New research from UC San Diego's Scripps Institution of Oceanography shows that the gooeyness of marine snow has a major effect on how much carbon reaches the deep ocean. Marine snow is the mix of dead plankton, mucus, and other detritus that sinks from the surface. Scientists estimate it moves more than 10 gigatons of carbon away from the surface each year, but only about 2 gigatons stays down long enough to be considered stored for centuries. The study, published in Science, found that bacteria break down less viscous marine snow more easily, which keeps more of its carbon near the surface. More viscous particles resist bacterial breakdown and sink deeper. Computer simulations suggest high-viscosity marine snow can carry more than six times the carbon to the deep ocean compared to low-viscosity particles. This is the first time researchers have watched live bacteria interact with the physical structure of marine snow. The new imaging method also has implications beyond the ocean, since mucus and bacteria interactions matter for coral reefs, kelp forests, and human health. For anyone tracking ocean carbon removal or climate models, this adds a variable that could shift how much carbon the ocean actually locks away.
