A new report warns that coral reefs are much rarer than had been previously thought, and they are being rapidly destroyed. Global warming may finish off these complex ecosystems altogether. No one has even begun to measure what the loss to mankind will be
CORAL reefs are one of the world's richest environments, the equivalent of rainforests on land. They provide food for millions of people and income from scuba diving and tourism as well as protecting shorelines from the ravages of the sea. Yet according to a new report published on Tuesday September 11th, coral reefs are also much rarer than people have previously thought. And they are vanishing quickly. Some scientists fear it is already too late and that within 50 years most of the world's coral reefs will be dead--bleached to barren skeletons from the effects of global warming.
The extent to which coral reefs are under assault from mankind is spelled out in the report, a comprehensive atlas of reefs published by the United Nations Environment Programme. It shows previous estimates of the extent of surviving coral-reefs have been grossly exaggerated. The atlas calculates the area of the world's coral as 284,000 square kilometres. Although that is an area about the size of Arizona, coral reefs are so prolific with marine life that they contain 60-70% of all the world's fish stocks.
Some scientists reckon that less than 10% of the species living on reefs have been identified. This means that, perhaps even more so than in the rainforests, coral reefs contain unique chemical compounds, some of which have already proved extremely valuable to mankind, especially in developing new drugs. AZT, which is used to treat people with HIV and AIDS, is based on chemicals extracted from a sponge which lives on a Caribbean reef.
Blasted, poisoned and suffocated
But coral reefs are being destroyed in many ways. Overfishing is upsetting the delicate balance of life on the reefs. The way fish are caught is also often destructive. Blast fishing, in which an explosive is thrown into the water to stun fish momentarily, is widely practised in some parts of the world, especially in South-East Asia. So too is cyanide fishing, in which a solution of poison is squirted at fish, also to stun them. Once the fish recover, they are sold. Live fish fetch high prices, both in restaurants (many Asian restaurants keep fish alive in tanks) and for aquariums.
Reefs are also being smothered with increasing sediment flowing from rivers. Because most rivers nowadays contain sewage and fertiliser, nutrient levels in the water and sediment which they are dumping on reefs have risen. This, in turn, is boosting the growth of algae which are choking many reefs to death. Irresponsible tourism is also causing damage.
Indonesia has more coral reefs than any other country, but these tend to be in the worst condition. Some 80% of Indonesia's reefs are endangered. Australia, with the Great Barrier Reef (often described as the world's biggest living thing) and the Philippines have the next largest expanses of coral. About a quarter of the world's reefs are controlled by developed countries, such as France, Britain and the United States. The UN Environment Programme hopes that its new study will lead to a greater understanding of the value of coral reefs, and more effort to protect them.
Given time, coral reefs can recover from mankind's ravages. But for most, time may have already run out. Coral reefs are built, usually in warm tropical waters, by living creatures which look like miniature sea anemones. They excrete their skeletons as they grow, and this forms the basis of the reef. These coral polyps have algae living symbiotically within their cells. The algae work like solar panels, converting into nutrients sunlight flickering down from the surface of the sea. The relationship benefits both the coral and algae, until the sea warms up. Even a slight temperature variation can cause the coral to suffer a form of stress, resulting in it expelling the algae. If the temperature of the sea fails to drop, the coral will not acquire new algae and it dies--a process known as bleaching.
Vast amounts of coral reef have already been bleached. An increase in sea temperatures caused by the El Nino weather event in 1998 may have destroyed 90% of the coral in the central Indian Ocean. With sea temperatures expected to rise over the coming decades because of the effects of global warming, the future for coral may be very bleak.
Rupert Ormond, a marine biologist from Glasgow University, told a recent science conference: "It is hard to avoid the conclusion that most coral in most areas will be lost." Even if humans immediately stopped producing greenhouse gases, which are held to be responsible for global warming, he predicted it would be too late to save most of the reefs. The world may be waking up to the value of one of its most beautiful and complex ecosystems just at the point it is about to vanish.
Source Citation:"Coral's fragile future; Coral reefs: A fragile future." Global Agenda (Sept 11, 2001): NA. Academic OneFile. Gale. BROWARD COUNTY LIBRARY. 24 Aug. 2009
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