HR: 0800h
AN: V51C-1500    [Abstracts]
TI: Phylogenetic and Physiological Diversity of Subseafloor Microbial Communities at Axial Seamount, Juan de Fuca Ridge: Summary of Results From the New Millenium Observatory (NeMO), 1998-2004
AU: Baross, J A
EM: jbaross@u.washington.edu
AF: University of Washington, School of Oceanography, Box 357940, Seattle, WA 98195 United States
AU: * Huber, J A
EM: jhuber@mbl.edu
AF: Marine Biological Laboratory, Josephine Bay Paul Center, 7 MBL Street, Woods Hole, MA 02543 United States
AU: Mehta, M P
EM: mausmi@ocean.washington.edu
AF: University of Washington, School of Oceanography, Box 357940, Seattle, WA 98195 United States
AU: Opatkiewicz, A
EM: opatka@u.washington.edu
AF: University of Washington, School of Oceanography, Box 357940, Seattle, WA 98195 United States
AU: Bolton, S A
EM: bolton@u.washington.edu
AF: University of Washington, School of Oceanography, Box 357940, Seattle, WA 98195 United States
AU: Butterfield, D A
EM: David.A.Butterfield@noaa.gov
AF: Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, NOAA/PMEL, 7600 Sand Point Way NE, Seattle, WA 98115 United States
AU: Sogin, M L
EM: sogin@mbl.edu
AF: Marine Biological Laboratory, Josephine Bay Paul Center, 7 MBL Street, Woods Hole, MA 02543 United States
AU: Embley, R W
EM: Robert.W.Embly@noaa.gov
AF: NOAA/PMEL, Ocean Environment Research Division, 2115 OSU Drive, Newport, OR 97365 United States
AB: Axial Seamount (45 ° 58' N; 130 ° 00' W) is an active submarine volcano located on the Juan de Fuca Ridge, approximately 300 miles off the coast of Oregon. Lying at the intersection of a seamount chain and a spreading axis, Axial is a unique study site from both the geological and biological perspective. In January of 1998, Axial experienced a week-long series of earthquakes, and subsequent water column and seafloor observations on the southeast portion of the caldera found temperature and chemical anomalies, extensive new seafloor lava flows, large "snow blower" type vents, and other characteristics commonly associated with diking-eruptive events. Due to its high activity and close proximity to shore, Axial was chosen as a site for a multi-year observatory (New Millenium Observatory, NeMO) to document changes and interactions between geology, chemistry, and biology on the mid-ocean ridge system. From 1998 through 2004, we extensively sampled diffuse vents at Axial Seamount to determine the physiological and phylogenetic diversity of subseafloor microbial communities and their relationship to the geochemical environment. Here we present a summary of those studies, including molecular-based phylogenetic surveys of bacteria, archaea, and potential nitrogen-fixing organisms, culturing results of thermophiles and hyperthermophiles from over 20 sites, and the distribution of one particular group of hyperthermophiles at diffuse vents throughout the caldera and how that distribution may be linked to the geochemical habitat. Results indicate that Axial supports a diverse subseafloor microbial community, including hydrogen and sulfur oxidizers, hyperthermophilic methane producers and heterotrophs, and many organisms with the potential to fix nitrogen. In addition, we find that the species composition of the microbial community changes in response to changes in the physical and chemical conditions at each vent site. The extent of seawater mixing with hydrothermal fluids has the most pronounced effect on microbial community diversity. Even at vent sites dominated by seawater, thermophilic and hyperthermophilic anaerobes are still detected and point to a hot, anaerobic subseafloor zone where biological carbon dioxide fixation and biofilm formation are dominant physiological strategies. Axial represents one of the most well-studied seamounts to date, and with a wealth of contextual information and samples, we are continuing our work there with a focus on using metagenomics to determine the genetic content of the subseafloor microbial community and how these genes relate to the biogeochemical environment.
UR: http://www.pmel.noaa.gov/vents/nemo/
DE: 0448 Geomicrobiology
DE: 0450 Hydrothermal systems (1034, 3017, 3616, 4832, 8135, 8424)
DE: 0456 Life in extreme environments
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
DE: 1032 Mid-oceanic ridge processes (3614, 8416)
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005