The waters around the Cayman Islands hit the threshold in recent weeks that could cause mass coral bleaching around the islands, part of a global event this year caused by warmer than usual water temperatures throughout the world’s oceans.
Coral bleaching occurs when the water temperatures get too warm and the algae living on the corals leave, taking with it the coral’s primary food source. The corals do not always die from bleaching, but those that survive are much more susceptible to disease.
The U.S. National Oceanic and Atmospheric Administration declared this year’s bleaching to be the third global bleaching event on record, and predicted that warm water will cause problems for almost 40 percent of the world’s corals.
“Right now we are experiencing quite a significant bleaching event,” Department of Environment Director Gina Ebanks-Petrie said earlier this week.
The DOE has seen bleaching on corals down to 150 feet below the surface, she said.
DOE Deputy Director Tim Austin said Thursday, “It looks like it’s been getting progressively worse.” He said the worst bleaching has been around Grand Cayman, but corals around the Brac and Little Cayman still have significant bleaching, but not as bad.
“Hopefully it’s stabilized,” Mr. Austin said.
The warm waters throughout the world’s oceans have caused major problems for corals from Hawaii to Australia and around to the Caribbean. Marine scientists agree that El Nino, a swath of warm water in the Pacific, is to blame for the warming oceans, along with a number of other major weather events like the drought in the western U.S. and a less severe hurricane season.
The DOE director said this week that Cayman and Jamaica are experiencing among the warmest waters and most bleaching, made worse by sunlight contributing to the warming.
Mr. Austin said recently that his department expected bleaching this year with the warming oceans. “This will happen more and more every year,” he said.
The cloudy, cooler weather has helped cool water temperatures and hopefully will help give the corals a break so they can recover from the bleaching that started to become a problem in August.
Scientists measure coral bleaching risks by counting the days the water temperature is over 87.2 F (31 C). For every week, and every degree Celsius above the temperature threshold, serious bleaching is more likely. This is measured in “degree weeks” and the threshold is eight degree weeks, which the Cayman Islands hit in the last two weeks.
Waters have since cooled, and DOE officials continue to monitor the corals, officials said.
“It’s been a gradual event this year rather than a sudden thing like the 1998 event,” Mr. Austin said. Cayman experienced a previous mass bleaching event in 1998, another severe El Nino year.