Key findings

• The open seas are still little affected by pollution and levels of monitored contaminants continue to fall, albeit slowly in many cases. This reflects reductions in riverine inputs of a range of contaminants and in atmospheric deposition of some heavy metals and polycyclic aromatic hydrocarbons (PAHs) to UK seas. However, a range of persistent chemicals appear in deep-sea fish and marine mammals off UK coasts, and we have also found litter at a depth of 1000 metres.
• New data show that the five areas assessed in the previous UK-wide assessment (Charting Progress) as being of concern from nutrient inputs (East England, East Anglia, Liverpool Bay, Solent, Firth of Clyde) do not suffer from eutrophication. However, we have identified 17 small harbours and estuaries that are problem areas for eutrophication. Measures are in place to control these but recovery is likely to be slow.
• Further regulation preventing the use of tributyltin-based antifouling paints on large seagoing vessels has led to a fall in the development of male characteristics in female dogwhelks in some areas.
• Levels of several flame retardant compounds are declining in porpoise blubber, following EU regulatory action and as a result of improvements in industry practice. However, polychlorinated biphenyls (PCBs) are present at levels that affect harbour porpoises around the UK, probably by suppressing their immune systems and making them more prone to death from infectious diseases. Levels are declining only slowly, despite a ban on these chemicals in the 1980s.
• Where there are problems, these usually occur in localised areas near the source rather than across whole regions. However, some substances travel long distances through the atmosphere and have been detected in fish offshore and some become concentrated as they pass through the food chain to accumulate in cetaceans.
• Some ‘legacy’ contaminants are present at high concentrations in estuaries historically contaminated by industrial processes. For example, in the northeast of England, PAHs are present in sediments at concentrations which may be toxic to organisms living in or on the seabed, and may take many tens to hundreds of years to degrade.
• There have been no major marine oil or chemical spills in UK waters since the publication of Charting Progress. Levels of oil in produced water discharged by the offshore oil and gas industry are falling in response to regulatory controls. Doses of radioactivity received by people and wildlife continue to be well within regulatory limits. Work is underway at Sellafield and Dounreay to retrieve radioactive particles from the beaches; the levels are not high enough for the beaches to be closed, but harvesting of seafood around Dounreay is currently banned.
• For algal toxins, only 0.3% to 1% of the roughly 1000 samples analysed annually give positive results, and even these are often not above regulatory limits. Controls are in place to prevent harvesting of shellfish contaminated to a level that would pose a risk to human consumers.
• We found microbiological contamination of coastal waters in some localised areas in both bathing waters and shellfish growing waters, although inputs from sewage treatment plants have fallen significantly because of investments in infrastructure. Shellfish harvested from contaminated areas are treated prior to sale to reduce microbiological contamination to safe levels.