Marine Pollution

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Pollution from toxic chemicals, sewage, oil, radioactive waste, urban and agricultural run-off and litter is not only a threat to marine life, it can also contaminate the fish we eat and ruin the natural beauty of our coasts.

Due in large part to the MCS Good Beach Guide campaign, sewage discharges to the sea are radically improved. Inputs of chemicals from outflow pipes are also being better controlled but there is still much to be done to stem the flow of diffuse pollutants from land run-off, storm drains and offshore sources. The level of pollution in the UK’s estuaries and coastal waters continues to be a major concern for the Marine Conservation Society.

On a global scale expansion in the production, use and disposal of plastic has created a major new pollutant for the 21st Century. On land, litter is an aesthetic problem, but at sea, litter and plastic litter in particular, is a potential catastrophe. Marine litter can directly harm wildlife through entanglement and ingestion. Furthermore plastics at sea don’t biodegrade, they just break down into smaller fragments. Recent evidence shows that plastic micro fragments can absorb toxic chemicals from seawater, leading to concentrations much higher than in the surrounding water. Marine invertebrates can ingest these contaminated particles, and the toxic chemicals may then enter the food chain.

There is one other consequence of our propensity to use and discard plastic: the transport of invasive alien species that live and grow attached to floating plastic fragments. Floating slowly in the surface waters plastic debris does not cross climatic zones fast enough to cause temperature shock, and plastic may be counted on to reach shores seldom visited by shipping. Once established in a new location, marine alien species cannot be removed. See side bar.

The UK has 22,00 combined sewer overflows which discharge urban waste water into rivers and the sea following heavy rainfall. Despite 20 billion pounds of investment in the UK's waste water treatment, a third of tested bathing sites still pose an unacceptable health risk to swimmers, largely due to combined sewer outflows and storm run-off.

Over 30% of estuaries and 15% of coastal waters are at risk from nutrients, pesticides, organic pollutants and heavy metals. To many nutrients cause eutrophication or excessive algal growth which leads to oxygen starvation for bottom dwelling organisms. Over a dozen UK estuaries are now recognised as eutrophic, largely caused by nitrate input from rivers.

A recent survey of UK estuaries found fish species suffering from reproductive problems caused by oestrogen pollution. In 2005 about 13% of commercial shellfish sites in England and Wales failed chemical water quality standards.