Microplastics Are Hurting Snails' Ability to Evade Predators

CC BY 2.0. Tim J Keegan

This could have serious implications for the entire food chain.

Microplastic contamination of seawater is affecting predator-prey interactions. An alarming study from the National Centre for Scientific Research in northern France, just published in the journal Biology Letters, has found that periwinkle snails living in microplastic-infused water fail to respond appropriately when hunted by a crab. It appears that the toxins in microplastics inhibit the chemical cues that would normally help a snail to know what to do. Researcher Prof. Laurent Seront explained,

"The whole set of behaviours are totally inhibited. It is worrying news. If the periwinkles are not able to sense and escape from the predator, they are more likely to disappear and then to disturb the whole food chain."
The common periwinkle is a main food source for crabs, although it is eaten by many humans too. Usually the snails evade death by withdrawing into their shells or hiding under rocks. But in the case of this study, which was conducted using wild snails found on a beach near Calais, France, the periwinkles were slow to withdraw into their shells and didn't wait as long as they should have before re-emerging. From the Guardian,
"The concentration of microplastics used in the experiments was similar to that on the beach. Microplastics are known to attract heavy metals and persistent organic pollutants and the researchers believe the release of this chemical cocktail interferes with the periwinkle's senses."

It is not the first time that scientists have noted plastics' toxic effects on animals. Mussel larvae have been found to grow abnormally as a result of microplastic exposure, and there are concerns about the way in which plastics move up through the food chain, being consumed by creatures as tiny as plankton and eventually making their into the seafood that humans eat for dinner. But never before has a study found that microplastic leachates are affecting an animal's ability to protect itself from a predator. This is truly alarming, with major implications for the entire food chain.

All the more reason to ban single-use plastics, mandate better water filtration systems on household washing machines and wastewater treatment facilities, and incentivize clothing made from natural fabrics.