A Worldwatch Addendum.
AS OF LATE 2000, AN ESTIMATED 27 percent of the world's coral reefs were severely damaged, according to the Global Coral Reef Monitoring Network. In 1992, the figure was only 10 percent, so the health of reefs is deteriorating quickly. The greatest losses have occurred in the Indian Ocean, in the Arabian Sea and Persian Gulf, and in Southeast Asia. (See table, opposite.)
More than 100 countries--many of them small islands--rely on coral reefs for essential goods and services valued at some $375 billion a year. Reefs shelter coastlines from storm damage, erosion, and flooding, providing protection and other benefits for an estimated half-billion people. They are important feeding and breeding grounds for commercial fisheries, producing roughly a tenth of the global fish catch and a quarter of the catch in the developing world. Reefs also generate significant tourism revenue, with Caribbean reefs alone bringing in some $140 billion annually.
Coral reefs cover less than 0.2 percent of ocean area, but are among Earth's most complex and productive ecosystems. The unique assemblages of tiny coral animals and symbiotic plants provide habitat for as many as 1 million species-including more than a quarter of known marine fish species. Reef-derived molecules have been used to develop medicines from antibiotics to HIV drugs.
An estimated 11 percent of the world's coral reefs have been lost as a result of direct human pressures. These include fishing and coral mining, coastal development, waste dumping vessel collisions, and inland deforestation and farming, which can cause runoff of \ harmful nutrients and sediments. Such activities now threaten nearly 60 percent of all reefs.
The booming demand for reef species for food and for aquariums has depopulated many coral ecosystems. In Southeast Asia, live reef fish exports jumped nearly 13-fold between 1989 and 1995, then dropped 22 percent in 1996-a crash attributed to overfishing. Worldwide, a survey of reefs in some 40 countries in 1998 found that many high-value species, such as lobster, grouper, and giant clams, were missing from areas where they were once abundant.
Fishers often use methods that are highly destructive to reefs. In Southeast Asia, "blast" fishers set off as many as 10 separate explosions to obtain 1 ton of fish, shattering up to 20 square meters of reef per blast. This practice has degraded an estimated 75 percent of Indonesia's reefs. And in the Philippines, more than a million kilograms of cyanide have been injected into reefs since the 1960s-a procedure that stuns or kills many nontarget species as well. Powerful trawlers can also devastate reefs, removing up to a quarter of seabed life in a single pass.
But the greatest threat to coral reefs today is global warming. Reefs live at the upper edge of their temperature tolerance, making them good indicators of climate change. Warming of a little as 1 degree Celsius above normal can stress the microscopic plants that inhabit the tissue of corals and provide them with food and color. If the stress endures, the corals expel the plants and turn white, often eventually dying.
Such "coral bleaching" events have increased in frequency and intensity since the early 1980s. In 1997-98, a combination of El Nino/La Nina-related climatic changes and record-high tropical sea surface temperatures caused the worst episode on record, affecting some 16 percent of the world's reefs, in at least 60 countries. Indian Ocean reefs alone suffered damages estimated as high as $8.2 billion. In some areas, 1,000-year-old corals died and losses neared 90 percent, at depths nearing 40 meters.
About a third of the bleached reefs show early signs of recovery, having retained or recruited enough live coral to survive. Roughly half could rebound in the next 20-50 years--if ocean temperatures remain steady and human pressures are low. But if the warming continues, scientists predict that as many as 60 percent of all reefs could be lost by 2030. Mass bleaching events could begin to occur annually by then, offsetting any real reef recovery. Moreover, some corals may already have exceeded their capacity to adapt to warmer waters, and rising ocean carbon dioxide levels could further impede coral growth.
As reef loss worsens, partnerships like the International Coral Reef Initiative, the International Coral Reef Action Network, and the Coral Reef Alliance are working to raise awareness, promote conservation, and assess threats. Another global project, Reef Check, enlists sport divers and locals to conduct annual reef surveys.
Innovative strategies are also emerging in developing countries, which typically lack the resources for effective reef protection. In Bonaire, a $10 dive tax brings in $170,000 annually, helping to pay for rangers and educational materials. And in one Indonesian park, a new reef patrol has helped reduce blast fishing by 80 percent since 1996.
Another key solution is creating marine reserves where activities like fishing and anchoring are banned. The United States plans to protect a fifth of its reefs in such reserves by 2010. But such actions may prove futile without parallel efforts to reduce emissions of climate-altering greenhouse gases.
Reprinted from the Worldwatch Institute annual Vital Signs 2001 (New York: W.W. Norton & Company, 2001) available late May, 2001.
Status of Coral Reefs Around the World Location Share Destroyed (percent) Southeast and East Asia 34 (30 percent of total reef area) Pacific Ocean 4 in Australia (25 percent) and Papua New Guinea; 9 in rest of Pacific Indian Ocean 59 (24 percent) Caribbean Sea and Atlantic Ocean 22 (15 percent) Middle East 35 (6 percent) Location Condition of Reefs Southeast and East Asia Reefs in southern Japan, Taiwan, (30 percent of total reef area) Vietnam, and parts of the Philippines and Indonesia hit hard by the 1998 bleaching, with losses of 30-90 percent in areas. Remote reefs have a fair chance for slow recovery. Others face serious human pressures: Indonesia, home to 14 percent of the world's reefs, has lost roughly half its reefs, mainly to blast and cyanide fishing. Pacific Ocean Reefs generally in good condition. (25 percent) Palau and inshore areas of the Great Barrier Central and Southeast Pacific reefs largely escaped this event. In early 2000, bleaching in the Solomon Islands and Fiji affected some 65 percent of Fiji's reefs, killing at least 15 percent. Other threats include development, sediment and nutrient runoff, over- fishing, and predation by crown-of- throns starfish. Indian Ocean The 1998 bleaching caused wide- (24 percent) spread damage, particularly in the Maladives, Sri Lanka, and parts of western India. Reefs off Kenya, the Sychelles, Tanzania, and Comoros saw live coral losses of 80-90 percent. Also serious damage from pollution, coral mining, and over- fishing. Reefs not affected by human pressures have a fair chance for recovery--with some early evidence of this in East Africa, the Seychelles, the Maldives, and the Lakshadweep Islands. Caribbean Sea and Atlantic Ocean Caribbean reefs experienced (15 percent) extensive bleaching in 1998, but many have shown near full recovery. Greatest threats are from over- fishing, sedimentation, pollution, and coral disease. In the Florida Keys, live coral now covers only 5 percent of the surface area of the largest reef, down from over 50 percent in 1975. Reefs off Central America suffered mass bleaching in 1995 and 1998, as well as damage from Hurricane Mitch in 1998. Middle East Nearshore reefs in the Arabian Sea (6 percent) and Persian Gulf virtually wiped out by bleaching in 1996 and 1998. Low chance of short-term recovery. Nothern Gulf affected by bleaching in late 2000. Red Sea reefs remain healthy, but are threatened by tourism, oil development, and shipping. Source: Conservation Biology (October 5, 2000); Environmental News Network (April 26, 2000); Environmental News Service (October 27, 2000); Nature (May 4, 2000); Reef Relief (www.reefrelief.org, December 12, 2000); Science (May 12, 2000); and other sources complied by Worldwatch.
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|Title Annotation:||includes table Status of Coral Reefs Around the World; coral reef damage|
|Article Type:||Statistical Data Included|
|Date:||May 1, 2001|
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