HR: 1330h
AN: B12A-0731    [PDF]
TI: Sulfide Bioavailability and Potential Toxicity in the Environment of Vent Organisms: a Comparison of Characteristic Habitats of the EPR 13$\deg$N and 9$\deg$N Vent Fields
AU: * Le Bris, N
EM: nlebris@ifremer.fr
AF: Ifremer, DRO-EP, BP 70, Plouzane, F-29280 France
AU: Gaill, F
EM: fgaill@snv.jussieu.fr
AF: Universite Paris 6, UMR 7138 SAE, 7, quai St Bernard, Paris, F-75005 France
AU: Govenar, B
EM: bwg122@psu.edu
AF: The Pennsylvania State University, 208 Mueller Laboratory, University Park, PA 16802 United States
AU: Fisher, C R
EM: crf2@psu.edu
AF: The Pennsylvania State University, 208 Mueller Laboratory, University Park, PA 16802 United States
AB: Sulfide is a key player of biogeochemical interactions in deep-sea vent ecosystems, owing to its essential role in bacterial primary production and its potential toxicity to aerobic organisms. Still, the relative importance of these constraints in the different vent habitats remains poorly known. Contrasted chemical controls in the habitat of two invertebrate species were hypothesized, resulting of different sulfide speciation. The variability of sulfide geochemical patterns between different habitats at one site or between similar types of habitat at different sites or vent fields also has to be considered. From in situ analysis of sulfide and ferrous iron combined to pH and temperature sensing and chemical modeling we addressed sulfide to temperature dependence and sulfide speciation in the close vicinity of Riftia pachyptila bushes and Alvinella pompejana colonies at different 13$\deg$N and 9$\deg$N EPR sites. Very different sulfide to temperature ratios appear to characterize the environment of the two dominant organisms, even at the scale of one single site. The A. pompejana surroundings display an unexpectedly high sulfide to temperature ratio while this ratio is much lower in the tubeworm environment. In this last case, up to one order of magnitude difference is observed between sites, resulting in very different sulfide levels for similar temperature ranges. The iron to sulfide ratio was suggested to drive the biological impact of sulfide. As previously shown, partial sulfide detoxification can be expected in the environment of A. pompejana. Still, due to iron depletion in the fluid, the contribution of the most toxic sulfide form can be much more important at some particular sites with respect to the more general case. To the opposite, iron does not appear to influence sulfide bioavailability in the R. pachyptila environment, even for colonies displaying very contrasted patterns. A more complex combination of environmental and biological factors should be considered.
DE: 0400 Biogeosciences
DE: 1050 Marine geochemistry (4835, 4850)
DE: 4802 Anoxic environments
DE: 4825 Geochemistry
DE: 4832 Hydrothermal systems
SC: Biogeosciences [B]
MN: 2003 Fall Meeting