HR: 14:30h
AN: B23C-04    [Abstracts]
TI: A Microbial Community in Sediments Beneath the Western Antarctic Ice Sheet, Ice Stream C (Kamb)
AU: * Skidmore, M
EM: skidmore@montana.edu
AF: Montana State University, Department of Earth Sciences, Bozeman, MT 59715 United States
AU: Han, S
EM: hansk@citrus.ucr.edu
AF: University of California at Riverside, Department of Environmental Sciences , Riverside, CA 92521 United States
AU: Foo, W
EM: wilson.foo@email.ucr.edu
AF: University of California at Riverside, Department of Environmental Sciences , Riverside, CA 92521 United States
AU: Bui, D
EM: duy.bui@email.ucr.edu
AF: University of California at Riverside, Department of Environmental Sciences , Riverside, CA 92521 United States
AU: Lanoil, B
EM: Brian.lanoil@ucr.edu
AF: University of California at Riverside, Department of Environmental Sciences , Riverside, CA 92521 United States
AB: In 2000, an ice-drilling project focusing on the "sticky spot" of Ice Stream C recovered cores of sub-glacial sediments from beneath the Western Antarctic Ice Sheet. We have characterized several chemical and microbiological parameters of the sole intact sediment core. Pore waters extracted from these sediments were brackish and some were supersaturated with respect to calcite.ÿ Ion chromatography demonstrated the presence of several organic acids at low, but detectable, levels in the pore water. DAPI direct cell counts were approximately 10$^{7}$ cells g$^{-1}$. Aerobic viable plate counts were much lower than direct cell counts; however, they were two orders of magnitude higher on plates incubated at low temperature (4 $\deg$C; 3.63 x 10$^{5}$ CFU ml$^{-1}$) than at higher temperatures (ca. 22$\deg$C; 1.5 x 10$^{3}$ CFU ml$^{-1}$); no colonies were detected on plates incubated anaerobically at either temperature. 16S rDNA clone library analysis indicates extremely limited bacterial diversity in these samples: six phylogenetic clades were detected. The three dominant bacterial phylogenetic clades in the clone libraries (252 clones total) were most closely related to Thiobacillus thioparus (180 clones), Polaromonas vacuolata (34 clones), and Gallionella ferruginea (35 clones) and their relatives; one clone each represented the other three phylogenetic clades (most closely related to Ralstonia pickettii, Lysobacter antibioticus, and Xylella fastidiosa, respectively). These sequences match closely with sequences previously obtained from other subglacial environments in Alaska, Ellesmere Island, Canada and New Zealand. Implications of this microbial community to subglacial chemistry and microbial biogeography will be discussed.
DE: 9310 Antarctica
DE: 1827 Glaciology (1863)
DE: 1615 Biogeochemical processes (4805)
DE: 1625 Geomorphology and weathering (1824, 1886)
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting