Center for Dark Energy Biosphere Investigations (C-DEBI)

The global ocean comprises the Earth’s largest biome, with microorganisms playing a dominant biogeochemical role. C-DEBI researchers have provided compelling evidence suggesting that the microbial abundance in subseafloor sediments equals that in the overlying ocean. C-DEBI researchers have also demonstrated that the microbial cell counts in marine sediments vary by many orders of magnitude from ocean margins to ocean gyres, and from the sediment-water interface to the deep subsurface. However, it remains unknown what environmental properties and processes control observed variations, what limits the extent and variety of life in the subseafloor, and how physiologically and phylogenetically diverse these sediment communities are. Despite the magnitude of these scientific unknowns, another marine biome may prove to be even more astonishing—the igneous crust. Researchers have shown that the igneous crust below the oceans and sediments is the largest aquifer system on Earth, extending across >300 million km. Most of this system is hydrologically active, with a vast flow of fluid exchanging between ocean basins and crustal reservoirs. This fluid carries heat, solutes, genetic material, microorganisms, spores, and viruses. Furthermore, the deep crustal biosphere appears to be very different from its counterpart in marine sediments, which, in turn, is very different from that in the overlying ocean. Given the connectivity of these three enormous biomes, the central scientific goal of C-DEBI is to resolve the extent, function, dynamics, and implications of the subseafloor biosphere through an integrated, multidisciplinary, and multi-institutional distributed infrastructure.