This year is not shaping up as a good one for Cayman’s coral population.
While those who monitor and study the local reefs were pleased by recent spawning events that bode well for the growth of coral populations, those same corals are now showing signs of bleaching, which can be deadly to the colonies.
“This has been the worst I’ve seen it in 22 years,” said Martin van der Touw, a field officer for the Department of Environment and owner of the Brac Scuba Shack. “It’s almost as if the ocean has a fever.”
Some bleaching has become typical from September to November, when the Caribbean waters are warmest. Bleaching occurs when coral is stressed and ejects the symbiotic algae that lives on it and helps provide it with nutrients and gives the coral its colour.
Corals are a key element on the lower end of the reef food chain, helping to sustain fish populations and other sea life.
This year’s conditions have been compounded by unusually sunny weather and calm winds, which have allowed surface waters to heat up into the lower 90s Fahrenheit. Complicating the picture are larger than usual algae and sargassum blooms.
“At the moment,” van der Touw said, “we are seeing coral bleaching down to 80 feet on the south side [of Cayman Brac]. On the north side, we’re seeing more algae growth than usual.”
There are reports of similar conditions in Little Cayman and Grand Cayman.
Katie Correia, science and education manager for the Central Caribbean Marine Institute, based on Little Cayman, said corals off the small island are not doing well. Some initial bleaching was seen in July and it has gotten worse since then, she said.
“We’re seeing bleaching across a depth that varies from 5 feet to 60 feet,” Correia said. “It’s not just shallow, warm water temperatures, but the shallower water corals are having a pretty hard time.”
It’s also not just the bellwether staghorn and elkhorn corals that tend to be the hardest hit. Correia said lettuce and mounded corals are also showing signs of bleaching.
As in the Brac, she said, Little Cayman is seeing more algae and sargassum than usual. Those organisms eat up much of the oxygen in the water, impacting the coral even further.
While she does not want to see another Hurricane Ivan hit Cayman, Correia said the corals would benefit from a nearby hurricane, which would stir up the ocean and draw cooler water from the depths of the Cayman Trench.
“Say we don’t have any storms and the temperatures keep increasing and the wind doesn’t come up,” she said. “It could be one of the worst bleaching events we’ve seen.”
“With just the general rise of temperatures globally and all the other problems delicate animals like coral are facing, it’s really hard to say what it’s going to look like in November,” she added.
A chart from the Department of Environment shows that aggregate temperatures are nearly as high or higher this year than in past years, going back to 1985.
Tim Austin, DoE deputy director, said predictions for bleaching this year are “not good”.
“We are in the hottest month and have just moved to bleaching alert Level 1,” Austin said in a prepared statement.
The alert follows several weeks of above-average water temperatures.
“Calm, hot days with no clouds during this period typically make conditions ripe for coral bleaching,” Austin said.
But he cautioned that the event should be seen in perspective. Coral bleaching is only one sign of stress on reef organisms, he said. Others include over-fishing and water quality.
“We must also do our part in the global effort to reduce carbon dioxide emissions,” Austin said. “Ultimately, it is a warming planet that drives the cycle of coral bleaching and loss of coral reefs.”