Microplastic ingestion decreases energy reserves in marine worms

The indiscriminate disposal of plastic to the environment is of concern. Microscopic plastic litter (<5 mm diameter; ‘microplastic’) is increasing in abundance in the marine environment, originating from the fragmentation of plastic items and from industry and personal-care products. On highly impacted beaches, microplastic concentrations (<1mm) can reach 3% by weight, presenting a global conservation issue. Microplastics are a novel substrate for the adherence of hydrophobic contaminants, deposition of eggs, and colonization by unique bacterial assemblages [4]. Ingestion by indiscriminate deposit-feeders has been reported, yet physical impacts remain understudied. Here, we show that deposit-feeding marine worms maintained in sediments spiked with microscopic unplasticised polyvinylchloride (UPVC) at concentrations overlapping those in the environment had significantly depleted energy reserves by up to 50%. Our results suggest that depleted energy reserves arise from a combination of reduced feeding activity, longer gut residence times of ingested material and inflammation.