Microplastics polluting the environment is an extremely topical and sensitive issue. Whilst there is an increasing body of evidence showing the ingestion of microplastics by a range of marine life, questions still remain. Is there transfer of microplastics between different trophic levels within these estuarine ecosystem, especially given the evidence for transfer of particles across the gut wall in certain species? Is there evidence for adverse impacts on the health of higher trophic level species, e.g. fish? Preliminary studies conducted at Royal Holloway indicate that both pelagic and benthic fish species from the Thames (and Clyde Sea) have plastic fibres and other fragments in their stomachs. Furthermore, certain fish species from the Thames Estuary, found with plastics in their alimentary canal, feed extensively on small bivalve molluscs as well as the commercially important brown shrimp, Crangon crangon. Both prey species have been shown to be polluted with microplastics. Mussels for human consumption can contain plastic particles with predicted annual ingestion by consumers of up to 11,000 particles. Other studies have shown that chemicals absorbed by plastics can accumulate in body tissues. The impacts are therefore potentially far reaching. Moreover, what is the consequence on the resident seal population in the Thames feeding extensively on fish in the Thames which we know contain plastics ?
This aim of this study is to investigate the potential for trophic transfer of microplastics in Thames Estuary food chains.