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Southeast Asian coral reefs have the highest levels of biodiversity for the world's marine ecosystems. They serve many functions, such as forming the of livelihood for subsistence fishermen and even function as jewelry and construction materials. Coral reefs are developed by the carbonate-based skeletons of a variety of animals and algae. Slowly and overtime, the reefs build up to the surface in oceans. Coral reefs are found in shallow, warm salt water. The sunlight filters through clear water and allows microscopic organisms to live and reproduce. The Indian Ocean holds 60% of the world's coastal reefs, 25% are in the Pacific and 15% are in the western Atlantic. There are coral reefs in the Persian Gulf, Madagascar, the Philippines, Hawaiian Islands and off Southeast Asia. Coral reefs have been preserved and identified in rocks over 400 million years old. Coral reefs are actually composed of tiny, fragile animals known as coral polyps. Coral reefs are significantly important because of the biodiversity. Although the number of fish are decreasing, the remaining coral reefs contain more unique sea creatures. The variety of species living on a coral reef is greater than anywhere else in the world. An estimation of 70-90% of fish caught are dependent on coral reefs in Southeast Asia and reefs support over 25% of all known marine species.〔(【引用サイトリンク】url=http://www.ioseaturtles.org/Education/coralreefbooklet.pdf )〕 However, those sensitive coral reefs are facing detrimental effects on them due to variety of factors: overfishing, sedimentation and pollution, bleaching, and even tourist-related damage. 〔Ohandley, Cassie. "Anthropogenic Effects on Coral Reefs" June 11, 2003〕 ==Depletion== For 50 percent of Southeast Asia’s coral reefs, they are at high or very high levels of threat. Only 12 percent of the reefs are at low risk. 64 percent of the regions reefs are threatened by overfishing and 56 percent are threatened by destructive fishing techniques. Indonesia and the Philippines together possess about 77 percent of the region’s coral reefs and nearly all of those reefs are threatened. Over 90 percent of the coral reefs in Cambodia, Singapore, Taiwan, the Philippines, Vietnam, China, and the Spratly Islands are threatened and over 85 percent of reefs of Malaysia and Indonesia are threatened. Heavy reliance on marine resources resulted in overexploitation and degradation of many coral reefs, especially those near major population centers. Major threats include overfishing, destructive fishing practices, sedimentation and pollution from land based sources. Human activities threaten an estimated 88 percent of Southeast Asia’s coral reefs, jeopardizing the biological and economic value to society.〔"Key Findings and Introduction from World Resources Institute ." N.p., n.d. Web. 31 May 2011. In recent years, the direct and indirect effects of overfishing and pollution from agriculture and land development have been the major drivers of massive and accelerating decreases in abundance of coral reef species, causing widespread changes in reef ecosystems. Philippines is covered with 35,000 km² coral reefs. But 70% of them are degraded.〔 Blast fishing, also called dynamite fishing, is a major contributor to the destruction of coral reefs. Even though blast fishing was banned in 1985, it still remains a huge threat to the Indonesia coral reefs. By filling up an empty bottle with fertiliser and kerosene a fisherman can create an improvised but powerful explosive and throw it into the ocean gaining immediate access to hundreds of dead fish.〔Lu, Andrea. "Turmoil in the Sea: Blast Fishing Destroys Coral Reefs." The Daily Californian. March 30, 2005. http://www.sfgate.com/default/article/The-depths-of-destruction-Dynamite-fishing-2816512.php〕 Laws created to prevent blast fishing are poorly enforced by officials of this area, and fisherman are highly motivated to continue this practice for survival and profit. "These are not poor Third World guys trying to put food on the table, go to the villages and find the people who head the dynamite fishing cooperatives are the people with new Jeeps and new satellite dishes in their houses. This is about greed,".〔 Indonesia and the Philippines contain about 77% of the regions coral reef systems, and with 98% of the Philippine coral reefs seriously threatened by human activities, it is obvious that there needs to be serious changes to the marine practices of the communities.〔Martin, Glen. 2002. "The depths of destruction. Dynamite fishing ravages Philippines' precious coral reefs." San Francisco Chronicle. Available at: http://www.sfgate.com/cgi-bin/article.cgi?file=chronicle/archive/2002/05/30/mn232485.dtl〕 Cyanide fishing originated in the Philippines in the 1960s due to the growing market for aquarium fish in North America and Europe.〔"Cyanide Fishing: A poison tide on the reef." World Resources Institute, 1982-2005. Another major problem facing the Southeast Asian Coral Reefs is sedimentation. Sedimentation is caused by development on land and agricultural runoff. Southeast Asian countries are experiencing rapid development, leading to deforestation, and construction projects near the reefs that lead to sediment eroding and covering the corals.〔Burke, Lauretta. Reefs At Risk., 2011.〕 This reduces sunlight, and smothers the coral colonies; clogging their mouths, which killing them.〔http://coris.noaa.gov/about/what_are/〕 The nutrient rich sediment also facilitates algae growth, which can overgrow the corals. Sedimentation will continue to be a major problem as Southeast Asian economies continue to grow.〔 The Philippine waters are considered as having nearly 70% of its coral reefs destroyed with only 5% in good condition. Although this dynamite and cyanide fishing may be targeted at one specific location, it destroys the surrounding habitat as well, spreading over one kilometer upon each impact. It takes over one hundred years for these reefs to grow into substantial sizes, at a rate of one inch every five years. These poor fishing practices not only threaten the food habitats for many species, but also the biodiversity that makes these Philippine and Indonesian coasts so beautiful. Inland human activities is what mainly pressures these reefs' pristine states; from indirect activities such as the increasing demand within the fishing industry as well as directly, through coastal run-off and pollution. The coral reefs of Indonesia and the Philippines are vital to food security, employment, tourism, and medicinal research. The value of the regions sustainable coral reef fisheries alone is US$2.4 billion a year.〔World Resources Institute 2002, Key Findings〕 These countries rely on the marine resources as a means to diversify their economy. Due to unsafe fishing practices, the coral reefs in these countries are experiencing a decline. There are no pristine coral reefs left in the world. Coral reefs in these countries are headed toward becoming ecologically extinct.〔Pandolfi_et_al.2003.coral_reefs.science.pdf〕 Without the abundance of Marine resources, the Philippines and Indonesia will experience a major hit to their economy. On September 24, 2007, Reef Check (the world’s largest reef conservation organization) stated that only 5% of Philippines' 27,000 square-kilometers of coral reef are in “''excellent condition''” : Tubbataha Reef, Marine Park in Palawan, Apo Island in Negros Oriental, Apo Reef in Puerto Galera, Mindoro, and Verde Island Passage off Batangas. Philippine coral reefs is 2nd largest in Asia.〔( Abs-Cbn Interactive, ‘RP coral reefs, second largest in Asia, in bad shape’ )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Southeast Asian coral reefs」の詳細全文を読む スポンサード リンク
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