EarthRef.org Digital Archive (ERDA) -- How Hydrology and Geochemistry at Seamounts Provide Habitats for Microbes

Description
In this keynote presentation for the SEAMOUNTS'09 Workshop Dave Emerson explains why seamounts are dynamic refugia in a comparatively static deep ocean that may provide unique habitats that stimulate microbial growth, especially because of the roles seamounts and basaltic outcrops play in guiding seawater circulation through the crust. As seawater circulates through the crust it interacts with the permeable basalt providing a supply of nutrients, and a redox potential suitable for a range of microbial metabolisms. Such seawater circulation systems are driven by a set of distinct hydrodrogeologic classifications (magmatic inputs of heat, lithospheric cooling, and compression) resulting in a range of fluid compositions, from high temperature (400ºC) to cool (2ºC), from acidic (pH 2) to basic (pH 12.5), from reducing to oxygen rich, and from metal rich to metal poor. Despite the potential for these fluids associated with seamounts to host such a wide range of habitats for bacteria and archaea, we know surprisingly little about seamount microbiology. Examples of open questions include, the percentage of seamounts harbor unique microbial communities, or how do hydrothermally-driven microbial communities at seamounts compare to similar communities at mid-ocean ridges? Futhermore, seamounts could make useful natural laboratories for studying such questions as how biogeography may influence microbial diversity. Dave provides the latest data from both Loihi seamount SE of Hawaii.