NOAA: Hot seas likely to increase coral bleaching in Keys

A third straight year of high sea temperatures across the planet seems almost certain to trigger bleaching of Florida Keys corals this summer, federal scientists reported Monday.

“Coral reefs across around the world will likely be exposed to higher-than-normal sea temperatures for an unprecedented third year in a row, leading to increased bleaching — and with no signs of stopping,” said a statement from the Coral Reef Watch program of the National Oceanic and Atmosperhic Administration.

“While the bleaching event is global, it will hit the U.S. hard, especially in Hawaii, Guam, the Northern Mariana Islands, Florida Keys, U.S. Virgin Islands and Puerto Rico,” NOAA says.

“This third global coral bleaching event began in mid-2014 is ongoing. Global warming, coupled with an intense El Nino, continues to make this the longest and most widespread coral bleaching event on record,” the report says. “Since its onset, all U.S. coral reefs have seen above-normal temperatures and more than 70 percent of them have been exposed to the prolonged high temperatures that can cause bleaching.”

In the Keys, the effects could show up later this summer, although some corals have already shown “minor paling,” said Cory Walter, coordinator of the local Coral Bleaching Early Warning Network, a program of Mote Marine Laboratory and the Florida Keys National Marine Sanctuary.

“Some of those might still be be showing stress from last year,” Walter noted.

Volunteer coral-watching divers have reported seeing some signs of coral disease on northern Key Largo reefs, which could be related to a severe disease outbreak that hit Miami-Dade reefs in 2015. “We urge our watchers to be diligent in reporting so we can establish a baseline,” Walter said.

“It is crucial that scientists and the public continue on-site monitoring of reefs to track the actual extent and severity of the bleaching,” said Mark Eakin, NOAA’s Coral Reef Watch coordinator.

Bleaching occurs when heat or other stressors cause corals to lose their zooxanthellae — the algae that give corals color and necessary nourishment. Many corals recover their zooxanthellae as water temperatures drop, but prolonged or repeated bleaching can kill corals or make them more susceptible to disease.

Kevin Wadlow: 305-440-3206