ScienceNot yet confirmed elsewhere1 publisher2 min readPublished
Viscous marine snow outlasts bacterial attack and carries more carbon to the deep ocean
Scripps Oceanography and University of Lincoln scientists estimate that gooey marine snow carries more than six times as much carbon to depth as less viscous particles. The team presents viscosity as one cause of why only about 2 of the 10-plus gigatons exported each year reach long-term storage.
The Scientist · Science desk
High-viscosity marine snow can carry more than six times as much carbon deep as low-viscosity snow, researchers estimate. Over 10 gigatons of carbon are exported yearly; two gigatons are believed stored long term; at least 8 gigatons do not reach storage depth.
| Figure | Value | Note | Claim |
|---|---|---|---|
| Est. carbon to depth, high vs low viscosity, over | 6 times as much | 11 | |
| Est. yearly export, over | 10 gigatons carbon | 1 | |
| Believed stored long term | 2 gigatons carbon | 2 | |
| Not stored deep, at least | 8 gigatons carbon | 15 |
What happened
- The team combined 3D confocal microscopy with specialized fluorescent molecules to map individual marine snow clumps and see how bacteria interacted with them.
- In laboratory experiments, more viscous marine snow took longer for bacteria to degrade and fragment.
- Computer simulations suggest that the more viscous marine snow is, the deeper it sinks.
- Phys.org reports that scientists had never before studied live bacteria engaging with the physical makeup of marine snow, or of any other mucus.
Why it matters
- decision Anyone folding this into a carbon-cycle model must choose what share of marine snow counts as viscous, because the six-fold estimate contrasts only high-viscosity with low-viscosity particles.
- constraint The depth result comes from computer simulation, so the six-fold estimate stays a model output until it is checked against sinking particles collected in the ocean.
- capability The researchers say the imaging method will help scientists study how bacteria behave in mucus, a question that also applies to coral reefs, kelp forests, plant roots and digestive tracts.
Viscosity matters because bacteria get in through the soft outside first. In the companion paper in Nature Communications, the researchers found that bacteria colonize the less viscous regions near a particle's surface far more easily than the more viscous regions deeper inside [7]. "Bacteria can latch on to less viscous portions of each particle, but cannot reach more viscous regions until they break it down," Bryce Inman said [8].
The size of the gap it has to explain is large. Subtract the roughly two gigatons that reach long-term storage [2] from the more than 10 gigatons exported each year [1], and at least 8 gigatons a year do not make it [15]. The authors present viscosity as one cause of that discrepancy [13]. Inman himself was plain about the limits of the picture. He said "How far marine snow can sink is a surprisingly complicated problem" [12].
The imaging is why the question could be asked at all. Inman began looking for a way to see individual bacteria on mucus in 2021. He and his colleagues, including Farooq Azam, tried and failed for four years before a method worked in 2025 [5].
There is a design question the phys.org account leaves open. Marine snow particles differ in their mix of organic and inorganic molecules as well as in how gooey they are [14]. The account does not say how the laboratory experiments separated viscosity from composition. We would want that separation shown before treating viscosity itself as the cause.
What to watch
- A test of the six-fold estimate against marine snow particles collected from the ocean, with their viscosity measured.
- Whether carbon-cycle models add particle viscosity as a parameter alongside breakdown and sinking depth.
- Whether other groups apply the Nature Communications imaging method to mucus in coral, kelp, roots or the gut.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence62
- Adoption
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- Hype gap+10
- Incentives
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- Confidence55
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- [1]
Scientists estimate that marine snow transports more than 10 gigatons of carbon away from the surface every year.
- [2]
Only two gigatons of the carbon marine snow transports are believed to sink deep enough to be stored for hundreds to thousands of years.
- [3]
A study in Science by scientists at Scripps Oceanography and the University of Lincoln reports that the viscosity of marine snow can have a major impact on how quickly it is broken down and how far it sinks.
- [4]
The researchers found that gooey marine snow can shuttle more than six times as much carbon to the deep ocean as less viscous particles.
- [5]
Bryce Inman began searching for a way to visualize the 'mucoscape' in 2021; he and colleagues including Farooq Azam tried and failed for four years, and it was not until 2025 that they found a way to make it work.
- [6]
Using 3D confocal microscopy and specialized fluorescent molecules, the researchers mapped the physical terrain of individual clumps of marine snow and saw how bacteria interacted with it.
- [7]
In a companion paper in Nature Communications, the researchers determined that bacteria can colonize less viscous areas near the marine snow's surface far more easily than its more viscous regions deeper inside.
- [8]
"Bacteria can latch on to less viscous portions of each particle, but cannot reach more viscous regions until they break it down," said Inman.
ReportedSupportedSource: Bryce Inman, formerly a postdoctoral scholar at Scripps OceanographyView cited source - [9]
In a series of laboratory experiments, the researchers found that more viscous marine snow takes longer for bacteria to degrade and fragment.
- [10]
Computer simulations suggest that the more viscous marine snow is, the deeper it will sink.
- [11]
Inman and his colleagues estimate that high-viscosity marine snow can carry more than six times as much carbon to the deep ocean as its low-viscosity counterparts.
- [12]
"How far marine snow can sink is a surprisingly complicated problem," said Inman.
- [13]
Scientists at Scripps Oceanography and the University of Lincoln discovered one cause of the discrepancy between the more than 10 gigatons of carbon exported and the two gigatons stored long term.
- [14]
No two marine snow particles are the same; they are made up of different combinations of organic and inorganic molecules that differ in their gooeyness.
- [15]
At least 8 gigatons of carbon exported by marine snow each year do not reach long-term storage depth.
- [16]
According to phys.org, this is the first time scientists have studied live bacteria interacting with the physical structure of marine snow, or any mucus.
- [17]
Coral reefs, kelp forests, land plant root systems and animal and human digestive tracts all rely on interactions between mucus and bacteria.
- [18]
The researchers say their findings and new mucus imaging method will help scientists study how bacteria behave in mucus.
Sources
1 independent publisher whose own reporting we read for this story.
- phys.orgThe gooier marine snow is, the better it is at transporting carbon, new study finds
1 article · October 12, 2026
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