Monday, April 17, 2006

The Bleaching of the Reefs

This, a quick pick up from Yahoo.com,: from 2002:

"An epidemic of coral bleaching has hit the Great Barrier Reef in Australia, the world's largest coral reef, for the second time in four years. It is also reported to be spreading through the coral islands of the South Pacific.
"An extensive survey of the Great Barrier Reef carried out over the last month has revealed "widespread bleaching", says Terry Done, chief conservation scientist at the Australian Institute of Marine Science. The survey was prompted by concerns at the start of 2002 and the full results will be published soon, he says.
"Coral bleaching occurs when high sea temperatures force the algae that give coral its colour out of the coral polyps. Usually, bleached coral recovers in the next cool season, but if all the algae are lost, the coral will die and reefs will crumble.
"Thomas Goreau, president of the Global Coral Reef Alliance in Chappaqua, New York, says he has received reports in recent days of bleached, dead coral across much of the South Pacific, including Tahiti, the Cook Islands, New Caledonia and Fiji.
"'It will take a long time before we have full confirmation of the magnitude of the disaster," he said. "But when it is all in, I predict we will have confirmation that almost all corals across the entire South Pacific have died in the last few months.' "








Hotter and longer










There has been growing concern among marine scientists about recent reports of widespread bleaching in Australia. But so far the Great Barrier Reef Marine Park Authority has not commented and did not respond to requests from New Scientist to make a statement.









However, the park authority has received numerous reports of bleaching from scientists, tour operators and visitors. According to information on its web site "bleaching around Keppel Island is extreme, with every species suffering". Other places badly hit include Whitsunday Island and Magnetic Island to the north.









The bleaching follows record sea temperatures since the beginning of the year. "Almost all the Great Barrier Reef was 2°C or more above normal for more than two months from early January to mid-March," says Goreau. "This was hotter and longer than the bleaching that wiped out the Maldives, Seychelles and western Australian reefs in 1998."








Global warming










The high temperatures appear to be connected to the likely onset of a new El Niño, which also caused the bleaching in 1998.









But Goreau says global warming is a key underlying factor. "It means reefs are already under stress before El Niño start," he said.









Donne told New Scientist that "there has been little mortality of corals yet". But Goreau says: "Catastrophic mortality will certainly have taken place." He claims the Australian government is reluctant to discuss the extent of bleaching on the reef because of its ambivalence about action on global warming.

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