A large proportion of the human population lives near the sea. A large part of their human wastes are discharged into the sea either in a raw state, or only partially treated. This sewage input has several effects. There is a great increase in nutrients which encourages the growth of algae, some of which are toxic to sea life and animals and humans who eat fish poisoned by the algae. The nutrients ought to be returned to the land, which would cut down the need for fertilizer and reduce the presence of excess nitrates in ground and river water. Human disease viruses and bacteria also enter the sea. The Victorian engineers who started putting sewage in the sea believed the sea water killed all disease organisms. They were mistaken.

Another source of poison in the sea is industry. Many chemical industries discharge chemicals into the sea, including heavy metals and complex organic compounds not found in the pre-industrial world.

Effects noticed are illness in humans swimming off beaches and deformed fish showing signs of cancers and other disorders. Virus diseases in marine mammals such as seals and dolphins are also suspected of being due to decreased immunity caused by industrial wastes (especially PCBs - Polychlorinated bi-phenyls).

A third source is nuclear discharges. Several European countries, especially Britain at Sellafield, Dounreay and Winfrith and France at La Hogue, discharge radioactive wastes into the sea. Eastern European discharges are also common via various rivers. The former Soviet Union has dumped nuclear reactors, waste, old weapons, old submarines all round its coasts. Russian ships were observed dumping waste in the Sea of Japan as recently as October 1993.

Another problem is plastic waste. Midway Island in the Pacific has been shown to be overwhelmed by the floating plastic waste, killing wildlife such as albatrosses, and never decaying. The only solution here would be to cease to produce these indestructible materials.

Some cultures use sea vegetation as food and sources of medicines. If the sea is poisoned these will become unusable. There are signs that they would be useful as sources of trace elements for fertilizer and medicinal purposes.

Rising proportions of carbon dioxide are altering the acidity of ocean water, possibly making the growth of shelled species difficult. Extinctions are considered probable.

Over-fishing problem

Cod returning to Grand Banks

The longest lasting civilizations are those which keep the land fertile. China is the world's longest continuing culture. Human wastes have always been returned to the land there. The western system of putting them in the sea seems likely to denude the land, in the long run, at the same time as the wastes poison the sea.

The standard should be that nothing should be put in the sea which was not present in pre-industrial times. This will require large investments in sewage processing plants, perhaps of a new type.

It also needs the redesign of industrial processes to ensure that non-biological substances do not flow into the sea. These policies require international co-operation and agreement. The European Union has already made regulations on Mediterranean and North Sea beaches.

Marine Stewardship Council