The Coral Triangle covers areas within six countries – Indonesia, Philippines, Malaysia, Solomon Islands, Papua New Guinea and Timor-Leste¹. It is shaped like a triangle because scientists have identified that these are the boundaries that delineate the epicenter of marine biodiversity on Planet Earth!
Why is the Coral Triangle (CT) Important?
  • It is home to a phenomenal 76 percent of the world’s coral species and 37 percent of the world’s reef fish species.
  • It directly sustains the livelihoods of over 126 million people.
  • It is one of the most important reproductive areas for the multi-billion dollar tuna industry, which feeds millions of people. Commercially important species such as yellowfin, skipjack and bigeye tuna all come from the region.
  • Reefs that are excellent condition in the region are estimated to be able to produce up to 40 metric tons of fish per year. ²
  • It hosts six of the world’s seven marine turtle species.
  • It supports a growing nature-based tourism industry, valued at over US$ 12 billion per year.
  • The value of just a 1km stretch of coral reef in the region can be as high as US$1.2 million, considering the goods and ecosystem services it provides.
  • Occupying less than one quarter of 1% of the marine environment, coral reefs are home to more than 25% of all known marine fish species
  • Stretching over thousands of kilometers the region provides critical migration and feeding routes for whales and other cetaceans (including the father of the ocean – the Blue Whale).
  • The Coral Triangle is the engine of the worlds’ oceans – producing larvae and species that migrate and re-stock other areas of the planet.
  • Oceans provide around 50% of the oxygen we breathe, primarily through phytoplankton living in the water. Therefore life in our oceans is critical. Our very survival is dependent on the Coral Triangle’s survival.
What are the threats facing the Coral Triangle?
  • Overfishing and destructive fishing: Nearly 85 percent of reefs are threatened by overfishing and/or destructive fishing, with 50 percent considered highly threatened. Destructive fishing alone threatens nearly 60 percent of the region’s reefs.
  • Coastal development: Development along the coast threatens more than 30 percent of the Coral Triangle Region’s reefs, with more than 15 percent of reefs under high threat. Threat is particularly high in the Philippines, where dense coastal populations and development threaten more than half of reefs.
  • Plastic pollution waste: Plastic that pollutes our oceans and waterways has severe impacts on our environment and our economy. Seabirds, whales, sea turtles and other marine life are eating marine plastic pollution and dying from choking, intestinal blockage and starvation. As plastic waste breaks down and becomes ‘microplastics’ they are ingested and incorporated into the bodies and tissues of many marine animals, ultimately killing them. And where fish who have consumed microplastics are caught for seafood, then humans in turn eat these microplastics.
  • Watershed-based pollution: More than 45 percent of the Coral Triangle Region’s reefs are threatened by watershed-based sediment and pollution, with more than 15 percent considered to be highly threatened. This threat is particularly high in much of the Philippines, central Indonesia, Timor-Leste, and parts of Solomon Islands.
  • Marine-based pollution and direct damage: Marine-based sources of pollution and damage threaten an estimated 4 percent of reefs across the Coral Triangle Region (though the extent of coral mining is unknown, so this figure is likely to be much higher). For shipping related pollution, the pressure is widely dispersed, emanating from ports and widely distributed shipping lanes.
  • Sea level rise: Coral reefs face a range of pressures through sea-level rise. They face challenges keeping their growth up with the rising sea levels (as they need sunlight to live). In addition to this, increased sediment dumping caused by the sea’s encroachment on land smothers and kills reefs, inundating and eroding coastal habitats, such as mangroves and turtle nesting beaches.
  • Thermal stress and bleaching: As sea temperatures fluctuate more widely through climate change, coral reefs exposed to high temperatures can experience thermal stress, which leads to a phenomenon known as bleaching. Assuming that greenhouse gas emissions continue on current trajectories (i.e. a “business-as-usual” emissions scenario) the World Resource Institute projections suggest that more than more than 95 percent of reefs in the Coral will experience thermal stress sufficient to induce severe bleaching by the 2050’s.
  • Ocean acidification: About 30 percent of the carbon dioxide emitted by human activities is absorbed into the surface layers of the oceans, where it reacts with water to form carbonic acid. This acid threatens all creatures with carbonate based exoskeletons, including reefs, effectively dissolving them, resulting in death. The best available data suggests that on a global scale by 2050 fewer than 15 percent of the world’s reefs will be in areas where the ocean will not be too acidic for growth.
How is CTC doing to address these threats?

