国际自然保护联盟的一份报告显示，加勒比海很多地方的珊瑚礁将在未来20年内消失。

　　Healthy coral reefs have declined by about 50% in the past 40 years

　　Healthy coral reefs have declined by about 50% in the past 40 years

　　Data from more than 35,000 surveys suggests that habitats have declined by more than 50% since the 1970s.

　　The report's authors believe that over-fishing and disease is mainly to blame.

　　They say the trend could continue if nothing is done, but with protection the reefs could bounce back.

　　Carl Gustaf Lundin, director of IUCN's Global Marine and Polar Programme, said the findings were alarming.

　　"The reefs support a number of different countries and populations," he said.

　　"Tourism is one of the biggest industries, and the health of the reef is essential to the well-being of many of the people living there. And of course they are immensely beautiful and wonderful places as well."

　　The report, which was also authored by the Global Coral Reef Monitoring Network, looked at data collected between 1970 and 2012 from 90 reef habitats and is the most comprehensive assessment of corals in this region.

　　The authors concluded that many reefs in the Caribbean were undergoing a dramatic transformation - changing from colourful realms, bursting with life, to barren habitats, covered in slimy algae.

　　They said the damage had been driven by the loss of some of the reefs' key inhabitants.

　　In the 1980s, a disease, thought to have been brought in from the Panama Canal, wiped out a large number of sea urchins（海胆）. While fishing on the reefs has also caused parrotfish to plummet.

　　Both of these creatures graze on reefs, and without them, algal species take over.

　　Dr Lundin said: "We saw that reefs with no grazers ended up getting smothered by algae. And after a period of time they see a significant or even complete collapse of the reef area."

　　He said that if no action was taken, the outlook for Caribbean corals would be bleak.

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