Sticky marine snow carries six times more carbon to the ocean floor
Researchers at UC San Diego uncover how particle viscosity shields sinking organic matter from bacterial decay
Ten gigatons of carbon leave the ocean surface each year inside clumps of biological debris known as marine snow, yet only two gigatons reach deep waters for long-term storage. A study published in Science by researchers at the Scripps Institution of Oceanography and the University of Lincoln explains this gap: gooey, highly viscous particles resist bacterial decay and deliver six times more carbon to the deep sea than thinner material.
A four-year quest to map the ocean muscoscape
Surface waters constantly shed drifting flakes of mucus, dead plankton, animal feces and silt. As this biological drift sinks, marine bacteria feed on the organic material, breaking it apart before it can settle onto the ocean floor. To examine why some particles survive while others dissolve near the surface, postdoctoral researcher Bryce Inman and microbiologist Farooq Azam spent four years creating a specialised imaging invention at the Scripps Institution of Oceanography, as reported by ScienceDaily.
The technical innovation arrived in 2025 when the team combined 3D confocal microscopy with custom fluorescent molecules. Confocal systems capture optical slices through a sample using targeted light, allowing three-dimensional digital reconstruction of delicate structures. By tagging structural polymers and living bacteria with fluorescent dyes, the scientists imaged bacterial motion inside intact marine mucus particles for the very first time.
“Bacteria can latch on to less viscous portions of each particle, but cannot reach more viscous regions until they break it down.”
— Bryce Inman, postdoctoral researcher at Scripps Oceanography
Dense mucus cores block microbial degradation
The microscopic observations, supported by a companion study in Nature Communications, demonstrated that marine snow does not possess a uniform density. Instead, particles exhibit a complex internal topography. Marine bacteria selectively gather on the outer surfaces where the material is watery and less viscous, while dense, gelatinous zones remain inaccessible.
In laboratory degradation trials, the stickiest particles preserved their structural integrity far longer than low-viscosity flakes. Computer simulations confirmed that this physical resistance enables the particles to fall through thousands of metres of water before fragmentation occurs. As a result, the stickiest marine snow delivers more than six times as much carbon to the deep seabed compared to looser aggregates, providing empirical data on how biological viscosity aids planetary sustainability.
Refining ocean carbon budget models
Quantifying carbon sequestration remains a core problem for climate science because only deep ocean deposits lock carbon away for centuries. Past oceanographic models treated marine snow as uniform sinking matter, which obscured why deep-water capture rates fluctuated. By measuring particle stickiness, oceanographers can now better predict how much atmospheric carbon reaches permanent storage depths.
The microscopy method also opens new research pathways into mucosal boundaries elsewhere in nature. Similar biochemical barriers exist in coral reefs, kelp forests, plant root systems and animal digestive tracts. As reported by the patent magazine, the research team plans to adapt the imaging technique to investigate how living bacteria navigate mucus barriers in other vulnerable aquatic environments.
Read also on The Patent: Physicists Observe Supersolid State of Light and Matter at Room Temperature · Activating Enzymes Switches on Cellular Protein Degradation Machinery
