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solonavi 14 December 2007 Coral Reefs 118 views No Comment Print This Post  Email This Post

MSNBC

John Bruno isn’t attending the U.N. climate talks being held in Bali, Indonesia, but he does have some advice for any delegates looking to take in the resort’s famed reefs: enjoy it now, because if sea temperatures continue to rise, expect to see more — and more severe — disease outbreaks that wipe out corals.

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One study found that coral coverage in the Indo-Pacific — an area stretching from Indonesia’s Sumatra island to French Polynesia — dropped 20 percent in the past two decades. That rate is much higher than Bruno’s team had expected.

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Bruno suspected warming ocean temperatures were playing a big role and the second study — which focused on the Great Barrier Reef — provided a strong connection.

That study compared new sea temperature data to six years of reef health surveys. The team found a strong correlation between white syndrome, a potentially fatal disease, and warmer waters.

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Unusually warm waters can also cause coral “bleaching,” where microscopic algae that live within the corals’ tissue and provide it with most of its nutrition are literally expelled. In the most severe cases, that literally kills entire coral colonies.

Even before any warming impact, reefs have long been stressed by runoff from farms, human sewage and fishing practices — including the use of dynamite to stun and then capture reef fish for the aquarium trade.

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He and other experts fear that another third could be gone in 30 years.

For Bruno, coral reefs don’t get the credit they deserve. He compares them to forests in that both create a complex ecosystem that is home to thousands of associated plants and animals.

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Besides any help that governments might provide, Mother Nature herself appears to have some tools to protect at least some coral species.

A December 2007 study by the Wildlife Conservation Society found that corals in “tough love” seas with wide-ranging temperatures are more likely to survive warming waters than corals in what had been stable environments.

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The study examined temperature variations and coral bleaching events off East Africa from 1998 to 2005.“The findings are encouraging in the fact that at least some corals and reef locations will survive the warmer surface temperatures to come,” added McClanahan.

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For Bruno, the study reflects “nifty mechanisms of adaptation” by some coral species.

But, he adds, “The key question is, ‘Will the frequency and magnitude of stressors (e.g., of summertime warming events) increase so much or so rapidly that coral populations cannot keep pace?’ This is a long-standing question in conservation biology.”

Green areas are where scientists surveyed Indo-Pacific reefs from 1980 and 2004. The chart shows the loss of coral there over 25 years, with the left axis reflecting the percentage of the bottom covered by living corals.