Cayman News Service 6 Nov 15;
(CNS) The Central Caribbean Marine Institute (CCMI), which has been monitoring coral bleaching around Cayman since June, has found that a potential devastation to local coral reefs due to the rise in ocean temperatures this summer was averted by a drop in sea temperature at the end of last month. In September sea temperatures passed 87 degrees F, the point at which coral bleaching begins.
Assistant Director of Research at CCMI, Dr Kristi Foster, said the Caribbean has experienced prolonged high temperatures since 2009, causing bleaching around the region.
“Unexpected but welcome relief arrived in Little Cayman during early October in the form of storms and high winds that churned the water, cooling it down. This has halted the bleaching progress and we are hopeful that anything that has survived to this point will recover,” she said.
Different species have handled the event differently; lettuce corals, for example, are more susceptible and were most affected. Scientists have been particularly concerned about staghorn and elkhorn corals, which are already endangered, but research so far shows that they appear, around Little Cayman at least, to be stable at this point, with as many as 90% appearing to be still healthy.
National Oceanic and Atmospheric Administration (NOAA) scientists have been predicting this phenomenon for more than a year. They had warmed that El Nino would bring steadily increasing temperatures, attributed to climate change, that would result in the third global coral bleaching event on record. This scenario has now been confirmed, with coral bleaching reported across the Caribbean, the North and South Pacific and the Indian Oceans since the summer of 2014.
CCMI, which is based at the Little Cayman research Centre, started to monitor coral bleaching with data loggers deployed at various depths around Little Cayman. Surveys will be conducted through next summer to gauge the extent of the bleaching event and recovery, CCMI said in a release Friday.
Coral bleaching is one of many threats and pressures on reefs the world over. Coral colonies are made up of thousands of genetically identical individuals called polyps. Polyps have microscopic, colourful algae, called zooxanthellae, living in their tissues that carry out photosynthesis and provide energy to their coral hosts, which helps reef-building corals create reef structures. Bleaching occurs when these symbiotic algae are expelled by the coral due to changes in water temperature, light or nutrients.
The pressure local reefs are under from bleaching is intensified by local fishing and coastal development. The combination of factors threatening the reefs is a major motivating factor in the Save Cayman campaign opposing government’s plans to dredge and destroy many acres of ancient coral reef in George Town.
With the coral already battling climate change, a decline in reef cleaning and supporting fish, as well as the destruction directly and indirectly from smaller scale coastal development, the potential loss of some 35-acres of ancient reef in and around George Town Harbour is devastating for the local reef system. With almost no hope of any meaningful relocation and the time it takes for new coral to form, the future survival of the reefs in Cayman, and in turn its tourism product, remain under serious threat.
Coral bleaching in Cayman passes 'mass event' threshold
Charles Duncan Compass Cayman 6 Nov 15;
Corals as deep as 100 feet along White Stroke Canyon have suffered bleaching in recent weeks. Corals as deep as 100 feet along White Stroke Canyon have suffered bleaching in recent weeks.
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.
