HR: 1340h
AN: B33A-0849    [Abstracts]
TI: Deciphering Life in Young Ocean Crust: Development and Testing of Methods for Subsurface Microbial Observatories and In-Situ Incubations
AU: * Orcutt, B N
EM: borcutt@usc.edu
AF: University of Southern California, Marine Environmental Biology, 3616 Trousdale Parkway, Los Angeles, CA 90089-0371, United States
AU: Edwards, K
EM: kje@usc.edu
AF: University of Southern California, Marine Environmental Biology, 3616 Trousdale Parkway, Los Angeles, CA 90089-0371, United States
AU: Wheat, G
EM: wheat@mbari.org
AF: Global Undersea Research Unit, PO Box 475, Moss Landing, CA 95039, United States
AU: Jannasch, H
EM: jaha@mbari.org
AF: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing, CA 95039, United States
AB: Biogeochemical processes within the ocean crust, a hydrologically active global habitat, are hypothesized to balance key elemental budgets in the ocean (i.e. Si, Fe), yet the importance of microbial activity in mediating these processes remains unexplored. Reduced iron makes up roughly 10% of the basalt that comprises ocean crust, making iron cycling a likely source of energy for microbial activity in these systems. Available data indicates that young sub-seafloor ocean crust may be the most redox active: weathering features are established early (within the first 10-20 Ma) and change little thereafter. Laboratory studies, field examinations, and in-situ colonization and weathering experiments have shown that chemoautotrophic Fe- and S-oxidizing microorganisms are abundant and active in weathering rocks exposed at the seafloor at low temperatures. A current challenge is adaptation of available techniques for use in subsurface hard rock environments to evaluate the extent and activity of the deep biosphere. Because of the importance to study microbial communities under their relevant environmental conditions, significant resources must be dedicated to investigate this realm in situ. To address these challenges, sub-seafloor microbial observatories designed to yield high-quality, undisturbed samples that are amenable to genomic, taxonomic, spatial and geochemical profiling are in development and testing. Deployment of these observatories within drilled boreholes will allow the scientific community unprecedented opportunities to investigate microbial processes experimentally in sediments as well as subsurface hard rock environments. Initial experiments during ocean drilling expeditions at both the young and relatively warm Juan de Fuca flank as well as the young and cold ridge flank of North Pond along the Mid-Atlantic Ridge are crucial for evaluating whether the sub-seafloor ridge flank habitat supports a unique microbial community, how the microbial community compares in diversity and activity to those of deep sediments and seawater, and the global significance of microbes in biologically-mediated oxidative weathering of basalts.
DE: 0400 BIOGEOSCIENCES
DE: 0463 Microbe/mineral interactions
DE: 1021 Composition of the oceanic crust
DE: 1023 Composition of the biosphere
DE: 4840 Microbiology and microbial ecology (0465)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting