Water and Marine Resources

Water use by industry

Water used by industry is often second in amount to that consumed by agriculture. The type of water used by industry is different to that used by agriculture and domestic consumers. In general manufacturing industry uses water for:

• cooling machinery, and ingots of metal;
• reducing dust;
• dilution of pollutants;
• the transport of waste products from factories.

These uses are often called 'withdrawal of water' in that given the right technology the waste water can be cleaned and re-used. The degree of cleaning does however vary. For example water used in cooling power station machinery may need to be cooled from 70°C back to the temperature of the river from which it was extracted. Similarly water used in high pressure jets to extract minerals contains much suspended sediment, so large lagoons are necessary where this sediment can settle out. Cleaning waste water which contains heavy metals such as mercury and cadmium or complex organic compounds is both technically very difficult and very expensive.

In the past industrialists often made little attempt to clean water, but relied on the abundance of the water cycle to wash away the waste. Legislation has, however, forced industrialists to clean up and re-use their water, so now industrialists in Japan, Israel and the Netherlands recycle 90% of their water.

Access to water resources has become an important factor in the location of many industries. Now the price of water and the cost of its cleansing have to be included in forecast production costs. Countries like Norway, with access to unrestricted supplies of water may, find themselves at an advantage in attracting industries.

Water conservation strategies

The privatisation of water supply in many EMDCs such as the UK has provided a motivation, through the search for profits, to re-assess strategies for water conservation. Private water companies often face a situation with a great increase in the demand for freshwater during the summer months. The traditional response to this scenario was to impose restrictions on the use of hosepipes and car washing. However to a profit-orientated company limiting water use can result in lower profits. So private water companies have a range of options which include:

• allocating water to priority users, such as hospitals, old people's homes, food processing industries;
• adjusting bills, so that non-metered homes pay more for their water than those with water meters;
• encouraging conservation measures, such as relining reservoirs with impervious materials to prevent loss by percolation. In other cases light- weight covers can be extended over small reservoirs to reduce losses through evaporation. Leakage from old cast iron water pipes which distribute the water in much of the UK can account for up to 45% of the water leaving a reservoir. These old pipes canbe replaced to reduce leakage, however even in modern systems losses of 20 per cent are considered normal;
• large consumers can be encouraged to re-use water;
• more reservoirs and other storage areas can be constructed. However this is difficult in EMDCs due to high
• land values, competing land uses and conservation concerns. Deeper boreholes bring their own problems;
• water can be transferred from neighbouring companies if they have a surplus;
• new technologies such as the desalinisation of sea water can be used.

Marine Resources

Oceans covering 70% of the Earth's surface represent a resource with enormous potential, for both use and abuse. Until 100 years ago the oceans were largely used for two main activities namely fishing and shipping. Since then, however, human interest in marine resources has extended from these two initial activities into energy production, underwater mining, waste disposal, research, tourism and conservation. The sheer size, diversity and flexibility of marine resources have proved a fatal attraction for the human species. Great wealth has been extracted from marine resources but the environmental costs have been high. Only recently have ideas of sustainable development been applied to the oceans and their resources and for some resources and some oceans this process is already too late.

There are three major oceans on the Earth -the Pacific, the Atlantic and the Indian -of which the Pacific is the largest covering 170 million sq. km.

This makes the Pacific as big as the other two oceans combined. The Pacific alone covers one-third of the Earth's surface and stretches nearly half way round it from east to west. It is so big that all the Earth's dry land could fit inside it. The Arctic Ocean is smaller than the other three and is mostly covered by ice. Other, smaller water-covered areas of the Earth are called seas, such as the Caribbean or the Mediterranean. These seas may be part of an ocean, as for example the Caribbean is part of the Atlantic, or they may be separated as in the case of the Mediterranean. The use and abuse of these oceans and their resource will be considered in relation to four main themes:

a) fisheries

b) mineral extraction

c) international conflicts over marine resources

d) pollution.

Fisheries

The sheer size of the world's oceans has led people to believe that they will serve as an inexhaustible supply of food. However from the 1960s onwards the fallacy of this belief became apparent as species after species declined in numbers, and overfishing became chronic in many of the world's oceans. As a result by 1994 the United Nations Food and Agricultural Organisation (FAO) reported that nine of the world's 17 major fishing grounds were suffering catastrophic declines in some species.

The FAO report also made the point that fishermen rely on relatively few species. Only 9000 out of the world's 20000 known species are caught, and a mere 22 species are taken in volumes of over 100,000 metric tonnes a year. Just five groups of species -herrings, cod, jacks, redfish and mackerel- make up half of the entire world catch.

The FAO report calculates that if world fishing fleets catch in total over 100 million tonnes a year of species currently exploited then stocks will be depleted. Figures indicate that the world commercial fish catch rose from 20 million tonnes in 1950 to 92 million tonnes in 1987 and 96 million tonnes in 1996. As this trend continues humanity is getting ever closer to the maximum sustainable yield of existing species.

The concept of maximum sustainable yield is an important one in relation to world fisheries. The total biomass (weight) of a fish species is called the stock. This stock can be increased either by the growth of adults in the population (G in Figure 4.9) and/or by young fish (R) joining the population.

Cod swims to oblivion as the EU flounders- The Guardian

Martin Walker in Brussels Last orders are looming in fish and chip shops as the one remaining cod fishery outside the Pacific, the Barents Sea off Norway, is plunged into crisis. Unless fishing is banned in the main spawning ground for Arctic cod, scientists warn in a report to be published soon, stocks could fall below 'the safe bio- logical minimum' next year.

With the Atlantic cod grounds on the Grand Banks off Canada and the United States closed after years of over-fishing, and the North Sea going the same way, Britain's favourite fish is swimming into extinction. 'Nobody can say they were not warned. Two years ago, cod and haddock were both put on the World Conservation Union's red list for endangered species, said Mike Sutton, who runs the fisheries campaign for the Worldwide Fund for Nature (WWF). 'When North Sea stocks began falling, the industry turned to the Grand Banks. And when that closed. ..they increased their fishing in the Barents Sea, with predictable results. Now there is nowhere left to turn, except to the Pacific cod, which is a different species. They'll probably fish that out next.'

The Barents Sea report, by the International Council for Exploration of the Sea (ICES), has provoked a political row. Based in Copenhagen, ICES produces surveys of the world's fisheries. But advance word of this report, claiming the cod population of the Barents Sea has been over-estimated, has caused outrage in Norway. Fishermen claim cuts in quotas would cost them £200 million. After a catastrophic fall in yields in the 1980s, which forced authorities to slash the catch from 800000 tons a year to 170000 tons, the Barents Sea is supposed to be one of the best-controlled fisheries. This latest crisis comes as European Union ministers scramble to resolve the last one, with a plan to require all EU fishing vessels to fit transponders so they can be tracked by satellite.

The campaign to ban drift nets on the high seas should be won next week, when EU fisheries ministers meet in Brussels. But the drift nets row reveals the weakness of EU fishing rules. The EU is still ignoring United Nations resolutions to ban nets longer than 1.5 miles. And Italian fishermen are still lobbying hard against an EU ban on the 10-mile-long nets they use to catch swordfish and tuna, but which devastate the Mediterranean dolphins.

'The EU still remains one of the really big problems,' Mr Sutton said. 'When the Commission pro- poses something sensible, it gets watered down or blocked in the Council, where ministers come under political pressure from their fishermen. , The battle is under way to rewrite the EU's Common Fisheries Policy, which is to be renegotiated in four years' time -'if there are any fish left by then,' the WWF notes drily. The issue is whether the political will can be mustered to stop the EU scheme under which it 'buys' fishing rights from third countries.

The EU spends £160 million a year, mainly paying African countries to let Spanish vessels scoop up their fish. This EU subsidy is part of the bizarre economics of global fishing, for which governments pump in an annual £15 billion in subsidies for a catch worth £55 billion. All the world's fisheries are in trouble after the global catch quadrupled in the 40 years after 1950. The answer has been to cut the fleet. But the EU target to reduce the fleet by 40 per cent in six years has been scrapped. The EU now has the worst of all worlds -failing to manage threatened stocks while infuriating fishermen.

