Morrison, J. M. and W. D. Nowlin, Jr. 1982. General distribution of water masses within the 

eastern Caribbean Sea during the winter of 1972 and fall of 1973. J. Geophys. Res. 

87(C6):4207-4229. 

Morrison, J. M., W. J. Merrell, Jr., R. M. Key and T. C. Key. 1983. Property distributions and 

deep chemical measurements within the western Gulf of Mexico. J. Geophys. Res. 

88(C4):2601-2608. 

Nowlin, W. D., Jr. 1972. Winter Circulation Patterns and Property Distributions. Pp. 3–5 in: L. 

R. A. Capurro and J. L. Reid (Eds.), Contributions on the Physical Oceanography of the Gulf 

of Mexico. Texas A&M University Oceanographic Studies, Volume 2,1. Gulf Publishing 

Co., Houston, 288 pp. 

Nowlin, W. D., Jr., A. E. Jochens, S. F. DiMarco, R. O. Reid and M. K. Howard. 2001. 

Deepwater Physical Oceanography Reanalysis and Synthesis of Historical Data: Synthesis 

Report. OCS Study MMS 2001-064, U.S. Dept. of the Interior, Minerals Management 

Service, Gulf of Mexico OCS Region, New Orleans, LA. 528 pp. 
30 

Nowlin, W. D., Jr., A. E. Jochens, S. F. DiMarco and R. O. Reid. 2000. Chapter 4: Physical 

Oceanography. Pp. 61-121, In Continental Shelf Associates, Inc., 2000. 

Nowlin, W. D., Jr., D. F. Paskausky and H. J. McLellan. 1969. Recent dissolved-oxygen 

measurements in the Gulf of Mexico deep waters. J. Mar. Res. 27(1):39-44. 

Nowlin, W. D., Jr., and H. J. McLellan. 1967. A characterization of the Gulf of Mexico waters 

in winter. J. Mar. Res. 25:25–59. 

Ochoa J., J. Sheinbaum, A. Badan, J. Candela and D. Wilson. 2001. Geostrophy via potential 

vorticity inversion in the Yucatan Channel. J. Marine Res. 59(5):725-747. 

Paluszkiewicz, T., L. A. Atkinson, E. S. Posmentier and C. R. McClain. 1983. Observations of 

a Loop Current frontal eddy intrusion onto the west Florida shelf. J. Geophys. Res. 

88(C14):9639–9651. 

Sheinbaum, J., J. Candela, A. Badan and J. Ochoa. 2002. Flow structure and transport in the 

Yucatan Channel. Geophys. Res. Letters 29(3):10-1 to 10-4. 

Sturges, W. 1993. The annual cycle of the western boundary current in the Gulf of Mexico. J. 

Geophys. Res. 98:18,053–18,068. 

Sturges, W. 1994. The frequency of ring separations from the Loop Current. J. Phys. Oceanogr. 

24:1,647–1,651. 

Sturges, W. and R. Leben. 2000. Frequency of ring separations from the Loop Current in the 

Gulf of Mexico: a revised estimate. J. Phys. Oceanogr. 30:1,814–1,819. 

Sturges, W., J. Evans, S. Welsh and W. Holland. 1993. Separation of warm-core rings in the 

Gulf of Mexico. J. Phys. Oceanogr. 23:250–268. 

Vázquez De la Cerda, A. M. 1993. Bay of Campeche Cyclone. Ph.D. Dissertation, Texas 

A&M University, 91 pp. 

Vidal, V. M. V, F. V. Vidal, A. F. Hernandez, E. Meza and J.M. Perez-Molero. 1994. 

Baroclinic flows, transports, and kinematic properties in a cyclonic-anticyclonic-cyclonic 

ring triad in the Gulf of Mexico. J. Geophys. Res. 99(C4):7571-7597. 

Vukovich, F. M. 1995. An updated evaluation of the Loop Current's eddy-shedding frequency. 

J. Geophys. Res. 100(C5):8655-8659. 

Welsh, S. E. and M. Inoue. 2000. Loop Current rings and the deep circulation in the Gulf of 

Mexico. J. Geophys. Res. 105:16,951–16,959. 

32 

Overview of the Geology/Geohazards of the Continental Slope of the 

Northwest Gulf of Mexico 

William R. Bryant 

Department of Oceanography, Texas A&M University, College Station, TX 

The engineering and geological constraints on the continental slope off Texas and Louisiana 

related to hydrocarbon recovery will require both novel geological and geophysical surveys and 

engineering methods. Significant seafloor engineering problems in deep water include slope 

instabilities, both short-term (slump) and long-term (creep); pipeline spanning problems; mass 

transport from unknown causes; and unusual stiffness and strength conditions. The geohazards 

(engineering and geologic constraints) present in and on the central and western continental 

slope are many in number and are mainly due to the activity of salt and rapid sedimentation. 

Specific examples include: faults (sediment tectonics, halokinesis); slope stability (slope 

steepening, slumps, creep, debris flow); gassy sediments (sediment strength reduction, hydrates, 

sediment liquefaction); fluid and gas expulsion features; diapiric structures (salt, mud, hydrates); 

seafloor depressions (blowouts, pockmarks, seeps); seafloor features (sediment waves, 

differential channel fill, brine-low channels, seabed furrows); shallow water flow; and deep 

water high-velocity currents (mega-furrows, seabed erosion). 

The Gulf of Mexico is unique in the construction and evolution of its northwestern continental 

margin and in particular the continental slope off Texas and Louisiana. The processes that 

determined the physiography of the continental slope are almost completely dominated by the 

halokinesis of allochthonous salt. Harry Roberts once noted that, “twenty-five years ago our 

knowledge of processes on the continental slope in the northern Gulf of Mexico was so limited 

that it was viewed simply as an accreting sedimentary structure.” In contrast, the continental 

slope off Texas and Louisiana is now viewed as one of the most complex and dynamic passive 

continental margins in the world. 

Bathymetric maps reveal the presence of over 90 intraslope basins with relief in excess of 150 m. 

Intraslope-interlobal and intraslope-supralobal basins occupy the upper/middle and lower 

continental slope, respectively. In addition to the many structural effects, salt movement creates 

subsurface conduits that allow liquids and gases to seep into near-surface sediments and the 

overlying water column. The extent of seepage on the slope as compared with the shelf is 

important from the standpoint of both chemistry and the chemosynthetic communities associated 

with seeps. 

The near-surface geology and topography (the area of most concern in relationship to submarine 

slope stability) of the continental slope off Texas and Louisiana are a function of the interplay 

between episodes of rapid shelf edge progradation and contemporaneous modification of the 

depositional sequence by diapirism and mass movement processes. Many slope sediments have 

been uplifted, folded, fractured, and faulted by diapiric action. Over steepening on the basin 

flanks and resulting mass movements have resulted in the appearance of highly overconsolidated 

sediments underlying extremely weak pelagic sediments. The construction of the Mississippi 

Canyon is in part a function of sidewall slumping and pelagic drape of low shear strength 
33 

sediments. In contrast, slope over steepening and subsequent mass movement have resulted in 

high pore pressures in rapidly deposited debris flows on the upper slope and on basin floors, 

resulting in unexpected decreased shear strengths. Biogenic and thermogenic gas induces the 

accumulation of hydrates and underconsolidated gassy sediments, which are common on the 

upper continental slope. On the middle and lower continental slope, gassy sediments are not 

common except in the basins that do not have a salt base such as Beaumont Basin. The salt 

nappe restricts the upward movement of gas from below. Holocene and Pleistocene sediment 

cores recovered from the continental slope off Texas and Louisiana from conventional piston 

coring and from DSDP activities reveal the presence of unconsolidated gassy clays, silty clays, 

sands, and clayey sands, many containing gas hydrates. 

The intraslope intralobal basins located on the upper slope continental range in water depths 

from 1,500 to 2,200 m. The bathymetry of the Central and Western Gulf areas is shown in 

Figure 1. The bathymetry of the upper to middle continental slope area consists of relatively flat 

ridges and basin floors separated by intraslope escarpments. The intraslope basin escarpments 

have relief up to 700 m and slopes between 5 ̊ to 30 ̊ and in specific locations up to 50 ̊. Ridges 

that rim the basins correspond to late laterally spreading flat-topped salt tongues overlain by a 

thin sediment cover (Bryant et al. 1995). The deeper portions of intraslope intralobal basins are 

salt free and exhibit a dissected topography consisting of a multitude of small submarine canyons 

along the walls. Cores taken on the wall of some basins indicate that as much as 3 m to 5 m of 

sediment has been removed by slumping. The intraslope supralobal basin on the lower 

continental slope where the physiography is comparatively smooth (Figure 1) shows that the 

relief exists mainly as a rounded depression. The formation of basins on the lower slope is 

where subsidence is accomplished by evacuation of underlying salt (salt withdrawal).

Figure 1. Bathymetry map of the northern Gulf of Mexico.
34 

The submarine canyons along the Sigsbee Escarpment, Alaminos, Keathley, Bryant, Cortez, 

Farnella and Green Canyon are the result of the coalescing of salt canopies and nappes, the 

migration of the salt over the abyssal plain and the erosion of the escarpment during periods of 

low sea stand (Bryant et al. 1992). The bathymetry of the canyons is illustrated in Figure 1. In 

addition to the canyons that form along the escarpment, numerous small submarine canyons and 

gullies line the escarpment along with large slumps. Seaward of the canyons submarine fans of 

various sizes extend out onto the continental rise. A significant portion of the canyon walls and 

the escarpment contains slopes of 5 ̊ to 10 ̊ and slopes in excess of 15 ̊ are not rare. Large slope 

failures are present in the Green Canyon area especially in the Mad Dog, Neptune and Atlantis 

prospects. 

The major faults on the continental slope are associated with massive accumulation of sediments 

and are called growth faults. These growth faults form contemporaneously and continuously 

with sediment deposition. The growth faults are found mostly on the upper continental slope and 

on the continental shelf where sediment accumulation is the thickest. The most common types of 

fault on the middle and lower continental slope are “groups of geometrically classified fault 

families and fault welds that are kinematically and genetically linked to each other and to 

associated salt bodies and welds. Linked fault systems can contain extensional, contractional, 

and strike-slip components. Extensional fault families are formed by basinward translation, 

subsidence into salt, or folding. Those fault families that accommodate basinward translation are 

balanced by salt extrusion or contract ional fault families” (Rowan et al. 1999). Rowan et al. 

related five associations of linked fault systems that are directly related to five types of salt 

systems: autochthonous salt (salt in place), stepped counterregional, roho, salt-stock canopy, and 

salt nappe. Faulting resulting from the formation of salt diapirs from autochthonous salt is the 

most common type fault on the upper slope while faulting from salt-stock canopy and salt nappe 

are most common on the middle and lower continental slope. Extensive faulting can be found on 

the rim of most intraslope intralobal and supralobal basin on the middle and lower continental 

slope. The faults are extensional faults caused by the upward movement of salt resulting from 

pressures created by sediment accumulation within basins. This type of faulting results in the 

occurrence of a large number of small faults in the area of the seafloor under going extension. In 

some areas of the slope the upward migration of salt results in the seafloor being totally fractured 

(faulted) and continuously displaced. 

Portions of some of the submarine canyons, like Bryant Canyon, are being filled with salt due to 

the loading of the salt by sediments on the margins of the canyon. The salt migrates upward; 

filling the canyon that was created by turbidity current flow active during times of low-sea stand. 

The migration of salt into the canyon may occur at the rate of centimeters per year. 

On the middle and lower continental slope, salt may be very close to the seafloor in certain areas 

and, on features such as the salt plug called “Green Knoll,” salt is exposed at the seafloor and is 

being dissolved by seawater, resulting in the collapse of the cap of the knoll (Figure 2). In Orca 

Basin, an intraslope intralobal basin, salt is exposed at the bottom of the northern portion of the 

basin and a famous brine pool has formed within the basin. Brine flows imitating from exposed 

salt along the Sigsbee Escarpment have been observed in the Mad Dog prospect, northwest of 

Green Knoll. When salt is close to the seafloor, the emplacement of structures that require 

foundation pile new engineering methods will be necessary. 
35 

Figure 2. 3D surface extraction showing the physiography of Green Knoll. The collapsed top 

of the knoll is the result of seawater leaching the knoll’s salt core. (WesternGeco 3D 

data). 

Water currents can be a problem to structures on the continental slope, but they may be a major 

problem to structures such as platforms, bottom assemblies and pipelines at the base of the 

Sigsbee Escarpment starting in water depths as shallow as 1,200 m and as deep as 3,300 m. 

Recent studies have revealed the presence of large mega-furrows all along the base of the 

Sigsbee Escarpment. These large bedforms, 20 to 30 m wide and as deep as 10 m, occur along 

the base of the Sigsbee Escarpment and extend to a distance of 30 km seaward of the escarpment 

(Figure 3). The mega-furrows are the result of high velocity bottom currents occurring along the 

base of the Sigsbee Escarpment. The mega-furrows have been found at the base of the 

escarpment extending from 90° to 94.5° W Longitudes, a distance of over 500 km (Figure 4). 
36 

Figure 3. Mego-furrows on the continental rise South of Green Knoll. (WesternGeco 3D data). 

Figure 4. Map illustrating the location of mega-furrows along the continental rise seaward of 

the Sigsbee Escarpment, Northwest Gulf of Mexico. 
37 

Shallow water flow, also known as geopressured sands, is the uncontrolled flow of sand and 

water that can create significant sediment pile up at the wellhead. Shallow water flow is the 

result of excess pore pressures in the confining strata as the result of underconsolidation, also 

called compaction disequilibrium and differential compaction of fine-grained sediments. The 

flow usually occurs at 360 to 530 m below the seafloor. It is more likely to occur on the upper 

and middle continental slope and less likely to occur above the salt nappe, the tabular salt 

blocking the escape of overpressures from below. 

Table 1 summarizes the properties related to geohazards of upper, middle, and lower continental 

slopes intraslope basins and lower slope canyons and the Sigsbee Escarpment. 

Table 1. 

Engineering constraints and possible geohazards of intraslope basins, canyons and escarpments. 

Upper to Middle Slope Intraslope Interlobal Basins 

• Steep sidewalls average 10o to 20o, maximum 50o 

• Small submarine canyons and gullies dissect basin escarpments 

• Basin wall sediments may be unstable and undergoing modification by creep and slump 

processes 

• Low shear strength debris flow sediments on basin floor 

• Basin floor subject to debris flows from side wall slumping 

• Stiff sediments on highly faulted ridges between basins 

• Hydrates, gas sweeps, carbonate bioherms and chemosynthetic organisms may be present 

• Basins may contain low shear strength gassy anoxic sediments 

• Isolated basins subject to formation of brine pools 

• Basin sediments underconsolidated at shallow subbottom depths 

Lower Slope Intraslope-Supralobal Basins 

• Elevated faulted ridges between basins 

• Elevated ridge along basin rim 

• Basins are bowl shaped with low angle basin floor 

• Soft surficial sediments within basin 

• Structures on basin floor subject to debris flow 

• Basin sediments underconsolidated at shallow subbottom depths 

Lower Slope Canyons and Escarpments 

• Side walls average 10o to 15 ̊, maximum 45 ̊

• Small submarine canyons and gullies dissect escarpment and smaller canyon escarpments 

• Canyons and escarpment structurally active from effects of halokinesis 

• Very rugged topography 

• Slump deposits and slope failure common 

• Small submarine fans on canyon floor formed from debris flows and turbidity currents 

• In very deep water 

• Sediments underconsolidated at shallow subbottom depths 

• High velocity bottom currents and mega-furrows present at base of Sigsbee Escarpment 

• Density currents along the base of the escarpment resulting from the leaching of exposed salt 

along the escarpment.
38 

References 

Bryant, W. R., G. S. Simmons and P. Grim. 1992. The morphology and evolution of basins on 

the continental slope northwestern Gulf of Mexico. Gulf Coast Association of Geological 

Societies Transactions 41:73-82. 

Bryant, W. R., J. Y. Liu and J. Ponthier. 1995. The engineering and geological constraints of 

intraslope basins and submarine canyons of the northwestern Gulf of Mexico. Gulf Coast 

Association of Geological Societies Transactions 45:95-101. 

Rowan, M. G., P. A. Jackson and B. D. Trudgill. 1999. Salt-related fault families and fault 

welds in the northern Gulf of Mexico. AAPG Bulletin 83(9):1,454-1,482. 

Presentation Not Available 
39 

Overview of Knowledge of the Benthos of the Deep Gulf of Mexico

Gilbert T. Rowe 

Department of Oceanography, Texas A&M University, College Station Texas 

Introduction 

The exploration of the biota of the deep Gulf of Mexico (GOM) can be divided historically into 

more or less three eras. The earliest explorations were concerned mostly with dredging the deepsea floor. The most extensive work is summarized by Agassiz (1888). Few generalizations 

could be made in these works; they dealt mostly with lists of species and descriptions of new 

species. Publications resulted on a broad suite of invertebrate taxa. None of the early studies 

penetrated the western Gulf. These early investigations have been reviewed by Galtsoff (1954) 

and Geyer (1970). 

The second important period of deep Gulf studies was initiated by Willis E. Pequegnat in the 

mid-1960’s. A diverse series of investigations employed the R/V Alaminos. Efforts were made 

to characterize all geographic areas of the deep Gulf and the far western Caribbean. The 

composite samples were divided up by taxon or by specialized ecological problems among the 

graduate students at Texas A&M working with Pequegnat. The individual studies are available 

at Texas A&M or at University Microfilms. Many sampling trips extended well into what is 

now recognized as Mexico’s Exclusive Economic Zone (EEZ) because at the time no restrictions 

had been placed on the scientific sampling of these international waters. A similar geographic 

distribution of studies would not be possible today without permission from Mexico. These 

studies have been summarized by Pequegnat (1983) in a volume submitted to the Minerals 

Management Service of the U.S. Dept. of the Interior. The work concentrated on samples taken 

with a sampling device developed by Pequegnat called a “skimmer” (Pequegnat et al. 1970). It 

was equipped with an odometer wheel to estimate distance covered. The anterior "mouth" of the 

skimmer measured 3 m wide by 1 m high. The anterior frame of the rigid, hour glass-shaped 

structure was covered with 1.25 cm galvanized wire mesh but its bulbous cod end was covered 

with 0.6 cm mesh. The distances traveled averaged several kilometers. The original meter 

wheel data are available in the field notes taken aboard ship at the time of sampling. The 

significant thing about this method is that it sampled “megafauna,” principally, and not other size 

categories. It had the advantage that the samples were protected by the rigid posterior 

framework, and thus fragile forms were damaged less than in conventional otter or beam trawls. 

Faunal groups studied from the deep Gulf included the crustaceans (Pequegnat 1970; Roberts 

1970; Firth 1971 ), echinoderms (Carney 1971; Booker 1971), molluscs (James 1972), and fishes 

(Bright 1968), among others. Tabulation of fish gut contents were intended to link the 

megafauna to its food source (Rayburn 1975). Kennedy (1976) compared the species 

composition of the eastern and western Gulf faunas and concluded that they were not the same. 

The macrofauna appeared to be grouped into assemblages that were distributed within zones 

down the slope onto the abyssal plain (Kennedy 1976; Roberts 1977), but no justification was 

found for separating the abyssal plain fauna into zoogeographic provinces by latitude or 

longitude. That is, even though the fauna along the slope changed with increasing depth, and 
40 

that these changing faunas differed in the east and west Gulf, down on the basin floor the fauna 

showed little in the way of east - west differences. 

The stations occupied by the Alaminos also incorporated bottom multi-shot photography to 

quantify areas of the sea floor. The principal rationale for this was to quantify the densities of 

the epibenthic megafauna captured by the skimmer and other miscellaneous trawls and dredge 

samples. It also allowed the users to count “lebenspuren” (animal tracks and burrows) and 

qualitatively categorize the types of sediments present. Although a 70 mm format camera was 

used on occasion, a 35 mm camera built by Alpine Geophysical seems to have produced more 

good film. It was rigged to take photographs on bottom contact of a trigger switch. The 

advantage of such an approach is that distance between the camera and the bottom is always 

known and this allows the operator to know the area each photograph covers with a given lens 

angle. This can be calibrated with a grid in shallow water, if necessary. The records available 

indicate that on the order of up to 50 photographs were taken per lowering and each photograph 

covered an area of ca. 1 m2. An appendix in Pequegnat (1983) features a large number of the 

photographs. 

In addition to the biological studies, photographs of an "iron stone bottom" north of the Yucatan 

Strait suggested deep bottom currents can be strong enough in the eastern Gulf to sweep large 

areas free of sediments (Pequegnat 1970). The negatives of the entire collection of lowerings are 

archived in the Oceanography Department at Texas A&M University (with the present exception 

of a station on loan to the Universidad Nationale Autonoma de Mexico). 

Abyssal plains constitute a significant proportion of the surface of the earth. Although generally 

acknowledged as the ultimate sink of detritus from the continents, their biota has long been 

considered sparse and depauperate. The abysso-benthic communities of the Sigsbee Deep in the 

western Gulf of Mexico, known as one of the flattest surfaces on the deep ocean floor, is less 

well known than many other abyssal plains, in spite of its modest depth (3.6 to 3.8 km) and 

proximity to the United States and Mexico. The works of Pequegnat remain the most extensive 

on Sigsbee Deep plain. 

The third historical time-frame represents the most extensive sampling of the sediment biota of 

the continental slope of the northern Gulf of Mexico to date. This was conducted in the 1980's 

by LGL Environmental, with support from the MMS. This consisted of paired Gray-O'Hara or 

GOMEX box cores (Boland and Rowe 1991), bottom survey camera lowerings and bottom 

trawling. The stations studied included three transects down the continental slope off Texas, 

Louisiana and Florida (Figure 1). Sampling stopped at depths just shy of 3 km and therefore did 

not extend out onto the abyssal plain. Thus, comparison with shelf and abyssal plain samples 

was not possible. 

The work on deep-water benthos at Texas A&M beginning in the 1960's up through the MMSsupported studies of the 1980's has been published in a concise summary by Pequegnat et al. 

(1990). The focus was on the northern continental slope. Other documentation of the studies of 

the slope includes reports to MMS (Gallaway 1988; Gallaway et al. 1988) and a dissertation on 

the polychaete annelid worms (Hubbard 1995). 

42 

Sigsbee Abyssal Plain, they have identified regions that contain enhanced biomass under surface 

water masses characterized by accelerated rates of primary production (Escobar-Briones et al. 

1997; 1999). Polychaetes dominated the infauna; they encountered a mid-slope maximum in 

abundance similar to that described in the northern Gulf (Pequegnat et al. 1990). The fauna 

could be partitioned into three groups that conformed to depth intervals of > 3 km, intermediate 

depths of 1.5 and 3 km, and shallow waters < 1.5 km. This contrasts with the view of Pequegnat 

et al. that the continental margin is characterized by 5 zones. 

In 1997, a two-ship operation by Texas A&M and UNAM was conducted at a common station 

(25o15' N. Lat. x 93o26' W. Long.) on the northern Sigsbee Abyssal Plain, at a depth of 3.65 km. 

The Justo Sierra traveled up from Tuxpan, sampling along an east - west line across the 

Cordillera Tampiquena or Mexican Ridges (Escobar Briones et al. 1999), while the Gyre went 

due south out of Galveston, directly to the site. As this site is well within the Mexican Exclusive 

Economic Zone (EEZ), all sampling conducted from the Gyre had to be approved a priori by a 

suite of Mexican federal agencies. It is nestled within several nearby locations that Pequegnat 

sampled with the skimmer and bottom photography. 

Total sediment community respiration was measured using a benthic lander containing a pair of 

automatically operated benthic incubation chambers used to measure fluxes of metabolic gases 

across the sediment water interface. The lander and its operation have been described previously 

by Rowe et al. (1997). Oxygen consumption by the bottom and its contained biota is calculated 

from the decline of oxygen within the chamber over time, the volume of the chamber and the 

area of the sea floor it covers. It was deployed once in the western Sigsbee Deep at a depth of 

3.6 km. 

Microbiota 

The microbiota of the deep Gulf sediments is not well characterized. While direct counts have 

been coupled with some in situ and re-pressurized metabolic studies in other deep ocean 

sediments (Deming and Baross 1993), none has been made in the deep Gulf. Direct counts using 

a fluorescing nuclear stain have been made at several depths down the slope, thus allowing the 

bacterial biomass to be estimated from their densities and sizes (Cruz-Kaegi 1998). This 

indicated that the bacteria are the most important component of the functional biota in terms of 

biomass. Comparisons are not yet possible with other ocean basins. Cruz-Kaegi (1998) 

developed a budget for carbon cycling based on her estimates of biomass and metabolic rates in 

the literature. Her budget illustrates that on the deep slope of the Gulf, a large fraction of the 

organic carbon supplying the benthos with energy is cycling through the bacteria. 

The Meiofauna 

The extensive sampling by the Northern Gulf of Mexico Continental Slop (NGOMCS) 

discovered that the meiofauna appears to have a biomass that is higher than that of the 

macrofauna. The regressions of log10 numbers per m2

 and biomass (as micrograms wet weight 

per m2

) were the following: 

Log density = 5.87 - 0.00018 (depth in meters), and 

Log biomass = 6.4 - 0.0002 (depth in meters). 
43 

0 1000 2000 3000 4000

0

1

2

3

4

Depth

Log Wet Weight (mg/m^2)

y = 2.86 - 0 00032x R^2 = 0.62

Unfortunately, no estimates of biomass were made directly. Biomass was estimated from 

conversion factors for each group in both the macrofauna and the meiofauna. The densities were 

2.5 log units higher than macrofauna, which is not unusual. The biomass was 0.5 log units above 

macrofauna, which is a reversal with the relationship found in shallow water environments. If 

true, this confirms earlier studies in the Atlantic (Rowe et al. 1991) that implied that meiofaunalsized organisms increase in importance (in terms of biomass) at deep-sea depths relative to the 

macrofauna. Cruz-Kaegi (1998) also observed this in her studies. No information is available 

on the species composition or diversity of the meiofauna of the deep Gulf. 

Figure 2. Density of macrofauna in the Gulf of Mexico (Rowe et al. 1974). 

The Macrofauna 

Abundance and Biomass: Anchor dredge samples across the Sigsbee Deep and van Veen grabs 

from the northern continental slope suggested that deep biomass in the Gulf was depauperate in 

numbers (Figure 1) and biomass (Figure 2), similar to that in other ocean basins, but 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; Rowe 1983). The log-normal 

relationship between biomass and depth has been confirmed now for numerous ocean basins 

(Rowe 1983), but the slope of the line (biomass as a function of depth) for the Gulf appeared to 

be steeper than that in most basins. It was suggested that this is due to the Gulf’s low primary 

productivity. 

Abundance values are a function of sieve size. The NGOMCS study on the slope used 300 

micron sieves and the studies aboard Justo Sierra used 125 micron sieves. It might be expected 

that they both sampled far more individuals per square meter than the earlier studies by Rowe, 

who used a 420 micron sieve. The values for the NGOMCS study samples however ranged from 

518 to 5369 ind/m2

, which is similar to that encountered by Escobar et al. in the southwestern 

Gulf and by Rowe et al. (1974) in the northern Gulf. 
44 

0 1000 2000 3000 4000

1

2

3

4

5

Depth

Log Density(Ind./m^2)

y = 3.31 - 0.00044x R^2 = 0.71

Regressions of biomass and abundance as a function of depth follow: 

Log(10) ind/m2

 = 3.52 - 0.000109 (depth in meters), and 

Log(10) microgram wet weight/m2 = 5.88 - 0.000227 (depth). 

The polychaete densities have been plotted (Figure 3) as an example of information available 

from the NGOMCS study by LGL. Note that there is a gradual decline in abundances down the 

continental slope. 

Figure 3. Biomass of macrofauna in the Gulf of Mexico (Rowe et al. 1974). 

It has become clear that deep offshore abyssal plains may have somewhat fewer organisms than 

the Sigsbee Deep, but they are at much greater depth (Glover et al. in press). The deep Gulf has 

on the order of 150 to 500 ind/m2

, depending on sieve size, which taxa are included, and region 

studied. Escobar-Briones et al. (1999) for example suggested that the southern Gulf, in the 

region of the Bay of Campeche, had fewer macrofauna than the northern Gulf. They suggested 

that this was due to higher primary production that resulted from the interaction of warm eddies 

and shelf water. 

The calculation of the diversity of the macrofauna was studied extensively in the NGOMCS 

study slope samples. The general pattern was a decline in diversity from the upper slope down to 

the lower slope, as reviewed by Lohse (1999). She suggested, by comparison with other studies 

on the outer shelf, that a “diversity maximum” was located on the upper slope. This contradicts 

earlier work in other basins which suggested that a diversity maximum is routinely encountered 

at 2 to 3 km depth. Hubbard (1995) also utilized the polychaete annelid fraction of the 

NGOMCS study to assess Gulf diversity. The polychaete fraction was used because it was the 
45 

most abundant taxon (65%) and he was confident that he could separate them at the species 

level. 

The studies of diversity used several measures. The diversity index referred to as the 

Information Function, or H’(s), was calculated from the polychaete data because it is simple to 

use, relatively independent of sample size, and has been used in numerous other studies, 

including Gulf of Mexico benthos. Fragments were not included in the analysis. The equation 

used follows: 

H’(s) = - Σ (ln pi x pi), 

where p is the proportion of each species, i, to the total population sampled, i through n. Also, 

Hurlbert’s revision of the Sanders “rarefaction” curve, or Expected Species (per 100 individuals), 

was calculated and plotted by Lohse, directly from the NGOMCS study data reports, and by 

Hubbard from his own polychaete data. 

In general the Gulf slope macrofauna is very speciose. Dominants are rare. Rare species are 

common. While shallow shelf studies in the Gulf typically encounter numerous individuals 

represented by 50 to 60 or so species, the slope data suggest that 100 or so species would be 

expected for a similar number of individuals. It has not yet been possible to compare the Gulf 

with other similar studies because of differences in technique. 

There has been little attempt to uncover any seasonal variation in deep Gulf standing stocks or 

processes. Sets of samples along the central transect of the NGOMCS study were taken in spring 

and fall which suggested that some change in biomass could be observed in the animal 

abundances on the upper slope < 1 km depth (Figure 4). Polychaete abundance is twice as high 

in spring than in two fall periods. Species composition did not appear to change, just densities. 

The best description of this is in Hubbard (1995). 

The Megafauna 

Megafauna in the Gulf appears to occur in zones that are restricted to fairly predictable depth 

intervals (Pequegnat 1983; Pequegnat et al. 1990). These were designated 1) the Shelf/Slope 

Transition, down to about 500 m; 2) the Archibenthal Zone, Horizon A (500 to 775 m); 3) the 

Archibenthal Zone, Horizon B (800 to 1000 m); followed by the Upper Abyssal, Meso-Abyssal 

and Lower Abyssal Zones. These span the following depths: 1 to 2.3, 2.3 to 3.2, and 3.2 down to 

3.8 km. These names were given earlier by Menzies et al. (1973) for similar zones encountered 

along several continental margins of the world oceans. In Pequegnat et al. (1990), percent 

similarities were presented as evidence that groups of fishes and megafauna in the region of the 

De Soto Canyon in the eastern Gulf occur in recurrent groups that could be considered zones. 

The rate of change in species composition of the bottom fishes also suggested that there are 

depth intervals that can be considered zones and other intervals that can be regarded as 

boundaries between zones. The authors mention the species that dominate each zone. Most of 

these can be found archived in the deep-sea systematic working collections at Texas A&M 

University. The predictability of zones such as this, regardless of what they are called, may be 

47 

approximately 5 per hectare at depths of 3.6 km. B. typica reached similar values: from 4 to 7 

individuals per hectare. Similar numbers were observed for the large crustaceans B. 

cereus/iridescens, Nematocarcinus ensifer, and the sea cucumber P. semperiana. It is not clear 

however if the crustaceans were caught on the bottom or in the water column; therefore they 

have been left out of the assessment of total benthic standing stocks. 

Biomass was not measured in these earlier studies. However, many of the specimens are 

archived in a "systematics working collection" originally established by Willis and Linda 

Pequegnat on the Texas A&M campus. This enabled our review to find a representative number 

of the dominants, B. typica and D. insignis, and determine their mean biomass on preserved 

specimens approximately 30 years after they were captured. The D. insignis were dried 

specimens. They had a mean dry weight of 2.88 g per individual (σ=2.2, n=11). Mean disk 

diameter was 23.3 mm (σ=9, n=11). The holothurian B. typica individuals have been preserved 

in 70% ethanol and they were measured wet: mean=4.04 grams per individual (σ=1.4, n=13). 

They had a mean length of 6.6 cm (σ=1.1, n=13) and a diameter of 1.7 cm (σ=0.35, n=13). 

Thus, the sea star had a mean dry weight of 14.4 g per hectare and the holothurian had a mean 

wet weight of 22.2 g per hectare. The latter value would be equivalent to approx. 3.3 g per 

hectare dry weight (Rowe 1983). The two together would be equivalent to approximately 

1.77x10-3 g dry weight m-2. 

Some megafauna are distributed in peculiar patches. The most consistent such animal patches in 

the Gulf appear to be the contagious distribution of the holothuroid Peniagone sp. These were 

rarely taken in trawls, but occurred as clumps of dozens of individuals all piled up, in the 

photographic surveys made in NGOMCS. The highest densities at a lowering were 1.6 x 105 per 

hectare at a depth of 1.25 km. The reasons for the patchiness is not known. Other patches have 

been attributed to the proximity to fossil hydrocarbon seeps. Odd "reefs" of sponges are seen 

occasionally, but the causes of these accumulations are not known. Densities estimated with 

photography were always far higher than that estimated with the trawls. 

Motile Scavengers 

Little is known about deep-living scavengers in the GOM. On several occasions baited traps 

have been used to capture organisms. None of the information in these studies has been 

published however. In the 1997 A&M/UNAM studies with Gyre and Justo Sierra, a deep baited 

trap was deployed and a single species was captured: the cosmopolitan amphipod crustacean 

Eurythenes grillus. The numbers taken however appeared to be small (21 per 24 hour 

deployment) compared to similar trap deployments in other ocean basins. The significance of 

this group needs further study in the deep Gulf. 

Community Metabolism 

Sediment oxygen consumption has been measured at a single site on the deep abyssal plain in the 

eastern Gulf, and the rate measured was equivalent to approximately 6.7 mg C m-2d-1 (Hinga et 

al. 1979). On the Sigsbee Abyssal Plain, an unpublished value of 4.1 mg C m-2d-1 was measured. 

At this time it is impossible to know if this difference is real or simply due to a difference in gear 

used. In any case, the two values are not remarkably different from values at similar depths and 
48 

temperatures elsewhere in the world’s oceans. Values listed by Smith and Hinga (1983) for this 

depth range from a low of 2.6 up to a high of 25 mg C m-2d-1, and so our rate falls at the low end 

of the range. 

Community Function – The Cycling of Organic Carbon 

The information on the stock sizes and respiration rates of the biota tabulated have been put 

together into a carbon budget for the slope and abyssal plain (Cruz-Kaegi 1998). A budget of 

this sort allows a comparison of how carbon is both stored and cycled within an ecosystem. 

Values for the boxes (see presentation) are standing stocks in units of mg C m-2, integrated to a 

depth of 20 cm, whereas the arrows are fluxes of carbon between the boxes, with units of mg C 

m-2d-1. The arrows that start as “little clouds” are inputs of organic carbon to the system 

whereas the arrows that end in clouds are losses of organic carbon from the system. Most of the 

losses are the remineralization of organic matter to CO2. The input term, in this case, is 

estimated from the sum of the respiration loss terms by the community, plus long-term burial. 

An independent estimate of input can also be derived from measures of primary productivity in 

the overlying water and then applying the “Suess relationship” (Suess 1980) to estimate arrival 

of particulate matter at the sea floor. We assume the input varied by a factor of two or so over an 

annual cycle, with the highest productivity occurring during the winter when the phytoplankton 

biomass is highest (Muller-Karger et al. 1991). 

Most of the loss terms (arrows terminated by cloud-like figures) are respiration. Respiration 

remineralizes organic carbon to metabolic CO2. It is the largest consumer of organics in any 

typical benthic community and it can be estimated from oxygen fluxes. The sum of the aerobic 

respiration by the sediment dwelling organisms (bacteria, meiofauna and macrofauna) is equal to 

the value measured with the incubation chambers. This can be converted to carbon by assuming 

an RQ of 0.85 (moles of CO2 produced per moles of O2 consumed). 

The respiration of the individual groups were estimated by Cruz-Kaegi independently from 

known size and temperature relationships in the literature (Mahaut et al. 1995). The regression 

produced by Mahaut et al. (1995) relating size and respiration rates was used to calculate a firstorder respiration coefficient for the mean size of each size group. 

The estimates of respiration for each size category allows us to further partition the flow of 

organic matter through the food web. The sum of the arrows entering each standing stock must 

equal the sum of the arrows leaving each stock, for the system to be in steady state. Given the 

information generated on the respiration rates of each of the components above, we can then 

calculate exchanges between the boxes to maintain steady state. This is a step-wise analysis that 

has been utilized previously on benthos over a broad range of latitudes (Cruz-Kaegi 1998), in 

addition to the Demerara Abyssal Plain (Rowe and Deming 1985) and the continental margin off 

NE Greenland (Rowe et al. 1997). The resulting solutions for the predator-prey relationships are 

not always unique. As indicated, they are based on reasonable inferences of how the size classes 

are most probably partitioning their resources. 

Cruz-Kaegi’s relationships are close to several of the measurements described in Relexans et al. 

(1996). A value for bacterial efficiency that is high tends to “conserve” carbon within the 
49 

system, rather than burning it off as metabolic CO2. The production of the bacteria must be held 

in check by bactivory to maintain steady state and this has been directed primarily into the 

meiofauna, with a small fraction into the macrofauna. It was assumed the meiofauna had a 10% 

growth efficiency and thus the loss terms are respiration and predation by macrofauna, as 

indicated. The total meiofauna demand must therefore be met by bactivory and direct sediment 

consumption. Macrofauna fluxes are calculated in a similar fashion. 

The megafauna was assumed to be growing at a very slow rate and this is transferred by 

predation to the fishes. Fish growth is assumed to be zero; thus, the megafauna growth rate is 

equal to fish respiration. 

The standing stock of the organic matter was calculated from the concentration of organic carbon 

(0.6%), the porosity (85%) and the density of the sediment. Thus, organic carbon in the surface 

5 cm of sediment is 3.6 g C m-2-5 cm depth. The burial rate was estimated from longterm burial 

rates (William R. Bryant, pers. comm.), as follows. Approximately 1 to 2 meters of Holocene 

pelagic sediments, composed primarily of foram ooze, are spread rather uniformly over the entire 

Sigsbee Deep. On the continental margins the thickness of the Holocene material is 3 to 4 

meters deep. Thus, the rate of accumulation on geologic time scales are ca. 100 to 200 cm per 

13,000 years; at the time scales of our budget this is ca. 0.015 cm y-1. Multiplying this by the 

concentration in a 1 cm thick layer (225 mg C m-2-cm depth) gives a burial rate of ca. 3.5 mg 

org. carbon m-2 per year, or 0.0095 mg C m-2d-1, the appropriate units in the budget. This value 

is comparable to the low flux rates estimated for the larger sized groups of organisms 

(megafauna and fishes). 

Comparison of the Gulf Benthos with Other Oceans 

The standing stocks of the principal components of the benthic community have been measured 

together for the first time at a site in the Sigsbee Deep in the northwest Gulf of Mexico. The 

relationship of bacteria numbers in abyssal sediments has been regressed on depth, organic 

carbon concentrations and POC fluxes to the sea floor by Deming and Baross (1993). They 

found that the best predictor of log10 total bacterial biomass was log10POC fluxes. If we assume 

that our “input” term in our budget, estimated from the sum of the measured or estimated carbon 

demand, is equal to the POC fluxes measured in sediment traps in their study, then we can use 

this term in their regression. Our value for biomass (408 mg C m-2-20 cm depth) suggests, based 

on their regression, that the POC flux should be on the order of 24 mg C m-2d-1. 

The abundance and biomass of the macrofauna was somewhat higher than previously estimated 

in the southern Gulf of Mexico (Rowe and Menzel 1971). Escobar-Briones et al. (1999) made 

comparisons with several similar ocean basins and noted that abundances were higher in the 

northern Gulf than in the Bay of Campeche. We suggest that this area experiences intensified 

surface primary production that results from the interaction of warm eddies (Muller-Karger et al. 

1991). The differences with the measurements in the southern Gulf presented by Rowe and 

Menzel (1971) may be due to gear: the earlier studies used a semi-quantitative anchor dredge and 

not a spade or box corer. 
50 

The biomass of the macrofauna was not statistically separable from a general mean for the 

“global” ocean at a depth of 3.7 km, based on more than 700 values measured with a wide 

variety of sampling gear (Rowe 1983). A regression of log10 biomass as wet preserved weight as 

a function of depth in meters suggests that biomass at 3.7 km depth at the deep end of the Gulf 

regression line would be expected to be ca. 0.64 g m-2. 

A fair number of trawls have been taken across extensive areas of the continental margin in both 

the NW Atlantic (Haedrich and Rowe 1977; Haedrich et al. 1980), and the NE Atlantic 

(Haedrich and Krefft 1978; Lampitt et al. 1986), thus making it possible to compare densities 

and biomass of megafauna and fishes with the Gulf. Lampitt et al. (1986) plotted log10biomass 

of total invertebrate megafauna as a function of depth in the NE Atlantic near the Porcupine 

Bight. Their regression line predicts that 0.31 g wet weight m-2 should be encountered at 3.7 km 

depth. Haedrich et al. (1980) measured a wet preserved weight of ca. 0.08 g m-2 of fishes and 

0.05 g m-2 of megafaunal invertebrates (echinoderms and crustaceans) between depths of 3.2 and 

3.7 km, suggesting that the abundance and biomass of these groups is lower than in the 

Porcupine Bight of the NE Atlantic. The lower value above is higher than we have estimated for 

similar depths in the Gulf (0.006 g wet preserved weight m-2= ca. 0.155 mg C m-2); thus, 

compared to the Atlantic, the deep Gulf megafauna appears to be relatively depauperate. The 

extensive data from both the east and west sides of the North Atlantic had ranges of as much as 

three orders of magnitude at any given depth. 

The diversity of the polychaete fraction confirms that the Gulf of Mexico harbors a diverse 

fauna, as is typical for much of the deep-sea floor (Rex 1983). The numbers of species, H’(s) 

and the expected number of species per hundred individuals however are rather low compared to 

values on the upper continental slope and outer continental shelf (Lohse 1999). This pattern 

relative to depth is different from that in other basins: maximum diversity, regardless of “index” 

used, is found on the lower slope or the upper rise. The values we encountered were somewhat 

lower than that in other basins. Thus, a preliminary conclusion is that the pattern in the Gulf is 

different from most basins, with maximum diversities at the shallower depths of the upper slope 

and outer shelf (100 to 1000 m), rather than at the slope base (2 km to 3 km), as described by 

Rex (1983). The apparent decline with depth might be due to the limiting sill depth, the 

variability of the deep water environment (seeps from fossil hydrocarbons buried deep in the 

sediments, temperature variations due to warm eddies originating in the loop current in the 

eastern Gulf, nepheloid layers associated originally with the Mississippi River, sediment slumps 

and turbidity flows), or inadequate sample size. The latter artifact cannot be discounted because 

we continued to add equal numbers of previously un-encountered species with each additional 

box core, thus suggesting that many more species were present than we had actually sampled. 

This question can only be answered by more intense sampling. 

The abyssal plain of the Gulf differs from those in the major ocean basins because it is shallower 

(3.6 to 3.8 km) and warmer (4.2o

C). Thus, one might expect that the characteristics of 

communities of organisms might differ from "typical" oceanic abyssal plains. 
51 

Summary

The study of the deep benthos of the Gulf of Mexico can be divided into three eras. Early studies 

prior to the 19th century were exploratory zoogeographic investigations. In the 1960's Willis 

Pequegnat initiated modern investigations of the standing stocks of the megafauna. In the 1980's 

the MMS supported an investigation of the continental slope that encompassed state-of-the-art 

quantitative sampling of the meiofauna, macrofauna and megafauna. Metazoan biomass is 

dominated by the meiofauna. The eastern Gulf is not similar in species composition to the 

western Gulf and this can be attributed to a difference in substrate. The western sediments are 

terrigenous whereas the eastern Gulf substrate is carbonate. Faunal diversity of the macrofauna 

is high but it is not characterized by a mid-depth maximum. The low biomass of the macrofauna 

and the megafauna suggest that the biota is food limited. Budgets of carbon cycling on the slope 

suggest that most of the organic matter is cycled through the smaller animals of the communities. 

References 

Agassiz, A. 1888. Three Cruises of the Blake. Mus. Comp. Zool., Harvard. 

Boland, G. and G. Rowe. 1991. Deep-sea benthic sampling with the GOMEX box corer. 

Limnol. and Oceanogr. 36(5):1015-1020. 

Booker, R. 1971. Some aspects of the biology and ecology of the deep-sea echinoid 

Phormosoma placenta Wyv. Thompson. M.S. thesis, Texas A&M University. 

Bright, T. 1968. A survey of the deep-sea bottom fishes of the Gulf of Mexico below 350 

meter. Ph.D. dissertation, Dept. of Oceanography, Texas A&M University. 

Carney, R. 1971. Some aspects of the ecology of Mesothuria lactea Theel, a common bathyal 

holothurian in the Gulf of Mexico. M.S. thesis, Texas A&M University. 

Cruz-Kaegi, M. E. 1998. Latitudinal variations in biomass and metabolism of benthic infaunal 

communities. Ph.D. dissertation, Texas A&M University. 

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55 

The Benthos of the Deep Gulf of Mexico 

Click on the title to view the presentation. 

The Benthos of the 

Deep Gulf of Mexico

Gilbert T. Rowe

Texas A&M University
56 

Overview of Fisheries of the Deep Gulf of Mexico

Randy E. Edwards* and Kenneth J. Sulak 

U.S. Geological Survey, Biological Resources Division, Florida Caribbean Science 

Center, Gainesville, Florida *

University of South Florida, College of Marine Science, St. Petersburg, Florida 

Introduction 

This paper summarizes information on important Gulf of Mexico (GOM) fish and fisheries in 

deepwater (depth >1,000 ft or 305 m) areas into which petroleum exploration and production has 

recently expanded (Baud et al. 2000). It also discusses the potential for GOM deepwater 

petroleum structures (DPSs) to affect fisheries by acting as fish aggregating devices (FADs) and 

how DPSs’ effects on fish and fisheries are very different from those of petroleum structures in 

shallower waters. 

Species

The most important fish in the deepwater environment are open-ocean, pelagic species, which 

the National Marine Fisheries Service (NMFS) terms highly migratory species (HMS). The most 

important HMS are marlins, sailfish (Istiophorus platypterus), swordfish (Xiphias gladius), 

tunas, and certain pelagic shark species. Dolphin (Coryphaena hippurus), wahoo 

(Acanthocybium solandri) are also important pelagic species in GOM deepwaters, although they 

do not fall within the NMFS HMS category. A few coastal pelagic species such as amberjacks 

(Seriola sp.), cobia (Rachycentron canadum), and king mackerel (Scomberomorus cavalla) are 

sometimes present in deepwater environments but usually are not as abundant as in shallower, 

shelf environments. Most benthic fish species, like red snapper (Lutjanus campechanus), red 

grouper (Epinephelus morio), gag (Mycteroperca microlepis), etc., that are important in 

shallower waters of the continental shelf are not found in deepwater environments. A few 

deepwater groupers, including misty grouper (Epinephelus mystacinus), yellowedge grouper 

(Epinephelus flavolimbatus), and snowy grouper (Epinephelus niveatus) extend into deepwaters 

of the GOM. 

The GOM deepwater environments serve as habitat for one important invertebrate species, the 

royal red shrimp (Hymenopenaeus robustus). Essential habitat for royal red shrimp has been 

designated by NMFS1

as the upper regions of the continental slope from 590 ft (180 m) to about 

2,395 ft (730 m) with specific types of sediments. Trawling for royal red shrimp in the northern 

GOM extends to depths of around 1,000 ft (305 m) and can be expected to go deeper in the 

future (D. B. Snyder, personal communication). 

 

1

 Source: NMFS Essential Fish Habitat Designations for South Atlantic Fishery Management Plans 

http://www nmfs noaa.gov/habitat/habitatprotection/images/SAFMC.pdf
57 

Commercial Fisheries 

Commercial finfish fisheries in the deepwater GOM consist almost exclusively of longline 

fisheries that target yellowfin tuna (Thunnus albacares) or swordfish, using drifting lines that 

typically are up to 40 mi (~65 km) long with up to about 1,000 baited hooks (Berkeley and 

Edwards 1997). Over the period of 1981-2000, the pelagic longline fishery had an average 

annual value of $16.6 million, of which yellowfin tuna accounted for $11.6 million and 

swordfish for $3.4 million. During that period, yellowfin tuna accounted for 71% of the catch, 

swordfish 20%, bluefin tuna (Thunnus thynnus) 5%, dolphin 4%, and blackfin tuna (Thunnus 

atlanticus) <1%. A host of miscellaneous species is also caught incidentally by longlines. 

A Japanese high-seas longline fishery for yellowfin tuna operated in the GOM from 1957 until 

1981 (Wilson 1988). A domestic GOM longline fleet was established in the early 1980’s, and 

yellowfin tuna catches peaked at 9.2 million lb with dockside value of $19.2 million in 19922

. 

Landings declined substantially over the next few years, and recently (1996-2000), GOM 

yellowfin tuna landings have averaged 4.7 million lb and $11.1 million. This is a small fraction 

of the total Atlantic yellowfin tuna landings (most taken in the eastern Atlantic) of around 300 to 

350 million lb/yr during the same period. Bluefin tuna (Thunnus thynnus) catches (incidental or 

sometimes targeted) were once an economically important component of the fishery, due to the 

very high prices bluefin tuna commanded in the Japanese market for sashimi. Bluefin tuna 

landings peaked in 1988 at 0.3 million lb and $4.1 million ($13.54/lb), but declined greatly 

thereafter in response to catch restrictions and declining prices (recently $4-5/lb) brought about 

as the market found new sources for sashimi-grade tuna in other parts of the world. 

Analyses of the extensive NMFS database of longline fishing locations and catches (Brown and 

Scott 2001; Snyder et al. 2001) show that considerable longline effort and catch of a variety of 

species occurs within areas of the continental slope into which deepwater petroleum activities 

have expanded or are expected to expand. Beyond the longline catch data, little is known about 

the distributions, movements, and migrations of pelagic fishes in the GOM. There have been no 

extensive tagging/recapture studies of any species. However, limited data from yellowfin tuna 

tagging and recapture (Ortiz 2001) suggests, from the fact that yellowfin tagged in the GOM and 

from other parts of the western Atlantic were recaptured in the large commercial fishery in the 

eastern Atlantic, that GOM yellowfin tuna are part of single Atlantic stock. The extent to which 

seasonal or annual variation in yellowfin migration patterns affect abundance in the GOM is 

unknown. It is known, however, that the GOM serves as the only known spawning grounds for 

the western Atlantic stock of giant bluefin tuna (Nemerson et al. 2000). Bluefin tuna spawn in 

the GOM during late spring and then migrate out of the GOM through the Straits of Florida in 

May or June to summer feeding grounds off the U.S. northeastern coast and the Canadian 

Maritimes. The western Atlantic stock of bluefin has declined to such low levels that some 

observers have suggested that it is threatened with extinction (Safina 1993). Skipjack tuna 

(Katsuwonus pelamis) is one of the most abundant tuna species in most oceans, but information 

about its abundance and distribution in the GOM is limited to observations that commercially 

exploitable quantities may exist there (Sakagawa 1986) and the fact that they have been caught 

in commercial quantities in pole-and-line fisheries around fish aggregation devices (FADs) 

 

2

 Commercial Landings Source: NOAA Fisheries http://www.st nmfs.gov/st1/commercial/
58 

deployed off the northern coast of Cuba (Martin 1999). However, U.S. GOM catch of skipjack 

tuna has been extremely small. 

Recreational Fisheries 

Recreational fisheries are also important in deepwater areas of the GOM. However, it is not 

possible to partition deepwater fisheries from the overall offshore recreational fisheries that 

include areas shallower than 1,000 ft. The overall GOM offshore recreational landings (1991-

2000 average2

) are dominated by dolphin (85%, 4.4 million lb), blackfin tuna (13%, 0.6 million 

lb) and yellowfin tuna (5%, 0.2 million lb). However, most offshore anglers target billfish, often 

for catch and release. Unfortunately, these fisheries have not been precisely quantified with 

regard to effort, catch or value. The NMFS recreational billfish survey (RBS) documented about 

16,000 to 27,000 trolling hours per year for the Gulf of Mexico from 1988 through 1995 (NMFS 

1997). The RBS GOM billfish catch per unit effort (CPUE) for 1994 was 3.0 billfish per 100 hr, 

which is comparable to CPUE in the Bahamas (3.2) and close to that for the Caribbean (3.8) and 

the Atlantic north of Florida (4.2). The 1994 GOM catch was comprised of about 54% blue 

marlin (Makaira nigricans), 35% white marlin (Tetrapturis albidus), and 11% sailfish (NMFS 

1997). Overall, a large, productive, and economically valuable recreational fishery takes place in 

GOM deepwater areas. 

GOM DPSs as Fish Aggregating Devices 

The issue of whether deepwater petroleum structures might act as fish aggregating devices was 

initially raised in a prior workshop on deepwater oil and gas development (Carney 1997). In 

response, the U.S. Geological Survey (USGS) researched available scientific literature and 

information on FADs, compiled a bibliography, and provided synthesis and analysis pertinent to 

GOM DPSs functioning as FADs (Edwards and Sulak 2002). Much of the following discussion 

is taken from that report. 

The literature on FADs is relatively limited and recent, and therefore Edwards and Sulak (2002) 

concluded that it is inadequate for extrapolation and prediction of GOM DPS FADs effects. 

However, a number of conclusions were possible. One of the most important is that 

relationships between deepwater petroleum structures and fish/fisheries are very different from 

those for structures in shallower waters. In deepwater environments, completely different 

biotopes, species, trophic linkages, and fisheries are involved. Hence, the fishery resource 

management issues for DPSs are very different from those that have been studied so intensively 

for shallower rigs. Therefore, if the effects and impacts of GOM deepwater petroleum structures 

are to be understood, direct study of DPSs will be needed. 

Various types of floating structures, both drifting and anchored, have been deployed in openocean environments to attract and aggregate fish for commercial and recreational purposes. 

FADs have been used around the world, and the primary species that are associated with FADs 

are tunas, especially yellowfin tuna, skipjack tuna and bigeye tuna (Thunnus obesus). FADs 

have been found to be so effective that most of the world commercial tuna catch is now taken 

from around FADs (Fonteneau et al. 2000). Additionally, a suite of other pelagic fishes has been 
59 

documented to also associate with FADs. They include dolphin, wahoo, blackfin tuna, blue 

marlin, bluefin tuna, and certain shark species. 

The reasons why tunas and other fishes aggregate around FADs are not well understood. Nine 

reasonable hypotheses for this phenomenon have been proposed (Freon and Misund 1999). Only 

one of these, that fish aggregate because a concentrated food supply exists around FADs, has 

been discounted (Freon and Daghorn 2000). This is particularly important in that it indicates that 

DPSs would not enhance fish production, as has been proposed for shallow rigs, and would 

result only in attraction. Recently, the remaining eight hypotheses have been consolidated into 

four hypotheses (Freon and Daghorn 2000). They are that fish aggregate around objects 

because: 1) objects provide shelter from predation, 2) objects provide a spatial reference in an 

otherwise featureless environment, 3) drifting objects are indicators of productive areas for 

feeding, and 4) objects provide an opportunity for individuals or small schools to meet and form 

larger schools. The factors that determine the degree to which an object aggregates fish remain 

unknown. After an intensive study, Hall et al. (1992) concluded that as long as an object had a 

minimum dimension of one meter, they could find no other factors that were statistically related 

to the abundance of the aggregated fish. Therefore, it is impossible to understand or predict the 

aggregating effect of diverse and structurally complex petroleum structures. 

However, it is known from acoustic tracking studies of yellowfin and bigeye tuna, that tuna 

movements are greatly influenced by the presence of FADs and that the radius of influence of a 

structure is on the order of 5 nmi (9 km) (Holland et al. 1990; Holland 1996; Marsac and Cayre 

1998). Furthermore, existence of a network of structures can affect movements. Presence of 

four or five FADs in a 27 nmi (50 km) x 27 nmi area reduces skipjack tuna movement out of an 

area by 50% (Kleiber and Hampton 1994). Such a network of structures already is in place in 

the deepwater GOM and is equivalent, in area and number of structures, to the FADs network 

that has been deployed around the Hawaiian Islands to provide recreational and artisanal fishing 

opportunities (Holland et al. 2000). 

Review of existing literature and information on FADs (Edwards and Sulak 2002) indicates that 

GOM DPSs may have positive or negative effects. Possible positive effects include increased 

catchability of fish for recreational and commercial fishermen, increased efficiency, and bycatch 

reduction under some circumstances. Possible negative effects include shift to smaller fish and 

resultant impacts on fishery yields, disruption of normal movements, impacts on spawning, 

increased fishing mortality, increased bycatch, user group conflicts, and fishery management 

problems. 

Unfortunately, existing FADs literature and science is inadequate for predicting which of the 

positive or negative effects will occur. Some of the potentially critical issues include possible 

effects of GOM DPSs on valuable yellowfin tuna fisheries (e.g., through development of 

commercial fishing for yellowfin tuna around DPSs), development of new fisheries (e.g., for 

skipjack tuna), and impacts on the already critically low stocks of bluefin tuna (Safina 1993) 

(e.g., by attracting them away from optimal spawning areas (Lamkin et al. 2001) and subjecting 

them to increased bycatch). 
60 

Numerous reports of GOM DPSs already having FADs effects have come to light recently. 

Recreational fishermen have reported that deepwater oil and gas structures attract pelagic fish 

like yellowfin tuna, blue marlin, wahoo, dolphin, blackfin tuna, and sharks (Sloan 2001). One 

magazine article described deepwater rigs as follows: “These offshore rigs act as fish-attracting 

devices, supporting whole ecosystems, pulling in great numbers of pelagics and smaller game 

fish” (Husser 1997). Another article (Olander 2001) described catches of deepwater grouper and 

other bottom fish near a GOM DPS. 

Research Needs 

Given that GOM DPSs are already acting as FADs and that existing scientific information is 

inadequate for understanding or predicting how increasing numbers of DPSs will affect GOM 

fish and fisheries, direct field studies are recommended (Edwards and Sulak 2002). A number of 

research approaches have been used to study FADs. They include: tagging, hydroacoustic 

survey, acoustic telemetry/tracking, acoustic telemetry using automated receivers, fishery 

dependent catch surveys, fishery independent hook-and-line fishing, experimental net fishing, 

and modeling. Of these, acoustic telemetry/tracking (e.g., Holland et al. 1990; Holland 1996; 

Marsac and Cayre 1998; Dagorn et al. 2000) and hydroacoustic survey (e.g., Josse et al. 1998; 

Josse et al. 2000) have been most effective in elucidating fish/FADs relationships. In the 

acoustic tracking studies, the fish were tagged with ultrasonic transmitters and were tracked for 

extended periods to determine their movements relative to FADs. Additionally, GOM DPSs 

offer the opportunity to deploy automated acoustic receiver systems (e.g., Klimley and Holloway 

1999) that can detect the periodic return of sonic-tagged fish. In the hydroacoustic studies, sonar 

instruments have been used to observe horizontal and vertical distributions of fish relative to 

FADs. Most recently, sonic tagging has been combined with hydroacoustic survey to allow 

individual fish to be recognized and species and sizes to be determined (Josse et al. 1998). Stateof-the-art multibeam, three-dimensional, computerized sonar systems (Gerlotto et al. 1999) 

could, in the future, provide detailed information about fish distributions around DPSs and other 

structures. 

