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September 2005
Investigations of Chemosynthetic
Communities on the Lower Continental Slope of the Gulf of
Mexico
Introduction
Scope and Objectives of This Project
Directed Missions of MMS
Background for This Project
Project Team
Scientific and Technical Context Write
Up (PDF download)
Introduction
TDI-Brooks has just been awarded a $3.16 million contract
(#0105CT39187) with the Minerals Management Service (MMS)
for a 4-year study of chemosynthetic communities on the lower
continental slope of the Gulf of Mexico. As a bureau of the
US Department of the Interior, the MMS has primary responsibility
for the management of the mineral resources located on the
nation's Outer Continental Shelf (OCS). The MMS administers
the OCS competitive leasing program for oil and gas exploration,
and oversees the safe and environmentally sound exploration
and production of our nation's offshore natural gas, oil,
and other mineral resources (www.gomr.mms.gov).
The award to TDI-Brooks includes a comprehensive study of
existing 3-D seismic information for the purpose of locating
the chemosynthetic communities, using a camera sled and other
high-tech gear for the reconnaissance of identified areas,
visiting known communities with the manned submersible ALVIN
(http://oceanexplorer.noaa.gov/technology/subs/alvin/alvin.html),
and documenting the communities with chemical sensors, microbiological
examinations, and digital video using an autonomous underwater
vehicle (AUV). This is an exciting, cutting-edge, multi-disciplinary
scientific study for which TDI-Brooks is honored to be the
prime contractor. In this capacity, TDI-Brooks will collaborate
with a group of world-class and internationally-recognized
scientists in the field of chemosynthetic communities.
Scope and Objectives of This Project
A. To characterize known, or newly discovered chemosynthetic
communities at depths below 1,000-meters in the central and
western Gulf of Mexico.
B. To characterize all other hard bottom biological
communities encountered regardless of association with active
hydrocarbon seep activity or living chemosynthetic community
species in the central and western Gulf of Mexico.
C. To determine the comparative degree of sensitivity
of anthropogenic impacts for both A and B above through a
variety of approaches such as rarity, unique taxonomy/biodiversity,
or other environmental risk assessment methodologies. This
objective includes understanding how these deep communities
are similar or different from their shallower water counterparts.
D. To further develop successful assessment methodologies
for correlation of remote sensing information such as bathymetry,
seabed acoustic reflectivity, subbottom structure, and other
geophysical signatures obtained by non-visual techniques with
the "potential" presence of non-soft bottom biological communities
at depths below 1,000 meters. The objective is specifically
targeted to result in some level of predictive capability
that can be used by MMS to avoid impacts to lower slope sensitive
biological communities.
E. To contribute to assessing and explaining diversity
distribution and abundance of marine species at depths below
1,000 m in the central and western Gulf, as well as improving
the understanding of the functional role of marine species
in areas of active hydrocarbon seep activity or living chemosynthetic
communities.
These objectives will be accomplished through a combination
of both exploratory work and more focused studies including
process-based work on known communities.
Directed Missions of MMS
Acting under acts of Congress, MMS serves as a prudent manager
of the nation's seafloor mineral resources. That management
role requires development of critical energy resources without
unacceptable impact on other ocean users, the natural environment,
and the human environment. The primary strategy that MMS employs
to eliminate or minimize environmental impact is to identify
sensitive habitat and then restrict or otherwise mitigate
exploration, development, and production activity. Typically,
reefs, other live bottoms, critical fish habitats, etc. are
classed as sensitive on the basis of accumulated prior knowledge
and directed MMS studies. The vast areas of seemingly homogenous
soft bottoms are classed as insensitive. Even in the case
of such insensitive areas, MMS and EPA regulations seek to
limit the area and degree of impact.
Increased oil and gas activity beyond the shelf break and
US recognition of the 200 m EEZ greatly increased MMS's environmental
coverage. Faced with a very poorly studied and remote environment,
MMS supported a series of deep surveys (Carney, 2001) along
the Atlantic and Gulf of Mexico continental margins in the
1980's. These studies confirmed the existence of vast soft
sediment habitats, but also recognized previously known live
bottoms, and found unexpected chemosynthetic communities.
Both deep live bottoms and chemosynthetic communities can
be classed as sensitive habitats. It can be noted that the
core participants in the propose work participated in these
previous surveys in many ways.
The results of MMS's first study of upper slope chemosynthetic
communities, Chemosynthetic Ecosystems Study (MMS Report 95-2001)
began the trend continuing to this day of submersible-based
investigation in a mixed exploration and detailed-study mode.
A second study, Stability and Change in Gulf of Mexico Chemosynthetic
Communities (MMS Report 2002-036) greatly increased knowledge
of the ecology of these systems. The scientific value of these
studies was increased by the initiative of the core members
who successfully sought competitive funds from NOAA, DOE,
and NSF.
