One third of the world's reef-building species of coral have an "elevated risk of extinction," according to a report out in the latest edition of the journal Science.

The study was the first-ever comprehensive global assessment to determine the conservation status of some 845 zooxanthellate reef-building coral species.

Leading coral experts joined forces with the Global Marine Species Assessment (GMSA), a joint initiative of the International Union for Conservation of Nature (IUCN) and Conservation International (CI), to apply the IUCN Red List Categories and Criteria to this important group of marine species.

The study found that of the 704 species that could be assigned conservation status, 32.8 percent are in categories with elevated risk of extinction.

The study says that declines in abundance are associated with bleaching and diseases driven by elevated sea surface temperatures, with extinction risk further exacerbated by local man made disturbances such as destructive fishing, declining water quality from pollution, and the degradation of coastal habitats.

The report says that the proportion of corals threatened with extinction has increased dramatically in recent decades and exceeds most land-based animal specie groups.

The Caribbean has the largest proportion of corals in high extinction risk categories while the Coral Triangle (western Pacific) has the highest proportion of species in all categories of elevated extinction risk.

The reports authors say their results emphasise the widespread plight of coral reefs and the urgent need to enact conservation measures.

Kent Carpenter, the lead author of the Science article, GMSA Director, IUCN Species Programme, says the results of the study are very disconcerting.

"When corals die off, so do the other plants and animals that depend on coral reefs for food and shelter, and this can lead to the collapse of entire ecosystems," he says.

© NewsRoom 2008