HR: 1330h
AN: B12A-0733    [PDF]
TI: The distribution of species and biomass in {\it Riftia pachyptila} communities from environmentally different hydrothermal vent habitats at 9\deg N (East Pacific Rise)
AU: * Govenar, B
EM: bwg122@psu.edu
AF: Pennsylvania State University, Department of Biology 208 Mueller Laboratory, University Park, PA 16802 United States
AU: Aperghis, A
EM: aba123@psu.edu
AF: Pennsylvania State University, Department of Biology 208 Mueller Laboratory, University Park, PA 16802 United States
AU: Glanville, J
EM: joanneglanville@hotmail.com
AF: Pennsylvania State University, Department of Biology 208 Mueller Laboratory, University Park, PA 16802 United States
AU: Le Bris, N
EM: nlebris@ifremer.fr
AF: IFREMER, Centre de Brest Departement Environnement Profond BP70, Plouzane, 29280 France
AU: Fisher, C R
EM: cfisher@psu.edu
AF: Pennsylvania State University, Department of Biology 208 Mueller Laboratory, University Park, PA 16802 United States
AB: Hydrothermal vents have been characterized by high biomass, high productivity, high endemicity, and low species diversity. However these ecological characteristics are rarely quantified at an ecosystem level. At 9\deg N (East Pacific Rise), the giant tubeworm {\it Riftia pachyptila} can form dense aggregations in the dynamic mixing zone of hydrothermal vent effluent and deep-ocean bottom water. {\it R. pachyptila} must obtain carbon dioxide, hydrogen sulfide, and oxygen in order to support an obligate nutritional symbiosis with chemolithoautotrophic bacteria. In this patchy and ephemeral habitat, the tubes of {\it R. pachyptila} provide biogenic substrate that can support high relative abundances of heterotrophic species. As one part of a multidisciplinary collaboration to model the productivity in these habitats, the purpose of this study is to quantify the species composition and the biomass distribution in the {\it R. pachyptila} community. Within the scope of this work, a sampling design was employed to concurrently test for spatial and temporal variability in the community structure. Quantitative samples of the {\it R. pachyptila} community were collected in consecutive years (2001, 2002) at two environmentally different sites. At one site (Riftia Fields), the mixing zone has relatively low concentrations of hydrogen sulfide, low pH, and high concentrations of iron, whereas the mixing zone at the other site (Tica) has a wider range of hydrogen sulfide concentrations, closer to neutral pH, and undetectable iron concentrations. Analyses of the species composition in eight quantitative samples indicate that there is not a significant difference in species richness and Shannon-Weiner (H') diversity values between sites or years, and that Bray-Curtis community similarity values are very high. When all of the species in a sample are added together, the total abundance and total biomass are much higher in the {\it R. pachyptila} community at Tica than at Riftia Fields. The results and of this project will be integrated with species-specific respiration rates and in situ environmental measurements to generate an ecosystem-level model of the net primary productivity.
DE: 3015 Heat flow (benthic) and hydrothermal processes
DE: 3035 Midocean ridge processes
DE: 4815 Ecosystems, structure and dynamics
SC: Biogeosciences [B]
MN: 2003 Fall Meeting