Acknowledgments 

Craig Brown, NMFS, and David Snyder, Continental Shelf Associates, generously provided 

copies of GOM longline catch and effort maps. Gary Brewer, USGS Eastern Regional Office, 

greatly aided and supported this work. 

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Nemerson, D., S. Berkeley and C. Safina. 2000. Spawning site fidelity in Atlantic bluefin tuna, 

Thunnus thynnus: the use of size-frequency analysis to test for the presence of migrant east 

Atlantic bluefin tuna on Gulf of Mexico spawning grounds. Fish. Bull. 98:118-126. 

Olander, D. 2001. Down the tubes: deep-dropping Gulf oil rigs. Sportfishing Magazine June 

2001 <http://www.sportfishingmag.com/SF_Main/1,3214,5-1-1-23304-162-336,00.html>. 

64 

Overview of the Current Status of Socioeconomic Studies in the MMS Gulf of 

Mexico Region 

Steve Murdock 

Texas A&M University, College Station, Texas 

Steve Murdock presented the preliminary findings of a White Paper, which he authored with F. 

Larry Leistritz and Stan Albrecht. The paper reviews MMS’s socioeconomic studies program 

for the Gulf of Mexico and is intended to provide workshop participants with an overview of the 

work that has been conducted since the last deepwater workshop. The paper will be used to 

frame the socioeconomic breakout group discussions. 

The White Paper focuses on recently completed studies and evaluates them using the following 

criteria: 

1. The extent to which they address the key socioeconomic dimensions related to 

socioeconomic impact assessment (SIA); 

2. The appropriateness, application, and documentation of the methodologies used; 

3. The quality of these studies relative to conceptual, methodological and state-of-the-art 

criteria; and, 

4. The likely utility of the work for communities and MMS managers and decision-makers. 

The authors found the timing of this review to be unfortunate because much of the key research 

is ongoing, hence its findings cannot be evaluated. This means that the findings of the White 

Paper must remain preliminary. 

The authors found that the MMS GOM socioeconomic studies program has shown substantial 

progress in the last decade. The agency has listened and responded to its critics and constituents 

and is aware of the critical socioeconomic dimensions in OCS development. 

For example, in 1992 a GOM Socioeconomic workshop and the National Research Council 

recommended studies on historical OCS impacts, public attitudes toward industry, effects on 

families, worker attitudes, and education. This research has been completed. 

The White Paper divides the review into three SIA dimensions: economic and fiscal, 

demographic and infrastructure, and sociocultural. 

Economic and Fiscal 

MMS GOM economic modeling has shown great progress over the last decade. After years of 

not being state-of-the-art, it is nearly state-of-the-art in all regards. MMS should continue 

building on these efforts. The White Paper emphasizes the continuing need for up-to-date 

information on industry expenditures and labor. Global competition and the industry’s long-term 

role in the Gulf should also be considered. 
65 

Fiscal issues have not been as systematically addressed although studies of the Florida Panhandle 

and Port Fourchon do take state-of-the-art approaches. Similar case studies elsewhere would 

address this issue more fully. 

Demographic and infrastructure 

The evaluation of Gulf demographic research is premature because of critical ongoing studies. 

However, the Gulf’s efforts in this area to date are not state-of-the-art. Developing more 

sophisticated demographic and public service model components should be given priority. 

Major demographic issues that need to be addressed are in- and out-migration, population 

retention, wage pressures, and foreign immigration. A Gulf study is addressing industry support 

infrastructure. However public service components that are a standard part of SIA have not been 

as thoroughly addressed. Examples include health, welfare, public safety, power, water, sewer, 

transportation, and recreational facilities. 

Sociocultural 

In the Gulf, research in this area has shown great progress and is increasingly approaching stateof-the-art in terms of methods used and subjects addressed. Of particular note in this regard is 

the work on families. 

Work should be extended to additional places and substantive areas and be expanded to identify 

a wider range of positive as well as negative effects. An effort should be made to more fully 

specify the groups that benefit and the ones that do not and to identify differences in areas and 

impacts across the Gulf. 

The White Paper identifies several overall issues that should be considered when designing 

future research: 

1. the difficulty in the separation of the baseline from OCS developmental effects; 

2. the difficulty of identifying the impact area; 

3. the problems of assessing commutative effects; 

4. the need to more fully incorporate study findings into the EIS process; and, 

5. the desire to make the EIS process more valuable to communities. 
66 

An Examination of Selected Recent MMS Socioeconomic Studies and Assessments in the 

Gulf of Mexico 

Click on the title to view the presentation. 

An Examination of Selected Recent MMS Socioeconomic 

Studies and Assessments in the Gulf of Mexico

Draft Report for the Minerals Management Service 

Gulf of Mexico Office

by

Steve H. Murdock

Department of Rural Sociology

Texas A&M University

F. Larry Leistritz

Department of Agricultural Economics

North Dakota State University

Stan Albrecht

Department of Sociology

Utah State University

May, 2002
67 

V. Breakout Group Summaries 

Ecology Breakout Group 

Co-Chairs: 

Michael Rex, University of Massachusetts 

Robert Avent, Minerals Management Service 

James P. Ray, Shell Global Solutions (US) Inc. 

Jeff Childs, Minerals Management Service 

Recorder: 

Margaret Metcalf, Minerals Management Service 

Introduction 

The aims of the Ecology Breakout Group in the broader context of the 2002 Deepwater 

Workshop were to: 

• review the current status of industry activity in deepwater 

• discuss environmental issues that have emerged since the first deepwater workshop five 

years ago (Carney 1997) 

• identify remaining data gaps and useful syntheses of information, relevant to points one 

and two above, that might form the basis of future environmental studies. 

The first two objectives were covered largely through presentations by petroleum industry 

representatives and selected principal investigators of ongoing MMS-sponsored studies during 

the first day of the workshop. The Ecology Breakout Group focused its attention on reviewing 

the current status of environmental knowledge about the deep Gulf, and discussing what new 

initiatives might address environmental impacts of deepwater petroleum exploration. 

The Ecological Issues Working Group of the first Deepwater Workshop (Carney 1997) reviewed 

deep-sea benthic ecology, including previous research in the Gulf of Mexico. The Working 

Group recommended a more comprehensive study of the structure and function of the deep 

benthic ecosystem, and intensified research on the ecology of recently discovered 

chemosynthetic communities begun in 1990 through the MMS-funded "Northern Gulf of Mexico 

Chemosynthetic Ecosystem Study" (CHEMO I). A continuation of the latter program, "Change 

and Stability in Gulf of Mexico Chemosynthetic Communities" (CHEMO II), has now been 

completed. The final report has been reviewed, and has recently been released. In response to 

recommendations of the first Deepwater Workshop, MMS sponsored the "Deepwater Program: 

Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology" (Deep Gulf of 

Mexico Benthos, DGoMB) study which began in 1999 and is still in progress. The study was 

extended into Mexican waters of the southern Gulf this year. The DGoMB study is intended to 

provide a much more thorough biotic survey of the deep Gulf, and to validate a model of 

ecosystem function in terms of carbon flux. Important conceptual advances of the DGoMB 
68 

study are that it incorporates a sampling design to test specific hypotheses of community 

structure formulated from results of earlier dredging, and that the process-oriented component is 

an entirely new direction that integrates energy flow in the benthic community. Discussions of 

the 2002 Ecology Breakout Group concerning the present state of knowledge were based on 

what might realistically be anticipated from the CHEMO II study (not officially released when 

we met) and the DGoMB study which is ongoing. Clearly, priorities for future studies must take 

into account the final results of CHEMO II and DGoMB when they become available. 

It is clear that petroleum exploration and production have extended into the deep Gulf far ahead 

of assessment studies to evaluate their potential environmental impacts (Baud et al. 2002). Also, 

physical and biological oceanographic research in the deep Gulf during the last decade has 

revealed an extremely complex ecosystem that includes many unanticipated novel habitats and 

ecological phenomena. Information is limited or not available on the geographic distribution of 

these habitats, the structure and function of their biological communities, and the ecological 

coupling among habitats, especially in deep water. Thus, designing new studies that can 

measure the environmental effects of deepwater drilling in a direct way presents a considerable 

challenge. 

Following an initial discussion of general environmental problems associated with deepwater 

drilling, the Ecological Breakout Group formed two subgroups, Benthic Systems (Chaired by M. 

Rex, R. Avent, and J. Ray) and Pelagic Systems (chaired by J. Childs). Later we reassembled to 

review our independent conclusions and to look for ecological patterns and environmental 

concerns common to pelagic and benthic realms. Below we present the substance of these 

discussions and conclusions, and make several recommendations about which there appeared to 

be a broad consensus among environmental scientists, industry representatives and government 

regulators. 

Benthic Systems Session

In the last several decades, ecological studies in the deep Gulf have progressed from descriptive 

biotic surveys to much more advanced approaches involving sampling programs designed to test 

biogeographic hypotheses, manipulative experiments and theoretical modeling. This is an 

impressive record and the pace of discovery has been dramatic. A more comprehensive picture 

of ecosystem structure and function is beginning to emerge, at least in broad outline. 

Discussions of the 2002 Ecology Breakout Group were concerned with building on this 

knowledge base to orient prospective studies more toward the immediate environmental effects 

of deepwater drilling. 

The Benthic Session discussed five basic issues that are relevant to determining the 

environmental effects of deepwater drilling. 

1. Spatial and Temporal Scale. Pattern and scale constitute the central problem of modern 

ecology (Levin 1992); a clear recognition of this is imperative to any applied study. Have we 

identified the relevant spatial and temporal scales at which environmental factors act to 

structure deep Gulf benthic communities? Deep-sea communities show geographic variation 

(Rex et al. 1997) that is shaped by processes operating at local (Grassle and Maciolek 1992), 
69 

regional (Cosson-Sarradin et al. 1998) and global (Rex et al. 1993, 2000) scales. Moreover, 

there is a complex interaction among phenomena occurring at different scales (Levin et al. 

2001). For example, local species diversity and community makeup represent a balance 

between local ecological opportunity and continued dispersal from the regional species pool. 

Similarly, the ecology of local deep-sea communities varies on time scales ranging from 

annual (Gage and Tyler 1991) and decadal (Smith and Kaufmann 1999; Smith et al. 2001) to 

millennial (Raymo et al. 1998) and longer (Cronin and Raymo 1997). Predicting the impact 

of disturbance by drilling and the recovery potential of deep-sea communities depends on 

understanding the spatio-temporal scales on which ecological structuring agents function. 

2. Distinguishing Disturbance by Drilling from Natural Cycles. The main problem in 

environmental impact studies is to separate natural spatio-temporal changes from those 

caused by anthropogenic activities. As pointed out above, deep-sea communities do show 

spatial variation on local to large scales, and experience temporal changes on short- and longterm scales. To assess the effects of deepwater drilling, it is necessary to know the type and 

magnitude of environmental change caused by drilling operations, the spatio-temporal 

variability of affected organisms and how these organisms respond to drilling activity. Much 

of the relevant basic information about community structure and dynamics may emerge from 

the DGoMB study. It is possible to design a controlled precision sampling study to 

distinguish drilling impacts from natural variation. The sampling design and its associated 

statistical tests require sampling multiple impact and control sites before and after drilling is 

initiated (Bernstein and Zalinski 1983; Stewart-Oaten et al. 1986; Underwood 1996, 1997). 

This approach might be particularly timely since drilling activity is currently expanding into 

deep water and opportunities exist for carefully planned before and after sampling programs 

that capture the appropriate spatial and temporal scales of natural variation. Clearly, such 

studies need to be long-term and will require taxonomy at the species level. The level of 

sample replication required can be determined by a power analysis (Cohen 1977); again, the 

results of the DGoMB study will be very useful in this regard. 

Oil industry representatives point out that the distribution of cuttings and associated mud in 

the deposition zone around drilling sites is heterogeneous. Because of this, a sampling 

program would have to be very precise, or the sampling strategy would need to include 

enough random stations to adequately characterize the physical, chemical and biological 

changes that have occurred in this impact zone. A similar density of sampling would have to 

be conducted at multiple reference areas so that local variability could be adequately defined. 

Other approaches to detecting impacts should also be considered. It may be possible to 

include potential anthropogenic disturbances into the food-web model being developed in the 

DGoMB study. Controlled experiments are the only way to directly determine a causal 

connection between drilling activity and changes in the natural community. All of these 

potential studies require careful selection of the appropriate response variable (e.g., standing 

stock, carbon flux, species diversity, and community composition, local or global extinction), 

and consideration of what constitutes an acceptable level of disturbance to the natural 

ecosystem. We stress again that it would be premature to design and implement such studies 

without considering the final results of the historic NGOMCS and the recently concluded 

(CHEMO II) and ongoing (DGoMB) MMS studies. 
70 

Conducting any of these studies in deeper water will be difficult, primarily because of the 

density of organisms decreases rapidly with depth. Lower animal abundance (and possibly 

the slower response times that attend colder and nutrient-poor environments) may mean that 

intensive sampling over a long period is necessary to detect both natural variation and 

potential impacts. Because of this, the Ecology Group urges a careful examination of 

existing information to optimize and inform the impact studies, including archival material 

and databases from earlier studies. Coordination of MMS, industry and environmental 

scientists is especially important. For example, industry representatives in the Ecology 

Group suggested that ROVs used on deepwater rigs may be available for sampling and 

conducting experiments. There was a general agreement among participants that the ability 

to distinguish drilling disturbance from natural cycles is a very high priority. MMS might 

consider a special workshop to explore existing data and to design studies using different 

possible approaches (sampling, experiments, modeling) to measure the potential impact of 

deepwater drilling in the Gulf. 

3. Understanding Biodiversity at Relevant Levels of Organization. The concept of conserving 

biodiversity is an appropriate and useful context in which to consider the environmental 

effects of deepwater petroleum exploration. It has become the major focus of national and 

international efforts to preserve and manage natural ecosystems, and to plan for sustainable 

development. The industry perspectives presented at the Deepwater Workshop by 

representatives from British Petroleum and ChevronTexaco stressed the significance of 

biodiversity and minimizing potential impacts to biological communities. 

In general, biodiversity simply means the variety of living organisms. It involves all levels 

of organization including landscape (or perhaps more appropriately "seascape"), communityecosystem, population-species and genetic (Lubchenco et al. 1991; Norse 1993; NRC 1995; 

Heywood 1995; Meffe and Carroll 1997; Frankham et al. 2002). The Gulf shows 

extraordinary biodiversity at the landscape level (variety of habitats) including numerous 

soft-sediment conditions, chemosynthetic systems, gas hydrates, brine pools, Lophelia

colonies, oxygen minimum zones, iron stone pavements and a vast array of unique 

topographic features. These habitats are ecologically linked. Exploiting a variety of habitats, 

directly or indirectly, may be vital to species persistence. For example, some mobile benthic 

predators derive their nutritional needs from both photosynthetic and chemosynthetic 

production (MacAvoy et al. 2002). 

The DGoMB study will produce a great deal of information about the population-species and 

the community-ecosystem levels of organization. Geographic patterns of species diversity 

and faunal turnover, relative abundance distributions of species, life-history attributes, and 

food-web structure can reveal a great deal about the susceptibility of populations and 

communities to disturbance. Mapping species ranges is also fundamentally important for 

estimating the likelihood of extinction from environmental impacts. It is the primary 

evidence for predicting whether an impact on some scale of time and space will cause local 

or complete extinction. Species with sufficiently large geographic ranges may suffer local 

extinction near the impact site, but subsequently be able to recolonize from elsewhere in their 

ranges. Species with small ranges situated near the impact zone are more vulnerable to 
71 

permanent extirpation. Hence, the degree of endemism (taxa restricted to a geographic area) 

in impacted areas is very relevant to extinction potential. Species' geographic ranges are 

poorly known in any deep-sea environment. The combination of DGoMB data, earlier 

databases and archived material could contribute very substantially to mapping species' 

ranges in the Gulf. 

Very little is known about biodiversity at the genetic level in deep-sea species. Techniques 

are now readily available for sequencing DNA of marine species, even from preserved 

specimens. This can be done in a very cost effective way, since the material is already being 

collected in MMS studies for other purposes. Genetic population structure is a critical 

component of biodiversity for conservation efforts in coastal and terrestrial systems 

(Frankham et al. 2002). Habitat loss and reduced population size erode genetic variation 

making populations more vulnerable to extinction and less able to adapt to changing 

environmental circumstances. Local extinction can, in turn, destabilize local communities 

and lead to lower species diversity. Genetic population structure can also reveal the extent 

and direction of migration (gene flow) which reflect the role of dispersal in maintaining 

population viability and community structure. Because of the importance of genetic 

biodiversity studies to resolving basic problems of vulnerability to extinction within species 

and the causes of benthic community structure, MMS might consider a pilot project using 

abundant widely distributed species to evaluate the usefulness of this approach for impact 

assessment. 

4. Interdisciplinary Approaches. MMS-sponsored studies in the Gulf have hugely increased 

our understanding of physical oceanography, marine geology, fisheries, deep-sea ecology as 

well as social and economic factors. It is now possible to forge a much more comprehensive 

multidisciplinary understanding of the Gulf ecosystem. For example, new information on 

current systems has an important bearing on larval dispersal and deep-sea community 

structure. High-resolution sonar imagery of bottom topography makes it possible, for the 

first time, for ecologists to ask specific questions about large-scale patterns of community 

structure and landscape-level biodiversity. In future Deepwater Workshops, we encourage 

interaction among the breakout groups to integrate and synthesize information from MMSsupported studies in geochemical, physical, biological and social disciplines, and from the oil 

industry. 

5. Importance of Integrated Databases. Much of the data resulting from earlier MMS studies 

remain unpublished and difficult to access. The data and archived material are very valuable 

resources for designing specific studies to measure the impact of deepwater drilling. We 

encourage MMS to consider establishing a professionally managed relational database of 

earlier (and current) studies that is available on the internet to industry, regulators, 

environmental scientists and the public. The database should also specify the location of 

archived material. This would greatly increase the benefits of these studies for both applied 

and basic research. Making the data available to the broader community would also greatly 

expand the potential for integration and synthesis among these databases, and with other 

deep-sea studies. While the regulatory responsibilities of MMS concern applied work related 

to offshore petroleum exploration, much information of very basic scientific interest emerges 

from these studies. The studies have also suggested important basic research not directly 
72 

related to the MMS mandate. We urge MMS to integrate their priorities and programs with 

those of other funding agencies that support marine research. 

The Ecology Breakout Group also discussed possible future studies, relevant to deepwater 

drilling, in specific Gulf habitats. For the sake of convenience, we divided habitats into 

chemosynthetic and nonchemosynthetic. 

1. Chemosynthetic Communities. The current status of knowledge on chemosynthetic habitats 

was difficult to evaluate in a thorough way because the CHEMO II final report was not 

released, and no principal investigators from this study participated in our session. Greg 

Boland and Robert Avent of MMS, pointed out that deeper seep systems in the Gulf were 

largely unexplored because most available submersibles used to study them had depth ranges 

limited to 1000 m. Since drilling has already extended much deeper than 1000 m, future 

investigations of the distribution, function and structure of seep communities below 1000 m 

is an obvious priority. One suggested approach to compare the recovery potential of seep 

communities above and below 1000 m is to conduct experiments on recruitment and growth 

rates of constituent species. The methodologies for doing this are well established. Oil 

industry representatives made the point that seeps are now protected and that drilling activity 

is not allowed within a certain distance of known seeps. 

2. Non-chemosynthetic Communities. While chemosynthetic communities are unique and 

important, non-chemosynthetic communities dominate the Gulf seafloor. As already 

mentioned, the DGoMB study will produce a wealth of information about the structure and 

function of soft sediment communities in the deep Gulf. This information will be essential 

for designing experiments and precision sampling studies and constructing models to 

measure the effects of deepwater drilling in a more direct way. It is clear that long-term 

datasets and an ecosystem-wide understanding of pattern, process and scale are essential to 

assess impacts. 

Most of our discussion centered on recently discovered habitats and ecological coupling 

among these habitats. William Schroeder briefed us on Lophelia (non-reef building coral) 

colonies, which may be widespread in the deep Gulf. They remain poorly know in terms of 

their biology and distribution, and have become an international priority for conservation. 

Other novel Gulf habitats include iron stone pavements, brine pools, gas hydrates, carbonate 

outcrops, oxygen minimum zones, and a huge range of topographic features including small 

bathyal basins, furrows, knolls and escarpments. Shipwrecks may provide information about 

patterns of ecological succession in hard-substrate communities and provide valuable 

information about whether or not they afford value as deepwater artificial reefs. Industry is 

interested in this issue, because future decisions will need to be made on whether or not 

deepwater subsea equipment will need to be, or should be, removed at the end of the oil 

fields lifespan. 

It is important to recognize, as already shown with seep and surrounding soft-sediment 

communities, that the rich variety of deep Gulf habitats collectively form the landscape level 

of biodiversity, and not a group of isolated entities. The ecological linkage between habitats, 

for nutrient availability and species range maintenance, is vital to the persistence of species, 
73 

and hence communities. We need to know much more about these unique habitats and their 

functional role in landscape biodiversity in order to predict the effects of disturbance from 

deepwater drilling. 

Recommendations of the Benthic Systems Session 

• Design studies to distinguish the disturbance by drilling from natural cycles. 

• Extend investigations to chemosynthetic systems below 1000 m. 

• Improve our understanding of ecosystem function and biodiversity at the landscape level. 

• Update plans for future studies after receipt of the DGoMB final report. 

References

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Williams, C. Doyle and M. Dorner. 2002. Deepwater Gulf of Mexico 2002: America's 

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Management Service, Gulf of Mexico OCS Region, New Orleans, Louisiana, 133 pp. 

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environmental biologists. Journal of Environmental Management 16:35-43. 

Carney, R. S. 1997. Workshop on environmental issues surrounding deepwater oil and gas 

development: Final report. OCS Study MMS 98-0022. U.S. Department of the Interior, 

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pp. 

Cohen, J. 1977. Statistical power analysis for the behavioral sciences. Academic Press, New 

York. 

Cosson-Sarradin, N., M. Sibuet, G. L. J. Paterson and A. Vangriesheim. 1998. Polychaete 

diversity at tropical Atlantic deep-sea sites: environmental effects. Marine Ecology Progress 

Series 165:173-185. 

Cronin, T. M. and M. E. Raymo. 1997. Orbital forcing of deep-sea benthic species diversity. 

Nature 385:624-627. 

Frankham, R., J. D. Bollou and D. A. Briscoe. 2002. Introduction to conservation genetics. 

Cambridge University Press, Cambridge. 

Gage, J. D. and P. A. Tyler. 1991. Deep-sea biology. Cambridge University Press, Cambridge. 

Grassle, J. F. and N. J. Maciolek. 1992. Deep-sea species richness: regional and local diversity 

estimated from quantitative bottom samples. American Naturalist 193:313-341. 

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Programme. Cambridge University Press, Cambridge. 
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Levin, L. A., R. J. Etter, M. A. Rex, A. J. Gooday, C. R. Smith, J. Pineda, C. T. Stuart, R. R. 

Hessler and D. Pawson. 2001. Environmental influences on regional deep-sea species 

diversity. Annual Review of Ecology and Systematics 32:51-93. 

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Lubchenco, J., A. M. Olson, L. B. Brubaker, S. R. Carpenter, M. M. Holland, S. P. Hubbell, S. 

A. Levin, J. A. MacMahon, P. A. Matson, J. M. Melillo, H. A. Mooney, C. H. Peterson, H. 

R. Pulliam, L. A. Real, P. J. Regal and P. G. Risser. 1991. The sustainable bioshpere 

initiative: an ecological research agenda. Ecology 72:371-412. 

MacAvoy, S. E., R. S. Carney, C. R. Fisher and S. A. Macko. 2002. Use of chemosynthetic 

biomass by large, mobile, benthic predators in the Gulf of Mexico. Marine Ecology Progress 

Series 225:65-78. 

Meffe, G. K. and C. R. Carroll. 1997. Principles of conservation biology. Sinauer, Sunderland, 

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National Research Council - National Academy of Sciences (NRC). 1995. Understanding 

marine biodiversity. National Academy Press, Washington, D.C. 

Norse, E. A. (Ed). 1993. Global Marine Biological Diversity: A strategy for building 

conservation into decision making. Island Press, Washington, D.C. 

Raymo, M. E., S. Carter, D. W. Oppo and J. McManus. 1998. Millennial-scale climate 

instability during the early Pleistocene epoch. Nature 392:699-702. 

Rex, M. A., R. J. Etter and C. T. Stuart. 1997. Large-scale patterns of species diversity in the 

deep-sea benthos. Pp 94-121, in: R. F. G. Ormond, J. D. Gage and M. V. Angel (Eds.), 

Marine biodiversity: patterns and processes. Cambridge University Press, Cambridge. 

Rex, M. A., C. T. Stuart and G. Coyne. 2000. Latitudinal gradients of species richness in the 

deep-sea benthos of the North Atlantic. Proceedings of the National Academy of Sciences 

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Rex, M. A., C. T. Stuart, R. R. Hessler, J. A. Allen, H. L. Sanders and G. D. F. Wilson. 1993. 

Global-scale latitudinal patterns of species diversity in the deep-sea benthos. Nature 

365:636-639. 

Smith, K. L., Jr. and R. S. Kaufmann. 1999. Long-term discrepancy between food supply and 

demand in the deep eastern North Pacific. Science 284:1174-1177. 

Smith, K. L., Jr., R. S. Kaufmann, R. J. Baldwin and A. F. Carlucci. 2001. Pelagic-benthic 

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Stewart-Oaten, A., W. M. Murdoch and K. R. Parker. 1986. Environmental impact assessment: 

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Underwood, A. J. 1996. On beyond BACI-sampling designs that might reliably detect 

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Detecting Ecological Impacts. Academic Press, San Diego. 

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Workshop on Deepwater Environmental Studies Strategy: Ecology Breakout Group 

Click on the title to view the presentation. 

Workshop on Deepwater Environmental Studies Strategy: 

A Five-Year Follow-Up and Planning for the Future

Ecology Breakout Group

Co-Chairs:

Robert Avent, Minerals Management Service,

Michael Rex, University of Massachusetts

James P. Ray, Shell Global Solutions (US) Inc.

Jeff Childs, Minerals Management Service

Recorder:

Margaret Metcalf, Minerals Management Service
76 

Pelagic Systems: Ecology Breakout Subgroup 

Chair: Jeff Childs, Minerals Management Service 

Humans have plied oceanic waters (greater than 200 m in depth) of the northern Gulf of Mexico 

for centuries, but, their presence at any one site has been ephemeral, lasting perhaps seconds to 

minutes to hours. The advent of placing semi-permanent fixed and floating OCS structures in 

the oceanic waters of the northern Gulf introduces an ongoing human presence, unlike that 

experienced in the past. And, like other frontier areas that humans have settled and developed 

elsewhere, there will be environmental impacts to the oceanic areas of the northern Gulf 

resulting from the introduction of semi-permanent OCS structures and ensuing associated 

activities. These impacts may be greatest to pelagic organisms, which by definition includes the 

flora and fauna inhabiting the open waters of the ocean. Many organisms live part, if not all, of 

their existence in the water column. For example, pelagic fauna include, but are not limited to, 

sperm whales, sea birds, tuna, grouper, flounder, crabs, bryozoans, and corals. Some benthic 

organisms, such as many corals, which are regarded as sessile (i.e., stationary) organisms, may 

undergo a pelagic stage early in life, after being spawned by sessile parents. Coral “spat” may 

then settle on a substrate whereby they affix themselves and may eventually form a colony. For 

many species undergoing a pelagic phase in life, that phase frequently occurs when they are 

neonates and juveniles; life history stages that are most vulnerable to various impact vectors that 

can have sub-lethal and lethal effects. 

The Pelagic Systems Session was tasked with identifying data gaps and useful syntheses of 

information relevant to the expansion of OCS Industry activities into oceanic waters of the 

northern Gulf of Mexico and potential environmental impacts associated with that expansion, so 

that such information might form the basis for future environmental studies. The session was 

attended by industry representatives, marine scientists, and government regulators, who 

identified basic and applied scientific information needs associated with the topic. The 

participants also ranked information needs based on their knowledge of existing information and 

opinions. 

The basic information needs recognized in the Pelagic Systems Session primarily focus on 

identifying and understanding baseline environmental patterns and processes in the oceanic 

waters of the northern Gulf. Some information needs reinforce those identified in the Gulf of 

Mexico Deepwater Operations and Activities Environmental Assessment (MMS 2000-001). 

Participants in the Pelagic Session emphasized the need for magnifying the scale of resolution 

concerning biotic distributions. For example, an atlas delimiting the three-dimensional 

distributions and abundances of each life history stage of keystone species would provide better 

information for management decisions. Studies to identify marine wildlife-habitat associations 

are very much needed. Such information, will improve our ability to assess the individual or 

cumulative impacts that semi-permanent fixed or floating OCS structures or associated activities 

may have on marine wildlife or their habitats. Specific information needs distinguished by 

participants of the Pelagic Systems Session include: 
77 

I. Three-dimensional hydrographic mapping of currents of the Gulf of Mexico 

II. Production of an ecological atlas of the Gulf of Mexico to include: 

a. GIS mapping of biotic resource distributions and abundances 

b. Three-dimensional ecological mapping of living resources at various scales (e.g., 

community, assemblage, species, population, sex, life history stage) that include: 

i. delineation of biotope types 

ii. vertical & horizontal distributions and abundances 

iii. temporal (e.g., seasonal) distributions and abundances 

iv. scalar patterns of distribution relative to phys-oceanographic and 

bathymetric features (e.g., sperm whale cow and calf pairs relative to 

warm and cold core water masses) 

III. Fish & wildlife-habitat association studies 

a. delineation of important habitat areas by use (e.g., mating, nursery, feeding, etc.) 

b. biotic (e.g., community, assemblages, species, populations, life history stages, 

sexes) vs. abiotic (e.g., physical-oceanographic and bathymetric) patterns and 

associations 

IV. Pelagic-benthic linkages 

a. Energy pathway studies: to include investigations within oceanic provincial 

ecosystem, as well as between neritic and oceanic provinces 

i. Food web modeling 

ii. Stable isotope studies 

V. Information search and synthesis of survey methodologies available for studying 

pelagic organisms 

VI. Identification of / monitoring of keystone species or assemblages representative of the 

oceanic Gulf for assessing changes in the ecology of the region. 

a. Bluefin / yellowfin tuna 

b. Sperm whale / beaked whales / Bryde’s whale 

c. Leatherback sea turtle 

d. Squid 

e. Grouper 

f. Billfishes 

g. Oceanic Sharks 

h. Mesopelagic crustaceans 

Applied information needs requiring scientific study include a diverse range of topics. Chief 

among these is the potential for semi-permanent fixed or floating OCS structures to function as 

artificial islands to Caribbean species that have yet to colonize continental shelf waters of the 

northern Gulf of Mexico. The Loop Current may transport non-indigenous species from the 

Caribbean Sea or Yucatan Peninsula to OCS structures placed in oceanic waters of the northern 

Gulf which may then be utilized by the non-indigenous species for dispersal into continental 

shelf waters of the northern Gulf. Such introductions may have a profound and significant 

impact on endemic populations, species, assemblages, or communities. Also important, are 

studies to investigate the potential effects that these structures may have upon the behavior of 

highly migratory species of fishes, birds, sea turtles, and marine mammals in the region. For 

example, will the placement of semi-permanent OCS structures in oceanic waters modify 

migratory behavior or movements of these creatures? The effects of anthropogenic sources of 
78 

noise continue to be a growing concern with respect to marine mammals and sea turtles; such 

studies were previously described in the Gulf of Mexico Deepwater Operations and Activities 

Environmental Assessment (MMS 2000-001). Applied information needs, as identified and 

ranked by order of importance by participants of the Pelagic System Session are: 

Positive / negative impacts of oil & gas structures / activities in oceanic province 

- Species introductions / re-distributions 

- non-oceanic species (e.g., reef creatures) 

- Caribbean species not occurring in northern GOM 

- Recruitment / survivorship 

- Sargassum assemblages including sea turtle hatchlings and juvenile 

fishes 

- planktonic larvae 

- “Sanctuary effect” 

- New habitat and niche space 

- Modification of behavioral ecology 

- Movement / migration 

1. Fish Aggregating Devices: Migratory distractions? 

2. seabirds and neo-tropical migratory birds 

3. marine mammals & sea turtles 

- Noise 

- noise measurements of: 

1. ambient and biogenic sources 

2. subsea structures 

3. floating structures 

4. catenaries / anchoring systems 

5. pipelines 

6. service vessel traffic 

7. helicopter traffic 

- Fisheries 

- commercial & recreational fisheries 

- socioeconomic aspects 

- stocks 

- stock assessments 

- Biotechnology 

- use of biofouling organisms for medical / commercial uses 

- Physical impacts 

- entanglement of large whales in catenaries or anchoring systems 

- vessel strikes 

- Fate & effects of hydrocarbon spills to pelagic species and the oceanic 

ecosystem 

- Structure removals 

- Impacts from methodologies (explosive / non-explosive) 

- Removal vs. leave-in-place 
79 

Participants of the Pelagic Systems Session also identified some general recommendations 

relevant to the development of environmental studies stemming from the Workshop. 

Specifically, these involve: 

I. Investigate what other agencies / entities are doing to investigate these topics 

(NOAA/NMFS/NOS/USGS/US Navy/NSF/ etc.) 

II. Collaborate with other agencies / entities to pool resources and funding; this should 

include collaboration with other countries bordering the GOM (e.g., Mexico and 

Cuba). 

III. Make data (not just reports) available to all...agencies, academics, etc. 

Presentation Not Available
80 

Geology/Geohazards Breakout Group 

Co-Chairs: 

Bill Bryant, Texas A&M University 

Sarah Tsoflias, Minerals Management Service 

Jim Niemann, ChevronTexaco 

Recorder: 

T. J. Broussard, Minerals Management Service

Geohazards of the Continental Slope and Rise, Northern Gulf of Mexico 

The engineering and geological constraints on the continental slope off Texas and Louisiana 

related to hydrocarbon recovery will require both novel geological and geophysical surveys and 

engineering methods. Significant seafloor engineering problems in deep water include slope 

instabilities, both short-term (slump) and long-term (creep); pipeline spanning problems; mass 

transport from unknown causes; and unusual stiffness and strength conditions (Dunlap 97). The 

geohazards (engineering and geologic constraints) present in and on the central and western 

continental slope and rise are many in number and are mainly due to the activity of salt and rapid 

sedimentation. Specific examples include: faults (sediment tectonics, halokinesis); slope 

stability (slope steepening, slumps, creep, debris flow); gassy sediments (sediment strength 

reduction, hydrates, sediment liquefaction); fluid and gas expulsion features; diapiric structures 

(salt, mud, hydrates); seafloor depressions (blowouts, pockmarks, seeps); seafloor features 

(sediment waves, differential channel fill, brine-low channels, seabed furrows); shallow water 

flow; and deep water high-velocity currents (mega-furrows, seabed erosion). 

Information “Needs” Identified at the 1997 Workshop and Progress 

Mass Movement Processes: The most impressive research on mass movement processes is the 

extensive investigation of the mass movement processes that had taken place in the British 

Petroleum Mad Dog and Atlantis prospects. The first use of a deep-water AUV to obtain side 

scan sonar, multibeam and subbottom profiles and extensive coring documented extensively the 

mass movement processes active along portions of the Sigsbee Escarpment. These studies will 

be the benchmarks for future investigations. 

Gas Hydrates: Knowledge of Gas Hydrate in the Gulf of Mexico has increased, but questions 

remain. The various DOE projects are well under way and several JIP’s have been announced. 

A major coring cruise of the R/V Marion Dufrense in June 2002 recovered 30 piston cores up to 

44 meters in length in areas of known hydrate presence. Observations using the DSV NR-1, DSV

Alvin and DSV Johnson SeaLink were obtained in hydrate rich environments. Gas seeps were 

identified from satellite observations. Recent observations indicate that not many hydrate sites 

are found in ultra-deepwater GOM and raises the question is Shallow Gas an issue in deepwater? 

Sediment Types: No assertive MMS program or project has addressed the issue of sediment 

types on the continental slope and rise of the Gulf of Mexico. The DGOMB Project supported 

by MMS has sampled several hundred box-core sites on the continental slope; Mississippi Fan 
81 

and the Sigsbee Abyssal Plain have added information on the surficial sediment distribution in 

the Gulf of Mexico. Individual projects at Rice University, Texas A&M University, and the 

Universities of Texas and Louisiana have also pursued this issue. 

Additional Concerns 

Bathymetry: The use of 3D seismic to determine bathymetry is the only effort outside of general 

geohazard surveys to add to our knowledge of the continental slope and rise in the northern Gulf 

of Mexico. 

Instrumentation: Technological and instrumentation improvements have taken great strides in 

the fields of ROV and AUV usage. 

New Issues in Past 5 Years 

Discovery of Mega-furrows and Intense Deepwater Currents 

While collecting data during a deep-tow survey, which consisted of a 3.5 kHz subbottom profiler 

and a 100 kHz side-scan-sonar, of the northern Gulf of Mexico continental slope and rise around 

Bryant Canyon in the spring of 1999, a series of longitudinal mega-bed-forms were observed in 

~3000 m of water along strike at the base of the Sigsbee Escarpment. The mega-bedforms 

surveyed included a field of sedimentary mega-furrows ~10 m deep and ~30 m wide, spaced 

~100 m apart in a field 10-25 km wide, south of the escarpment. Earlier deep tow surveys in 

1997 observed sedimentary furrows proximal to the escarpment north and south of Green Knoll 

in water depths ranging from 1400 m to 1900 m and on the slopes of Vaca Basin. Sedimentary 

furrows are longitudinal bed-forms that occur in fine-grained sediment, and have been observed 

in a wide variety of settings ranging from the deep ocean, to deep lakes, to the Hudson River. 

The existence of furrows in deep sea settings suggest that unidirectional bottom currents exist in 

the range of 1 to 100 cm/sec and higher. Such currents may be continuous or highly episodic, 

and the furrows are inferred to be formed due to helical secondary circulation. Sedimentary 

furrows were first produced in the lab by Allen (1969). Allen found a hierarchy of bed-forms 

ranging from uniform furrows at low flow conditions, to meandering furrows and flute casts; at 

the highest flow conditions, he found sheet flow. All the conditions described by Allen are 

present in the area due south of Bryant Canyon on the continental rise. The significance of these 

features is the high water velocities necessary for their formation and the large amount of erosion 

occurring at the base of the Sigsbee Escarpment. Indications are that the erosional processes are 

active during high-sea stands and depositional and infilling of the furrows are active during lowsea stands. The impact of these features and the currents on pipeline and platform activities may 

be significant. 

An extensive field of mega-furrows has been recently discovered on the seafloor at the base of 

the Sigsbee Escarpment in the northwestern Gulf of Mexico (Bryant et al. 2000). Texas A&M 

deep-tow data and 3-D seismic data supplied by WesternGeco show that the scale of this field far 

exceeds anything previously observed in the world's oceans. These data allow the furrows to be 

resolved in unprecedented detail. The size of the furrows, variations in their morphology, and 

their orientation relative to large topographic features all suggest that the furrows are produced 
82 

by strong deepwater flow. Individual furrows can be traced continuously for at least 50 km on 

the 3-D surface renderings, they are among the longest continuous individual sedimentary bed 

forms on the surface of the Earth. Data from a near bottom current meter confirms that strong, 

previously unknown, currents do exist at the base of the escarpment (Hamilton and LugoFernandez 2001). The furrows and associated environmental processes are dominant features of 

the northwestern Gulf of Mexico and similar features will probably be found to exist in many 

other areas of the world's oceans. 

