Development of the Capability to Measure Proxies of Microbial Activity Within Oceanic Crust

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This collaborative technology development project will be undertaken by investigators at the Universities of Hawaii, Washington, and Illinois-Chicago. Specialized seafloor instrumentation will be developed to test for the presence of a sub-seafloor biosphere hundreds of meters below the water-rock interface, by detecting specific metabolic products which accompany the hydrothermal fluids as they vent from the crust into the overlying seawater. To test the sub-surface biosphere hypothesis, an instrumented "bio- blanket" will be built and deployed that isolates a small area of surface rock from seawater, and focuses up-welling fluid through scavenging columns that serve as traps for metabolic (organic carbon) products which are associated with these sub-surface microbial communities. These diagnostic organic compounds should accompany the hydrothermal fluid that is known to circulate within the upper crustal rocks and eventually discharges into the overlying seawater at diffuse vent sites in exposed rock outcrops. The proposed instrumented blanket would also measure up-welling temperatures and velocities as the fluid vents into seawater. The development of the bio-blanket will be in several graduated stages, with the initial deployments being carried out at a ridge axis, where the fluid flux levels are substantial, and the dissolved carbon metabolic concentrations are relatively high. The direct detection of a wide-spread biological community, living within the sub-surface ocean floor would dramatically alter estimates of biological productivity and the global carbon budgets, and have a profound impact on our philosophical view of the earth.