HR: 1330h
AN: B12A-0756    [PDF]
TI: Microbial diversity in subseafloor fluids from Explorer Ridge, Northeast Pacific
AU: * Bolton, S
EM: bolton@u.washington.edu
AF: University of Washington, School of Oceanography, Box 357940, Seattle, WA 98195 United States
AU: Huber, J A
EM: huberja@ocean.washington.edu
AF: University of Washington, School of Oceanography, Box 357940, Seattle, WA 98195 United States
AU: Embley, R
EM: embley@pmel.noaa.gov
AF: Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Hatfield Marine Science Center, Newport, OR 97365 United States
AU: Butterfield, D A
EM: butterfield@pmel.noaa.gov
AF: Joint Institute for the Study of Atmosphere and Ocean, University of Washington, Box 357940, Seattle, WA 98195 United States
AU: Baross, J A
EM: jbaross@u.washington.edu
AF: University of Washington, School of Oceanography, Box 357940, Seattle, WA 98195 United States
AB: The Gorda, Juan de Fuca and Explorer Ridges are first order spreading centers located in the northeast Pacific. While the Gorda and Juan de Fuca Ridges have been extensively sampled for chemical and microbiological analyses, what little is known about the Explorer Ridge is from preliminary observations made in the mid-1980's. A cruise in 2002 revisited the area and discovered vigorous hydrothermal activity at Magic Mountain, a site located outside the primary rift valley. Explorer Ridge is an important site to compare with other well-described vent sites on the Juan de Fuca Ridge. Our research has focused on describing the phylogenetic and physiological diversity of bacteria and archaea in low temperature hydrothermal fluids in an effort to identify subseafloor indicator organisms and to use the physiological characteristics of these organisms to help constrain subseafloor habitat characteristics. We have previously established that there are microbial taxa that are unique to subseafloor habitats associated with diffuse flow fluids at Axial Seamount and at Endeavour both located on the Juan de Fuca Ridge. These included cultured anaerobic, thermophilic and hyperthermophilic heterotrophs, methanogens and sulfur metabolizers. Moreover, results from molecular phylogeny analyses using the 16S rRNA sequences identified a phylogenetically diverse group of bacteria belonging to the epsilon-proteobacteria. While anaerobic hyperthermophiles were cultured from some diffuse-flow vent sites at Explorer, they were less abundant than at Axial Volcano and Endeavour, and curiously, no methanogens were cultured or detected in 16S rRNA clonal libraries. Like Axial, a diverse group of epsilon-proteobacterial clones were found with many similar to those identified from Axial Seamount and other hydrothermal vent sites, although there appears to be some unique species. The overall bacterial diversity at Explorer appears different than at Axial, possibly linked to temperature or chemical characteristics. This study extends the distribution of the epsilon-proteobacteria to the Explorer Ridge and further indicates that while similar phylotypes of microorganisms are present in all subseafloor habitats at vents, the species composition differs reflecting different habitat characteristics.
DE: 3035 Midocean ridge processes
DE: 4803 Bacteria
DE: 4840 Microbiology
DE: 8424 Hydrothermal systems (8135)
SC: Biogeosciences [B]
MN: 2003 Fall Meeting