Conversely the fish stock is depleted by the deaths from disease, old age and predators (M) and by capture by fishing (F). In theory the end stock should be the same biomass as the beginning stock, that is end stock = beginning stock + (G+R) - (M + F). In an equilibrium situation the biomass of the fish stock does not change, so (G + R) = (M + F). This is the equilibrium stock. The aim of managing fish stocks is to achieve the highest catch year after year without destroying this equilibrium stock. Such catches represent the maximum sustainable yield, that is the biomass that can be caught each year without jeopardising the stock of one fish species.

Problems arise in this theoretical situation as fishing increases. This means that the equilibrium stock figure is exceeded and the stock is reduced i.e. M+F are greater than G+R. This is a situation of overfishing. There are two main types of overfishing. Growth over fishing occurs when too many small fish are caught, so their growth potential is not exploited. Recruitment over fishing occurs when too many adults are caught, leaving not enough fish to spawn to produce new recruits.

Overfishing herring in the North Sea

The herring fisheries of the North Sea illustrate the operation of growth and recruitment overfishing. Between 1950 and 1962 the herring catch remained at about 0.85 million tonnes. However after 1963 fishing increased to produce a peak catch in 1965 of 1.4 million tonnes. Thereafter the catch declined to 0.7 million tonnes in 1971 and 0.1 million tonnes in 1977. Such a dramatic decline was due to growth overfishing followed by recruitment overfishing. The situation became so bad that in 1977 Britain imposed a ban on North Sea herring catches. This has allowed the stock to slowly increase and recover. By 1982 stocks had recovered and the ban was lifted and limited fishing allowed. Experts calculate that the maximum sustainable yield for North Sea herring is 0.75 million tonnes.

Fisheries management in the North Sea

The case of the North Sea herring illustrates the problems of fishing and management policies which focus an a single species. This single species management is not a realistic long-term approach to managing the world's fish. A much more realistic approach is that of multi-species management which considers the effects and changes of fishing on a wide range of species, and how they interact with each other. For example adult herring feed mostly on planktonic animals and as such are in competition with other pelagic fish. The herring are also a source of food for cod and other species. Hence the dramatic decline in the number of herring had important consequences for the stock of cod and other species. A change in the stock of one species can have a vital impact on the stock of other species. Unfortunately the interactions between species are very complex and, as yet, not fully understood, making multi-species management a theoretical rather than a practical approach.

The global dimension to overfishing

Overfishing varies greatly from place to place around the world. Stocks of all the main fish species in the north west Atlantic have been overfished and catches have fallen by 32 per cent since 1970. Similarly the main stocks in the north east Atlantic of cod, haddock, hake, sardines, herring and anchovies have all declined as a result of the

Regulating North Sea fisheries

Governments and organisations like the European Union (EU) have adopted a range of measures in order to regulate the amount of fish extracted from the North Sea, and to prevent exceeding the maximum sustainable yield. The main types of measures are:

a) regulations limiting size of mesh on fishing nets or amount of fish which may be landed;

b) regulations limiting the total catch for a country or region via quotas. When the quota has been reached no more fish may be caught until the following year;

c) regulations limiting the number of fishing vessels. This creates problems of unemployment when boats are laid up or scrapped. For example 30000 jobs have been lost in the fishing industry of Hull since 1945 and a deep sea trawler fleet of 300 smallish vessels has been replaced by 15 very large vessels; and

d) regulations to restrict the fishing season and/or to restrict fishing in certain areas, mainly to protect spawning grounds.

The main problem with all these measures is that implementing them leads to international disagreements, especially over restrictions and quotas operation of fleets from Denmark, Norway, the UK, Iceland, Russia, Poland, Spain, France, the Netherlands and Germany.

In the north west Pacific catches are dominated by the Japanese, who represent the world's biggest fishing nation. Similarly catches in the Black Sea and Mediterranean Sea are all in the 1990s in excess of sustainability. Elsewhere in the world, especially in the south east Atlantic, north east, south east and central Pacific and the Indian Ocean catches are approaching their maximum sustainable yield.

Fishing in Economically Less Developed Countries (ELDCs)

Statistics of total world fish catches exclude those fish taken by people in ELDCs. Here the fish are eaten and traded locally by the 8 million fishermen in ELDCs, who it is estimated catch 24 million tonnes a year. Fish are the largest single source of protein for millions of people in poorer countries, but even here catches are declining. For example at St. Vincent in the West Indies catches have fallen by half since 1980.

All over south east Asia, East and West Africa coastal fisheries are being over-exploited. Many local fishermen use dynamite and poisons in order to catch enough fish to make a living. In doing so they not only contribute to the decline in fish stocks but inflict considerable damage on fish habitat.

Peru illustrates the combination of natural and human actions in leading to falling catches. In 1974 there was a devastating decline in Peru's anchovy fisheries. Catches which had reached 12 million tonnes (20 per cent of the world's total) had fallen to 2 million tonnes by 1975. Overfishing was partly to blame, but so were the effects of El Nino -a current of warm water which periodically flows along the Peruvian coast. Plankton do not thrive in the warm water of El Nino so anchovy numbers declined drastically. By 1983 the catch was a mere 100,000 tonnes and has risen little since then.

Future pressures on world fish resources

• Pressure on world fish resources will continue because:

• consumption is rising in ELDCs with growing populations where fish is a vital source of protein;

• many ELDCs have used international loans to invest in a fishing industry whose products earn valuable foreign exchange. Eight of the world's 11 biggest fishing nations are ELDCs -China, India, Indonesia, Thailand, Philippines, South Korea, Peru and Chile. The main markets for fish exports are Japan, the USA and E.U.; and

• the destruction and pollution of mangroves, coral reefs and sea grasses. These are all areas vital to the growth and development of young fish. Such coastal waters contain rich sources of food and nearly all fish spend their first, vulnerable years in these waters. Nearly all the world's fish are caught within 400 km of land, yet these are just the waters most affected by pollution and degradation.

Alternative futures for fish resources

The future of the fishing industry and of fish resources looks very fragile. There are some future possibilities such as:

• developing new fishing grounds. The main areas are in the south west Atlantic off Argentina, near New Zealand and in the western parts of the Indian Ocean. However these are not huge areas and their potential is very limited;

• take different species of fish. At present squid and octopus are under-exploited as are deep sea fish like the lantern fish. However the largest potential is the shrimp-like krill that live in billions in the Antarctic Ocean. Trawlers can scoop up several tonnes of krill every hour and there is still room for expansion. The krill have to be processed quickly so factory ships have to accompany the trawlers;

• fish farming in coastal cages and ponds is another way to increase production. Its recent growth produces over 10 million tonnes of fish each year -from crustaceans, to molluscs and bivalves. But the chemicals used on the fish farms have led to the pollution and destruction of coastal habitats such as the mangroves of south east Asia; and

• currently 30 million tonnes of fish is converted into fishmeal which is fed to pigs, chickens, salmon and shrimps. Experts estimate that 10 million tonnes of this could be saved by more efficient processing of the fish caught.

The outlook for world fisheries is not good. Overfishing continues despite attempts by quotas and bans to conserve stocks. Habitat destruction by development and pollution is a big problem. Disputes between nations over control of fishing grounds grow in number and intensity every year. Fishing fleets from the world's richer countries are now plundering the seas around ELDCs having exhausted their own waters. Sensible, workable, management policies are needed, and soon, because the livelihoods and diets of millions of people currently hang in the balance.

Mineral resource Extraction

The discovery of oil and natural gas in the North Sea after 1965led to massive drilling activity in different parts of the North Sea. However sea water itself contains dissolved minerals, especially salt. For centuries people have been obtaining salt by evaporating sea water. There are in total over 80 different mineral elements in sea water but only two are so far extracted on a large scale. Half the world's magnesium comes from sea water, as does two-thirds of the world's total bromide production. However sand and gravel are probably the two most valuable marine minerals currently dredged from ocean floors. In Britain 10 per cent of the total sand and gravel production used in the construction industry is dredged from the sea bed. In other countries like Iceland shells dredged from the sea bed are used for cement production.

Placer deposits

Some minerals have been carried to the ocean by rivers and deposited on the sea bed as placer deposits. Off the coast of Indonesia for example tin is mined from such placer deposits where reserves over 650 000 metric tonnes are known to exist. Other metals mined in this way around the world are silver, iron, tungsten, platinum, titanium, sulphur phosphates and diamonds.

The largest mineral resources lie in the deepest parts of the sea bed. The Red Sea is one important area where mineral rich sediments lie 2000 metres beneath the surface. Atlantis II Deep is the largest of these deposits and lies halfway between the Sudan and Saudi Arabia. Silver, zinc, copper and gold are all to be found in the sediments which range from 2 to 23 metres in thickness. The minerals could be extracted by pumping to the surface but large-scale extraction will depend on the world price for these minerals. Once the costs of land-based mining start to rise ocean mining will become a reality.

But in addition to accidents for hundreds of years people have systematically used oceans as the main depository for humanity's waste products. Areas such as the Mediterranean in the zone close to the Nile delta or the lagoons of Venice have been hazards to human health for centuries. However in recent years the scale of pollution has grown, and now the once localised examples have spread to include the open ocean.

Oceans like the Black Sea, Baltic and Mediterranean are particularly vulnerable to pollution because they are partially enclosed. In these cases the water circulates only slowly and so pollutants are not diluted or swept away. Similarly areas with weak ocean currents, such as the German Bight in the North Sea have more serious pollution than those places where Currents flow more strongly.

River estuaries and harbours are concentration points for pollution, and in general terms coastal waters are more heavily polluted than the open oceans. Despite this pollutants such as DDT or PCBs have been found all over the world including in the tissues of penguins and seals from the Pacific to the Arctic and Antarctic Oceans. None of the world's oceans are free from pollution. Only ~he degree varies.

Polluting the oceans- The Guardian

The tanker finally grounded on the rocks of Garth Ness, on the west coast of Shetland, at 11.19 that morning. All 85,000 tonnes of the crude oil loaded in Norway was spilt as she broke up in gales. According to the Marine Pollution Control Unit re- port, also published yesterday, environmental disaster was only avoided because of the violent weather conditions and the low viscosity of the oil. T

he Braer's troubles began, according to the Department of Transport's maritime accident investigation branch, when spare steel pipes broke loose on the after deck on the severe southerly gale.

Source of marine pollution

Oceans are polluted both directly and indirectly, Direct pollution includes dumping (10 per cent of the total), pollution from shipping (12 per cent of the total) and pollution from offshore oil and gas production (1 per cent of the total), About 32 per cent of total pollution comes directly as fallout from air pollution which dumps oxides of sulphur and nitrogen into the sea, Indirect pollution enters the seas via rivers, This accounts for 45 per cent of the total and the main sources are

(a) agriculture -especially pesticides, herbicides and nitrates;

(b) urban areas generating domestic and industrial sewage as well as toxic chemicals, heavy metals and oils;

(c) industry which produces toxic wastes;

(d) radioactive waste from nuclear power stations; and

(e) oil refineries adding 200000 tonnes of oil to marine pollution each year .

Different parts of the ocean vary in both the degree and types of pollution they experience. Discharges from rivers mostly affect coastal waters. Pollution from shipping tends to be concentrated on transport routes. Air pollution is greatest close to industrialised nations. For example airborne pollution of the Baltic and Mediterranean Seas is about 10 times as great as in the North Atlantic and 1000 times greater than in the South Pacific.

Sewage and chemicals

In many countries raw sewage is pumped directly into the seas. In the UK 70 per cent of the sewage from coastal towns and cities is discharged with little or no treatment. In the Mediterranean the figure is 66 per cent. One result of this failure to treat sewage is that a quarter of UK beaches fail European Commission Safety Standards.

