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Australia's Great Barrier Reef, the world's largest living organism, may be confronting a new enemy as an unknown disease spreads almost imperceptibly through its multi-hued coral. Australian Institute of Marine Science ecologist Cathie Page said on Thursday that a condition scientists are calling white syndrome was found on 33 of 48 reefs surveyed in the national marine park, one of Australia's prime tourist attractions.
The syndrome, which leaves white marks where it has killed living tissue, has increased significantly in the past year, raising the spectre of a new threat to coral already stressed by record temperatures and careless mariners. "I think it's a little bit too early to say that it's potentially devastating because we haven't seen any devastation from it yet; we've seen little bits and pieces of mortality," said Page from north-eastern Australia. "It's something that we're going to continue to monitor and hopefully understand... and hopefully it won't increase." The term white syndrome was deliberately broad, she added, because the condition could involve a number of different diseases.
RECORD TEMPERATURES BAKE CORAL
The Great Barrier Reef, which stretches over 345,400 square km (133,400 square miles) down the coast of the eastern state of Queensland, suffered the warmest seawater temperatures ever recorded last summer. Mass bleaching - which occurs when coral becomes stressed by high temperatures and its symbiotic relationship with algae breaks down and often leading to death, affected around 60 percent of the reef in early 2002. Scientists say the return this year of the El Niņo weather event, which coincides with a warming of Pacific waters, promises more destructive bleaching late this year and in early 2003.
Page said there was a possibility that the bleaching had undermined the coral's ability to resist disease, and that could be a factor leading to the increase of white syndrome. White syndrome was first detected on the Great Barrier Reef in 1993 but was not considered worth monitoring until 1999, Page said. Between 2001 and 2002, surveys found that its prevalence increased to 33 reef structures from 7, out of 48 being monitored for environmental degradation. In most reefs, it is limited to a few coral colonies, and divers marvelling at the marine life might not even notice it. But on outer shelf reefs the syndrome was found to be widespread. Page said the disease's microbiology was being analysed but did not appear to be similar to syndromes afflicting coral in the Caribbean or the Western Atlantic. One thing did appear to be clear. The condition was unlikely to be related to coastal or marine pollution as its prevalence was higher in the outer rim of the Great Barrier Reef where the environment was pristine. "It's something to keep an eye on," Page said.
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