In a new study published in this week’s PNAS, researchers from NAI’s University of Rhode Island Lead Team report the vertical and geographical distribution of microbes in deeply buried marine sediments of the Pacific Ocean Margin. Sediment cores from the Peru and Cascadia Margins were obtained, and thousands of clones were studied to describe the nature of the biomass in areas with and without methane hydrates. The data suggest that prokaryotic communities from methane hydrate-bearing sediment cores are distinct from those in hydrate-free cores. This study is an important step in understanding the role of biology in Earth’s essential biogeochemical processes.