Current and Future Deepwater Geology and Geohazard Information Needs as of July 2002 

High Priority Items 

1. Slope Stability / Pore Pressure 

2. Sea Floor Morphology 

3. Mega-furrows and Associated Currents 

Slope Stability/Pore Pressure 

MMS Significance: Need for these studies may grow as more deepwater activities face slope 

stability related problems. The complex bathymetry of the upper, middle and lower continental 

slope off Texas and Louisiana related to the halokinesis of allochthonous salt renders many intraslope basins with high-angle basin walls. Slumps and slides are known to have occurred in many 

of the continental intraslope basins. The areas within and around the Mississippi Canyon have 

experienced extensive slope failure. The most important parameters in slope failure are the slope 

angle, the shear strength of the sediment and the pore pressure within the sediment. We know 

the general slope angles of the intraslope basin walls from multi-beam data but know very little 

of the shear strength and pore pressures within the continental slope and rise and along the 

Sigsbee Escarpment. 

Impacts of slope stability on seafloor structures such as pipelines, seafloor templates, BLPs, etc 

is obvious, slumps and slides are extremely powerful events and seafloor structures can rarely be 

designed to withstand such forces. The best approach is locating structures in areas that will be 

least affected by such events. 

Some of the questions that arise: is the data on hand relative to slumping relevant to deep-water 

operations? Are most of the observed slump features older that 2,000 to 10,000 year ago? Are 

slope failures a concern given the deepwater operational timeframe (~100 yrs)? What are the 

affects of high velocity bottom currents on the stability of the Sigsbee Escarpment? 

To partially answer some of these questions we need to examine the knowledge of previous 

investigations/data collections such as was taken by BP for their Mad Dog and Atlantis 

Prospects. These two studies set the benchmark for future slope investigations. 

A forum on “RISK ASSESSMENT FOR SUBMARINE SLOPE STABILITY” was held in 

Houston, Texas on May 10 and 11, 2002 and was sponsored by the Minerals Management 

Service. The following is part of the summary of the report following the meeting. 
83 

The Forum brought together a number of participants with broad views and backgrounds related 

to issues of risk assessment for slope stability in deep water. In reality the field is even much 

broader than represented by the participants. Views ranged from relatively narrow, well-focused 

views of technological needs in specific areas to broader views of issues such as integration and 

planning. Based on the discussion over the course of the Forum at least several observations 

were made: 

• There is a need for better integration of geological, geotechnical, and geophysical data 

gathering and interpretation. The high cost of obtaining these data limits how much can 

be obtained and requires that the information be integrated to optimize its usefulness. 

• There is a need for more advanced planning and investigation. "Paper" or "desktop" 

studies and studies in the very early stages of planning should improve the understanding 

and maximize what can be learned. Often there is neither time nor money to do as 

thorough an investigation as might otherwise be possible. 

• The understanding of properties and processes at a single, site-specific point is very good 

compared to the understanding of properties and processes both spatially and temporarily. 

While additional resources might improve on this, better integration of data and earlier 

starts to investigations could also help. 

• There is still need for improved technology and more data collection. How pore 

pressures develop and how soils behave as failure progresses, e.g., a change of state from 

a solid to a fluid, are examples of where further investigation is warranted. There is also 

need for fundamental understanding of the triggering mechanisms for slope failure and 

how that slope failure progresses. 

• Standards comparable to those that have been developed for foundations and for risk 

assessment for earthquakes would be beneficial and probably could be developed even 

with the present state of knowledge. 

• There is a lack of well-documented case histories. Often the triggering mechanisms are 

unknown and there is usually a paucity of good geological, geotechnical or geophysical 

data. In some instances well-documented cases may exist, but are not in the public 

domain and thus, not available to many. 

Sea Floor Morphology 

MMS Significance: Detailed Bathymetry Data is an underlying need for several Deepwater 

Research areas (i.e., currents, biological interactions); would assist preliminary operations 

planning. 

There are large gaps in Western and Eastern Gulf of Mexico bathymetry data that generally 

include areas outside the NOAA multibeam data set taken a decade ago. The NOAA multibean 

bathymetry is the best data on hand that covers a good portion of the continental slope off Texas 

and Louisiana. 

The highest resolution bathymetry available, besides AUV and Deep-Tow data sets, is the use of 

surface extraction of 3D seismic data sets taken by the seismic industry. The need for 

information sharing of bathymetry data extrapolated from existing 3D surveys would help to 

determine basic seafloor morphology, planning with regards to pipeline installation and routing 
84 

and slope stability analysis and many other benefits. The resolution of the 3D bathymetry is an 

order of magnitude better than the existing NOAA multibeam data. Attempts should be 

undertaken to investigate how the seismic industry could benefit thru the release of 3D 

bathymetry data sets. 

Mega-Furrows and Associated Currents 

The Mississippi Fan Fold Belt/Green Canyon area of the Sigsbee Escarpment is the primary area 

of ultra-deepwater oil and gas prospects in the United States. In this area and the rest of the 500 

km long escarpment as well, an extremely large field of mega-furrows on the seafloor and 

associated strong bottom currents have recently been discovered. Existing seismic data is 

limited, but initial analysis of it indicates that mega-furrows are long, relatively narrow 

depressions in the seafloor that are generally oriented parallel to the escarpment. Individual 

mega-furrows are ~1 to 10 m deep and ~5 to 50 m wide with ~20 to 200 m between individual 

furrows. The whole field of furrows appears to cover an area in excess of 15,000 km2

. 

Extremely limited current velocity measurements show that near bottom currents can exceed 2 

knots (100 cm/sec). The spatial variations of furrow topography have not been characterized and 

the spatial and temporal variations of the bottom water flow field are also unknown. Knowledge 

of the spatial and temporal variations of furrows is necessary to understand the processes 

forming furrows and to predict the variations of sediment properties with depth below the 

seafloor. It will also provide important insight into the geological development of the 

continental rise. 

There are significant practical reasons to better understand the mega-furrows and associated 

strong currents along the base of the escarpment and in other areas where strong currents erode 

muddy sediments. The following are several technical and environmental concerns associated 

with the furrows and associated currents: 

• Extreme topographic relief and strong flow affects the pattern that cuttings and drilling 

mud might be deposited on the seafloor, 

• Topographic relief and strong flow complicates the design and installation of pipelines, 

• Erosional scour affects stability of pipelines, foundation piles, and seafloor installations, 

• Slope undercutting by erosional scour potentially leads to hazardous slumps and slides, 

• Strong bottom-water flow may produce vortex-induced vibrations that cause fatigue and 

failure of riser strings, platform tension legs, and anchor cables, 

• In several recent instances, strong currents prevented the use of industrial type remotely 

operated vehicles (ROVs) intended to assess geohazards and inspect seafloor 

installations, 

• Observational data derived from study of the furrows and associated strong bottom water 

flow will provide valuable data for calibration and validation of numerical models used to 

predict trajectories of pollutant plumes, 

• To better understand the significance of channelized density flows related to the leaching 

of exposed salt along the Sigsbee Escarpment. 

The Geology/Geohazards Breakout Group addressed several additional topics of concern 

including: 
85 

1. groundtruthing geophysical signatures indicative of sensitive biological features, 

2. knowledge of canyons and associated currents, 

3. naturally occurring gas hydrates, 

4. subsidence associated with petroleum extraction, 

5. shallow water flows, 

6. salt movement and rheology, 

7. shallow gas hazards in the deepwater Gulf of Mexico (GOM). 

Subsidence and salt movement were cited as potential future problems as development and 

production of hydrocarbon progresses throughout the deepwater GOM. A similar MMS 

Deepwater Workshop in 1997 discussed gas hydrates, gas hazards and shallow water flows but 

additional information, experience and improved processes have reduced the scope and 

uncertainty of these problems. The advance of technical instrumentation and seismic data has 

revealed potential new concerns as well as the opportunity to better characterize, evaluate and 

protect valuable economic and biological assets. 

Groundtruthing Geophysical Signatures Indicative of Biological Features 

The Geology/Hazards Subgroup suggests a study to correlate and compare seismic signatures 

and attributes with known ocean floor biological communities. This study would guide the 

MMS in developing effective and appropriate avoidance regulations, least disruptive pipeline 

right-of-ways and more effective focusing of marine biologic research. Subset structures such as 

wellheads, flow lines, manifolds in addition to anchors and mooring lines must be located away 

(500 feet) from suspected ocean bottom dwelling biological communities. These communities 

can be inferred from seismic bathymetry data and side scan sonar imagery of faults scarps, gas 

vents or oil seeps that may support a biological community. In addition seismic amplitude plots 

of the seafloor reflection may be indicative of gas charged sediment, hydrates or carbonate 

accumulation associated with biological activity. 

Positive verification of biological activity inferred by acoustic signatures require expensive 

remote-operated vehicles (ROVs) or manned submersible dives to obtain visual identification or 

more disruptive piston core and grab sampling. A comprehensive study of seafloor biological 

communities correlated with their seismic characteristics including amplitude, structure, dip, 

coherence and other attributes would be extremely useful for groundtruthing seismic 

investigations elsewhere. Such a study would dramatically increase the value of 2D and 3D 

seismic surveys to map out seafloor biological communities without additional expense or 

disruption to the environment. Calibration of the vast amount of available 3D seismic data could 

afford marine researchers a tremendous opportunity to conduct regional ecological surveys 

across much of the U.S. deepwater Gulf of Mexico. 

Canyons and Associated Currents 

Detailed studies of canyons and their associated currents will lead to better understanding of 

upwelling, nutrient cycles and the links to marine biology and ecology. There is now an 

opportunity with prolific seafloor bathymetry data from regional speculative 3D seismic surveys 

and the increased interest and study of deepwater bottom currents associated with mega furrow 
86 

structures to understand and map out the interactions of GOM continental slope canyons, their 

associated currents and the impact on marine ecology. 

Naturally Occurring Gas Hydrates 

Naturally occurring gas hydrates and associated gas trapped beneath hydrates pose a potential 

hazard to well bore stability while drilling and during production. These hydrates also represent 

a possible significant energy resource for the future. The 1997 MMS Report on Environmental 

Issues in Deepwater cited gas hydrates as a potential and largely unknown hazard to installations 

and operation in the deepwater environment. Gas hydrates are crystalline solids composed of 

gas molecules (usually methane) enclosed in a lattice of water molecules. These substances can 

only exist where there is a supply of hydrocarbon (gas) at extremely low temperatures or 

relatively low temperatures and high pressures. The GOM continental slope is ideal for hydrate 

formation with nearly freezing temperature, high pressure and potential sources of gas from 

bacterial generation and migration of thermogenic hydrocarbon from vents and seeps along faults 

and fault complexes. 

Observations from coring studies and industry exploration drilling suggest very little volume of 

hydrate in the ultra-deepwater GOM sediments. Most documented hydrate occurrences on the 

continental slope are associated with hydrocarbon seeps and vents along fault scarps, at the 

fractured margins of tabular salt bodies and at the top of salt sheets. These hydrate occurrences 

appear to be mostly surface occurrences rather than thick layers, although sparse data from 

shallow logs and drilling returns does not definitively rule out the presence of pervasive hydrate 

in the subsurface. The scarcity of shallow gas sands (relative to the shelf) in deepwater 

sediments suggests a relatively small supply of gas in ultra-deepwater sediments. In addition, the 

presence of tabular salt bodies across a vast section of ultra-deepwater area precludes the 

migration of significant thermogenic hydrocarbons to the shallow sediments (except along faults 

and the margins of salt bodies) where temperatures are low enough for hydrates to form. Beyond 

the salt escarpment, hydrocarbon source beds are not believed to be sufficiently mature to 

generate significant gas to the shallow section. 

In addition to the studies mentioned above, ChevronTexaco has been contracted by the DOE to 

conduct a Joint Industry Project (JIP) study of naturally occurring hydrates in the Gulf of 

Mexico. The goals of this JIP are to: 

• Develop technology to characterize naturally occurring deepwater hydrates in the GOM, 

• Understand how natural gas hydrates affect seafloor stability, 

• Gather data to aid climate studies, 

• Determine how gas hydrates might act as trapping mechanisms for shallow oil or gas 

reservoirs. (http://www.theenergyforum.com/hydrates_032002/WorkshopReport.pdf) 

Gas hydrates remain a concern for the long-term stability of selective deepwater subsea facilities 

and operation. The relative scarcity of subsurface hydrate in the deepwater GOM, as seen by 

exploratory drilling, mitigates the concern that hydrates are a pervasive geohazard, a threat to 

global warming and casts doubt on the hope of hydrates as a significant future gas resource (for 

the Gulf of Mexico). Current research efforts and existing geohazard identification practices 
87 

appear adequate at this point to address present and potential future hazards to deepwater GOM 

development. 

Long Term Subsidence Associated with Petroleum Extraction 

Production of hydrocarbons from shallow, thick, overpressured reservoirs could induce 

subsidence at the seafloor negatively impacting subsea production facilities, wellheads, 

producing well bores, and pipelines. The earth’s stress field has three basic components: the 

overburden or total stress (caused by the overlying weight of sediment and water), the pore 

pressure, and the effective stress (portion of stress borne by the sediment framework). Effective 

stress is equivalent to the overburden minus the pore pressure. As oil and gas is produced from 

reservoirs, the reservoir pressure may drop significantly over time increasing the effective stress. 

Porosity is exponentially related to the effective stress (Terzaghi and Peck 1948), so as the 

effective stress increases, porosity decreases and the reservoir (along with some portion of the 

bounding sediment) will compact. This compaction deformation will be transmitted (to more or 

less degree) through the overlying overburden to the surface as subsidence. Several workers 

(Geertsma 1973; Martin and Serdengecti 1984) have shown that the magnitude of the subsidence 

is related to the depth of burial, the degree of pressure decline, the consolidation state of the 

sediment, and the ratio of the thickness of reservoir to its area extent or diameter. 

Spectacular examples of subsidence due to oil production exist in California, most notably the 

Wilmington field near the city of Long Beach (http://www.ci.long-beach.ca.us/oil/subsidence. 

html). International examples include the Groningen gas field in the Netherlands, the Bolivar 

Coastal oil field in Venezuela and the Po Delta field in Italy (Xu et al. 2001). In the Gulf Coast, 

Pratt and Johnson (1926) documented about 1 meter of subsidence at the Goose Creek field near 

Galveston, Texas. Offshore, subsidence of >8 meters at the Ekofisk field in the North Sea has 

required an expensive program of initial platform jacking (6 meters) plus water and gas injection 

and extensive redevelopment (Balson et al. 2001). The Louisiana Division of Natural Resources 

(DNR) reviewed subsidence associated with oil and gas production in Louisiana and concluded 

that subsidence is probably widespread but so minimal that it is not likely to be noticed (http:// 

www.dnr.state.la.us/SEC/EXECDIV/TECHASMT/lep/subsid/subsid.htm). The DNR cites 

Martin and Serdengecti’s (1984) analysis of Louisiana oil and gas reservoirs that showed that 

most reservoirs in South Louisiana are deeply buried, relatively thin, have low thickness to areal 

extent ratios, and are normally (hydrostatically) pressured often with strong water drives (thus 

maintaining pressure through production decline). Reservoirs in North Louisiana tend to be 

shallowly buried but the reservoirs are well consolidated and do not compact as readily with 

pressure decrease. All these factors tend to reduce the amount of reservoir compaction 

associated with extraction or mute the subsidence response at the surface. Operators in 

California and other parts of the world have minimized and in some cases reversed the effects of 

subsidence by artificially maintaining or increasing pressures in the formation reservoirs through 

gas or water injection, restraining production to allow water driven mechanisms to keep up with 

hydrocarbon extraction or ceasing production altogether (Poland 1984). 

Xu et al. (2001) modeled subsidence in the Lost Hills/Belridge oil field area of Southern 

California as a function of the depth, radius of the reservoir, Poisson’s Ratio, pressure drop due 

to production, thickness of the reservoir and Young’s Modulus. They found good agreement of 
88 

the predicted subsidence from pressure decline in the field with the actual subsidence measured 

by satellite radar interferometry. 

Hydrocarbon reservoirs in the deepwater GOM typically are overpressured and undercompacted 

(with high porosities) even at shallow depths due to the rapid loading of deepwater sediments in 

intraslope salt basins and the poor hydraulic conductivity of the sand poor sedimentary section. 

Many reservoirs may be at shallow depths relative to seafloor. Due to large reserve requirements 

for commercial deepwater development and the often restricted areal extent of deepwater sand 

distribution, deepwater producing reservoirs likely will have high thickness to areal extent ratios. 

Other reservoirs however reside at great depths below the seafloor or may be covered by layers 

of mobile salt that will prevent compaction from inducing subsidence at the seafloor. 

It is clear that there is potential for subsidence associated with production from deepwater GOM 

reservoirs but the magnitude of the subsidence and its impact on facilities is unclear. The critical 

factors in surface subsidence appear to be well understood and the MMS may have sufficient 

information in its databases to assess the long term risk for subsidence in existing deepwater 

producing fields. Given the level of understanding of the problem and potential solutions, 

subsidence due to oil and gas production may become a problem for select producing fields; 

however, it is unlikely to be a constraint or barrier to development and production across the 

deepwater Gulf of Mexico. 

Shallow Water Flows 

Shallow water flows are flows of water, gas and/or sand from shallow buried, overpressured 

sands in a deepwater setting, Shallow, overpressured sands are common in the deepwater where 

isolated sand bodies are deposited and encased in sealing shales and rapidly loaded by overlying 

sediments (Alberty et al. 1997). Well bore flows generally are prevented by the circulation of 

dense, weighted (greater than seawater) drilling muds down through a large pipe (marine riser) 

extending from the drilling rig through the water column to the wellhead on the seafloor. If the 

pressure exerted by the mud column is greater than the pressure in the permeable formation, the 

well bore will not flow. However, the consolidation and fracture strength of shallow, deepwater 

sediments is not sufficient to hold the pressure of a weighted mud column from sea level without 

fracturing and allowing fluids to escape to the seafloor. Therefore the first 1500-3000’ of section 

below the mudline must be drilled without a riser pipe using seawater as the drilling fluid and 

risking the occurrence of flows from overpressured sands. Flows can range from gas bubbles to 

minor wispy flows to major turbulent flows that eject tremendous quantities of sand, mud, gas 

and formation water. 

Deepwater, shallow water flows are primarily a conservation issue with subsidiary 

environmental and safety concerns. A shallow water flow necessitates time consuming, 

expensive circulation of heavy drilling mud in the open hole to “kill” the flow. If the flow 

cannot be controlled or plugged, then the well bore may be abandoned and a new hole drilled. 

Even if the flow is stopped, significant sediment may be eroded from the borehole to create a 

large void down hole that cannot be cemented behind pipe. The flow may resume (now behind 

pipe) as the weighted mud is displaced by lighter, less dense cement requiring additional 

cementation, circulation of mudweight behind pipe, and redrilling of the hole. Alternately the 
89 

well bore may buckle because of inadequate support from the sediment as additional pipe weight 

is added to the wellhead. This can lead to junking of the well before objectives are reached or 

make the well unusable for future completion and production operations. Additional 

consequences include the ejection of sediment, formation and drilling fluids on the seafloor. 

The MMS has sponsored and participated in a number of forums devoted to the understanding 

and prevention of shallow water flow. In addition, the industry has gained experience in drilling 

and mitigating shallow water flows and the adverse consequences of those flows. The primary 

method for prevention of shallow water flow is detailed seismic stratigraphic evaluation from 

exploratory 3D and/or high resolution 2D or 3D seismic. Drill locations can be selected to avoid 

or minimize the penetration of sedimentary facies that have a high risk for shallow water flow. 

