It is not all gloom and doom, as in one notable way by the construction of sea defences and groynes, man's impact has improved the fauna on stretches of sand and shingle beaches. Because of the environmental concerns that first received popular attention as a result of Rachel Carson's book 'Silent Spring', the articles have proved very popular with students, if not with the membership.
Previous reports on sewage in the sea in Glaucus
have been couched in relatively simple terms because they have only investigated
the effects of sewage outfalls on the marine fauna.
The articles concluded that even raw sewage discharges into the sea would not be detrimental, except in in special wildlife areas or marine reserves. The increase in turbidity could possible cause some impoverishment but this would be small in comparison to the damage caused by scallop dredgers. (but see the note below).
However, it is recognised that in the course of the study and investigation of marine life, members will snorkel, dive, and fish in contaminated waters, and will frequently collect and consume seafood, including bivalve molluscs (mussels, cockles etc.) that could prove harmful to their health.
The E.C. Bathing Water Directive 76/160/EEC obliged the U.K. government to bring in laws to achieve the following levels:
95% of samples should contain these levels.
Guide (G) Mandatory (I)
Total coliforms/100ml 500 10,000
Faecal coliforms/100ml 100 2,000
In order to comply with the Directive 80% of the samples must meet the G-levels and 95% of the samples must meet the I-levels.
The Directive 91/492/EEC applies to shellfish.
1999 Bathing Water
Water Quality Information
Department of the Environment, Transport and the Regions
RAISING THE QUALITY
Implementation of nitrates Directive
Implementation of the Shellfish Waters Directive
Health Risk Surveys
"Establishing a link between minor illnesses such as gastroenteritis and ear, nose and throat infections is extremely difficult because these conditions are so common and may have various causes. Some headway has been made from large epidemiological studies which have compared the symptoms of swimmers with those of people who stayed out of the water" (Alison Walker, British Medical Journal).
All surveys have concluded that there is a significant statistical risk in contracting a minor illness e.g. gastroenteritis, upper respiratory infections after bathing in contaminated seas. However, although the numbers tested run in many thousands, the controls were not rigorous enough to become convincing. The results of a four year research project coordinated by the Department of the Environment are available.
Local opinion that I have been able to ascertain from Sussex where the beaches regularly exceed the mandatory coliform levels indicate that bathers, divers, shellfish collectors could expect to have abrasions infected, and these may take along time to clear up. There is at least one report from a regular swimmer who has contracted an unpleasant stomach complaint (gastroenteritis) after swimming for long periods (over 15 minutes) on a regular basis. Illness from eating prawns or fish caught in contaminated seas is fortunately non-existent, which was surprising because shrimps, prawns, and even mussels and cockles have been eaten from contaminated waters near the coast.
The biggest discrepancy of information occurs in an area where it could be expected to obtain accurate information. This is on the efficiency of the secondary biological treatment process in removing bacteria, viruses, and other pathogens.
It must be remembered that the bacteriological (or biological) treatment has a principal function of reducing the organic load and biological oxygen demand, and the removal of solid material. (See Part 2).
Campaigners against sewage pollution in the sea have claimed that that secondary treatment is necessary to make the seas safe to swim in, and to comply with the EEC Directives. Southern Water (and other water companies) have maintained that secondary treatment is not necessary and that the various alternative methods, usually primary treatment with a long sea outfall will ensure that the bathing waters are clean enough to swim in.
The difficulty that arises is the definition of what constitutes secondary treatment. The degree of reduction will vary depending on the type of secondary treatment employed, for example activated sludge or trickling filtration. Published data indicates that bacterial removal during secondary filtration varies between approximately 40% and 90%. This does not take into account the percentage removed during primary treatment which again varies with the process employed.
The problem is quite different if the wastewater (sewage) discharges contains industrial effluents, e.g. discharges into the River Mersey and from other heavy industrial areas.
Introduction: Sewage Disposal at Sea (Sussex example)
Effects on Marine Fauna
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