A report presented at the International Coral Reef Symposium has found three quarters of the world's reefs are threatened by climate change, pollution and over fishing.
The report by the World Resources Institute, an environmental think tank, says Fiji, Indonesia, Kiribati, the Philippines and Vanuatu make up five of nine countries most vulnerable to reef degradation.
The report found a higher proportion reefs are threatened in the coral triangle region in South East Asia and the Western Pacific, which has the greatest variety of fish and coral species on earth.
In the triangle 85 percent of reefs are threatened and 45 percent are at high or very high threat levels.
The institute says all reefs are threatened by ocean acidification and temperature rises due to climate change.
However it says coral should be able to resist these impacts without additional stresses from overfishing and pollution.