Coral atlas maps world's fast disappearing coral reefs

Posted: 11 September 2001

The most detailed assessment of coral reefs ever undertaken, shows that these precious marine ecosystems occupy a much smaller area of the planet than previously assumed.

Although distributed in 101 countries and territories, where they are vital for fisheries, coastal protection, tourism and wildlife, coral reefs occupy less than one tenth of one per cent of the oceans.

The findings give new urgency to protect and conserve these important, valuable and seductively beautiful habitats which are under increasing threat from activities such as dynamite fishing, pollution, and climate change.

The World Atlas of Coral Reefs, prepared by the UN Environment Programme World Conservation Monitoring Centre (UNEP-WCMC), provides a new global estimate for coral reefs world-wide: 284,300 sq km, an area just half the size of France or Thailand. For the first time, it also provides reef area estimates for individual countries and includes detailed maps and statistics for all the world's coral reef nations.

"Our new Atlas clearly shows that coral reefs are under assault," says Klaus Toepfer, UNEP Executive Director. "They are rapidly being degraded by human activities. They are over-fished, bombed and poisoned. They are smothered by sediment, and choked by algae growing on nutrient rich sewage and fertiliser run-off. They are damaged by irresponsible tourism and are being severely stressed by the warming of the world's oceans. Each of these pressures is bad enough in itself, but together, the cocktail is proving lethal."


The Atlas shows that Indonesia, with 51,020 sq km, followed by Australia (48,960 sq km) and the Philippines (25,060 sq km) are the largest reef nations, while France comes in fourth, with 14,280 sq km of reefs located in its overseas territories, and Papua New Guinea is fifth (13,840 sq km). With more coral than the USA, the UK is the 12th largest reef nation and has over 5,500 sq km of coral reefs (2% of the world total), all located in its overseas territories.

These area estimates are based on the most detailed map of coral reefs ever produced. Previous estimates were based on very simple maps or models, and incorporated deeper reef areas, which although still important are less diverse and less productive.

Diego Garcia Island in the Indian Ocean, a UK dependency, seen from the space shuttle. Credit: NASA

"Many coral reefs are under the ownership of the world's wealthiest nations. Between them, Australia, France, the UK and the USA account for over one quarter of the world's coral reefs - a critical resource in powerful hands," says Mark Spalding, lead author for the Atlas.

"Previous estimates of coral reef area, which didn't have the benefit of our detailed maps, have been double or in some cases ten times over what we have now found to be the case," says Spalding. "Furthermore, we also found that coral reefs are degrading fast in almost every country of the world. The Atlas provides a critical baseline and a focus for action to reverse these trends."

Human benefits

Coral reefs are an important source of food for hundreds of millions of people, many of whom have no other source of animal protein. They also provide income and employment through tourism, and marine recreation, and export fisheries, and for many coastal villages, and some entire nations are the only source of this income and employment. Furthermore, they offer countless other benefits to humans, including supplying compounds for medicines. AZT, a treatment for people with HIV infections, is based on chemicals extracted from a Caribbean reef sponge and more than half of all new cancer drug research focuses on marine organisms.

Often referred to as the "rainforests of the oceans," coral reefs host an extraordinary variety of marine plants and animals (perhaps up to 2 million) including one quarter of all marine fish species. It has been estimated that so far only about 10 per cent of these species have been described by scientists.

The Atlas contains the latest information on coral biodiversity. The most diverse region of the world for coral reefs is centred on the Philippines, Indonesia, Malaysia and Papua New Guinea, with between 500 and 600 species of coral in each of these countries.

Unfortunately, these are also some of the most threatened coral reefs in the world. In Indonesia, 82 per cent are "at risk", threatened by such human activities as the illegal practice of blast fishing. This is the most destructive fishing method on reefs. Explosives are typically thrown towards the reef and explode on the water surface. The shock wave from the blast kills the majority of fish species on the reef and causes severe damage to its structure. (Some 96-97 per cent of reefs in Thailand and The Philippines are identified as threatened, 91 per cent of those in Malaysia, 46 per cent in Papua New Guinea and 32 per cent in Australia.) Threat and conservation

This new Atlas from UNEP-WCMC builds on earlier scientific work that found some 58 per cent of the world's coral reefs were threatened by human activities. It includes new information on the impacts of global warming and coral bleaching, including the El Niño event in 1998 that caused the loss of 90 per cent of the corals in some parts of the Indian Ocean, representing 5 per cent of the world's reef area. Much of this damage passed almost unnoticed by the world's policy-makers. Marine scientists point out that had such levels of damage occur in terrestrial environments they would have caused a major public outcry.

Schooling Bannerfish, often seen as the emblem of healthy reefs. Credit: M Spalding

It also provides new data on the spread of coral diseases that affect 106 types of coral in 54 countries. It shows that entire coral reefs have been decimated by disease in the Caribbean.

For the first time, the Atlas also maps the 660 marine protected areas worldwide that incorporate coral reefs. It notes that unfortunately, many of the protected areas exist on paper only, that they are poorly managed and have little or no support or enforcement. It says they often only focus on controlling the direct impacts of humans on coral reefs ignoring the more remote sources of threats to reefs, notably pollution and sedimentation from the adjacent land.

"Often remote from reefs, deforestation, urban development and intensive agriculture are now producing vast quantities of sediments and pollutants which are pouring into the sea and rapidly degrading coral reefs in close proximity to many shores," says Toepfer.

Economic potential

The Atlas looks at the economic arguments for better reef management and the potential income from 15 million scuba divers worldwide. It describes a new database listing 2,500 dive centres in 91 countries. It says that diving, well planned, can add value to the reefs for local people and promote conservation. Tourism can become a force for good, giving an added value to reefs in the eyes of the local communities, and often providing a direct income, through park fees, for the management of marine protected areas.

Signs of hope

"One of the saddest facts about the demise of reefs is that it is utterly nonsensical," says Spalding. "Protecting and managing reefs is not just for the good of the fishes, in every case it also leads to economic and social benefits for local communities. We now have dozens of examples from around the world of small-scale, often community led, systems for managing reefs. These have led to massive booms in productivity and some very happy local fishermen. They stand out as clear sparks of hope which we must use to teach others the message," Spalding adds.

"The growth of mass-tourism, combined with the boom in popularity of scuba diving, has brought the plight of coral reefs to public attention across the planet," says Toepfer. "Let us all now commit ourselves to the strenuous efforts needed to respond to the crisis of declining coral reefs documented in this Atlas, and to ensure that this unique ecosystem continues to feed, protect and dazzle us and our descendants for generations to come."

  • Most of the coral reefs of the world's oceans may disappear within 30 to 50 years, according to Rupert Ormond, director of the university marine biological station at Millport in Scotland. Within 10 to 20 years, as sea temperatures rise, he forecasts "massive bleaching" of the coral. "One can predict looking at these figures that within perhaps 50 years there will be very little left of corals in coral reef countries."