Query: Over the last 30-40 years 80% of coral in the Caribbean have been destroyed and 50% in Indonesia and the Pacific.

Relevant passages:
2004 Indian Ocean earthquake and tsunami <=SEP=> The 2004 Indian Ocean earthquake occurred at 00:58:53 UTC on 26 December with the epicentre off the west coast of Sumatra , Indonesia . The shock had a moment magnitude of 9.1 -- 9.3 and a maximum Mercalli intensity of IX ( Violent ) . The undersea megathrust earthquake was caused when the Indian Plate was subducted by the Burma Plate and triggered a series of devastating tsunamis along the coasts of most landmasses bordering the Indian Ocean , killing 230,000 -- 280,000 people in 14 countries , and inundating coastal communities with waves up to 30 m high . It was one of the deadliest natural disasters in recorded history . Indonesia was the hardest-hit country , followed by Sri Lanka , India , and Thailand .   It is the third-largest earthquake ever recorded on a seismograph and had the longest duration of faulting ever observed , between 8.3 and 10 minutes . It caused the entire planet to vibrate as much as 1 cm and triggered other earthquakes as far away as Alaska . Its epicentre was between Simeulue and mainland Indonesia . The plight of the affected people and countries prompted a worldwide humanitarian response . In all , the worldwide community donated more than US$ 14 billion ( 2004 ) in humanitarian aid . The event is known by the scientific community as the Sumatra -- Andaman earthquake . The resulting tsunami was given various names , including the 2004 Indian Ocean tsunami , South Asian tsunami , Indonesian tsunami , the Christmas tsunami , and the Boxing Day tsunami .

Coral bleaching <=SEP=> Coral bleaching occurs when coral polyps expel algae that lives inside their tissues . Normally , coral polyps live in an endosymbiotic relationship with the algae and that relationship is crucial for the coral and hence for the health of the whole reef . Bleached corals continue to live . But as the algae provide the coral with 90 % of its energy , after expelling the algae the coral begins to starve . Above-average sea water temperatures caused by global warming have been identified as a leading cause for coral bleaching worldwide . Between 2014 and 2016 , the longest global bleaching events ever were recorded . According to the United Nations Environment Programme , these bleaching events killed coral on an unprecedented scale . In 2016 , bleaching hit 90 percent of coral on the Great Barrier Reef and killed 29 percent of the reef 's coral . In 2017 , the bleaching further expanded to areas of the park that were previously spared , such as the central one .   __ TOC __

Coral <=SEP=> Corals are marine invertebrates in the class Anthozoa of phylum Cnidaria . They typically live in compact colonies of many identical individual polyps . The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton .   A coral `` group '' is a colony of myriad genetically identical polyps . Each polyp is a sac-like animal typically only a few millimeters in diameter and a few centimeters in length . A set of tentacles surround a central mouth opening . An exoskeleton is excreted near the base . Over many generations , the colony thus creates a large skeleton that is characteristic of the species . Individual heads grow by asexual reproduction of polyps . Corals also breed sexually by spawning : polyps of the same species release gametes simultaneously over a period of one to several nights around a full moon .   Although some corals can catch small fish and plankton using stinging cells on their tentacles , most corals obtain the majority of their energy and nutrients from photosynthetic unicellular dinoflagellates in the genus Symbiodinium that live within their tissues . These are commonly known as zooxanthellae and the corals that contain them are zooxanthellate corals . Such corals require sunlight and grow in clear , shallow water , typically at depths shallower than 60 m. Corals are major contributors to the physical structure of the coral reefs that develop in tropical and subtropical waters , such as the enormous Great Barrier Reef off the coast of Queensland , Australia .   Other corals do not rely on zooxanthellae and can live in much deeper water , with the cold-water genus Lophelia surviving as deep as 3000 m . Some have been found on the Darwin Mounds , north-west of Cape Wrath , Scotland . Corals have also been found as far north as off the coast of Washington State and the Aleutian Islands .