Alteration of oceanic volcanic glass: textural evidence of microbial activity
The subsurface biosphere may constitute as much as 50 percent of Earth's biomass. Direct and indirect evidence suggests that an extensive biosphere exists in the rocks below the sea floor. This survey of basalts of the Atlantic, Pacific, and Indian Oceans supports the hypothesis that bacteria have colonized much of the upper oceanic crust, which has a volume estimated at 10(18) cubic meters. Although this is the largest habitat on Earth, its low abundance of bacteria constitutes much less than 1 percent of Earth's biomass.
M. R. Fisk, College of Oceanic and Atmospheric Sciences, 104 Ocean Administration Building, Oregon State University, Corvallis, OR 97331-5503, USA. S. J. Giovannoni, Department of Microbiology, 220 Nash Hall, Oregon State University, Corvallis,
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Thorseth