The accumulation of microplastics in seafood may be underestimated and there is concern that potentially harmful bacteria such as E. coli are moving up the food chain, a study found.
Researchers at the University of Portsmouth tested a theory that microplastics covered in a layer of microbes called biofilm are more likely to be ingested by oysters than by clean microplastics.
Although the experiment was conducted on oysters under laboratory conditions, scientists believe similar results could be found with other edible marine species that also filter seawater for food.
“We know that microplastics can be the mechanism by which bacteria accumulate in coastal waters, and this shows that they can be more easily ingested by shellfish and transferred to humans or other marine life,” said lead researcher Dr. Joanne Preston.
It is known that microbes easily colonize microplastics that enter the ocean. This study compares the uptake rates of clean microplastics compared to microplastics with an E.coli biofilm coating.
The results showed that oysters contained ten times more microplastics when exposed to the biofilm-coated beads. This could be because the coated plastics seemed more like food to the oysters, the scientists said.
The ingestion of microplastics is not only bad for the oysters, but also has an impact on human health as it is not broken down by marine animals and is consumed by us.
“We found that microplastic is really the Trojan horse of the marine world,” added Preston. “We found that clean plastic had little effect on the oysters’ breathing and feeding rate, but did have an effect when they were fed the microplastic hidden in the biofilm.
“The oysters ingested more and that was bad for their health. It’s not certain how much this could affect the food chain, but the likelihood is that the creatures will ingest more plastic and potentially disease-causing organisms, which will ultimately have a negative impact on human health.
“We know that microplastics can be the mechanism by which bacteria accumulate in coastal waters, and this shows that they can be more easily ingested by shellfish and transferred to humans or other marine life.”
Professor Steve Fletcher, Director of the Revolution Plastics Initiative at Portsmouth University, said, “The results of this research give us further insight into the potential harm of microplastics in the food chain. It shows how we could seriously underestimate the effects of microplastics at the moment. It is clear that further studies are urgently needed. “
In June, another research team developed self-propelled micro-robots that swim, attach to plastics and break them down.
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