Science Watch

Microplastics found in half of South Wales river insects

by Nia Jones

Research led by the Cardiff School of Biosciences has found microplastics in 50% of insects sampled across South Wales rivers.

Microplastics are pieces of plastic under five millimetres in diameter, meaning they are almost invisible to the naked eye and are often mistaken for food by aquatic organisms. The resulting ingestion of plastics or absorption of pollutants on their surface can harm growth, reproduction and survival of marine animals and riverine insects. This makes microplastics a widespread and invasive threat to our marine, and now freshwater environments. Professor Steve Ormerod, Co-Director of Cardiff University’s Water Research Institute said “our understanding of the risks to wildlife and people is absolutely rudimentary. We need to improve this situation urgently to know how best to manage the problems”.

Although the presence of microplastics was greater in river sections downstream from waste water input, the study showed that plastics were found both upstream and downstream in all the rivers surveyed. This is indicative of diverse and complicated sources of microplastic.

Fred Windsor, PhD Student at the School of Biosciences, said: “Every year, between eight and twelve million tonnes of plastics are thought to be entering the World’s oceans, but around four million tonnes of it passes along rivers. In some cases, there can be over half a million plastic fragments per square metre of river bed, so that ingestion by insects is very likely.”

South Wales’ rivers have a long history of industrial pollution with over 70% of them once classed as ‘grossly polluted’. However, many have undergone a major recovery since. This study highlights reducing microplastic concentration as a new challenge for river management in the region, and a new focus for pollution campaigners. Professor Isabelle Durance, Director of the Water Research Institute at Cardiff University said that “the potential problem of plastics in river ecosystems has been seriously overlooked.”

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