This year’s spate of coral bleaching wasn’t as bad as scientists originally feared, said fisheries biologist Jeff Miller.
“We’re cautiously optimistic,” said Miller, who works with the National Park Service’s Inventory and Monitoring program assigned to the Virgin Islands and based on St. John.
By early November 2005, the year that saw the territory’s corals decimated by bleaching, the corals across the territory were in very bad shape. Ultimately, 90 percent of the corals at study sites suffered bleaching, and 60 percent ultimately died.
This year, about 50 to 55 percent of the corals at three study sites are discolored but not bleached white or dead, Miller said.
“There is less coral bleached than 2005, and the severity is less,” he said.
The bleaching problem occurs when unusually warm water causes the algae that live in the corals to be expelled or die. This leaves the corals with a bleached look because the colorful algae is gone, Miller has said.
According to Miller, two factors contributed to the improved coral condition. He said that water temperatures probably weren’t as warm as they were in 2005, and when they were warm, they weren’t as warm as long.
He said the average water temperature for October was 84.5 degrees. Bleaching occurs when temperatures rise over 85 degrees.
As water temperatures began to rise this summer, Miller and other scientists feared that this year would be a repeat of 2005.
While the early October rains and those that fell Sunday and Monday lowered the water temperature, Miller said they were a double-edged sword because the rain caused dirt to flow downhill onto the coral reefs.
“Sedimentation stresses the reefs,” Miller said.
This sedimentation on top of this year’s bleaching means that boaters, swimmers, divers, and snorkelers have to be careful not to further impact the reefs.
“It’s like kicking a person when they’re down,” he said.
He urged boaters to take care when anchoring, and for swimmers, divers and snorkelers to not stand on the reefs or kick up sand that will smother them.
Miller is also concerned about disease hitting the stressed coral reefs. This is what happened in 2005 and caused them to die.