We work with guardians of the seas across the Coral Triangle to, together, implement solutions to the challenges being faced throughout the region. Our CTC Academy provides a range of training courses on a range of marine and coastal management topics for a wide variety of practitioners: from government staff to community groups, private sector industries to tourism operators. Our field learning sites showcase effective on-ground management of marine and coastal systems, providing a platform for field based learning of best practices. Our learning networks link people across the region, to share ideas, experiences and solutions. Our regional Hub brings all of this information to the world and drives changes in our societies. It is a learning center where everybody – from conservation practitioners to schoolchildren, industry leaders to tourists – can learn about the challenges the region is facing, and their own role in implementing the solutions that exist.

Part of our work focuses on the establishment of effectively managed Marine Protected Areas (MPAs) throughout the region. Designed, developed and managed effectively, these areas offer critical sanctuaries for reef ecosystems and marine species. Established in appropriate locations, MPAs can prove resilient and resistant to the challenges facing the regions seas, and provide stepping stones that interlink ecosystems, to ensure that they can remain robust in the face of such a myriad of threats.

How can you help?
We need your support to do our work. You can help by becoming a Friend of CTC, or by making a donation to our programs.
You can also start your own fundraising campaign to support our work.
You can join our facebook page, and subscribe to our newsletter. Tell your friends, and help spread the word about the importance of this region.
At home, you can minimize the waste you produce – ensure you recycle all your plastics (and reduce your purchase of them), and never buy products that contain ‘microplastics’ (look for the names in the labels of your toothpaste, facewash and other toiletries, and avoid them: Polyethylene / Polythene (PE), Polypropylene (PP), Polyethylene terephthalate (PET), Polymethyl methacrylate (PMMA).
You can also be savvy in your purchases of seafood. Choose only sustainably caught species. You can learn more on this topic through the marine stewardship councils website:
Be climate conscious – use energy efficient products in the home, and be aware of your own carbon footprint on the planet.
If there is a Marine Protected Area near where you live, you can explore volunteer opportunities with them to support their work.
We also sometimes have volunteer or internship opportunities here at CTC. Click here to learn more.
¹ This may soon expand to seven countries, to include Brunei.
² That means that if all the reefs in the Coral Triangle were in ‘excellent’ condition, the fish and seafood production could feed billions of people and eradicate poverty in Asia.
Coral Triangle Center

Growing coastal populations in the region and increasing demands for seafood from international markets has significantly impacted fish stocks. Heavily fished reefs are left with mostly small fish and are prone to algal overgrowth due to the absence of larger herbivores to graze the algae. Overfished reefs also appear to be generally less resilient to stressors, more vulnerable to disease, and slower to recover from other human impacts. Destructive fishing methods, such as the use of explosives to kill fish, often destroy coral reefs in the process. Although illegal in many countries, blast (or dynamite) fishing remains a persistent threat in the Coral Triangle. Poison fishing is also destructive to corals. This practice typically involves using cyanide to stun and capture fish alive for the lucrative live reef food fish or aquarium fish trades. The poison kills corals. Fishers also often break corals to extract the stunned fish, while other species in the vicinity are killed or left vulnerable to predation.


Fishing is not only for food fish, but also to supply the ever growing ornamental fish industry. Aquarium keeping is a popular hobby for millions of enthusiasts worldwide. Together all countries of the European Union are the largest market for ornamental fish; however, the United States is the single largest importer of ornamental fish in the world. Although exact figures on the value and trade of the ornamental fish industry do not exist, the aquarium trade has been estimated to value between $278 million US dollars (FAO 1996-2005) and $1 billion USD annually. The fish are predominantly wild caught, with the majority of fish and other species coming from SE Asia. There is also a popular and rapidly expanding trend in the hobby to establish marine reef mini-ecosystems within the aquarium, using live hard and soft corals, invertebrates such as crustaceans (e.g., crabs, hermit crabs, and shrimps), mollusks (e.g., snails, clams, and scallops), echinoderms (e.g., starfish, sand-dollars, and sea urchins), and of course, the endless variety of colorful fish.

