Brine seeps are caused by the dissolution of salt that was deposited when the Gulf of Mexico was an evaporative basin and then buried beneath sediments. When salt deposits come into contact with seawater, they dissolve, and form brines many times saltier than seawater. Salt migration creates faults in the sediment column and drives seepage of brine fluids and materials from the deep subsurface to the seafloor. These heavy brines flow out of the seafloor forming puddles, pools, and lakes of brine. Brine seeps occur along continental margins, but surprisingly little is known about the diversity and activity of their microbial communities. Brine seeps are fueled by persistent fluid and gas discharge over periods of decades to centuries, thus it is likely that distinct free-living microbial communities have adapted to these habitats. Brine seep habitats may be analogs for brine seeps on other worlds as are thought to occur on Europa, Titan or Mars. The laboratories of Drs. Samantha Joye of the University of Georgia, Ian MacDonald of Texas A and M and Andreas Teske of the University of North Carolina and colleagues from Germany and Denmark will be characterizing the distribution and activity of the microbes in Gulf of Mexico brine seeps, examining the interactions of the microbial communities with their unusual environment, and evaluating the biogeochemical role of these communities in the brine seep habitats. They will be using a three-pronged approach that includes in-situ sampling, long-term monitoring, and experimentation to quantify the abundance, diversity and activity of microorganisms mediating carbon and sulfur transformations in brine seeps, to identify the environmental controls on these microbial activities and distributions, to trace carbon and sulfur flow through the microbial food web using stable isotope biomarkers, DNA and RNA and to isolate and characterize novel microorganisms from these brine seeps. This project will include a diverse portfolio of outreach activities. The research will include undergraduate and graduate students and postdoctoral scientists. An exchange program between US, German and Danish collaborators will permit US graduate students to live and work in Bremen, Germany or Odense, Denmark. A middle or high school science teacher will be participating in the research cruises through collaboration with the Centers for Ocean Science Education Excellence-Southeast program. The science teacher will work in one of the PI?s laboratories to develop course materials for use in middle and/or high schools. The PIs will have interactive web casts of research cruises and a project web page will be available, by year one of the project, for the scientific community and for the general public.
