Microbeads have been proven hazardous to oysters, in a recent study featured in the journal Proceedings of the National Academy of Sciences.
The findings, presented on Monday, February 1, were based on an experiment conducted by Arnaud Huvet, an expert in invertebrate physiology at the French Research Institute for Exploitation of the Sea (Ifremer).
The researcher and his team from Plouzané took a group of Pacific oysters (scientifically known as Crassostrea gigas) and placed them in two separate kinds of water tanks: some contained solely phytoplankton, while the others had also been strewn with polystyrene microbeads.
These tiny fragments of plastic, measuring between 1 nanometer and 5 millimeters, have risen great concern recently, after proving extremely hazardous to marine wildlife.
For instance, it has been determined that echinoderms such as sea urchins and crustaceans such as common water fleas and copepods have trouble digesting these small pellets that can easily absorb pollutants. The sea creatures also experience disruptions in their reproductive cycle, because the plastic interferes with their endocrine system.
Other complications consist in neurological issues, immune system disorders, and higher mortality rates, after ingesting toxic chemicals found in the tiny plastic particles.
Now, this new study has shown that oysters are similarly perturbed after being exposed to microbeads, even for short lengths of time (2 months).
More precisely, mollusks kept in water tanks containing microplastics started producing a smaller number of oocytes (egg cells), and these few ones were also abnormally small.
In addition, oysters that ingested microbeads had a much lower sperm motility, therefore having a lower likelihood of securing conception.
Furthermore, the number of larvae that resulted from Pacific oysters inhabiting plastic-ridden tanks was approximately 41% lower than the one identified among the control group kept in the other aquariums.
Last but not least, these offspring had a much more delayed growth cycle, and were approximately 18% tinier than their counterparts kept in uncontaminated environments.
Based on these findings, study authors are now arguing that pollution triggered by microbeads has a much greater impact that previously thought, on a wide variety of species.
The fact that oysters are affected by the presence of microplastic in their environment is especially alarming, when considering that many other marine species rely on mollusks for their survival, and even humans frequently indulge in this type of seafood.
In addition, oyster reefs represent a natural barrier against coastal erosion, while also boosting water quality by filtering bacteria, sediments, nutrients and toxins.
While previously the focus had been solely on large pieces of plastic, such as bottles and bags that reach water bodies, being eventually ingested by aquatic creatures or seabirds, in recent months more emphasis has been placed on microplastic.
Prior studies have determined that around 5 trillion microbead particles, amounting to approximately 250,000 tons have already reached the ocean.
Apparently, one of the main sources for this pollution is represented by the personal care industry, given the fact that microbeads are commonly found in cosmetics such as exfoliating gels, facial washes and scrubs, and in personal hygiene products like toothpaste.
For instance, one such toiletry item can contain up to 100,000 microplastics, which is why the Obama administration has recently signed the Microbead-Free Waters Act, calling for the use of such chemicals in cosmetics and personal hygiene items to be discontinued by July 1, 2017.
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