HR: 12:05h
AN: B52A-08    [Abstracts]
TI: Life in Subseafloor Sediments of the South Pacific Gyre
AU: * D'Hondt, S
EM: dhondt@gso.uri.edu
AF: Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, United States
AU: Abrams, L
EM: abramsl@uncw.edu
AF: Department of Geography and Geology, University of North Carolina, Wilmington, 28403, United States
AU: Ferdelman, T
EM: tferdelm@mpi-bremen.de
AF: Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, D- 28359, Germany
AU: Fischer, J
EM: jfischer@mpi-bremen.de
AF: Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, D- 28359, Germany
AU: Hasiuk, F
EM: franek@umich.edu
AF: Department of Geological Sciences, University of Michigan, Ann Arbor, 48109, United States
AU: Kallmeyer, J
EM: kallm@gfz-potsdam.de
AF: Geoforchungszentrum Potsdam, University of Potsdam, Potsdam, D-14473, Germany
AU: Pockalny, R
EM: rpockalny@gso.uri.edu
AF: Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, United States
AU: Schrum, H
EM: hschrum@gso.uri.edu
AF: Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, United States
AU: Smith, D C
EM: dcsmith@gso.uri.edu
AF: Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, United States
AU: Spivack, A
EM: spivack@gso.uri.edu
AF: Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, United States
AU: Stancin, A
EM: stancin@umich.edu
AF: Department of Geological Sciences, University of Michigan, Ann Arbor, 48109, United States
AU: Shipboard Science Party, K
EM: dhondt@gso.uri.edu
AB: The middle of the South Pacific Gyre (SPG) is farther from continents and productive oceanic zones than any other site on Earth. To understand the nature of life in the most oxidized and food-limited subseafloor sediments, expedition Knox-02RR surveyed and cored the sediment at ten sites throughout the Gyre and one site at the southern margin of the Gyre. The sediment has accumulated extraordinarily slowly at all of the SPG sites (0.1 to 1 m/myr). These sediments contain a living community that is characterized by very low biomass and very low metabolic activity. At every depth in the cored SPG sediments, cell abundances are two to six orders of magnitude lower than at the same depths in all previously explored subseafloor communities. The net rate of respiration by the subseafloor sedimentary community at each SPG site is one to three orders of magnitude lower than the rates of subseafloor communities at previously explored sites. Due to the low rates of respiration and the thinness of the sediment, interstitial waters are oxic throughout the sediment column in most of this region. Consequently, the subseafloor sedimentary community of this region is predominantly aerobic, unlike previously explored subseafloor communities. Generation of hydrogen by radiolysis of water may be a significant food source for this subseafloor community.
DE: 0448 Geomicrobiology
DE: 0456 Life in extreme environments
DE: 0460 Marine systems (4800)
DE: 0463 Microbe/mineral interactions
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting