MARATHON, Fla. — The alarming scenario has spread to waters of Caribbean: Large coral colonies bleaching white, and then dying.

Marine biologists in the Florida Keys have seen it already.

"The declines now being seen on reefs in the Virgin Islands and Caribbean are very similar to declines that have been seen on Keys reefs, caused by bleaching and disease," said Cheva Heck, information officer for Florida Keys National Marine Sanctuary.

"It shows the problems are the same all over," Heck said. "It's not just the Keys, but the region and the world. We've heard reports from the Pacific, as well."

According to an Associated Press report, recent estimates from Puerto Rico and the U.S. Virgin Islands say that about one-third of the coral in official monitoring sites has recently died.

"It's an unprecedented die-off," said National Park Service fisheries biologist Jeff Miller, who last week checked 40 stations in the Virgin Islands.

"The mortality that we're seeing now is of the extremely slow-growing reef-building corals," Miller said. "These are corals that are the foundation of the reef ... colonies that were here when Columbus came by have died in the past three to four months."

Sunday, Edwin Hernandez-Delgado, a University of Puerto Rico biology researcher, found a colony of 800-year-old star coral that towered more than 13 feet high had recently died in waters off Puerto Rico.

"We did lose entire colonies," he said. "This is something we have never seen before."

Wednesday, Tyler Smith, coordinator of the U.S. Virgin Islands Coral Reef Monitoring Program, dived at a popular spot for tourists in St. Thomas and saw an old chunk of brain coral, about 3 feet in diameter, that was at least 90 percent dead from the disease called white plague.

"We haven't seen an event of this magnitude in the Caribbean before," said Mark Eakin, coordinator of the National Oceanic and Atmospheric Administration's Coral Reef Watch.

For the Caribbean, it all started with hot sea temperatures, first in Panama in the spring and early summer, and got worse from there.

New NOAA sea-surface temperature figures show the sustained heating in the Caribbean last summer and fall was by far the worst in 21 years of satellite monitoring, Eakin said.

"The 2005 event is bigger than all the previous 20 years combined," he said. It remained hot for weeks, even months, stressing the coral.

The heat causes the symbiotic algae that provides food for the coral to die and turn white. That puts the coral in critical condition. If coral remains bleached for more than a week, the chance of death soars, according to NOAA scientists.

In the past, only some coral species would bleach during hot-water spells and the problem would occur only at certain depths. But in 2005, bleaching struck far more of the region at all depths and in most species.

February NOAA report calculates 96 percent of lettuce coral, 93 percent of the star coral and nearly 61 percent of the brain coral in St. Croix had bleached.

In 1997 and 1998, Keys waters suffered consecutive years with widespread coral bleaching, followed by an onset of diseases that caused a steep decline in the amount of living coral locally.

"It's something that concerns the sanctuary and we continue to monitor the situation," Heck said. "Our corals were starting to bleach heavily last year, but the waters cooled and the coral seemed able to recover.

"But we never had much of a winter, and we are concerned about the water temperatures as summer approaches."

Source: Knight Ridder/Tribune Business News