The research underscores growing concerns about how ultra-small plastic particles move through marine ecosystems and into foods people rely on.
Stacey Leasca
Fri, February 20, 2026
FOOD & WINE
lessydoang / Getty Images
Key Points
Researchers studying mangrove forests in Colombia found that fiddler crabs can ingest microplastics and grind them into even smaller fragments, potentially accelerating plastic degradation.
The crabs accumulated microplastics at levels 13 times higher than in their surrounding sediment, with most particles found in their digestive systems and gills.
While the crabs’ activity helps fragment plastic faster than sunlight or waves alone, it also produces nanoplastics that can enter the food chain and potentially affect human health.
Microplastics, those teeny, tiny shards of plastic that take more than 400 years to fully decompose, are just about everywhere, and the world's mangrove forests are no exception. Hidden in the tangled roots and sediment where they settle, one tiny critter appears to be helping break those plastics down just a little faster. And while this may sound like nature fighting back against pollution, scientists warn the process could actually accelerate the spread of even smaller plastic particles into the food chain.
In December, researchers from Universidad de Antioquia, the University of Exeter, and the Corporation Center of Excellence in Marine Sciences (CEMarin) in Bogotá published their findings in the journal Global Change Biology, examining fiddler crabs and their role in scooping up microplastics and digesting them into smaller pieces — fragments that may be even harder to track and contain.
To understand the crabs and their relationship to microplastics, the team studied a large population of crabs in a polluted mangrove forest in Turbo, along the north coast of Colombia. The researchers said the area has some of the "highest levels of plastic contamination reported anywhere in the world." They then selected five one-meter-square plots of mangrove and sprayed each with fluorescent red and green polyethylene microspheres, tiny plastic beads that glow under a microscope. Over the next 66 days, they sampled the soil and 95 crabs within it to see what happened next.
“We set out to answer three specific questions. The first question was: What is the uptake of microspheres by the crab under natural feeding conditions? Secondly, we wanted to learn how the microspheres are distributed among the major organs. And finally, we sought to find out whether the crab’s interaction with microspheres resulted in their physical fragmentation into smaller particles," Professor José M. Riascos, who led the research, explained.
The study found that the crabs accumulated microplastics at 13 times the concentration in the surrounding sediment, with most of the plastic located in their hindguts, digestive organs, and gills. A solid portion (about 15%) of the plastic particles had been broken into smaller pieces by the crab's grinding digestive system, and female crabs were more likely than males to contain fragmented particles. (The research did not examine whether these fragments harmed the crabs' health, only whether they ingested them and what happened to them afterward.)
FOOD & WINE
lessydoang / Getty Images
Key Points
Researchers studying mangrove forests in Colombia found that fiddler crabs can ingest microplastics and grind them into even smaller fragments, potentially accelerating plastic degradation.
The crabs accumulated microplastics at levels 13 times higher than in their surrounding sediment, with most particles found in their digestive systems and gills.
While the crabs’ activity helps fragment plastic faster than sunlight or waves alone, it also produces nanoplastics that can enter the food chain and potentially affect human health.
Microplastics, those teeny, tiny shards of plastic that take more than 400 years to fully decompose, are just about everywhere, and the world's mangrove forests are no exception. Hidden in the tangled roots and sediment where they settle, one tiny critter appears to be helping break those plastics down just a little faster. And while this may sound like nature fighting back against pollution, scientists warn the process could actually accelerate the spread of even smaller plastic particles into the food chain.
In December, researchers from Universidad de Antioquia, the University of Exeter, and the Corporation Center of Excellence in Marine Sciences (CEMarin) in Bogotá published their findings in the journal Global Change Biology, examining fiddler crabs and their role in scooping up microplastics and digesting them into smaller pieces — fragments that may be even harder to track and contain.
To understand the crabs and their relationship to microplastics, the team studied a large population of crabs in a polluted mangrove forest in Turbo, along the north coast of Colombia. The researchers said the area has some of the "highest levels of plastic contamination reported anywhere in the world." They then selected five one-meter-square plots of mangrove and sprayed each with fluorescent red and green polyethylene microspheres, tiny plastic beads that glow under a microscope. Over the next 66 days, they sampled the soil and 95 crabs within it to see what happened next.
“We set out to answer three specific questions. The first question was: What is the uptake of microspheres by the crab under natural feeding conditions? Secondly, we wanted to learn how the microspheres are distributed among the major organs. And finally, we sought to find out whether the crab’s interaction with microspheres resulted in their physical fragmentation into smaller particles," Professor José M. Riascos, who led the research, explained.
The study found that the crabs accumulated microplastics at 13 times the concentration in the surrounding sediment, with most of the plastic located in their hindguts, digestive organs, and gills. A solid portion (about 15%) of the plastic particles had been broken into smaller pieces by the crab's grinding digestive system, and female crabs were more likely than males to contain fragmented particles. (The research did not examine whether these fragments harmed the crabs' health, only whether they ingested them and what happened to them afterward.)
This breakdown of plastic over such a short time could be seen as good news, since sunlight and ocean waves can take years to fracture plastic into smaller pieces. However, the group explained that this process can release nanoplastics into the crab's tissue and, eventually, the food chain. These even smaller pieces become harder to track, easier to spread, and ultimately end up in the seafood humans eat. As Food & Wine previously reported, microplastics have been widely found across the seafood we eat, including black rockfish, lingcod, Chinook salmon, Pacific herring, Pacific lamprey, and pink shrimp. These, in turn, have the potential to affect many areas of human health, including our digestive, respiratory, and immune systems.
“The results emphasise that living creatures are not just passive components of the marine ecosystem but may be finding ways to cope with chronic anthropogenic pressures according to their evolutionary histories," Daniela Díaz, a researcher at the Universidad de Antioquia, said. "The results could lead to a better understanding of how animals adapt to pollution and the fate of plastics in the environment.”
How to reduce your exposure to microplastics from seafood
Microplastics are now widely detected in marine environments — and in many of the seafood species people eat. While you can’t eliminate exposure entirely, these seafood-specific steps may help lower it:
Vary the types of seafood you eat. Rotating between different species may help reduce repeated exposure from a single source or ecosystem.
Be mindful of shellfish. Bivalves like mussels and oysters — and small shrimp eaten whole — may contain higher concentrations because their digestive systems aren’t removed before eating.
Clean and prep fish carefully. Removing the guts and rinsing the cavity of whole fish may help reduce the concentration of particles in the digestive organs.
Balance seafood with other protein sources. Rotating between plant-based or land-based options can help limit overall exposure while maintaining dietary variety.
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