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Microplastics are everywhere. They're in the deep sea, accumulating on some the planet's tallest mountains and getting trapped in polar glaciers.
Microplastics are also being found in abundance in coastal ecosystems, and new research suggests the pollution's presence can have disruptive effects on coastal food chains.
Scientists conducted a series of lab tests to better understand how microplastics can travel up the food chain and negatively affect a range of species.
Experiments showed that while larval fish sometimes eat microplastic particles directly, they are more likely to acquire microplastic particles by ingesting contaminated larval fish. Tests also showed that larval fish were more likely to ingest microplastics when they were attached to a common pollutant -- in this case, the pesticide DDT.
"Larval fish exposed directly to microspheres ingested significantly fewer than those exposed via contaminated prey," researchers wrote in their paper, published this week in the journal Limnology and Oceanography. "Larvae ingested significantly more ciliates containing DDT‐treated microspheres than ciliates containing untreated plastics but did not discriminate when exposed directly."
Previous studies have shown that some basal species, plankton, crustaceans and corals, preferentially consume microplastics under certain conditions.
In addition to demonstrating the different ways microplastics can enter and make their way up the food chain, the newest research was able to show that exposure to microplastics can stunt the growth of larval fish, which could yield ecosystem-wide impacts over longer timescales.
When researchers exposed larval inland silversides, Menidia beryllina, for just two hours, the fish had lower weight values than those in the control group after 16 days.
"Our findings indicate that trophic transfer may be an important route for microplastic exposure in estuarine food webs and that even short exposure to high levels of microplastics can impair growth of an important prey fish," lead study author Samantha Athey, researcher at the University of Toronto, said in a news release. "Because estuaries are incredibly productive habitats that are home to many of our commercial seafood species in the United States, it is important to understand the sources, fate, and effects of microplastics and associated pollutants in these systems."
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