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Coral reefs

Corals under threat

Assessments to late 2000 now indicate that 27% of the world's reefs have been effectively lost, with the largest single cause being the massive climate-related coral bleaching event of 1998. While there is a good chance that many of the 16% of damaged reefs will recover over time, some predict that half will never adequately recover. The latest global predictions suggest that a further 14% of the world's coral reefs will be lost by 2010, and another 18% in the 20 years following, without reductions in the current human-induced stresses on reef ecosystems from growing coastal populations and economies. This means that 59% of the world's reefs are under immediate threat of loss within several decades.

Regional status of coral reefs

Arabian/Persian Gulf region: The near-shore reefs of the Arabian/Persian Gulf were severely damaged by severe coral bleaching in 1996 and 1998, while offshore reefs were less affected. Major coral bleaching occurred in late 2000 in the northern Gulf, while Red Sea reefs remain predominantly healthy with few localized anthropogenic stresses. Rapid growth in tourism and shipping present the potential for growing physical degradation and destruction in the region.

South Asia: Most coral reefs in the region were severely affected by the extreme climate events of 1998, most significantly in the Maldives, Sri Lanka and parts of western India. These losses have added to the major human-induced damage off the mainland of India and Sri Lanka particularly from coral mining, over-fishing and land-based pollution.

Eastern Africa: Significant levels of sediment runoff, nutrient pollution and over-exploitation of reef resources from growing populations remain the largest threats to coral reefs in the region. There was a massive coral-bleaching event and subsequent coral mortality with the El Niño climate switch of 1998, with some areas losing up to 80% of live corals, particularly parts of Kenya and Tanzania.

Southern Indian Ocean: The reefs of the northern part of the region suffered damage during 1998 as a result of the El Niño event, with losses of 80 to 90% of the corals in parts of the Comoros and of the Seychelles. Coral reefs of Madagascar continue to be under very high human-induced threats.

Southern Asia: Some reefs in the region were damaged by the 1998 bleaching event, but the region is the center of a live fish trade worth over US $1 billion per year, with virtually all reefs being physically damaged or destroyed by destructive cyanide and blast fishing methods.

East Asia: The reefs of southern Japan and Taiwan were severely affected by coral bleaching and mortality during the 1998 La Niña climate switch in the region. There are many reports of coral losses of 30 to 60% with some losses as high as 80 to 90%. Some localized extinctions of prominent corals have been reported.

Australia and Papua New Guinea: Australian coral reefs continue to have the lowest levels of human-induced impacts of any continental reefs. In general, they are considered to be in good to excellent condition, although problems with sediment and nutrient run-off from land-based sources have been identified on the Great Barrier Reef. Increasing pressure from professional and recreational fishing is now being experienced and a population explosion of crown-of-thorns starfish is currently attacking offshore reefs. Most of the reefs of Papua New Guinea are in generally very good condition, except for localized areas of damage from excessive logging and increasing levels of exploitation on near shore reefs.

Micronesia: Coral reefs of Micronesia remain predominantly in good to excellent condition, although some damage from coastal development activities on the high islands and over-fishing around centers of population has been experienced. Most of the region has escaped damage from the 1997-1998 bleaching event; however, there were significant losses of coral around Palau.

Southwest Pacific: While this region escaped major bleaching in 1997-1998, it was damaged by relatively severe coral bleaching between February and April 2000 with extensive mortality in some parts of Fiji and the Solomon Islands. Human impacts on these reefs are steadily increasing but still concentrated at a few sites per country, mainly around the capital cities and in lagoons. Most reefs in the region remain in healthy condition, with some local over-fishing for subsistence and small-scale commercial activities.

Southeast Pacific: Most of the coral reefs in this region remain healthy, with few human-induced threats, concentrated around population centers and within enclosed lagoons. Considerable shoreline modification on these islands for tourism developments has resulted in damage to the near shore reefs, but the outer reefs facing the ocean show no real impacts. Fishing pressures are increasing in the region and there are increasing conflicts between fishers and tourist operators.

North-east (American) Pacific: Strong population and economic growth in the Hawaiian Islands is resulting in considerable local damage to reefs around the major population centers and tourist operations, while all coral reefs are experiencing increased fishing pressure. Collecting for the aquarium trade has caused major depletion of some species. In contrast, the scattered islands are under minimal human-induced threats and none experienced climate related bleaching in 1998.

The American Caribbean: The region is experiencing significant problems with over-fishing and physical damage to coastal nursery areas of mangrove forests and seagrass beds. The primary threats to coral reefs off Florida are pollution from agriculture and growing tourism and recreational fishing industries.

Northern Caribbean and Western Atlantic: Primary threats to coral reefs in Jamaica, Haiti and the Dominican Republic are over-fishing and pollution, while over-exploitation is less significant in Cuba, Bahamas, Turks and Caicos Islands. Reefs in Bermuda and Cayman Islands are healthy, resulting largely from the demands of the tourism industry. White-band disease has caused a reduction of Acropora spp. Reefs close to land still show low cover (e.g., coral cover in northern Jamaica dropped from 52% in the 1970s to 3% in the early 1990s, but is gradually recovering (currently 10-15%). Bleaching in 1998 was severe in places, but there was little or no mortality. Much of the tourism development based of the coral reefs is poorly planned and results in sediment run-off and nutrient pollution damaging the reefs.

Central America: Though most of the region escaped the Caribbean bleaching events in 1995 and 1998 and the intense Hurricane Mitch, also in 1998, coral reefs from the Mexican Yucatan to Nicaragua were heavily impacted, with losses in coral cover of 15 to 20% across the region with some losses as high as 75% in parts of Belize. Throughout large parts of the region there are intense fishing pressures (Honduras and Nicaragua, and Veracruz and Campeche in Mexico), and major damage to reefs from sediment runoff because of poor land-use.

The Eastern Antilles: Within the region, primary island threats are currently over-exploitation, sedimentation and nutrient pollution to near-shore coral reefs. Coral cover on some islands has dropped recently due to the passage of hurricanes and coral bleaching, with St. Lucia experiencing a decline from 50% to 25% at a depth of 3 metres and from 35% to 17% at 10 metres.

South America: Coral reefs in the region experienced significant declines in the 1980s and early 1990s due to both natural and human-induced stresses. Repeated coral bleaching episodes have resulted in cumulative mortalities, while human-induced threats from increased sediment and nutrient pollution on the near shore reefs have resulted from deforestation, poor agricultural practices and diversion of rivers. Offshore reefs are being increasingly over-exploited for fisheries, coral rock and sand, resulting in distinct declines of coral cover and fish populations.