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Common periwinkel is easy prey because of toxic microplastics

Amsterdam, 29 November 2018 – The common periwinkel (Littorina littorea), a sea dwelling snail, is on the menu of the green shore crab (Carcinus maenas). Normally, the periwinkle defends itself by retreating into its shell as soon as it spots the crab. Research is now showing that this defence mechanism, called chemosensory, does not work any more because of the toxic substances from microplastics.

In the laboratory of the Centre National de la Recherche Scientifique (CNRS) in France, snails were placed in water with a concentration of microplastic pellets. New pellets were used and, in the same experimental set-up, pellets from the beaches of the Calais Strait. This last group of pellets had been in the sea for a long time. The new and still clean pellets had some impact on the behavioural change of the periwinkels, but the pellets from the sea had a much greater impact. Microplastics in the sea attract toxic substances from their surroundings like a magnet. The research is published in Biology Letters.

The chemical substances that attach to the plastic in sea water or that leach out of the plastic, impair the defence mechanism of the periwinkle. They are rendered unable to detect the predatory crabs on time. The results suggest a drastic effect of microplastics at sea on animals that are dependent on chemosensory. This is the first study that not only looks at the consequences of one species, but also at the interaction between two species, one of which is the prey of the other.

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