Tuesday, March 14, 2006

Ghostly coral bleachings haunt the world's reefs

By Michael Perry

SYDNEY (Reuters) - When marine scientist Ray Berkelmans went diving at Australia's Great Barrier Reef earlier this year, what he discovered shocked him -- a graveyard of coral stretching as far as he could see.

"It's a white desert out there," Berkelmans told Reuters in early March after returning from a dive to survey bleaching -- signs of a mass death of corals caused by a sudden rise in ocean temperatures -- around the Keppel Islands.

Australia has just experienced its warmest year on record and abnormally high sea temperatures during summer have caused massive coral bleaching in the Keppels. Sea temperatures touched 29 degrees Celsius (84 Fahrenheit), the upper limit for coral.

High temperatures are also a condition for the formation of hurricanes, such as Katrina which hit New Orleans in 2005.

"My estimate is in the vicinity of 95 to 98 percent of the coral is bleached in the Keppels," said Berkelmans from the Australian Institute of Marine Science.

Marine scientists say another global bleaching episode cannot be ruled out, citing major bleaching in the Caribbean in the 2005 northern hemisphere summer, which coincided with one of the 20 warmest years on record in the United States.

"In 2002, it would appear the Great Barrier Reef went first and then the global bleaching followed six to 12 months later. Is it the same this time around? No," said Berkelmans.

"The Caribbean beat us to it. We seem to be riding on the back of that event. We don't know what is ahead in six months for the Indian Ocean reefs as they head into their summer."

"This might be part of a global pattern where the warm waters continue to get warmer."

Other threats to coral reefs -- vast ecosystems often called the nurseries of the seas -- include pollution, over-fishing, coastal development and diseases.

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