HR: 0800h
AN: B21A-1024    [Abstracts]
TI: Prokaryotic diversity associated with high rate of organic matter mineralization in continental margin sediments in Santa Barbara Basin
AU: * Zhang, H
EM: husen@gps.caltech.edu
AF: Department of Geological and ences, California Institute of Technology, 1200 East California Blvd, Pasadena, CA 91125 United States
AU: Berelson, W
EM: berelson@usc.edu
AF: Department of Earth Sciences University of Southern California, 3651 Trousdale Ave., Los Angeles, CA 90089-0740 United States
AU: Sansone, F
EM: sansone@hawaii.edu
AF: Department of Oceanography, University of Hawaii, 1000 Pope Road, Honolulu, HI 96822 United States
AU: Orphan, V J
EM: vorphan@gps.caltech.edu
AF: Department of Geological and ences, California Institute of Technology, 1200 East California Blvd, Pasadena, CA 91125 United States
AB: In Santa Barbara Basin sediments, sulfate and total carbon dioxide profiles (TCO2) define a 'hot zone' where sulfate concentrations go to 0 and TCO2 gradients decline dramatically. The average linear gradient of sulfate as it approaches the 'hot zone' defines the sulfate flux of 0.426 ? 0.036 mmol-S per m2 per day. The average linear gradient of TCO2 defines diffusion away from this zone = 0.615 ? 0.077 mmol-C per m2 per day. The difference between the sulfate flux to the zone and the TCO2 flux away from the zone requires a source of TCO2 generated within the 'hot zone' which does not involve the simple reaction stoichiometry of anaerobic methane oxidation. Little is known about the diversity and distribution of prokaryotic community in the 'hot zone'. In the present study, a gravity core (1.7 m in length) was collected at a continental margin site in Santa Barbara Basin (water depth of 591 m). The prokaryotic diversity was analyzed for four sediment horizons that are within, above, and below the 'hot zone', Genomic DNA was extracted and amplified using 16S rDNA primers targeting Bacteria and Archaea. Screening of more than 300 colonies from these 16S rDNA clone libraries revealed a diversity of bacterial species, including members from Proteobacteria, Green-Non-Sulfur bacteria, Planctomycetes, and Candidate division JS1. The detection of sequences related to uncultured Desulfobacter sp. suggests that sulfate reduction is one of the electron-accepting processes. Archaeal populations were affiliated with members from the Crenarchaeota marine benthic group B, the Euryarchaeota marine benthic group D, the Terrestrial Miscellaneous Euryarchaeotal Group (TMEG), and other uncultured relatives of the Thermoplasmatales. Preliminary findings suggest the abundance of marine benthic group B Crenarchaeota decreased with depth, while marine benthic group D Euryarchaeota populations increased with depth. The detection of marine benthic group B and D was consistent with previous reports for their presence in deeper, anoxic sediments, both from continental margin and deep-sea sediments.
DE: 0410 Biodiversity
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
SC: Biogeosciences [B]
MN: Fall Meeting 2005