Microbial Observatories Designed to Assess the Basaltic Ocean Crust Deep Biosphere

Although the current census of life indicates a large biomass of life in deep marine subsurface sediments, there is a relative dearth of information regarding microbial life in the hard rock environment of the ocean crust. Considering that the ocean crust comprises the largest hydrologically active environment on Earth, that crustal rocks can be out of redox equilibrium with percolating crustal fluids, and that recent evidence shows that seafloor exposed basalts harbor abundant and highly diverse microbial communities, it is likely that ocean crust basalt supports a significant microbial habitat. Due to current obstacles faced by the scientific community in sampling the oceanic hard rock seafloor, innovative microbial observatories have been deployed at the seafloor and deep in ocean crust to address whether sub-seafloor ocean crust basalts harbors a deep biosphere. These observatories are designed to encourage growth of in situ organisms on specific mineral surfaces for spatially resolved characterization of the microbial processes and populations involved in deep basalt weathering.