Abiotic Controls of Microbial Biogeography in Deep-Sea Hydrothermal Vent Deposits

Gilberto E. Flores

Department of Biology, Portland State University, Portland, OR 97201, USA.

Deep-sea hydrothermal environments support highly productive biological communities.  These communities thrive in the complete absence of sunlight because Archaea and Bacteria are able to harness the abundant geochemical energy available in the hydrothermal fluids. Numerous studies have attempted to describe the free-living bacteria associated with active hydrothermal vent deposits from around the globe. While these studies have provided an inventory of the types of organisms present in these environments, relatively few studies have attempted to understand the abiotic controls on microbial biogeography at the vent field scale. Through our recent work at the Mid-Atlantic Ridge (MAR), we have been able to show that environmental factors, particularly hydrothermal fluid chemistry and fluid mixing styles, can have a dramatic impact on microbial community structure and composition. Community differences are evident at phylogenetic and functional levels within and between individual vent fields along the MAR. We are currently extending this research to other vent fields, including the East Pacific Rise (EPR) and Eastern Lau Spreading Center (ELSC), in order to elucidate other abiotic factors that may influence microbial community composition and structure. Integrating our microbiological data with the existing geochemical and microbiogical data from the EPR and ELSC will be vital for us to determine other abiotic controls of microbial biogeography.