HR: 10:05h
AN: OS41C-08 INVITED    [Abstracts]
TI: Biological and Geological Characteristics of the Gakkel Ridge
AU: * Shank, T M
EM: tshank@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543, United States
AU: Bailey, J
EM: jbailey@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543, United States
AU: Edmonds, H
EM: edmonds@utmsi.utexas.edu
AF: University of Texas at Austin, Marine Science Institute 750 Channel View Drive, Port Aransas, TX 78373, United States
AU: Forte, P
EM: pforte@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543, United States
AU: Helmke, E
EM: Elisabeth.Helmke@awi.de
AF: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570, Bremerhaven, 27570, Germany
AU: Humphris, S
EM: shumphris@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543, United States
AU: Kemp, J
EM: jkemp@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543, United States
AU: Nakamura, K
EM: koichi.nakamura@aist.go.jp
AF: National Institute of Advanced Industrial Science and Technology, AIST Tsukuba Central 7, 1-1-1 Higashi, Tsukuba, 305-8567,
AU: Reves-Sohn, R
EM: rsohn@whoi.edu
AF: National Institute of Advanced Industrial Science and Technology, AIST Tsukuba Central 7, 1-1-1 Higashi, Tsukuba, 305-8567,
AU: Singh, H
EM: hsingh@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543, United States
AU: Willis, C
EM: cwillis@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543, United States
AB: The Gakkel Ridge (Arctic Ocean) is one of the slowest (1.0 cm per yr), deepest (5000 m axial depth), and most hydrographically and tectonically isolated mid-ocean ridge systems on earth. This isolation from the global ridge system should have profound implications for the evolution and ecology of resident chemosynthetic fauna. The July 2007 Arctic GAkkel Vents Expedition (AGAVE) sought to define this Arctic biogeographic province and the relationship of Arctic vent fauna to Atlantic, Pacific, and hydrocarbon seep fauna through the use of an new under- ice vehicle `Camper', a fiber-optic video-guided sampling system drift towed 1 to 3 m above the seafloor. The imaging, sampling, and sensing capabilities were used to obtain high-resolution seafloor imagery to identify and collect benthic samples with a clamshell `grab' sampler and a suction 'slurp' sampler. Imagery from five video cameras, including obliquely-mounted video and downlooking digital high-definition color cameras were used to construct maps of seafloor features and faunal composition during 3 dives in the peridotite-hosted 7°E region and 13 dives in the volcanic 85°E region. The 7°E site was dominated by an almost continuous cover of pelagic sediment with abundant animal tracks, brittle stars, anemones, and shrimp. The explored 85°E area was dominated by relatively diverse and young lava morphologies- from large pillows hosting delicate surface ornamentation to lobates, long lava tubes, and fresh sheet flows, all with the upper surfaces covered (often cm thick) of fresh volcanic glass 'sediment' suggestive of explosive volcanic activity in the `recent' past. Fauna in these areas consisted mainly of sponges, anemones, amphipods and shrimp. Characterization of the newly-discovered Asgard volcanic chain, including `Oden', `Thor', and `Loke' volcanoes, in the 85°E axial valley revealed extensive microbial mats in the form of: 1) yellow `fluffy' material (often >5 cm thick) in places; and 2) yellow `pebbly' material that may represent older microbial byproducts or inorganic material remnant of past microbial activity. The microbial mats were often associated with weak temperature (e.g., 0.07°C) and Eh anomalies (up to 80 mV) less than 3 meters above the mats, suggesting that they live in regions where reducing and slightly warm fluids are seeping through cracks in the fresh volcanic terrain. The rock margins adjacent to the microbial mats were orange-brown suggesting bio-chemical alteration. The microbial mat material may be sustained by weak fluid discharge from cracks in the young volcanic surfaces. Biological samples, including mat material, sponges, and amphipods were preserved for shore-based taxonomic, phylogenetic, and biogeographic analyses.
UR: http://www.divediscover.whoi.edu/expedition11/index.html
DE: 0408 Benthic processes (4804)
DE: 1034 Hydrothermal systems (0450, 3017, 3616, 4832, 8135, 8424)
DE: 4207 Arctic and Antarctic oceanography (9310, 9315)
DE: 4804 Benthic processes, benthos (0408)
DE: 4811 Chemosynthesis
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting