The underwater killing fields

Half of the world's coral reefs could disappear within 25 years unless radical steps are taken to turn large areas of the world's oceans into protected areas. This is the stark message of some of the world's leading marine scientists attending the 9th International Coral Reef Symposium in Bali, Indonesia, which ended today.

Half of the world's coral reefs could disappear within 25 years unless radical steps are taken to turn large areas of the world's oceans into protected areas. This is the stark message of some of the world's leading marine scientists attending the 9th International Coral Reef Symposium in Bali, Indonesia, which ended today.

The scientists paint a haunting picture of the extent of the damage, and the rate at which it is likely to get worse. They estimate that about 11 per cent of the world's coral reefs have already been lost as a direct result of human activities, such as poor forestry and farming practices, and industrial and sewage pollution. The damage from direct impact is focused around major centres of human population, especially South East and Southern Asia, Eastern Africa and the Caribbean.

Another 16 per cent have been all but killed off in the huge "bleaching" events that hit coral reefs in 1997 and 1998. In large parts of the central Indian Ocean more than 90 per cent of coral reefs died. It began by the coral expelling the microscopic plants that give the organism is vibrant colour, turning them white in the process. Scientists at this week's symposium, plus the governments of the affected countries where many people's livelihoods depend on the reefs, blame global warming.

A detailed assessment of the extent of the damage, drawing on local, national and international monitoring programmes, comes in a massive new report by the Global Coral Reef Monitoring Network, a group of governments, scientific institutes and non-governmental organisations from more than 80 countries. The network's major supporters include the US National Oceanic and Atmospheric Administration, the UK's Department for International Development, the Swedish International Development Agency and the governments of France, Australia and Japan.

The causes of coral death from direct human impacts are well understood and are not scientifically questioned. Sediments running down rivers and into the sea from land degraded by deforestation and other poor land-use practices deprive them of sunlight so that the algae that live within the corals - a branch of the animal kingdom that first evolved hundreds of millions of years ago - can no longer generate energy through photosynthesis. As a result, both the algae and the corals, which depend upon each other, starve.

Direct impacts on coral are greatest in the major centres of rapid economic population and economic growth, notably South and South East Asia, where most of the world's corals are found. Poisoning by pollution from industry, sewage and fertilizers is a major cause of coral death. Run-off of agricultural fertilisers, and leaching of fertilisers also encourages the growth of plant species that out-compete coral. Coral diseases are on the increase worldwide as a result of these pressures, according to the scientists. Other major reasons for coral devastation include dredging and major construction projects, such as building airports for tourists.

A single healthy reef may be the home of 200 species of coral, 300 species of fish and between 10,000 and 100,000 invertebrates. One square kilometre can produce food for 2,500 people a year, providing its ecosystem is left intact.

Certain fishing practices, such as the use of dynamite, cyanide (to stun fish and capture them alive for sale to mainly Chinese markets for consumption), long lines and nets are destroying coral reefs on which these fish species depend. Nowhere is this more apparent than Indonesia, where the past three years of political and economic turmoil have put unprecedented pressure on the nation's coral reefs.

When marine scientists met at the last symposium four years ago, the consensus was that climate change would not become a big threat for at least several decades. Now the ground has shifted dramatically. Several points are now clear: when the sea temperatures rise above a certain level corals start to die, and average sea temperatures are rising. The other point is that the scale of the bleaching events of 1997 and 1998 appear to be unprecedented. The feeling is that global warming is making El Niño events - when the warm Pacific Ocean current goes into reverse - far more pronounced. This is leading to conditions where coral ecosystems that have survived for millions of years are being wiped out, and will be wiped out even faster in the next few decades.

One of the big questions for scientists is what they can do to avert a potential catastrophe. One suggestion is to create protection zones where some 20 per cent of the world's reefs can be kept alive and healthy in order that they can be used to re-seed other areas destroyed by bleaching. "We must show something, some success here," says Clive Wilkins, editor of the Status of the Coral Reefs of the World report.

The report demonstrates that there has been progress in implementing global monitoring networks and providing sound information on the state of the world's reefs. But there are important gaps. Involving local communities, who have a direct stake in the well-being of their reefs, will be key, says Rili Djohani of the Nature Conservancy, Coastal and Marine Programme, Indonesia.

The scientists and conservationists have some powerful allies, including US presidential candidate Al Gore, who has written a special introduction for the report.

But it's a race against time. "The pressures are increasing hugely," says Ms Djohani. In the countries with the richest coral reefs, such as Indonesia, conservation budgets have been cut by 80 per cent since the economic crisis of 1997/98, she says. And also in Indonesia, exports of fish caught illegally, much of it from reefs, are thought to be twice as large as legal exports.

San Salvador island in the Philippines is an important example of a successful project to foster community management of the coral reef. In the Eighties the villagers were using cyanide and explosives to catch fish. The size of fish catches fell by two thirds as a result, from around 20kg per trip to under 5kg a trip by the end of the Eighties. In 1989, after encouragement from a local environmental group and a popular vote, San Salvador created a 137-hectare reserve, including part of the reef in the best preserved part of the shoreline. Fishing was banned here. Villagers helped to patrol the reserve and violators were punished. Within two years catches in an extensive area outside the reserve had increased by two-thirds.

An ultimate goal, it's being suggested, should be Marine Protection Zones to cover 20 per cent total cover of all marine habitats, not just coral reefs. Only then can there be some reasonable chance of preserving these essential assets into the 21st century as pressures build inexorably on areas outside the zones.

To really make this work will require developing plans for ocean use as a whole, linked to land-use management plans, and operating in similar ways to those that are familiar to existing policing institutions. The rich countries will probably need to lead the way, demonstrating better management of their own marine resources and providing resources both at home and in the developing world.

It's an enormously ambitious goal. Less than half of one per cent of the world's seas enjoy some form of protection, and only a tiny fraction of that half per cent are "no-take" zones. What's more, even in that tiny fraction, the total protection policies are seldom enforced effectively.

If it works, it may not save all corals, but it could at least limit the potential damage to what some biologists refer to as the rainforests of the oceans.