Development in the coastal zone—linked to human settlements, industry, aquaculture, or infrastructure—can have profound effects on nearshore ecosystems. Impacts of coastal development on the reef can occur either through direct physical damage such as dredging or land filling, or indirectly through increased runoff of sediment, pollution, and sewage.

Garbage thrown into the ocean / ending up in the ocean from river run off etc is particularly destructive. Huge amounts of plastic is entering our oceans today. In 2010 alone scientists estimated that between 4.8 and 12.7 million metric tons (that's about 10.5 billion to 28 billion pounds) of plastic entered the oceans (in that year alone). This kind of pollution not only destroys the marine and coastal ecosystem, but has huge costs for taxpayers and local governments that must clean this trash off of beaches to protect public health, prevent flooding from trash-blocked storm drains, and avoid lost tourism revenue from filthy beaches.


This is a global problem, but here in the Coral Triangle, it is critical that nations address the problem of plastic pollution. A recent study (released 2015) listed the worst country offenders of plastic pollution in the oceans, and two of the Coral Triangle Countries (Indonesia and Philippines) are at the top of that list!!


Plastic takes a very long time to breakdown, but when it does, it becomes “microplastics”. These are small plastic particles in the environment that are generally between 1 and 5 mm and persist for many decades, possibly forever. In addition to microplastics coming from plastics being broken down, some manufacturers purposefully make and include microplastics in products – such as toothpaste and face washes with microplastic beads for exfoliation etc. UNESCO estimated in 2008 that about 245 metric tons of microplastics are produced per year, with many of those products ending up in water and ultimately going into the ocean.

Human activities far inland can impact coastal waters and coral reefs. As forests are cut or pastures plowed, erosion adds sediment to rivers. In the Coral Triangle Region, where land clearing and cultivation frequently occur on steep slopes and in places with heavy rainfall, this effect is even more pronounced. Runoff of fertilizers and pesticides also flow via rivers to reefs. Livestock can compound these problems through overgrazing or runoff of livestock waste. Once they reach the coast, sediments, nutrients, and pollutants disperse into adjacent waters. Mangroves and seagrass beds, which can help to trap sediments and remove nutrients from the water, can reduce these impacts on reefs.

Commercial, recreational, and passenger vessels can threaten reefs with contaminated bilge water, fuel leakages, raw sewage, solid waste, and invasive species. In addition, reefs are exposed to more direct physical damage from groundings, anchors, and oil spills.


Coral quarrying and mining is also carried out throughout the coral triangle region. Hard corals are mined primarily for local traditional construction (to make bricks, or broken up to make limestone and sand for cement), but in recent years corals are being increasingly mined for: the pharmaceutical industry (to go into calcium supplements); to make jewelry and souvenirs; harvested live for the aquarium trade; and harvested for medical research.


Finally, with increasing numbers of tourists visiting the region (Indonesia tourist numbers have nearly doubled in the last 7 years alone), reefs are being put under greater threat from careless tourists walking across reef flats at low tide, or kicking / breaking corals whilst snorkeling or diving.

Over the last half century, the global average sea level rose by about 2-3 mm per year. This has been caused by increases of pollutants such as carbon dioxide entering the atmosphere, leading to increased global temperatures. These increased temperatures are in turn are melting the ice-caps and causing ocean expansion, which leads to seas around the world rising. Scientists suggest that the overall net vertical growth rate of reefs (i.e. how quickly they can grow upwards to keep pace with rising seas) may be much slower than the growth of individual coral colonies, thus reducing corals’ ability to keep pace with sea-level rise. Sea-level rise is also likely to increase sedimentary processes due to shoreline erosion, which will pull more sediment from the land and dump it onto the reef as the sea starts to encroach on land. Such sediment dumping could smother reefs or reduce sunlight needed for their partner zooxanthellae’s photosynthesis. Even small increases in sea level (e.g., 0.2 m) can increase turbidity (churning up and sediment) on fringing reefs.


People in coastal regions of Asia, particularly those living in cities, could face some of the worst effects of sea level rise. Hundreds of millions of people are likely to lose their homes as flooding, famine and rising sea levels sweep the region, one of the most vulnerable on Earth to the impact of global warming. According to scientists, hundreds of millions of people around the world will be affected by coastal flooding and land loss if global temperatures rise as predicted, and the majority of these losses will be in east, south-east and south Asia.

