The Coral Triangle is a geographical term so named as it refers to a roughly triangular area of the tropical marine waters of Indonesia, Malaysia, Papua New Guinea, Philippines, Solomon Islands and Timor-Leste that contain at least 500 species of reef-building corals in each ecoregion. This region encompasses portions of two biogeographic regions: the Indonesian-Philippines Region, and the Far Southwestern Pacific Region.  The Coral Triangle is recognized as the global centre of marine biodiversity and a global priority for conservation. It also called the "Amazon of the seas" and covers 5.7 million square kilometers of ocean waters. Its biological resources sustain the lives of over 120 million people.
More than 3,000 species of fish live in the Coral Triangle, including the largest fish - the whale shark, and the coelacanth. It also provides habitat to six out of the world's seven marine turtle species.
The large area and extraordinary range of habitats and environmental conditions have played a major role in maintaining the staggering biodiversity of the Coral Triangle.
Table coral Acropora latistella
Christmas tree worms (Spirobranchus giganteus)
Anemonefish (Amphiprion ocellaris)
The biodiversity and natural productivity of the Coral Triangle are under threat from poor marine management (including coastal development, and overfishing and destructive fishing), lack of political will, poverty, a high market demand and local disregard for rare and threatened species, and climate change. An estimated 120 million people live within the Coral Triangle, of which approximately 2.25 million are fishers who depend on healthy seas to make a living. These threats are putting at risk livelihoods, economies and future market supplies for species such as tuna. Studies have highlighted the alarming decline of coral cover in this region.
The Coral Triangle is the subject of high-level conservation efforts by the region's governments, nature conservation organizations such as World Wide Fund for Nature, The Nature Conservancy and Conservation International, and donor agencies such as the Asian Development Bank, the Global Environment Facility and USAID.
The primary criteria used to delineate the Coral Triangle were:
- High species biodiversity (more than 500 coral species, high biodiversity of reef fishes, foraminifera, fungid corals, and stomatopods) and habitat diversity
- Oceanography (currents)
There is considerable overlap between the boundaries of the Coral Triangle that are based primarily on high coral biodiversity (more than 500 species), and the boundaries based on the area of greatest biodiversity for coral reef fishes.
- Veron et al. Unpublished data
- Veron, J.E.N. 1995. Corals in space and time: biogeography and evolution of the Scleractinia. UNSW Press, Sydney, Australia: xiii + 321 pp.
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- Briggs, J. C. 2005a. The marine East Indies: diversity and speciation. Journal of Biogeography 32: 1517-1522
- WWF Coral Triangle Program
- The Nature Conservancy. Coral Triangle Facts, Figures, and Calculations: Part II: Patterns of Biodiversity and Endemism, December 16, 2008
- http://www.panda.org/what_we_do/where_we_work/coraltriangle/problems/ WWF - Problems in the Coral Triangle
- Peñaflor et al. 2009. Sea-surface temperature and thermal stress in the Coral Triangle over the past two decades. Coral Reefs 28:4. pp 841-850
- The Nature Conservancy. 2004. Delineating the Coral Triangle, its ecoregions and functional seascapes. Report on an expert workshop, held at the Southeast Asia Center for Marine Protected Areas, Bali, Indonesia, (April 30 - May 2, 2003), Version 1.1 (June 2004)
- Hoeksema BW. 2007.Delineation of the Indo-Malayan Centre of Maximum Marine Biodiversity: The Coral Triangle. In: W. Renema (ed.) Biogeography, Time and Place: Distributions, Barriers and Islands, pp 117-178. Springer, Dordrecht.
- Coral Triangle Initiative, main site
- Coral Triangle Photo Expedition Blog
- The Nature Conservancy - Coral Triangle Center
- WWF Coral Triangle Programme - international website
- WWF Coral Triangle Programme - US website
- The biodiversity in the coral triangle of Indonesia | Why could develop so many species in Indonesia? (engl.)