Over the past decade, biologists have learned that hydrothermal faunas are not globally cosmopolitan and that biogeographic provinces of the known fauna may be correlated with geographic and tectonic parameters. The result is a biogeographic puzzle, from which several major pieces are still missing due to their remote locations. Of these missing pieces, the Indian Ocean ridge systems stand out as one of the most important, perhaps serving as the link between Pacific and Atlantic faunas. This project will test this hypothesis by locating and sampling a hydrothermal vent on the Central Indian Ridge for which there is a full suite of existing preliminary data, including bathymetry and plume data. The site is "mature", ready for detailed investigations according to standards established by the RIDGE community. Six major approaches will be utilized in this study: Plume Prospecting will relocate plumes observed by German and Japanese scientists and trace these plumes to their source on the seafloor. Biogeography and Evolutionary Biology will include taxonomic identifications of invertebrates and molecular characterization of selected fauna. Ecological Investigations will examine trophic interactions with an emphasis on clarifying the role of symbiosis in the system and will include microbial diversity studies, faunal distributions, biodiversity measures, and other descriptive ecology. Studies in a Geological Context will identify proximal geological controls on fluid flow and map the distribution of hydrothermal sites within the vent field. Hydrothermal Fluid Chemistry will establish end-member fluid chemistry and measure availability of reduced compounds in low-temperature fluids for chemoautotrophic production. Sulfide and Basalt Characterization will provide a mineralogical context for the hydrothermal setting. Each of these program elements are critical for interpretation of biogeography of the fauna. This study will provide a preliminary perspective of an Indian Ocean hydrothermal system and the data required to place it within the spectrum of global mid-ocean ridge hydrothermal processes.