Where moderate to high shallow water flow potential sites cannot be avoided, dense drilling mud 

can be pumped down the drill string while drilling in a riserless mode with the mud returning to 

the wellhead and depositing on the seafloor. The combination of low seawater pressure gradient 

in the ocean column and the higher pressure gradient of the heavy drilling mud yields an 

effective down hole pressure gradient sufficiently high enough to prevent formation water flow 

but not high enough to break down the weak, shallow formation. Drilling mud can be circulated 

at the first sign of flow detected by annular pressure monitored in real time down the hole or 

visually from a ROV monitoring the wellhead. Drilling mud may also be circulated at a 

predetermined depth to preemptively avoid the possibility of shallow water flow. 

Shallow water flow sands remain a cost and drilling risk concern for deepwater drilling and 

development; however the issue now is considered an engineering constraint rather than a barrier 

to deepwater development and production. 

Salt Movement and Rheology 

Salt movement is a concern for seafloor modification and initiation of slope failure impacting 

pipelines and sea floor facilities. Movement of salt may initiate fault movement causing 

deformation and possible shearing of well bores. Movement of salt bodies at or near the seafloor 

causes deformation and disruption to sediments and the seafloor that readily can be observed 

from seafloor bathymetry maps and seismic cross sections. The time scale and rate of movement 

of salt deforming the seafloor needs to be studied to determine what impact, if any, will be had 

on casing, flow lines, subsea structures and pipelines. 

Other features related to salt movement and rheology may also impact drilling and development 

operations. Shale inclusions, sutures (sediment entrained between merged salt bodies) and 

subsalt deformation zones may exhibit abnormally high pore pressures and/or abnormally weak 

formation integrity resulting in increased drilling costs, time and possible abandonment of 

resource objectives. 

There is a great deal of research on salt movement and rheology related to salt mining, basin 

modeling and petroleum extraction which will not be reviewed here. Very little work however 

has focused on the impact of salt movement for drilling and producing operations in the 

deepwater marine environment. Although most impacts to deepwater operations by salt 
90 

movement may turn out to be engineering constraints rather than barriers, the long term impact 

of salt movement to subsalt oil field development and production remains to be determined. 

Shallow Gas Hazards in the Ultra-Deepwater GOM 

Shallow gas sands are a significant safety hazard on the shelf for bottom-founded drilling rigs 

and production platforms. The shallow hazard/geotechnical evaluation industry and the 

extensive geotechnical regulatory framework have developed largely in response to this 

particular hazard. In the deepwater, the utilization of floating drilling and production structures 

mitigates much of the safety concern associated with breaching of the seafloor; however shallow 

gas sands remains a concern for subsea blowouts and well control. Deepwater operators 

frequently have encountered shallow water flow sands (often with associated gas) but rarely have 

encountered shallow gas reservoirs. Partly this may be a function of industry avoidance of 

obvious seismic amplitude (“bright spots”) anomalies in the shallow seismic section. It may also 

be a function of scarce gas in the shallow section either due to the blocking of thermogenic gas 

by tabular salt sheets mentioned previously or a lack of bacterial generation or activity within 

shallow sediments. The possible suppression of bacterial activity, specifically methane 

generation, by the high pressures and low temperatures of the ultra-deepwater may be a good 

subject for future research. While shallow gas hazards always will pose a concern for marine 

drilling operators, the lack of shallow gas occurrences suggest that shallow gas is not a big 

concern in the ultra-deepwater and/or deepwater operators and regulators are doing a good job of 

prevention and avoidance of shallow gas problems. 

References 

Alberty, M. W., M. E. Hafle, J. C. Minge and T. M. Byrd. 1997. Mechanisms of shallow water 

flows and drilling practices for intervention. Offshore Technology Conference, Houston, 

TX. OTC 8301, Pp. 241-247. 

Allen, J. R. L. 1969. Erosional current marks of weakly cohesive mud beds. J. Sedimentary 

Petrology 39:607–623. 

Balson, P., A. Butcher, R. Holmes, H. Johnson, M. Lewis and R. Musson. 2001. North Sea 

Geology – Strategic Environmental Assessment (SEA2) Technical Report TR_008, British 

Geological Survey. Pp. 14-15. 

Bryant, W. R., T. Dellapenna, A. Silva, W. Dunlap and D. Bean. 2000. Mega-Furrows on the 

Continental Rise South of the Sigsbee Escarpment, Northwest Gulf of Mexico. AAPG 

Annual Meeting, New Orleans La. 

Geertsma, J. 1973. Land Subsidence above compacting oil and gas reservoirs. Journal of 

Petroleum Technology. Pp. 734-744. 

Hamilton, P. and A. Lugo-Fernandez. 2001. Observations of high speed deep currents in the 

northern Gulf of Mexico. Geophysical Research Letters 28:2867-2870. 
91 

Martin, J. C. and S. Serdengecti. 1984. Subsidence over oil and gas field. Review in 

Engineering Geology Volume 6, Geological Society of America. Pp. 23-34. 

Poland, J. F. and Working Group. 1984. Review of methods to control or arrest subsidence, Pp. 

127-130, in Guidebook to Studies of Land Subsidence Due to Ground-Water Withdrawal: 

UNESCO. (Out of print but can be accessed electronically at http://www. 

rcamnl.wr.usgs.gov/rgws/Unesco/). 

Pratt, Wallace E., and Douglas W. Johnson. 1926. Local subsidence of the Goose Creek Oil 

Field. Journal of Geology 34(7, part 1): 577-590. 

Terzaghi, K. and R. B. Peck. 1948. Soil mechanics in engineering practice. John Wiley and 

Sons, Inc., New York, 566 pp. 

Xu, H., J. Dvorkin and A. Nur. 2001. Linking oil production to surface subsidence from 

satellite radar interferometry. Geophysical Research Letters 28(7):1307-1310. 

http://www.indiana.edu/~lcg/ACTIVE/SaltTectonics/salttectonics.html -Indiana University 

Laboratory for computation dynamics. 

http://www.geol.lsu.edu/nunn/#Salinity –Jeff Nunn website. 

Workshop on Deepwater Environmental Studies Strategy: Geology/Geohazards Breakout 

Group 

Click on the title to view the presentation. 

Workshop on Deepwater 

Environmental Studies Strategy

Geology/Geohazards Breakout Group

Co-Chairs

Bill Bryant, Texas A&M

Sarah Tsoflias, MMS

Jim Niemann, ChevronTexaco

Recorder

T. J. Broussard
92 

Socioeconomics Breakout Group 

Co-Chairs: 

Steve Murdock, Texas A&M University 

Harry Luton, Minerals Management Service 

Recorder: 

Connie Landry, Minerals Management Service 

A major theme of the socioeconomic breakout group discussion was the recognition of the 

significant maturation that has occurred in socioeconomic studies in the Gulf of Mexico Region 

(GOMR) over the last several years. Just five years previously, in 1997, the socioeconomic 

breakout group for the MMS Gulf of Mexico Region Deepwater Workshop expressed frustration 

at the lack of completed studies to review. Similar concerns had been expressed previously 

during other reviews and at other workshops. However, by 2002, the picture has changed 

significantly. The last several years have produced a plethora of studies addressing a broad 

range of critical socioeconomic issues. Major themes identified by earlier reviews and 

workshops as necessary areas for research in the GOMR have been or are being addressed by a 

regular stream of studies. Many of these studies are now published and available to the public; 

others will soon be completed. As a consequence, the white paper prepared for discussion at the 

2002 workshop was able to review and evaluate a much larger number of completed studies that 

extend across an impressive range of research issues. The one concern raised by participants at 

the workshop was that of timing; while a number of studies were available for review and 

discussion, a number of others are in the final stages of completion, but were not available to 

review. 

While it would have been nice to have these to include in the review, it was acknowledged that 

much of the growth of the Environmental Studies Program in the GOMR in recent years has 

occurred in the socioeconomic arena. In this sense, the workshop was a celebration of the 

substantial progress that has been and is now being made. 

In the socioeconomic breakout sessions, the white paper was used as a reference point, not as a 

focus of analysis. As described above, it summarizes and critiques work completed to date, and 

identifies future studies that are needed. This was used as a point of departure for the workshop 

discussions. Many of the conclusions and recommendations that emerged from those 

discussions are consistent with findings of the white paper. However, a number of new issues 

were identified, as well. Throughout the sessions, it was acknowledged that many of the gaps in 

research identified in the white paper, and by workshop participants, are being addressed by 

studies currently underway. 

Based on the review of the white paper and group interaction, the following general conclusions 

emerged from the 2002 workshop: 

1. Industry studies have become an important part of the socioeconomic study agenda, and 

should continue to be a key component of the studies program. For example, international 
93 

labor market studies are particularly critical since GOMR oil and gas activity must compete 

with international labor demands. Moreover, it is no longer possible to depend heavily on a 

local labor market, as may have been the case earlier. 

2. Economic studies remain central to the studies program. The studies reviewed in this area 

by the white paper were found to be quite strong; economic projections were particularly 

well-developed. Among the recommendations in this area were the following: a) the cost 

functions study should be updated regularly to keep up with changes in the industry. b) 

Labor needs surveys are important, though there was some discussion of potential need for 

some reconfiguration of this work. c) Projections at the sub-area level are useful, but there is 

a need to develop projections at the local level, as well, if these studies are to be of greatest 

value to local community leaders and decision makers. d) Finally, it was noted that it is 

important to study projects through all phases of their development, and particularly not just 

on the front end. 

3. Demographic studies were described as somewhat weak, both in the white paper and in the 

breakout group discussion, although ongoing studies will partially address these weaknesses. 

Other issues defined as important to examine in this area are in-migration, out-migration, 

population retention, wage pressures, and foreign immigration to meet labor demands. It was 

also noted that demographic changes at the local level are the major cause of public 

infrastructure needs. 

4. Public service needs should be addressed, and are particularly important to local 

jurisdictions. Those identified as most important were health, police and fire protection, 

power, water and sewer, transportation, and education. Workshop attendees agreed that these 

public services should be considered in community-level analyses because of their 

importance at the local level. Education was defined as particularly important and is being 

heavily impacted by demographic changesCfor example, changes in the oil and gas industry 

workforce have resulted in changes in curricular needs. Increasingly, labor needs demand 

more technical preparation, and schools are changing to address these needs. Also, as the 

workforce has become more ethnically diverse, new educational needs have become evident 

as in the need for training in English as a second language. 

5. Fiscal considerations are generally covered quite well in the studies. Because these are 

important as drivers of local community effects, they should continue to be included in the 

research agenda. 

6. Several studies have addressed the attitudes of local populations toward various aspects of 

the oil and gas industry. It has been noted, for example, that attitudes of residents in the Gulf 

area are changing. There is less worker loyalty, largely as a consequence of industry 

restructuring, layoffs, and changing labor needs. Employment in the industry is defined as 

less attractive as a career choice among members of the younger generation. While studies 

of attitudes were recognized as important, workshop participants acknowledged their 

limitations for the EIS process, particularly in light of OMB regulations. 
94 

7. Both the white paper and the workshop discussion concluded that sociocultural impacts are 

the least well-defined. At the same time, they are very important to our understanding of the 

local effects of the industry. Several examples bear this out: a) changes in hiring patterns are 

resulting in more Hispanic and Asian workers in the area. This is changing the local 

cultural/ethnic mix. b) A good deal of work has been done on family impacts associated 

with the industry. For example, several studies have addressed the effects of work patterns 

on family interaction and satisfaction. However, most studies have tended to focus on 

married male workers and their patterns of adjustment, adapting, and coping. Less attention, 

however, has been given to women, singles, minorities, and older workers. c) As noted in 

the discussion of attitudes, worker morale has changed and has been affected by changes in 

the industry-mergers, cost reduction initiatives, fragmentation of work teams, increased 

contract labor, and irregular and call-out work schedules. This affects the ability of the 

industry to attract and retain workers. 

Several important recommendations resulted from the group discussions. These include: 

1. Continuing effort must be made to make study findings a more central part of the EIS 

process. As currently done, the EIS process, and the GOMR socioeconomic studies activities 

almost occur independently of one another. 

2. Efforts must also be made to make the EIS process of greater value to the communities. 

Community leaders and residents should be able to use the EIS findings for planning 

activities more directly. 

3. It was agreed that there is a continuing need for industry studies to monitor change and 

impacts. 

4. Studies are needed to address the long-term role of the oil and gas industry in the Gulf. 

While important historical studies have been conducted, it will be important to address 

longer-term industry impacts on the region. 

5. Additional attention should be given to global competition. Increasingly, this is a global 

economy, and activities in the Gulf are significantly impacted by forces that affect the oil and 

gas industrial worldwide. 

6. MMS should continue efforts in economic impact modeling. After years of not being stateof-the-art in this area, significant progress is now reflected in current studies. The 

development of more sophisticated demographic and public service components of such 

models should be given priority. 

7. Continuing attention should be given to two difficult areas: separation of baseline and OCSrelated development (it was noted in the workshop that may be an almost impossible task), 

and identification of specific impact areas. 

8. Finally, two different approaches were reviewed and recommended in the area of impact 

areas: a) developing a series of comparative case studies that focus on ports; and b) directing 
95 

additional effort to monitoring local jurisdictions and more clearly identifying impacts 

specific to these jurisdictions. 

Workshop on Deepwater Environmental Studies Strategy: Socioeconomic Breakout Group 

Click on the title to view the presentation. 

Workshop on Deepwater Environmental 

Studies Strategy:

SocioEconomic Breakout Group

Overview

Co-Chairs:

Harry Luton, Minerals Management Service

Steve Murdock, Texas A&M University

Recorder:

Connie Landry, Minerals Management Service
96 

VI. Appendices 

Appendix 1. Deepwater Workshop Agenda 

May 29th Morning 

Welcome: William Schroeder 8:30 – 8:40 

 University of Alabama 

Introduction: Chris Oynes, Regional Director 8:40 – 8:50 

 MMS, Gulf of Mexico Region 

Industry Perspective: David Walker 8:50 – 9:10 

 BP America, Inc. 

 Paul Siegele 9:10 – 9:30 

 ChevronTexaco 

DeepSpill Experiment: Dan Allen 9:30 – 9:50 

 ChevronTexaco 

Morning Break: 9:50 – 10:10

Technical Overviews: 

 Physical Oceanography Ann Jochens 10:10 – 10:30 

 Texas A&M University 

 Geology/Geohazards Bill Bryant 10:30 – 10:50 

 Texas A&M University 

 Deep Gulf Ecology Gil Rowe 10:50 – 11:10 

 Texas A&M University 

 Deep Gulf Fisheries Randy Edwards 11:10 – 11:30 

 USGS Biological Resources Division 

 Socio/Economic Steve Murdock 11:30 – 11:50 

 Texas A&M University 

Closing Remarks: William Schroeder 11:50 – 12:00 

May 29th Afternoon & May 30th

Ecology Breakout Group 

Co-Chairs Recorder 

 Michael Rex, University of Massachusetts Margaret Metcalf, MMS 

 Robert Avent, Minerals Management Service 

 James Ray, Shell Offshore 
97 

Geology/Geohazards Breakout Group 

Co-Chairs Recorder 

 Bill Bryant, Texas A&M University T. J. Broussard, MMS 

Sarah Tsoflias, Minerals Management Service 

 Jim Niemann, Chevron/Texaco

Socioeconomic Breakout Group 

Co-Chairs Recorder 

 Harry Luton, Minerals Management Service Connie Landry, MMS 

 Steve Murdoch, Texas A&M University 

May 31st Morning 

Summaries, Recommendations and General Discussion 

8:45-9:00 Workshop Summaries 

 William Schroeder 

9:00-9:20 Socioeconomics Working Group

Chair: Stan Albrecht 

 Harry Luton 

9:20-9:40 Geology/Geohazards Working Group

Chair: Bill Bryant 

 Sarah Tsoflias 

 Jim Niemann 

9:40-10:00 Ecology Working Group

Chair: Mike Rex 

 Robert Avent 

 Jim Ray 

 Subgroup 

 Chair: Jeff Childs 

10:00-10:15 Break

10:15-11:30 General Discussion

11:30-11:45 Concluding Remarks

William Schroeder 
98 

Appendix 2. Breakout Group Participants 

Floaters

Mary Boatman, USDOI - Minerals Management Service 

Gary Goeke, USDOI - Minerals Management Service 

William Schroeder, University of Alabama/Dauphin Island Sea Lab 

Geology/Geophysics 

Adnan A. Ahmed, USDOI - Minerals Management Service 

Mary Boatman, USDOI - Minerals Management Service 

T. J. Broussard, USDOI - Minerals Management Service 

Bill Bryant, Texas A&M University 

Robert A. George, C & C Technologies, Inc. 

Ann E. Jochens, Texas A&M University 

Ed Malachosky, INTEQ Drilling Fluids 

James Niemann, ChevronTexaco 

J. Douglas Oliver, Florida Department of Environmental Protection 

Samuel Reed, Williams Energy Services 

G. Ed Richardson, USDOI - Minerals Management Service 

Natalia Sidorovskaia, University of Louisiana - Lafayette 

Sarah L. Tsoflias, USDOI - Minerals Management Service 

Physical Oceanography 

Antoine Badan, CICESE 

John Blaha, Naval Oceanographic Office 

Donna Bourg, USDOI - Minerals Management Service 

Carole Current, USDOI - Minerals Management Service 

Ronald J. Lai, USDOI - Minerals Management Service 

William Lang, USDOI - Minerals Management Service 

Alexis Lugo-Fernandez, USDOI - Minerals Management Service 

Jose' Ochoa, CICESE 

Elizabeth Peuler, USDOI - Minerals Management Service 

Michael Vogel, Shell Global Solutions 

Michael Wild, Naval Oceanographic Office 

Judy Wilson, USDOI - Minerals Management Service 
99 

Ecology 

Tom Ahlfeld, USDOI - Minerals Management Service 

Dan Allen, ChevronTexaco 

Bob Avent, USDOI - Minerals Management Service 

Robert C. Ayers, Jr., Robert Ayers & Associates, Inc. 

John Blaha, Naval Oceanographic Office 

Greg Boland, USOI - Minerals Management Service 

Carolyn Burks, National Marine Fisheries Service 

Jeff Childs, USDOI - Minerals Management Service 

Susan Childs, USDOI - Minerals Management Service 

Carole Current, USDOI - Minerals Management Service 

George Dennis, US Geological Survey 

Kevin Dischler, Sherry Laboratories 

Dave Dougall, Agip Petroleum Company 

Robert Dubois, US Fish & Wildlife Service 

Randy Edwards, US Geological Survey 

Anita George-Ares, Exxon/Mobil Biomedical Sciences Inc. 

Andrew Glickman, ChevronTexaco 

Alan Hart, Continental Shelf Associates, Inc. 

Doug Heatwole, Ecology & Environment, Inc. 

James J. Kendall, USDOI - Minerals Management Service 

Jan Kenny, TEi Construction Services 

Paul R. Krause, Blasland, Bouck & Lee, Inc. 

Roy K. Kropp, Pacific Northwest National Laboratory 

Alexis Lugo-Fernandez, USDOI - Minerals Management Service 

Jamie McKee, SAIC 

Margaret Metcalf, USDOI - Minerals Management Service 

Paul Montagna, University of Texas at Austin 

Mike Nunley, SAIC 

Michael E. Parker, ExxonMobile Production Company 

Jim Ray, Shell Global Solutions (US) Inc. 

Larry Reitsema, Marathon Oil Company 

Mike Rex, University of Massachusetts 

Carol Roden, USDOI - Minerals Management Service 

Bob Rogers, USDOI - Minerals Management Service 

Pat Roscigno, USDOI - Minerals Management Service 

Gil Rowe, Texas A&M University 

Ricahrd F. Shaw, Coastal Fisheries Institute - LSU 

Joseph P. Smith, ExxonMobil Upstream Research Company 

Michael G. Strikmiller, Environmental Enterprises USA, Inc. 

Ken Sulak, US Geological Survey 

Tim Thibaut, Barry A. Vittor & Associates Inc. 

Debby Tucker, Florida Department of Environmental Protection 

Dick Wildermann, USDOI - Minerals Management Service 

Judy Wilson, USDOI - Minerals Management Service 
100 

Socioeconomics 

Stan L. Albrecht, Utah State University 

Jeff Chapman, ExxonMobil 

Rodney E. Cluck, USDOI - Minerals Management Service 

Craig Colten, Louisiana State University 

Vincent F. Cottone, ChevronTexaco 

Donald W. Davis, Louisiana State University 

David E. Dismukes, Louisiana State University 

Warren Emerson, Conoco Inc. 

