Coral reefs are dying around the Indian Ocean and Southeast Asia at rates that may be the worst ever recorded, scientists said this week.

Death rates as high as 80 percent have been recorded for some species, according to the study performed by the ARC Centre of Excellence for Coral Reef Studies and James Cook University.

“It is certainly the worst coral die-off we have seen since 1998. It may prove to be the worst such event known to science,” said Andrew Baird, a principal research fellow for James Cook University in Australia.

The coral bleaching extends from the Seychelles in the middle of the Indian Ocean to the Philippines in Southeast Asia and encompasses much of the Coral Triangle, an area scientists refer to as the “Amazon rainforest of the seas” or the most diverse marine ecosystem on Earth.

A mass of abnormally hot water which moved into the Indian Ocean several months ago is behind the bleaching, according to the ARC report. The hot water caused the corals to shed microscopic algae which help nourish them. The algae also give color to the corals, so when the algae are gone, the corals starve and appear white or bleached.

Dive operators reported water temperatures were 4 degrees Centigrade higher than average during the die-off, according to the ARC report.

The scientists said coral coverage in the affected areas could drop from 50 percent to 10 percent, hurting fishing and tourist industries over the long term as dead reefs support less marine life than live ones. And with that loss of diversity, they attract fewer fishermen and fewer divers.

“While it may take up to two years for some fish species to be affected by the loss of coral habitat, fisheries yields will decline and this combined with a drop in the number of scuba divers visiting could have major long-term effects on the local economy,” Baird said in a statement.

Baird blamed “human-induced global warming” for the decline of the corals and said action must be taken to reduce carbon emissions that help retain heat in the atmosphere.

“This is not just about warmer temperatures: it is also threatening the livelihoods of tens of millions of people and potentially the stability of our region,” Baird said in a statement.