ATHENS, Ga.-- Scientists worldwide have been perplexed for more than a decade by extensive bleaching in the ecologically important coral reefs that ring the globe. Suspected culprits in the damage have been everything from bacteria to pollution.

Recent studies have strongly implicated the gradual warming of ocean temperatures as a major cause of coral reef bleaching, and a new study by researchers at the University of Georgia confirms it. It turns out, however, that the higher temperatures aren't necessarily damaging the reef-building corals directly but instead are degrading the ability of symbiotic algae, upon which the survival of their hosts is dependent, to convert light into utilizable energy.

"Because coral bleaching is occurring on such a global scale, the idea that the problem was a direct effect of elevated temperature in sea water made sense," said Dr. Mark Warner, a postdoctoral researcher in botany and ecology at UGA. "The chance that we were seeing, instead, activation by heat of a pathogen everywhere was remote."

The research from the UGA team, which includes botany professor Gregory Schmidt and ecology associate professor William Fitt, in addition to Warner, was published this week in the Proceedings of the National Academy of Science. It will also be presented next Wednesday, July 14, at the meeting of the American Society for Photobiology in Washington. D. C.

Coral reefs are extremely important to ecosystems and to the tourist industry. They cover around two million square kilometers and support some 2500 species of coral and more than 5000 species of fish. But coral bleaching has been worrying researchers since the mid-1980s, and scientists have known that one reason is the reefs' loss of the corals' symbiotic algae and their photosynthetic pigments.

"Corals can be compared to a machine or an automobile in that certain components are more susceptible to stress than others," said Fitt, who is also on the board of direct
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Contact: Gregory Schmidt
schmidt@dogwood.botany.uga.edu
706-542-0280
University of Georgia
9-Jul-1999