HR: 1340h
AN: OS43A-0528    [Abstracts]
TI: Biogeochemical Processes in Mid-Ocean Ridge Hydrothermal Plumes
AU: * Cowen, J P
EM: jcowen@soest.hawaii.edu
AF: SOEST, University of Hawaii, 1000 Pope Road, Honolulu, HI 96822
AU: Thomson, R E
EM: ThomsonR@pac.dfo-mpo.gc.ca
AF: Institute of Ocean Sciences, 9860 West Saanich Road, Sidney, BC V8L4B2 Canada
AU: Kadko, D C
EM: dkadko@rsmas.miami.edu
AF: RSMAS/MAC University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149
AU: Wakeham, S G
EM: stuart@skio.peachnet.edu
AF: Skidaway Institute of Oceanography, 10 Ocean Science Circle, Savannah, GA 31411
AU: Bertram, M A
EM: mbertram@ocean.washington.edu
AF: School of Oceanography, University of Washington, Box 357940, Seattle, WA 98195-7940
AU: Lam, P
EM: plam@soest.hawaii.edu
AF: SOEST, University of Hawaii, 1000 Pope Road, Honolulu, HI 96822
AU: Popp, B N
EM: popp@hawaii.edu
AF: SOEST, University of Hawaii, 1000 Pope Road, Honolulu, HI 96822
AB: Hydrothermal production is an important source of labile organic carbon (OC) to the deep-sea ecosystem along a ~60,000 km mid-ocean ridge corridor of enhanced productivity. Both the source flux and dispersion of OC derived from hydrothermal environments are poorly constrained. The dispersion is controlled by a complex interaction of dissolved OC to particulate OC transformations, particle scavenging and settling processes, buoyant plume dynamics and near-bottom circulation. Dissolved (DOC) and particulate (POC) organic carbon in hydrothermal plumes are derived from i) subseafloor microbial and thermochemical processes, ii) vent macrofaunal communities through exudation, sloughing, feeding, and export of reproductive products, iii) in situ production within the buoyant and neutrally buoyant plumes, iv) background deep-water entrained during plume formation, and v) descending particles delivered from surface water production. The quantitative contributions from first two sources are not presently known, whereas more measurements exist of in situ production within hydrothermal plumes and the importation of OC from the upper water column. Inspired by the early work of Jack Dymond and colleagues, the accumulating data (1980's to present) from the Endeavour Segment and other areas indicate that in situ production of POC from the oxidation of H2S, H2, CH4 and NH4, alone, may contribute $>$300% of the surface derived OC flux to plume depths along a 20 km wide corridor. It is likely that this value is conservative since `hydrothermally derived' DOC is almost totally unaccounted for Furthermore, the labile nature of this fresh `hydrothermal' OC relative to the more refractory ambient deep water OC underscores its potential significance to deep-water organisms. This production and its dispersion must strongly influence the abundance and diversity of deep water and benthic micro- and macro-fauna along the ridges and ridge flanks, creating an "oasis" of labile organic-C that focuses biological activity over and on the MORs.
DE: 4805 Biogeochemical cycles (1615)
DE: 4832 Hydrothermal systems
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting