Coral bleaching threat in Florida is minimal: experts

Kevin Wadlow KeysNet.com 18 Sep 10;

High ocean temperatures have raised the chances of severe coral bleaching in the southern Caribbean but the Florida Keys may escape significant damage, according to a monitoring program.

"For us, it seems to be shaping up as a fairly common year," said Cory Walter, a Mote Marine Laboratory biologist who coordinates the local BleachWatch program. "We're getting reports of some bleaching on the inshore patch reefs, but that's relatively common at this time of year."

Water temperatures "seem to be leveling out" around 86 degrees, near the worrisome point that could cause a surge in bleaching. "Hopefully, the wind and rain will help chill the water," Walter said.

In a Friday report, she noted, "Most of the Florida Keys region is presently experiencing minimal thermal stress."

Observations from the National Oceanic and Atmospheric Administration "shows that sea surface temperatures continue to be only slightly elevated for this time of year in the Florida Keys."

Other areas of the southeast Caribbean and the western Gulf of Mexico, however, have experienced "significant bleaching thermal stress," or high temperatures capable of causing coral bleaching, according to a report from NOAA Coral Reef Watch coordinated C. Mark Eakin.

Satellite "monitoring shows that thermal stress levels capable of causing bleaching have continued to develop in the southeastern Caribbean since July, bearing a similar signature to the thermal stress observed at the same time period in 2005, the year of a record mass coral bleaching event," Eakin reported.

Bleaching occurs when high temperatures cause corals to expel algae that live in a symbiotic relationship with the coral. Bleaching can weaken coral and render them more susceptible to disease. Some corals recover from bleaching, but not all.

Hurricane Earl actually helped alleviate some warming threat to Florida, Eakin said.

"Hurricane Earl left a clear track of cooler water ... including reports of cool water at depth in the U.S. Virgin Islands," he said. "Other weather disturbances have cooled temperatures from Texas to the Virgin Islands. Mixing and cooling from a hurricane can reduce thermal stress to a reef and prevent severe bleaching."

Keys divers can submit reports and photos of bleaching events to BleachWatch. Go to www.mote.org.