Accumulation of microplastics in typical commercial aquatic species: A case study at a productive aquaculture site in China

The widespread occurrence of microplastics in the marine environment has drawn global attention because microplastics may impact the populations of marine organisms. As such, aquaculture industry may suffer from microplastic pollution, especially when plastic products are widely used for aquaculture. Here, we assessed the abundance and characteristics (type, size and composition) of microplastics in sediment and typical commercial species (fish, bivalves and shrimps) in an aquaculture site at Xiangshan Bay, which has been operated intensively for decades. Satellite remote sensing images revealed that aquaculture activities were associated with microplastic pollution in sediment, where the microplastics (51-88 items/kg dry weight) were mostly fibres (>94%) and between 500 and 2000 µm. Cellulose was the predominant polymer (60-88% of microplastic composition), followed by polypropylene. Microplastics accumulated in all the commercial species (0.95-2.1 items per individual), where shrimp (Parapenaeopsis hardwickii) had lower potential for microplastic accumulation than the other species. The predominance of fibres and cellulose in the commercial species implies their limited ability to recognize the type and composition of microplastics during ingestion. Given the limited accumulation of microplastics in these typical commercial species even at a productive aquaculture site, we suggest that microplastics may not increase the health risk of consuming seafood and their impacts on commercial species may be less deleterious than previously thought.