Microbial Activities in Deep Subseafloor Sediments

Presenter: Steven D'Hondt, University of Rhode Island
When: April 30, 2007 11AM PDT

Recent studies by URI investigators and our collaborators have advanced understanding of Earth’s subsurface life in several ways. These advances include the following discoveries: (1) respiration per subseafloor cell is much lower than canonical estimates of respiration required for cell maintenance; (2) thermodynamic cooperation sustains complex subsurface communities for millions of years; (3) subseafloor biomass and predominant redox activities vary predictably with the chlorophyll content of the surface ocean; (4) subseafloor redox activities ultimately affect the chemistry of the ocean and atmosphere; and (5) Earth’s subsurface biomass is much smaller than the canonical estimate. Preliminary data suggest that hydrogen from radiolysis of water may be a significant food source for microbial communities in the low-activity sediments that characterize much of the open ocean.

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