Microbe Metropolis

Sinking microbial cities may solve a key ocean mystery

- —Damien Pine

WHEN “MARINE SNOW” made of dead plankton’s shells, fish poop, dust particles, and other debris descends to the ocean floor, it carries atmospheric carbon the plankton used to make their calcite shells. It’s one of the ways the ocean stores carbon, helping to keep greenhouse gases from turning the planet into an oversize toaster oven. Yet scientists realized that something has been dissolving those calcite shells and releasing carbon dioxide, reducing the ocean’s carbon-trapping capacity. A study published in the Proceedings of the National Academy of Sciences USA identified the culprit: dense microbe “cities” living inside the marine snow.