The extremely warm ocean waters fueling this season's record hurricane season are stressing coral reefs throughout the Caribbean and may kill 80% to 90% of the structures in some areas, scientists reported Monday.
These colorful undersea landmarks — homes for tropical fish and magnets for divers and snorkelers — are turning white, or "bleaching" in an area extending from the Florida Keys to Puerto Rico and Panama because of warmer-than-usual water that has persisted in the Atlantic for months.
"These levels are like nothing we've ever seen" in 20 years of satellite monitoring, said Al Strong, coordinator for the National Oceanic and Atmospheric Administration's Coral Reef Watch. "It's twice the thermal stress that we've ever seen for corals. We are talking extremely high percentage of bleaching and what seems to be extreme mortality." Coral bleaching started showing up in the Florida Keys this summer and has spread throughout much of the Caribbean. Puerto Rican scientists report that 85% to 95% of the coral reefs there were bleached, as were 70% of the reefs in Grenada.
"We are in the middle of the biggest bleaching event ever recorded in the Caribbean," said Drew Harvell, an expert on coral at Cornell University who saw bleaching in more than half the reefs she recently surveyed off Panama. This year's bleaching episode worries scientists who have been watching a rapid decline of coral reefs around the world. Corals are sensitive animals that require clean, clear water that is warm — but not too warm. In recent decades, clouding from excess sediment, fertilizer, sewage and other pollutants has taken a toll, while overfishing has removed many of the fish that graze algae off reefs and keep them clean.
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