‘Marine snow’ study shows how the ocean eats carbon

‘Marine snow’ study shows how the ocean eats carbon

Written by Susan Cozier

From its sunlit peaks 200 meters deep, plankton carcasses, excreta, and molting particles constantly drift toward the depths. As this so-called marine snow sinks, its pieces can solidify or break apart, speed up, sink slower, or be eaten by bacteria. They descend through dark, cold, dense ocean waters, carrying carbon with them and depositing it on the ocean floor as biomass.

The ocean absorbs billions of tons of carbon every year, and this process is crucial to account for in climate models. But researchers have long been puzzled about how much carbon actually reaches the ocean floor and stays there. To figure that out, oceanographers are studying how carbon is eaten, excreted, and otherwise drifts through what some scientists think of as the ocean’s “digestive system.” We are investigating whether it is affected by

Measuring carbon storage rates means scrutinizing the composition of what sinks, how particles stick together and fall, and the moderating effect of slime-producing phytoplankton. sciencedietary preferences of specific microorganisms.

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“Currently, we don’t have a good way to connect processes at the surface with what reaches the ocean floor,” said Colleen Durkin, an oceanographer at the Monterey Bay Aquarium Research Institute. “We know they’re related, but it’s been very difficult to observe the mechanisms driving that association.”

Recent advances in sensor development, imaging, and DNA sequencing now allow researchers to closely observe specific organisms and processes at work. By isolating and testing bacterial populations in marine snow, study co-author Benjamin Van Mooy, a researcher at Woods Hole Oceanographic Institution, and his colleagues found that a particular population of microbes, called lipids, They discovered that they prefer to eat phytoplankton that contain certain types of fatty acid biomolecules.

Because lipids make up up to 30% of particulate organic matter on the ocean surface, the dietary preferences of bacteria in a particular region can greatly alter the amount of carbon-containing biomass that reaches the seafloor. “If we can begin to understand what[microorganisms]are capable of, we can imagine a future where we can potentially begin to predict the fate of carbon based on the organisms that are present,” he said. Mr. Van Mooy said. For his work, he was awarded a MacArthur Fellowship in 2024.

Scientists are also working to record what falls in specific locations over different time frames. Sediment traps reveal snapshots of marine snow in specific areas, and Durkin and his colleagues deploy sensors with autonomous cameras to observe settling particles over long periods of time. Looking at the complexity of ocean snow distribution, Kay Biddle, a microbial oceanographer at Rutgers University, said, “We can’t necessarily model and understand carbon fluxes using the very simple structures, equations, and laws that we’ve had so far. has become clear.”