Oysters that consume the small pieces of plastic that are littering the world’s oceans produce fewer and less-healthy offspring, a study suggests — fuelling concern that the material may be damaging marine life. Millions of tonnes of plastic end up in the world’s oceans every year; one recent calculation suggests that, by around 2050, there will be more plastic than fish, by weight. But researchers are increasingly concerned about the effects of tiny ‘microplastic’ fragments — those smaller than 5 millimetres — which are created when larger objects break apart, or manufactured for industrial products including cosmetics and packaging materials.
Arnaud Huvet, a scientist at France’s national marine research agency (Ifremer) in Plouzané, and his colleagues placed Pacific oysters (Crassostrea gigas) in water laced with micrometre-sized spheres of polystyrene, at levels similar to those that have been recorded in the wild in some locations. After two months, oysters exposed to the plastic produced fewer and smaller egg cells, less-mobile sperm and fewer offspring than did animals raised in water without the plastic1. The offspring themselves grew more slowly, the researchers report. Microplastics have been shown to reduce the fertility of other marine animals, including tiny crustaceans such as copepods and daphnia. But the latest study broadens the case file to oysters, says Huvet.