The work proposed herein is designed to meet MMS' information
needs concerning the location and functioning of seep communities
deeper than the artificially imposed limit of 1000 m. Preliminary
studies have shown that seep communities at the slope base
are different from those on the upper slope in much the same
way that the normal background fauna differ. Therefore, MMS
can not simply extrapolate upper-slope data down the entire
margin.
Background for This Project
Over the last half century, offshore exploration for hydrocarbons
in the northern Gulf of Mexico has advanced from the bays
and inner shelf to the continental slope-to-continental rise
transition. Geophysical and geotechnical data collected in
support of both exploration and production has largely been
responsible for the foundation of our present understanding
of slope geology. This database emphasizes the extremely complex
geological framework of the northern Gulf's continental slope
and the surprisingly important role that the expulsion of
subsurface fluids and gases has on shaping surficial geology
and biology of the modern seafloor.
Regional topography of the slope consists of basins, knolls,
ridges, and mounds derived from the dynamic adjustments of
salt to the introduction of large volumes of sediment over
long time scales. Superimposed on this underlying topography
is a smaller class of mounds, flows, and hard grounds that
are the products of the transport of fluidized sediment, mineral-rich
formation fluids, and hydrocarbons to the present sediment-water
interface. The geologic response to the expulsion process
is related both to the products being transported and the
rate at which they arrive at the seafloor. Mud volcanoes and
mudflows are typical of rapid flux settings where fluidized
sediment is involved. Slow flux settings are mineral-prone.
Authigenic carbonate mounds, hard grounds, crusts, and nodules
are common to settings where hydrocarbons are involved. Barite
in the form of small cones, chimneys, and crusts may also
be found where expulsion of barium-rich water occurs. In settings
between mud-prone rapid flux and mineral-prone slow flux environments,
unique conditions occur to support and sustain densely populated
communities of chemosynthetic communities. These areas correlate
well with the occurrence of surficial exposures of gas hydrate.
Direct observation and sampling of these unusual geologic
and biologic environments by the key personnel of our contract
started in the mid-1980s using manned submersibles. To date,
most submersible-supported research has been concentrated
on the upper slope (<1,000 m). However, fluid and gas expulsion
features, chemosynthetic communities, brine seeps, and slope
instabilities occur over the slope's full depth range as imaged
on geophysical data and confirmed by limited numbers of deep
submersible dives and remotely operated vehicle (ROV) bottom
imaging transects and samples.
Project Team
TDI-Brooks International Inc. (TDI-Brooks) has assembled
a team that combines the most knowledgeable and experienced
researchers specific to the requirements of this project in
the Gulf of Mexico and includes scientists that are internationally
recognized for their contributions to the global understanding
of cold seep ecology, microbiology, physiology and geology.
All of the key US members of the team are also very experienced
with, and have led, large multidisciplinary projects and cruises.
Dr. James Brooks will be the Project Manager and will take
the lead in administration of this project and assist in the
geochemical studies. Dr. Charles Fisher (Pennsylvania State
University) will coordinate the biological studies, Dr. Harry
Roberts (Louisiana State University) will coordinate the geological/geophysical
studies, and Ms. Liz Goehring (Penn State and NSF Ridge 2000
office) will coordinate the education and outreach activities.
Dr. Charles Fisher will oversee the biological aspects of
the study and the interface with geochemical measurements
and studies. He will work closely with Dr. Roberts and other
PIs to plan and conduct the submersible/ROV portions of the
field work. His research group will take responsibility for
in situ methane analyses, growth studies, quantitative collections,
community composition and structure analyses, and trophic
studies of the endemic and other closely associated seep and
coral fauna. He will also be responsible for coordination
with international collaborators. Dr. Erik Cordes will work
with Fisher's team on studies of seep communities and take
a leadership role on synthesis and publication of results
for other hard bottom communities discovered. Dr. Stephane
Schaeffer will oversee work in his laboratory, including molecular
phylogenetic screening of foundation species and their symbionts
(tubeworms, mussels and clams) and other potential new species
(and symbioses) as needed. Dr. Robert Carney will lead the
studies of interactions with background fauna and trophic
exchange between seep/hard bottom communities and larger mobile
fauna. Drs. Fisher, Carney, and Cordes will share responsibility
for coordination with taxonomists and molecular phylogenists
and proper curation of samples. Dr. Ian MacDonald will direct
the use of digital imagery in all phases of the study, from
the initial site survey and selection process to site descriptions
and contributions to faunal inventory. Dr. Samantha Joye will
be responsible for the microbial ecology and sulfide geochemistry
studies.