Swimming in sewage contaminated water, whether in the UK or the Mediterranean causes gastro- intestinal infections as well as ear, eye and skin diseases. There are reported cases of medical wastes, which include syringes washed up on beaches in the north east USA, as well as on the Italian and French Rivieras. Chemicals such as DDT from pesticides and PCBs (used in the manufacture of a wide range of goods from electrical appliances to glues) have been found in many oceans. These chemicals are toxic and persist for many years in the water. The richer industrialised countries have been making strenuous efforts to cut down on the discharge of such chemicals into rivers and seas and this source of pollution has been reduced. However on a global scale as countries like India, Malaysia, South Korea and Brazil industrialise they add to the extent and degree of marine chemical pollution. The effects of these chemicals is to cause diseases in fish which affect the rest of the food chain from dolphins and sea birds to humans.

Russia dumps 20 N- reactors at sea- Geoffrey Lean Environment Correspondent

The true horror of the nuclear waste catastrophe around Russia's shores has been revealed in a top-level internal report presented to President Yeltsin. Russian ministers say the country's submarine fleet is so awash with nuclear waste that it can no longer operate safely and that 20 nuclear reactors have been dumped off the country's Arctic and Pacific shores -eight of them in only 60ft of water. Plutonium from abandoned nuclear warheads is about to contaminate one of Europe's richest fishing grounds, regularly exploited by British trawlers. Canisters of nuclear waste have been shot at and holed to make them sink faster.

The report admits the Soviet Union 'completely violated' international treaties and lied to the International Maritime Organisation, which enforces them. But it adds that Russia has no alternative but to go on dumping at sea until 1997, when new reprocessing plants will come on stream. The extraordinarily frank report -by a government committee chaired by Alexei Yablokov, President Yeltsin's special adviser on the environment and health -is bound to spark protests from European and Asian governments. South Korea has already demanded that Russia stops dumping in the Sea of Japan.

Yesterday President Yeltsin ordered tighter controls on all Russia's nuclear facilities, following last week's explosion at the waste reprocessing plant at Tomsk-7 in Siberia- the worst nuclear accident since the Chernobyl disaster seven years ago this month. The Russian Atomic Energy Ministry admitted yesterday that plutonium had been released by the accident, caused by a 'gross violation of procedures' at a building size miles outside the city of Tomsk, where half a million people live. Up to 75 square miles of land -including at least one village -have been contaminated.

The committee of inquiry included five Ministers, the vice-chairman of the country's nuclear and health inspectorates, and the chairman of its navy headquarters. The report reached Greenpeace, because its Moscow offices possessed one of the few photocopiers in the city capable of reproducing it properly. Dr Yablokov offered the pressure group a copy if, in return, it agreed to print the report. It warns of imminent plutonium contamination of one of the world's most productive spawning grounds, 300 miles north of Norway. It admits, for the first time, that a submarine NMS Komsomolets, which sank after a fire in 1989, is rapidly breaking up, and says that within the next three yeas there will be an 'un- controlled' and 'impulsive' leak of plutonium from its nuclear warheads.

The report predicts 'contamination of commercial fish species to twice the permitted levels', estimates put the damage at $2.5 billion and says there will undoubtedly be a negative political reaction from European countries. Salvaging the wreckage would cost $250 mil- lion and may be 'impossible' because it is so badly damaged. The report gives details, including precise references of the dumping ground for reactors from Soviet nuclear powered ships -10 sub- marines and the ice-breaker, Lenin -off Russia's coasts since 1965. All are highly radio active, and seven are still fully charged with legal spent nuclear fuel.

Eight -including four containing spent fuel- lie only 60 feet beneath the waves of Abrosimova Bay in Novaya Zemlya. Highly radioactive fragments of fuel rods have been found washed up on the shores of the giant Arctic island. The report estimates that the Soviet Union and the new Russian Federation have between them dumped a total of 12 trillion becquerels of radioactivity in the sea since 1959. It says 'a significant portion' of this must already have leaked from its containers. It adds: 'There were cases when the metal containers were shot at, to speed up their sinking.'

