Aquatic Sciences Meeting, Albuquerque 2001

SS03 Chemosynthetic Processes at Oxic-Anoxic Interfaces (Environmental Connections)

Date: Tuesday, February 13, 2001, Time: 4:15:00 PM

Location: Mesilla

Boetius, A, , Max Planck Institute for Marine Microbiology, Bremen, Germany, aboetius@mpi-bremen.de

Elvert, M, , Max Planck Institute for Marine Microbiology, Bremen, Germany, melvert@mpi-bremen.de

Nauhaus, K, , Max Planck Institute for Marine Microbiology, Bremen, Germany, knauhaus@mpi-bremen.de

Ravenschlag, K, , Max Planck Institute for Marine Microbiology, Bremen, Germany, kravensc@mpi-bremen.de

Rickert, D, , GEOMAR Research Center for Marine Geosciences, Kiel, Germany, drickert@mpi-bremen.de

Schubert, C, J, Max Planck Institute for Marine Microbiology, Bremen, Germany, cschuber@mpi-bremen.de

Treude, T, , Max Planck Institute for Marine Microbiology, Bremen, Germany, ttreude@mpi-bremen.de

ANAEROBIC OXIDATION OF METHANE MEDIATED BY A SYNTROPHIC MICROBIAL CONSORTIUM ABOVE MARINE GAS HYDRATE (CASCADIA CONTINENTAL MARGIN, NE-PACIFIC)

At the Cascadia convergent margin off the coast of Oregon, discrete methane hydrate layers are exposed at the seafloor, at a water depth of 600-800 m corresponding to the hydrate stability limit. Undisturbed sediment cores were obtained using a video-guided multiple corer during RV SONNE Cruise SO143-2 and SO148-1 in August 1999 and 2000. Integrated over the upper 15cm, the sulfate reduction rates in the zone of anaerobic oxidation of methane (AOM) are >100 mmol/m2/d1 and represent some of the highest values ever measured in cold marine sediments. The combination of biomarker studies involving stable isotope analysis and fluorescence in situ hybridization provides evidence that a structured consortium of archaea and sulfate reducing bacteria (SRB) is responsible for AOM in these sediments. These symbiotic microorganisms occur in extremely high numbers of 10^10 cells per ml sediment. The methane oxidation rates mediated by these consortia was measured for the first time in parallel to sulfate reduction rates in surface and subsurface zones of methane seeping sediments containing gas hydrates. A large fraction of the methane from dissociating hydrates is converted to CO2 via anaerobic oxidation with sulfate. New data are presented concerning the distribution, abundance and diversity of the archaea/SRB consortia in methane rich sediments.

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Aquatic Sciences Meeting, Albuquerque 2001

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