Marine debris and particularly floating plastic is a major hazhard for wildlife. Seabirds, turtles and marine mammals may ingest plastic, which may cause their death. Discarded plastic erodes to microscopic particles, which can enter the human food chain. Some plastic softeners may mimic endocrine hormones which impact reproduction.
Marine debris washes up on the Guernsey shore regularly. Much of it is from shipping including fishing boats. Storms bring up smashed up lobster pots. When beach cleaning we always find the odd shoe, cigarette lighters, fishing twine and line, pieces of styrofoam and insulation foam, plastic bags and plastic bottles, and thousands of pieces of hard plastic including disposable plastic cutlery, plastic bottle tops and plastic toys.