Keys corals may get a break from bleaching

A brain coral off the Upper Keys suffers from a 2014 bleaching event that threatens the corals’ survival. This summer may not be as dire, scientists say.
A brain coral off the Upper Keys suffers from a 2014 bleaching event that threatens the corals’ survival. This summer may not be as dire, scientists say.

Coral reefs worldwide “may finally catch a break from high ocean temperatures,” says a Monday report from the federal Coral Reef Conservation Program.

If conditions follow estimates prepared by National Oceanic and Atmospheric Administration scientists, a three-year run of warming ocean water that imperiled coral reefs worldwide could be winding down.

“The latest NOAA forecast shows that widespread coral bleaching is no longer occurring in all three ocean basins: Atlantic, Pacific and Indian,” says the statement.

That indicates “the likely end to the global coral-bleaching event,” it says. “Scientists will closely monitor sea surface temperatures and bleaching over the next six months to confirm the event’s end.”

The Florida Keys have the only living coral reef in the continental United States and the third largest in the world. Keys corals have been been affected during the three years of warm ocean temperatures.

Since 2015, “all tropical coral reefs around the world have seen above-normal temperatures, and more than 70 percent experienced prolonged high temperatures that can cause bleaching,” NOAA reports. “U.S. coral reefs were hit hardest, with two years of severe bleaching in Florida and Hawaii.”

“This global coral-bleaching event has been the most widespread, longest and perhaps the most damaging on record,” C. Mark Eakin, NOAA’s Coral Reef Watch coordinator, says in the statement.

Coral bleaching can occur when water temperatures stay near 87 degrees Fahrenheit for a period of several weeks. When the coral colonies become stressed, they expel the algae (zooxanthellae) that give corals their distinctive color, leaving them bone white.

Bleached corals can recover as water cools but the severe damage often proves fatal to the reef-building corals.

“Coral reefs are not beyond help,” said Jennifer Koss, director of the NOAA Coral Reef Conservation Program. “Many proactive steps to make coral reef ecosystems more resilient are being taken around the world. We are reducing local threats to coral, and are looking into innovative ways to increase coral populations and species that are more resilient to rising ocean temperatures and acidified waters.”

NOAA staff cautioned that “some U.S. coral reefs are still not completely in the clear.”

A four-month coral bleaching outlook predicts “some risk” to Florida corals, along with reefs in Hawaii and the Caribbean.

However, windy weather can help lower water temperatures, a factor credited with helping the Keys avoid a mass bleaching event in the summer of 2016.

The Florida Keys Bleachwatch program, based at Mote Marine Laboratory on Summerland Key, uses trained volunteer divers to keep an eye on local reefs.

Kevin Wadlow: 305-440-3206