05/21/2026
Understanding How Marine Snow Acts as a Carbon Sink.
In some parts of the deep ocean, it can look like it’s snowing. This “marine snow” is the dust and detritus that organisms slough off as they die and decompose. Marine snow can fall several kilometers to the deepest parts of the ocean, where the particles are buried in the seafloor for millennia.
Now, researchers at MIT and their collaborators have found that as marine snow falls, tiny hitchhikers may limit how deep the particles can sink before dissolving away. The team shows that when bacteria hitch a ride on marine snow particles, the microbes can eat away at calcium carbonate, which is an essential ballast that helps particles sink.
The findings, which appear this week in the Proceedings of the National Academy of Sciences, could explain how calcium carbonate dissolves in shallow layers of the ocean, where scientists had assumed it should remain intact. The results could also change scientists’ understanding of how quickly the ocean can sequester carbon from the atmosphere.
Marine snow is a main vehicle by which the ocean stores carbon. At the ocean’s surface, phytoplankton absorb carbon dioxide from the atmosphere and convert the gas into other forms of carbon, including calcium carbonate—the same stuff that’s found in shells and corals. When they die, bits of phytoplankton drift down through the ocean as marine snow, carrying the carbon with them. If the particles make it to the deep ocean, the carbon they carry can be buried and locked away for hundreds to thousands of years.
But the new study suggests bacteria may be working against the ocean’s ability to sequester carbon. By eroding the particles’ calcium carbonate, bacteria can significantly slow the sinking of marine snow. The more they linger, the more likely the particles are to be respired quickly, releasing carbon dioxide into the shallow ocean, and possibly back into the atmosphere.
Learn more: https://ecomagazine.com/news/research/understanding-how-marine-snow-acts-as-a-carbon-sink/?utm_campaign=34322705-Ocean%20Insights%202026&utm_medium=email&_hsenc=p2ANqtz-9AEhP509Zsiwa-4J8HtGmpGxtYrdu3WLTU5J0lnUHS9yx5bBh9UV2hXVhTYK_IJZqYO5oDSEwcRBr7ufw0Zol0RtsG1A&_hsmi=410828832&utm_content=410828832&utm_source=hs_email
Image credit: Yuval Jacobi
