HR: 1340h
AN: B43E-1651    [Abstracts]
TI: Foraminiferal Ecology and Stable Isotope Geochemistry of Methane Seeps in Monterey Bay, California
AU: Waggoner, J
EM: wagg8@mchsi.com
AF: Indiana State University Geology Program, 159 science Bldg, Terre Haute, IN 47809, United States
AU: * Rathburn, A E
EM: arathburn@indstate.edu
AF: Indiana State University Geology Program, 159 science Bldg, Terre Haute, IN 47809, United States
AU: * Rathburn, A E
EM: arathburn@indstate.edu
AF: Scripps Inst. of Oceanography IOD-0218, 9500 Gilman Drive, La Jolla, CA 92093, United States
AU: Martin, J B
EM: jbmartin@ufl.edu
AF: University of Florida Dept. of Geological Sciences, 241 Williamson Hall, Gainesville, FL 32611, United States
AU: Bernhard, J M
EM: jbernhard@whoi.edu
AF: Woods Hole Oceanographic Inst. Dept. of Geology and Geophysics, MS 52, Woods Hole, MA 02543, United States
AU: Gieskes, J
EM: bgieskes@worldnet.att.net
AF: Scripps Inst. of Oceanography IOD-0218, 9500 Gilman Drive, La Jolla, CA 92093, United States
AU: Ziebis, W
EM: wziebis@usc.edu
AF: University of Southern California, Dept. of Biological Sciences 3616 Trousdale Pkwy AHF 335, Los Angeles, CA 90089, United States
AB: In an ongoing effort to understand the factors that influence the stable isotopic composition of benthic foraminifera, clam beds associated with methane seepage in the Clam Flats area of Monterey Bay, California were sampled using the remotely operated vehicle Jason II. Pore water chemistry and vertical and spatial distributions and stable isotopic signatures of benthic foraminifera (stained with Rose Bengal or labled with Cell Tracker green) were examined in push cores in seeps and non-seep environments (about 990 m water depth). Pore water profiles of alkalinity and sulfide concentration reflect highly reduced environments within the seeps, but less than 30 cm from the edge of the seeps, these profiles are similar to the profiles from the non-seep environments. This result indicates that the seeps are highly localized. Microprofiles of oxygen and hydrogen sulfide measured in intact cores showed distinct differences of microhabitats within and between cores. Dominant taxa of foraminifera living in surface sediments of Clam beds included Cibicides, Bolivina, and Epistominella. Comparisons between these results and previous results from the area suggest that there is an influence of methane seepage on the carbon isotopic values of foraminiferal calcite. However, the carbon isotopic composition of DIC in pore water and those of the foraminifera associated with pore water can differ by as much as 40 per mil. Possible reasons for this disequilibrium will be explored.
DE: 0448 Geomicrobiology
DE: 0456 Life in extreme environments
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 1050 Marine geochemistry (4835, 4845, 4850)
DE: 3004 Gas and hydrate systems
SC: Biogeosciences [B]
MN: 2007 Fall Meeting