In addition to this core team, we have assembled a team of
collaborators that significantly expands our taxonomic expertise
and brings in some of the top international seep research
groups, at a very small additional cost to the project (transportation
costs to cruises, minor supply costs, and shipping and curation
costs for samples). Dr. Tim Shank (WHOI) has indicated his
willingness to phylogentically characterize any potential
new species of megafaunal crustaceans and to include at least
the shrimp in his ongoing biogeographic analyses. Dr. Bob
Vreijenhoek (MBARI) will do the same clams and their symbionts
and other gastropods as needed. Limpets and snails will also
be sent to Anders Waren (Swedish Museum of Natural History)
and chitons to Julia Sigwart (University College Dublin) for
morphological characterization. Dr. Stéphane Hourdez (Stacione
Biologique de Roscoff, France) will take the lead on polychaete
phylogenetic characterizations and descriptions of new species
of polynoids and siboglinids (using both molecular and classical
approaches). He will also assist with molecular characterization
of foundation species during visits to PSU after the cruises
(working in S. Schaeffer's laboratory at PSU). Dr. Stephane
Cairns (Smithsonian) will oversee curation and identification
of cnidarians, with assistance of Daphne Fautine (University
of Kansas) and Dennis Opreska (Oak Ridge). Dr. Cheryl Morrison
(USGS Leetown Science Center) has confirmed her willingness
to include any samples of Lophelia pertusa collected in her
ongoing studies of the phylogeography and population genetics
of this foundation coral species, and also to collaborate
with Dr. Cairns by contributing to the molecular systematics
of other hard corals as needed. Dr. Sabine Stohr (Swedish
Museum of Natural History) has agreed to examine all ophuiroids
collected and is already working a brittle star that was one
of the dominant species collected with mussels at some of
the deeper sites in 2003. Dr. Monika Bright and her research
team (Univ. Vienna) will sort and identify meiofauna collected
with mussel and tubeworm communities and in sediment cores.
Other faunal groups will be sent to appropriate experts as
needed.
Additionally, two internationally recognized research groups
from the Max Planck Institute of Marine Microbiology in Bremen
will bring unique expertise and equipment to bear on the study.
Nicole Dublier's group will use quantitative mRNA analyses
to determine the relative activities of chemoautotrophic and
methanotrophic symbiont populations in the dual symbiont-containing
mussels. Antje Botieus' group will bring their in-situ seep-chemistry
analysis system and expertise on the ALVIN and ROV cruises.
Letters of commitment from all collaborators are available
upon request.
TDI-Brooks' management and analytical team will provide critical
support for the project. Dr. Bernie Bernard, TDI-Brooks Director
and Laboratory Manager, will coordinate the isotope, hydrocarbon
and ancillary measurements that are conducted in our laboratory.
Dr. Thomas McDonald will be the principle hydrocarbon chemist
for the project. Dr. Gary Wolff will act as the projects Data
Manager as he has for numerous previous large multi-disciplinary
MMS projects. Mr. Kathy Allen will be the projects technical
editor. She along with Ms. Suzanne Cardwell will provide financial
and project administrative support.
As described above, each of these PIs will have their own
areas of responsibility with respect to analyses, equipment,
manpower and deliverables. However, the activities of the
groups will be integrated from planning and site selection
through implementation and interpretation of the results.
All biological studies will be interpreted in the context
of the geochemical and geophysical characterization of the
region and the specific sites. Nested within these base maps
will be studies of fine scale geochemistry, mobile fauna densities,
and microhabitat distribution of specific types of chemosynthetic
or coral communities. Dr. Carney's work will provide the context
on the background fauna expected at different depths necessary
to interpret Dr. MacDonald's time lapse optical sampling of
mobile fauna to the sites. Dr. Carney's trap and targeted
collection samples will allow analysis of trophic interactions
between this component of the deep sea fauna and the communities
that are the focus of this project. Fisher's quantitative
collection-based analyses of community structure and function
will be interpreted in the context of these studies and Dr.
MacDonald's photo surveys of each site. Dr. Carney's detailed
studies of bivalve/gastropod interactions will be interpreted
in the context of Dr. Fisher's quantitative studies and those
of collaborating European investigators. The animal distribution
and activity data will be interpreted in the context of sediment
microbial activity and geochemical data collected by Dr. Joye's
group and in situ water column data obtained by Dr. Boetius'
group. Outreach activities will include input from all teams
and will be coordinated by Liz Goehring, who is currently
the Education and Outreach coordinator for the NSF Ridge 2000
Program. In addition to integrating this project into programs
she has designed, she will work closely with the GoM area
COSEE center in Southern Mississippi and the Ocean Exploration
Program.
Scientific and Technical Context
Click below for a detailed technical discussion of the work
in Adobe Acrobat Format.
Investigations
of Chemosynthetic Communities on the Lower Continental Slope
of the Gulf of Mexico PDF Download
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