Bleaching Expanding Rapidly As Caribbean Water Temps Exceed 2005 Records - Warmest Yet To Come

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SAN JUAN, Puerto Rico — Caribbean corals are being exposed to water temperatures higher than those reported during a record bleaching period five years ago and could start dying in the coming weeks, scientists said Tuesday.

The warning comes after islands entered the warmest month of the year for water temperatures, which means the problem is just starting, said C. Mark Eakin, coordinator for the National Oceanic and Atmospheric Administration's Coral Reef Watch network. "I would love for the forecast to be wrong," he said. "But the potential for bleaching this year is higher than in 2005."

When corals are exposed to very warm water, they either expel or consume the colorful algae they host, which leads to the bleached color. If the stress is not too severe and decreases in time, the affected corals can regain their symbiotic algae. But if the stress is prolonged and the algae populations do not recover, the coral host eventually dies. In 2005, up to 90 percent of corals in parts of the eastern Caribbean suffered bleaching, and more than half died.

This week, water temperatures surpassed those recorded in 2005, said Eakin, who blamed a mild winter and a second straight year of El Nino, a weather phenomenon that leads to unusually warm waters. A larger area also is being affected this year than in 2005, he said. Scientists swimming in warm waters are reporting that chocolate-brown corals are turning shades of tan and gold, a precursor to bleaching. But they are celebrating that the reef-building elkhorn and staghorn corals have not yet been affected. They are the first corals to be listed as threatened under the U.S. federal Endangered Species Act.

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