Nov. 3, 2005 — Coral around St. John is recovering after high water temperatures threatened much of the important underwater reefs, officials said Thursday.
Almost 90 percent of coral around St. John lost its color – an indication of poor health – when sea water temperatures rose in August and September, said Rafe Boulon, a spokesman for the St. John National Park.
Sea water temperatures, which are measured 55 feet below the surface, reached 88 degrees in the summer months, bleaching the coral that usually thrive in 70 to 85 degree sea water, Boulon said. "It was pretty dramatic. It was the worst bleaching that has ever occurred here, ever," he said.
Although Boulon did not report on St. Croix coral, there were reports from swimmers and divers of an unusual amount of bleaching around that island this summer, too.
The recovery of the coral was due in part to heavy October rains that cooled water temperatures, Boulon said.
Whereas much of the coral is regaining its health, it was still too early to know how much died and will not return, he said.
Additionally, Boulon said scientists are studying a possible new disease developing in Elkhorn Coral, a recent candidate for the federal threatened species list.
Coral color comes from oxygen-providing algae that live on the coral's surface. When coral is stressed, it dispels the algae, he said. Coral reefs, a fragile and vital part of undersea ecosystems, are threatened world-wide by pollution and runoff from land-based construction projects.

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