Microplastics and their toxicity in the marine environment Microplastics are spread in the world’s oceans and can pose a major threat to marine organisms. Marine invertebrate and fish can ingest these particles. Climate Change and Environment Food and Natural Resources Health © Sascha Corti, Shutterstock Since plastics are non-biodegradable they merely breakdown into smaller and smaller fragments with exposure to sunlight, wind and wave action. These fragments, known as microplastics (MPs), are only between 5 mm and 1 μm long and are reported to be the most abundant pieces of plastic found in marine ecosystems. They are also manufactured as small particles or fibres, which eventually find their way into the natural environment. The effect of MPs on marine organisms was investigated by the EU-funded project MARMICROTOX (Marine microplastics toxicity: Investigating microplastics and their co-contaminants in marine organisms). This work assessed the extent and type of MPs found in wild mussels collected from sites around the coast of Scotland. Laboratory studies were also conducted to investigate the effects of MP uptake in the gills and digestive gland material of mussels and to assess the effect on fish. Results indicated that MPs were present in very low levels in wild mussels in Scotland and in mussels located in cages placed in the estuary of the river Forth, in Edinburgh, United Kingdom. The bioavailability to mussels of co-contaminants in the form of cadmium and benzo(a)pyrene sorbed onto MPs were only detected through digestion of high plastic particle concentrations. Studies of rainbow trout showed there were no overall indications of distress in fish exposed via ingestion to MPs or MPs with sorbed triclosan (a bactericide present in toiletry products), but that triclosan seemed to be bioavailable to the fish under study. MARMICROTOX represents an important step in the assessment and analysis of MP contamination levels and effects, leading to a clearer understanding of possible ecological risks. Keywords Microplastics, marine organisms, MARMICROTOX, co-contaminants, mussels, fish