Jordan B. Fiesta, University of South Florida 

Roy Francis, LA1 Coalition Inc. 

Gerry Gallagher, Ecology & Environment, Inc. 

Stephanie Gambino, USDOI - Minerals Management Service 

John E. Gibbons, John E. Gibbons Associates 

Scott A. Hemmerling, Louisiana State University 

Connie Landry, USDOI - Minerals Management Service 

Larry Leistritz, North Dakota State University 

Harry Luton, USDOI - Minerals Management Service 

Brian G. Marcks, Louisiana Department of Natural Resources 

Thomas R. McGuire, University of Arizona 

Steve Murdock, Texas A&M University 

Robin L. Petrusak, ICF Consulting 

John S. Petterson, Impact Assessment, Inc. 

Allan G. Pulsipher, Louisiana State University 

Jeff Reidenauer, The Louis Berger Group Inc. 

Claudia M. Rogers, USDOI - Minerals Management Service 

Edella Schlager, University of Arizona 

Joachim Singelmann, Louisiana State University 

Meg Streiff, Louisiana State University 

Debra Vigil, USDOI - Minerals Management Service 

Barbara Wallace, TechLaw, Inc. 

Dick Wildermann, USDOI - Minerals Management Service 

Vicki R. Zatarain, USDOI - Minerals Management Service 
101 

Appendix 3. Workshop Attendees and Addresses 

Tom Ahlfeld 

Biological Oceanographer 

USDOI - Minerals Management Service 

381 Elden Street 

Herndon VA 20170 

thomas.ahlfeld@mms.gov

Adnan A. Ahmed 

Geophysicist 

USDOI - Minerals Management Service 

1201 Elmwood Park Boulevard 

New Orleans LA,70123 

adnan.ahmed@mms.gov

Stan L. Albrecht 

Utah State University 

Provost's Office 

1435 Old Main Hill 

Logan UT 84322 

sla@champ.usu.edu;sla@cc.lsu.edu

Dan Allen 

ChevronTexaco 

935 Gravier Street 

New Orleans LA 70112 

allj@chevron.com

Bob Avent 

USDOI - Minerals Management Service 

Gulf of Mexico Region 

1201 Elmwood Park Boulevard 

New Orleans LA 70123-2394 

robert.avent@mms.gov

Robert C. Ayers Jr. 

Robert Ayers & Associates, Inc. 

6329 Rutgers 

Houston TX 77005-3317 

bobo60@aol.com

Antoine Badan 

CICESE - Oceanography 

Box 2732 

Ensenada Mexico 

abadan@cicese.mx

Eliot Barron 

National Ports & Waterways Institute 

1600 Canal Street, Suite 727 

New Orleans LA 70112 

homerule12@yahoo.com

John Blaha 

Naval Oceanographic Office 

N33 - 1002 Balch Boulevard 

Stennis Space Center MS 39522-5001 

blahaj@navo.navy.mil

Mary Boatman 

USDOI - Minerals Management Service 

Gulf of Mexico Region 

1201 Elmwood Park Boulevard 

New Orleans LA 70123-2394 

mary.boatman@mms.gov

Greg Boland 

USDOI - Minerals Management Service 

Biological Sciences Unit 

1201 Elmwood Park Boulevard 

New Orleans LA 70123 

gregory.boland@mms.gov

Donna Bourg 

USDOI – Minerals Management Service 

1201 Elmwood Park Boulevard 

New Orleans LA 70123-2394 

donna.bourg@mms.gov

T. J. Broussard 

USDOI - Minerals Management Service 

NEPA/CZM Coordination Unit 

1201 Elmwood Park Boulevard 

New Orleans LA 70123 

tommy.broussard@mms.gov

Bill Bryant 

Texas A&M University 

Department of Oceanography 

College Station TX 77843-3146 

wbryant@ocean.tamu.edu

Carolyn Burks 

National Marine Fisheries Service 

3209 Frederick Street 

Pascagoula MS 39567 

carolyn.m.burks@noaa.gov
102 

Jeff Chapman 

ExxonMobil 

800 Bell Street - Room 4111C 

Houston TX 77002 

jeff.s.chapman@exxonmobil.com

Susan Childs 

USDOI - Minerals Management Service 

GOMR/Leasing and Environment 

1201 Elmwood Park Boulevard 

New Orleans LA 70123 

susan.childs@mms.gov

Jeff Childs 

USDOI - Minerals Management Service 

Environmental Sciences 

1201 Elmwood Park Boulevard 

New Orleans LA 70123-2394 

Jeff.Childs@mms.gov

Rodney E. Cluck 

USDOI - Minerals Management Service 

381 Elden Street 

Herndon VA 20170 

Rodney.Cluck@mms.gov

Craig Colten 

Louisiana State University 

Geography & Anthropology 

227 Howe-Russell 

Baton Rouge LA 70809 

ccolten@lsu.edu

Vincent F. Cottone 

ChevronTexaco 

Deepwater Business Unit 

935 Gravier Street 

New Orleans LA 70112-1625 

cottovf@chevrontexaco.com

Carole Current 

USDOI - Minerals Management Service 

Environmental Sciences Section 

1201 Elmwood Park Boulevard - MS 5433 

New Orleans LA 70123 

carole.current@mms.gov

Donald W. Davis 

Louisiana State University 

LA Applied & Educ. Oil Spill R&D Program 

258A/B Military Science Building 

Baton Rouge LA 70803 

osradp@attglobal.net

George Dennis 

USGS 

7920 NW 71st Street 

Gainesville FL 32653 

george_dennis@usgs.gov

Kevin Dischler 

Sherry Laboratories-Louisiana 

Bioassay Division 

2417 West Pinhook Road 

Lafayette LA 70508 

kevind@sherrylabs.com

David E. Dismukes 

Louisiana State University 

Center for Energy Studies 

Baton Rouge LA 70803-0301 

dismukes@lsu.edu

Dave Dougall 

Agip Petroleum Co 

1201 Louisiana - Suite 3500 

Houston TX 77002 

david.dougall@agippetroleum.agip.it

Robert Dubois 

U.S. Fish & Wildlife Service 

646 Cajundome Boulevard - Suite 400 

Lafayette LA 70506 

robert_dubois@fws.gov

Randy Edwards 

USGS 

College of Marine Science 

600 Fourth Street South 

St Petersburg FL 33701-4846 

redwards@usgs.gov

Joan Elterman 

Dominion Exploration & Production Inc. 

1450 Poydras Street 

New Orleans LA 70112 

joan_a_elterman@dom.com

Warren Emerson 

Conoco Inc. 

Magnolia 

Houston TX 77252 

Warren.Emerson@conoco.com
103 

Caryl Fagot 

MMS - ORD 

1201 Elmwood Park Boulevard 

New Orleans LA 70123 

caryl.fagot@mms.gov

Jordan B. Fiesta 

University of South Florida 

2664 Champion Ridge Drive 

Lakeland FL 33813 

Fiesta@helios.acomp.usf.edu

Roy Francis 

LA1 Coalition Inc. 

NSU 

PO Box 2048 

Thibodaux LA 70310 

slec-rpf@nicholls.edu

Sandi Fury 

ChevronTexaco 

935 Gravier Street 

New Orleans LA 70112 

sfur@chevrontexaco.com

Gerry Gallagher 

Ecology & Environment Inc. 

1950 Commonwealth Lane 

Tallahassee FL 32303 

gagallagher@ene.com

Stephanie Gambino 

USDOI - Minerals Management Service 

LE-EA-NEPA/CZM 

1201 Elmwood Park Boulevard - MS 5412 

New Orleans LA 70123 

stephanie.gambino@mms.gov

Robert A. "Tony" George 

C & C Technologies Inc. 

Geosciences 

730 E. Kaliste Saloom Road 

Lafayette LA 70508 

tony.george@cctechnol.com

Anita George-Ares 

ExxonMobil Biomedical Sciences Inc. 

Occupational & Public Health 

1545 Route 22 East 

PO Box 971 

Annandale NJ 08801-0971 

anita.george-ares@exxonmobil.com

David Gettleson 

Continental Shelf Associates Inc. 

759 Parkway Street 

Jupiter FL 33469 

dgettleson@conshelf.com

John E. Gibbons 

John E. Gibbons Associates 

1115 Ranch Point Way 

Antioch CA 945310 

JEGCA@aol.com

Andrew Glickman 

ChevronTexaco 

Energy Research and Technology Co. 

100 Chevron Way 

Richmond CA 94802 

aglickman@chevrontexaco.com

Gary Goeke 

Ecology and Environment, Inc. 

220 West Garden Street, Suite 404 

Pensacola, FL 32501 

ggoeke@ene.com

Alan Hart 

Continental Shelf Associates Inc. 

759 Parkway Street 

Jupiter FL 33477 

ahart@conshelf.com

Doug Heatwole 

Ecology & Environment Inc. 

220 W. Garden Street - Suite 404 

Pensacola FL 32501 

dheatwole@ene.com

Scott A. Hemmerling 

Louisiana State University 

Geography & Anthropology 

539 Park Boulevard #3 

Baton Rouge LA 70806 

shemme1@lsu.edu

Ann E. Jochens 

Texas A&M University 

Department of Oceanography 

3146 TAMU 

College Station TX 77843-3146 

ajochens@tamu.edu
104 

James J. Kendall 

USDOI - Minerals Management Service 

381 Elden Street - Mail Stop 4041 

Herndon VA 20710-4817 

james.kendall@mms.gov

Jan Kenny 

TEi Construction Services - DEMEX Division 

720 Grefer Avenue 

Harvey LA 70058 

demex-nola@msn.com

John Kenny 

TEi Construction Services - DEMEX Division 

702 Grefer Avenue 

Harvey LA 70058 

demex-nola@msn.com

Robert King 

Kvaerner Oilfield Products 

1255 N Post Oak Road 

Houston TX 77055 

robert.king@kvaerner.com

Paul R. Krause 

Blasland Bouck & Lee Inc. 

Life Sciences 

301 E Ocean Boulevard - Suite 1530 

Long Beach CA 90802 

pkrause@bbl-inc.com

Roy K. Kropp 

Pacific Northwest National Laboratory 

Marine Sciences Laboratory 

1529 West Sequim Bay Road 

Sequim WA 98382 

roy.kropp@pnl.gov

Ronald J. Lai 

USDOI - Minerals Management Service 

381 Elden Street 

Herndon VA 20170 

ronald.lai@mms.gov

Connie Landry 

USDOI - Minerals Management Service 

Gulf of Mexico OCS Region 

1201 Elmwood Park Boulevard 

New Orleans LA 70123-2394 

connie.landry@mms.gov

William Lang 

USDOI - Minerals Management Service 

1201 Elmwood Park Boulevard 

New Orleans LA 70123 

bill.lang@mms.gov

Larry Leistritz 

North Dakota State University 

Fargo ND 58105 

lleistri@ndsuext.nodak.edu

Alexis Lugo-Fernandez 

USDOI - Minerals Management Service 

1201 Elmwood Park Boulevard 

New Orleans LA 70123-2394 

alexis.lugo.fernandez@mms.gov

Harry Luton 

USDOI - Minerals Management Service 

Gulf of Mexico Region 

1201 Elmwood Park Boulevard 

New Orleans LA 70123-2394 

harry.luton@mms.gov

Ed Malachosky 

INTEQ Drilling Fluids 

2001 Rankin Road 

Houston TX 77073 

ed.malachosky@inteq.com

Brian G. Marcks 

Louisiana Department of Natural Resources 

Coastal Management Division 

617 N 3rd Street 

Baton Rouge LA 70802 

BrianM@dnr.state.la.us

Jonathan Martin 

Dauphin Island Sea Lab 

101 Bienville Boulevard 

Dauphin Island AL 36528 

jmartin@disl.org

Thomas R. McGuire 

University of Arizona 

Bureau of Applied Research in Anthropology 

Tucson AZ 85621 

mcguire@u.arizona.edu

Jamie McKee 

SAIC 

1140 Eglin Parkway 

Shalimar FL 32579 

mckeew@saic.com
105 

Margaret Metcalf 

USDOI - Minerals Management Service 

Leasing and Environment 

1201 Elmwood Park Boulevard 

New Orleans LA 70123-2394 

Margaret.Metcalf@mms.gov

Paul Montagna 

University of Texas at Austin 

Marine Science Institute 

750 Channel View Drive 

Port Aransas TX 78373 

paul@utmsi.utexas.edu

Steve Murdock 

Texas A&M University 

Department of Rural Sociology 

Building E - Suite 100 

College Station TX 77843-2125 

smurdock@tamu.edu

James Niemann 

ChevronTexaco 

Deepwater Business Unit 

935 Gravier Street 

New Orleans LA 70112 

jamesniemann@chevrontexaco.com

Mike Nunley 

SAIC 

1140 Eglin Parkway 

Shalimar FL 32579 

nunleyj@saic.com

Jose' Ochoa 

CICESE 

Oceanography Research 

Mm 107 Carr- Tijuana-Ensenada 

Baja California Mexico 22800 

jochoa@cicese.mx

J. Douglas Oliver 

Department of Environmental Protection 

Office of Intergovernmental Programs 

3900 Commonwealth Boulevard - MS-47 

Tallahassee FL 32399-3000 

Doug.Oliver@dep.state.fl.us

Chris Oynes 

USDOI - Minerals Management Service 

Gulf of Mexico Region 

1201 Elmwood Park Boulevard 

New Orleans LA 70123-2394 

chris.oynes@mms.gov

Michael E. Parker 

ExxonMobil Production Company 

800 Bell Street - Room 4289 

Houston TX 77002 

michael.e.parker@exxonmobil.com

Robin L. Petrusak 

ICF Consulting 

9300 Lee Highway 

Fairfax VA 22031 

robinpetrusak@icfconsulting.com

John S. Petterson 

Impact Assessment Inc. 

2166 Avenida de la Playa - Suite F 

La Jolla CA 92037 

iai@san.rr.com

Elizabeth Peuler 

Physical Sciences Unit 

USDOI - Minerals Management Service 

1201 Elmwood Park Boulevard 

New Orleans LA 70123 

elizabeth.peuler@mms.gov

Allan G. Pulsipher 

Louisiana State University 

Center for Energy Studies 

One East Fraternity Circle 

Baton Rouge LA 70803 

agpul@lsu.edu

Jim Ray 

Shell Global Solutions (US) Inc. 

Westhollow Technology Center 

3333 Highway 6 South 

Houston TX 77082 

james.ray@shell.com

Samuel Reed 

Williams Energy Services 

2800 Post Oak Boulevard 

Houston TX 77056 

samuel.reed@williams.com

Jeff Reidenauer 

The Louis Berger Group Inc. 

100 Halstead Street 

East Orange NJ 07018 

jreiden@louisberger.com
106 

Larry Reitsema 

New Ventures and Technical Support 

Marathon Oil Corporation 

5555 San Felipe 

Houston TX 77056 

lareitsema@marathonoil.com

Mike Rex 

University of Massachusetts 

Department of Biology 

100 Morrissey Boulevard 

Boston MA 02125-3390 

michael.rex@umb.edu

G. Ed Richardson 

USDOI - Minerals Management Service 

Leasing and Environment 

1201 Elmwood Park Boulevard 

New Orleans LA 70123-2394 

ed.richardson@mms.gov

Carol Roden 

USDOI - Minerals Management Service 

Leasing and Environment 

1201 Elmwood Park Boulevard 

New Orleans LA 70123 

carol.roden@mms.gov

Claudia M. Rogers 

USDOI - Minerals Management Service 

817 Phlox Avenue 

Metairie LA 70001 

claudia.rogers@mms.gov

Bob Rogers 

Biological Sciences Unit 

USDOI - Minerals Management Service 

1201 Elmwood Park Boulevard 

New Orleans LA 70123 

Robert.Rogers@mms.gov

Pat Roscigno 

USDOI - Minerals Management Service 

1201 Elmwood Park Boulevard 

New Orleans LA 70123 

pasquale.roscigno@mms.gov

Gil Rowe 

Texas A&M University 

Department of Oceanography 

College Station TX 77843-3146 

growe@ocean.tamu.edu

Edella Schlager 

University of Arizona 

Tucson AZ 85721 

eschlager@bpa.arizona.edu

Randy Schlude 

Dauphin Island Sea Lab 

101 Bienville Boulevard 

Dauphin Island AL 36528 

rschlude@disl.org

William Schroeder 

The University of Alabama 

Dauphin Island Sea Lab 

101 Bienville Boulevard 

Dauphin Island AL 36528 

wschroeder@disl.org

Cheryl Sephus 

University of New Orleans 

Department of Physics 

UNO PO BOX 1014 

New Orleans LA 70148 

midsea20@hotmail.com

Richard F. Shaw 

Coastal Fisheries Institute - LSU 

Oceanography & Coastal Science 

Wetlands Resources Building 

Baton Rouge LA 70806 

rshaw@lsu.edu

Natalia Sidorovskaia 

University of Louisiana - Lafayette 

Department of Physics 

UL BOX 44210 

Lafayette LA 70503 

nsidorovskaia@louisiana.edu

Paul Siegele 

ChevronTexaco 

935 Gravier Street 

New Orleans LA 70112 

Joachim Singelmann 

Louisiana State University 

Department of Sociology 

Baton Rouge LA 70803 

joachim@lsu.edu
107 

Joseph P. Smith 

ExxonMobil Upstream Research Co 

Offshore Division 

3616 Richmond 

Houston TX 77046 

joe.p.smith@exxonmobil.com

Meg Streiff 

Louisiana State University 

Center for Energy Studies 

2543 Hundred Oaks 

Baton Rouge LA 70808 

mstrei1@lsu.edu

Michael G. Strikmiller 

Environmental Enterprises USA Inc. 

58485 Pearl Acres Road - Suite D 

Slidell LA 70461 

mstrikmiller@eeusa.com

Ken Sulak 

USGS 

Biological Resources 

7920 NW 71st Street 

Gainesville FL 32653 

ken_sulak@usgs.gov

Tim Thibaut 

Barry A. Vittor & Associates Inc. 

8060 Cottage Hill Road 

Mobile AL 36695 

tthibaut@bvaenviro.com

Sarah L. Tsoflias 

USDOI - Minerals Management Service 

1201 Elmwood Park Boulevard - MS 5433 

New Orleans LA 70123-2394 

Sarah.Tsoflias@mms.gov

Debby Tucker 

Department of Environmental Protection 

Office of Intergovernmental Programs 

3900 Commonwealth Boulevard - MS-47 

Tallahassee FL 32399-3000 

Debby.Tucker@dep.state.fl.us

Debra Vigil 

USDOI - Minerals Management Service 

1201 Elmwood Park Boulevard 

New Orleans LA 70123 

debra.vigil@mms.gov

Michael Vogel 

Shell Global Solutions 

3737 Bellaire Boulevard 

Houston TX 77025 

michael.vogel@shell.com

David Walker 

British Petroleum 

501 Westlake Park Blvd 

Room 20.186 

Houston TX 77079 

walkerdb@bp.com

Barbara Wallace 

TechLaw Inc. 

4340 East West Highway - Suite 1120 

Bethesda MD 20814 

bwallace@techlawinc.com

Michael Wild 

Naval Oceanographic Office 

Stennis Space Center MS 39525 

wildm@navo.navy.mil

Dick Wildermann 

USDOI - Minerals Management Service 

Branch of Environmental Assessment 

381 Elden Street 

Herndon VA 20171 

richard.wildermann@mms.gov

Judy Wilson 

USDOI - Minerals Management Service 

381 Elden Street 

Herndon VA 20170 

judy_wilson@mms.gov

Carolyn Wood 

Dauphin Island Sea Lab 

101 Bienville Boulevard 

Dauphin Island AL 36528 

cwood@disl.org

Vicki R. Zatarain 

USDOI – Minerals Management Service 

1201 Elmwood Park Boulevard 

New Orleans LA 70123 

vicki.zatarain@mms.gov