<P> Rising carbon dioxide levels could confuse brain signaling in fish . In 2012, researchers reported on their results after studying the behaviour of baby clown and damselfishes for several years in water with elevated levels of dissolved carbon dioxide, in line with what may exist by the end of the century . They found that the higher carbon dioxide disrupted a key brain receptor in the fish, interfering with neurotransmitter functions . The damaged central nervous systems affected fish behaviour and diminishing their sensory capacity to a point "likely to impair their chances of survival". The fishes were less able to locate reefs by smell or "detect the warning smell of a predator fish". Nor could they hear the sounds made by other reef fish, compromising their ability to locate safe reefs and avoid dangerous ones . They also lost their usual tendencies to turn to the left or right, damaging their ability to school with other fish . </P> <P> Disease is a serious threat to many coral species . The diseases of coral may consist of bacterial, viral, fungal, or parasitic infections . Due to many of the dramatic changes in climate and stress caused by pollution, coral become more vulnerable to diseases . Some examples of coral disease are vibrio, white syndrome, white band, rapid wasting disease, and many more . These diseases have different effects on the corals, ranging from damaging individual corals, killing individual coral, or even wiping out entire reefs . In the Caribbean, white band disease is one of the primary causes for the death of over eighty percent of Staghorn and Elkhorn coral (Reef Resilience). It is a disease that can destroy miles of coral reef fast . A disease such as white plague can spread over a coral colony by a half an inch a day . By the time the disease has fully taken over the colony, it leaves behind a dead skeleton . Dead standing coral structures are what most people see after disease has taken over a reef . </P> <P> Within the last 20 years, once - prolific seagrass meadows and mangrove forests, which absorb massive amounts of nutrients and sediment, have been destroyed . Both the loss of wetlands, mangrove habitats and seagrass meadows affect the water quality of inshore reefs . </P> <P> Coral mining is another threat . Both small scale harvesting by villagers and industrial scale mining by companies are serious threats . Mining is usually done to produce construction material which is valued as much as 50% cheaper than other rocks, such as from quarries . The rocks are ground and mixed with other materials, like cement to make concrete . Ancient coral used for construction is known as coral rag . Building directly on the reef also takes its toll, altering water circulation and the tides which bring the nutrients to the reef . The pressing reason for building on reefs is simply lack of space . </P>

What is the major cause of coral reef destruction