As temperatures on the planet grow, so too do temperatures in the ocean. Warming seas have caused widespread damage to reefs through mass coral bleaching, which occurs when corals become stressed and lose, en masse, the zooxanthellae that normally live within their tissues and provide the coral with food. These zooxanthellae are what give the coral color; therefore when lost, the corals all turn white (thus the term ‘bleaching’). Corals can sometimes survive without zooxanthellae for up to two weeks; but if temperatures remain such that the zooxanthellae don’t return in time, the corals will die.


Mapping of past thermal stress from 1998–2007 suggests that almost 40 percent of coral reefs have experienced water temperatures warm enough to induce severe coral bleaching on at least one occasion since 1998. Mass coral bleaching is also becoming more frequent, more intense, and more widespread as higher temperatures recur. Assuming that greenhouse gas emissions continue on current trajectories (i.e. a “business-as-usual” emissions scenario) the World Resource Institute projections suggest that more than 80 percent of reefs in the Coral will experience thermal stress sufficient to induce severe bleaching in at least five out of ten years during the 2030s. By the 2050s, this percentage is expected to grow to more than 95 percent for both the Coral Triangle Region and the world.

The production of carbonic acid in the oceans caused by the absorption of carbon dioxide has profound effects on the chemical composition of seawater, especially on the availability and solubility of mineral compounds such as calcite and aragonite, which corals and other organisms need to build their skeletons. Initially these changes to ocean chemistry are expected to slow the growth of corals, and may weaken their skeletons. Continued acidification will eventually halt all coral growth and begin to drive a slow dissolution of carbonate structures such as reefs. In other words, coral skeletons will be acid –dissolved and unable to survive. And of course this acidification is not only affecting corals – all marine species with carbonate based structures (i.e. all shellfish, crabs, crustaceans etc) will effectively experience a melting of their shells, resulting in death and loss. It is difficult to project specific impacts from this threat, as it is slow and pervasive. However, the best available data suggests that on a global scale by 2030, fewer than half of the world’s reefs will be in areas where aragonite levels are adequate for coral growth (i.e. the rest of the ocean will be too acidic for growth). By 2050, only about 15 percent of reefs will be in areas where aragonite levels are adequate for growth. The reefs of the Coral Triangle Region are particularly sensitive to climate change because of the extent to which they are already threatened by local stressors.

A coral reefs’ resilience refers to the ability of reef colonies to bounce back and recover after damage has occurred. Resilience can be promoted when at least some of the threats facing the system are removed. Threats compound together to weaken the integrity of a system, therefore where a reef may cope with some degree of one particular threat, it faces challenges coping with this threat if other threats are also present. For example, a reef can prove more resilient to bleaching (i.e. it has the capacity to recover) when it is not experiencing other threats such as a destructive fishing.

A coral reefs resistance refers to the level at which reef colonies are strong enough to resist getting damaged in the first place. Resistance in a system may be integral to a particular area or ecosystem. For example, reef systems located in areas where the underwater topography means that deep, cooler water regularly washes over the reef may be naturally more resilient to bleaching events, as cooler water counteracts the thermal stress being encountered in the shallows. Reefs can also become more resistant in the face of threats when those threats are not compounded: i.e. when one or more threats are removed from a system.

In this context MPAs established at appropriate locations and networked to link together across ocean current systems can enable a ‘stepping stone’ effect to occur. This is when marine species (and larvae of species such as coral) leave a secure area such as an MPA, and face numerous threats in the marine and coastal system. Linked and networked MPAs provide refuges, stopping points, ensuring survival of sufficient individuals to maintain a robust, interconnected ecosystem.

An ecosystem is a complex set of relationships among the living resources, habitats and residents of an area. Ecosystems can vary greatly in size, but each is a functioning unit of nature. A coral reef is a good example of an ecosystem. Everything that lives in an ecosystem is dependent on other species and elements that are also part of that ecological community. If one part of an ecosystem is damaged or disappears, it has an impact on everything else. When an ecosystem is ‘sustainable’ it means that all the elements are in balance and are capable of reproducing themselves successfully and maintaining life.