DIVING TO EXTREMES : STUDYING THE DEEP SEA HYDROCARBON-BASED ECOSYSTEMS OF THE GULF OF MEXICO

July 02, 2001 to July 19, 2001
R/V SEWARD JOHNSON & RESEARCH SUBMERSIBLE JOHNSON-SEA-LINK II


During this mission a multidisciplinary team of scientists will examine the molecular microbial ecology and biogeochemistry of methane hydrates and brine pools to determine the distribution and activity of microorganisms in two extreme deep sea environments. Researchers will send dispatches from the ship to report on findings obtained from submersible dives on these two distinctly different chemosynthetically-based environments.

The Gulf of Mexico seafloor contains vast reservoirs of liquid and gaseous hydrocarbons that overlay thick accumulations of Jurassic salt. Conduits, or focused flow regions, permit rapid vertical migration of thermogenic hydrocarbons from deep reservoirs to the sediment-water interface and, ultimately, into the water column. The close association of salt and hydrocarbon systems results in frequent co-migration of brine and hydrocarbons (oil and gas). Upon reaching the surface, the co-migration of these fluids creates distinct extreme environments capable of supporting prolific microbial communities and complex chemosynthetically-based food webs.

The Gulf of Mexico setting is complicated by the mode of hydrocarbon occurrence. At one extreme, free gas and/or liquid oil is a component of a complex fluid contained in seafloor brine pools or diatremes. The fluid in these pools is hypersaline, can reach temperatures of 40°C or greater, and may entrain quantities of silt or clay as ejecta or debris flows. At the opposite extreme, hydrocarbons and H2S form ice-like clathrates with water called gas hydrates. In the Gulf of Mexico, hydrates occur as shallow layers and vein-filling plugs that breach the sediment interface and slowly decompose in contact with seawater. These extremes define a broad spectrum of temporally and spatially varying environmental conditions creating a wide variety of microbial niches requiring special adaptations. Relatively little is known, however, about the types of microorganisms dwelling in these environments, their genetic diversity, or their ecology and ecophysiology.

This project will test the hypotheses that brines and hydrates form distinct microbial niches containing specialized communities and functions and that the dynamic interaction between the microbial activity and geochemistry of these systems results in distinctive geochemical signals that can be detected in the environment. We will collect brines and hydrates from four well-characterized settings in the Gulf of Mexico. Key functional and phylogenetic groups in the community will be identified by analysis of microbial and genetic diversity. The organisms can then be linked to their characteristic activities through measurement of biogeochemical rates (e.g. sulfide and methane oxidation, methanogenesis, sulfate reduction). Evidence of these processes is recorded in both the microbiota and the surrounding environment and can be revealed through stable isotopic analysis of cellular and environmental molecules.

This project exploits the relative accessibility of shallow hydrocarbon-based ecosystems in the Northern Gulf of Mexico. The research plan is interdisciplinary by necessity and will permit us to document the microbial biogeochemistry and molecular ecology of hydrate and brine environments, as well as the biogeochemical markers and indices that are characteristic of these communities. The information gained through this project will contribute to the field of deep-sea microbiology as well as permit us to understand the adaptations of microorganisms to unique environments that might be present on other planetary bodies (e.g., hydrates on Europa).

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PRINCIPAL INVESTIGATORS:
Dr. Patricia A. Sobecky
Assistant Professor - School of Biology - Georgia Institute of Technology
patricia.sobecky@biology.gatech.edu

Dr. Joseph Montoya
Associate Professor - School of Biology - Georgia Institute of Technology
joseph.montoya@biology.gatech.edu

Dr. Samantha Joye
Assistant Professor - Department of Marine Sciences - The University of Georgia
mjoye@arches.uga.edu

Dr. Ian MacDonald
Geochemical and Environmental Research Group - Texas A & M University
ian@gerg.tamu.edu
Georgia Tech:
Chris Payne, Research Technician
Carrie Holl, Graduate Student
Cary Reynolds, Undergraduate Student
Cassie Hodges, Undergraduate Student
Heath Mills, Graduate student
Lance Miller, Graduate Student

University of Georgia:
Stephen Carini, Graduate Student
Jen Fisher, Graduate Student
Beth Orcutt, Undergraduate Student
Samantha Lugo, Graduate Student

Texas A&M University
Ira Leifer, Post-doctoral Fellow
Sophie De Beukelaer, Graduate Student
Michael Vardaro, Graduate Student

Others:
Antje Boetius, Visiting Scientist
Heide Schulz, Visiting Scientist
Erik Cordes, Graduate Student (Penn State University)
Sigurd Tesche, Video Documentation/Producer (TescheFilms)
This mission is made possible through a grant from from the National Oceanic and Atmospheric Administration as part of the National Undersea Research Program (NURP) and the National Science Foundation.

National Undersea Research Program (NURP)
The National Undersea Research Program (NURP), within the National Oceanic and Atmospheric Administration (NOAA), provides a unique national service by providing undersea scientists with the tools and expertise they need to work in the undersea environment. Equipping scientists with submersibles, remotely operated or autonomous underwater vehicles, mixed gas diving gear, underwater laboratories and observatories.

National Science Foundation (NSF)
The National Science Foundation is an independent U.S. government agency responsible for promoting science and engineering through programs that invest over $3.3 billion per year in almost 20,000 research and education projects in science and engineering.

National Undersea Research Center (NURC)
The National Undersea Research Center at University of North Carolina at Wilmington for the Southeastern United States and Gulf of Mexico region (NURC/SEGM) explores ocean waters in the South Atlantic Bight (NC to FL), Florida Keys, and Gulf of Mexico. This is one of six regional National Undersea Research Centers (NURC's). Each center is funded by a grant from NOAA.




 

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