<P> The most prevalent coral in the reefs of Belize in 1998 was the lettuce coral, Agaricia tenuifolia . On 22 and 23 October, surveys were conducted at two sites and the findings were devastating . Virtually all the living coral was bleached white and their skeletons indicated that they had died recently . At the lagoon floor, complete bleaching was evident among Agaricia tenuifolia . Furthermore, surveys done in 1999 and 2000 showed a near total mortality of Agaricia tenuifolia at all depths . Similar patterns occurred in other coral species as well . Measurements on water turbidity suggest that these mortalities were attributed to rising water temperatures rather than solar radiation . </P> <P> Since 1970 the coral reef cover in the Caribbean has decreased from 50% to only 10% . In 2013 there was a study done to see how the coral was doing after the mass bleaching event in 2010 . Only one year later in 2011, the majority of the dominant species declined by about 62% . As well as the dominant species the coral abundance declined by about 50% . However, between 2011 and 2013 the cover of coral did increase for 10 of the 26 dominant species but declined for 5 other populations (Buglass, et al. 2016). </P> <P> Coral in the south Red Sea does not bleach despite summer water temperatures up to 34 ° C (93 ° F). Coral bleaching in the Red Sea is more common in the northern section of the reefs, the southern part of the reef has been plagued by coral eating starfish, dynamite fishing and human impacts on the environment . In 1988 there was a massive bleaching event that affected the reefs in Saudi Arabia and in Sudan, the southern reefs were more resilient and affected them very little . Previously it was thought that the North suffers more from coral bleaching but they show a fast turnover of coral and the southern reef was thought to not suffer from bleaching as harshly, they show more consistency . However, new research shows where the south reef should be bigger and healthier than the north it was not . This is believed to be because of major disturbances in recent history from bleaching events, and coral eating starfish . In 2010, coral bleaching occurred in Saudi Arabia and Sudan, where the temperature rose 10 to 11 degrees . Certain taxa experienced 80% to 100% of their colonies bleaching, while some showed on average 20% of that taxa bleaching . </P> <P> According to Brian Skoloff of The Christian Science Monitor, "If the reefs vanished, experts say, hunger, poverty and political instability could ensue ." Since countless sea life depend on the reefs for shelter and protection from predators, the extinction of the reefs would ultimately create a domino effect that would trickle down to the many human societies that depend on those fish for food and livelihood . There has been a 44% decline over the last 20 years in the Florida Keys, and up to 80% in the Caribbean alone . </P>

What are the main causes of coral bleaching