The committee admits that the dumping comprehensively broke international treaties, particularly the London Dumping Convention. But it adds that though Russia has greatly scaled down the dumping, it is 'impossible' to stop it for at least another four years, even though the Convention now bans it completely. This is mainly because of the 'critical problems' faced by its nuclear fleet.

Russia's 235 nuclear-powered ships contain 407 reactors and produce about a million cubic feet of nuclear waste each year. But the report reveals that the country has no way of treating the waste, and that the problem 'was never given special attention'. As a result large parts of the fleet have effectively become floating nuclear waste stores. As reactors are refuelled and submarines taken out of service under disarmament agreements, a backlog of 140 reactor cores full of spent fuel has built up; there is only enough storage for three. The top-level committee concludes the situation is 'critical' and the nuclear undersea fleet can no longer be operated safely.

Oil pollution

Of the three million metric tonnes of oil which finds its way into the seas every year, about half comes from ships and half from land-based pollution. Oil tankers still use sea water to wash out their empty tanks thus polluting water along the main shipping lanes. Relatively small amounts of oil can damage delicate marine organisms such as plankton and larvae. World attention focusses on marine oil pollution when there is a tanker wreck such as the Exxon Valdez in Alaska or the Braer off the coast of the Shetland Islands. Often sea birds and sea animals such as otters die and beaches are coated in oil. However such spectacular events are not as serious as the steady pollution from ships and from the land via rivers.

Dumping

Industrial wastes, sewage sludge and radioactive wastes have all been dumped in the oceans. Vigorous efforts are being made around the world, especially in the North Sea area, to phase out the dumping of industrial waste and sewage sludge. However the results of past dumping remain in the oceans, and are slow to dissolve or dissipate. Further the problem of radioactive waste seems to be growing as Figure 4.15 shows: Each year up to 150000 metric tonnes of plastic nets, lines and containers are dumped in the sea from fishing boats and other vessels. Plastic degrades very slowly or not at all. Sea creatures from fish, dolphins and sea birds to whales eat the plastic or get tangled in its mesh. As many as 100000 creatures die each year as a result of dumping plastic items in the seas and this type of pollution continues to increase.

Algae

In recent years vast blooms of algae have appeared to pollute oceans from the Adriatic to the North Sea. This algae bloom can be up to 10 metres deep and 10 kilometres wide. It kills fish, pollutes beaches and can cause disease in people or animals bathing near it. It is caused by the accumulation of nitrogen and phosphorous compounds from fertiliser, sewage and industrial wastes. These chemicals allow the algae to grow very rapidly and release their poisons. Areas affected include 100000 sq. km. of the Baltic where half the deep water is virtually dead, the Adriatic, and the Seto Inland Sea of Japan.

The poisons released by the algae contaminate sea food and currently 50000 people per year are affected by neurological, cardiovascular or gastro- intestinal symptoms.

Managing marine pollution

The oceans provide considerable scope for waste disposal but they need careful management. Past pollution needs to be cleaned up and present pollution controlled at source. The International Convention for the Prevention of Pollution from Ships (known as MARPOL) has set limits on the amount of oil ships can discharge. In sensitive areas like the Mediterranean Sea and Persian Gulf oil cannot be discharged at all. As a result oil pollution by ships at sea has been reduced. MARPOL is also tackling the dumping and discharge of wastes at sea.

Technology can be an aid to better management. New and better ways of incinerating waste are being developed together with better ways of dispersing sewage sludge and more effective ways of keeping toxic contaminants out of chemical waste.

There have also been agreements between groups of countries to clean up their seas. The seven Baltic states signed a treaty in 1974 which has helped reduce pollution. The North Sea states have reached agreements to halt the dumping of industrial and sewage wastes, and to reduce river pollution. The Mediterranean countries launched their own clean-up plan in 1975, this being the first of 10 'Regional Seas' programmes coordinated by the United Nations Environmental Programme. Such agreements are important because of the scale and complexity of ocean ecosystems which frequently transcend national and even international boundaries. In order to prevent pollution and manage seas productively more binding international agreements will be necessary.