Fear for food chain as crustacean breaks down plastic

A NEW study has raised concerns over the presence of plastics in the food chain after finding that microplastics can be broken down into even smaller particles by a common freshwater animal.

Microplastics are typically smaller than 5mm, but researchers in University College Cork found a small crustacean called Gammarus duebeni, which is approximately 22mm in size, can break down plastics to about one-fivethousandth of its original size.

Examples of microplastics include small plastic pellets used in some manufacturing processes, plastic fibres and microbeads which were commonly found in cosmetic products such as exfoliants.

Microbeads have been banned in Ireland since February of this year following a European Union resolution.

Study leader Dr Alicia Mateos-Cárdenas, of UCC’s School of Biological Earth and Environmental Sciences and Environmental Research Institute, said this crustacean is able to ‘fragment microplastics into different shapes and sizes, including nanoplastics in less than four days’.

These crustaceans break down the microplastics as part of their digestive process, and the fact that such a common invertebrate animal can rapidly produce vast numbers of nanoplastics is particularly worrying for researchers.

‘Whilst this species lives in Irish streams, they belong to a bigger animal group of invertebrates commonly found around the world in freshwaters and oceans. Our finding has consequences for the understanding of the environmental fate of microplastics,’ said Dr Mateos-Cárdenas.

It was previously assumed that the breakdown of plastics was a very slow process in the marine environment, through sunlight and wave action, which could take decades.

‘These invertebrates are very important in ecosystems because they are prey for fish and birds, hence any nanoplastic fragments that they produce may be entering food chains,’ Dr Mateos-Cárdenas added.

The study, which was funded by the Environmental Protection Agency and published in Scientific Reports, also raises concerns that nanoplastics could penetrate the cells of fish, where their effects could be much harder to predict.

In a separate study, researchers in University College Dublin and UCC found that birds known as Manx shearwaters can track plankton through its smell.

According to the study, plankton give off a scent that seabirds can sense, and this may be key for ocean-faring species hunting for prey.

The team were based in UCC for the study and tracked dozens of birds over three years at colonies on High Island, off the coast of Galway, and Great Blasket Island, off the coast of Kerry. The team used GPS tags to track the birds.