There was very minor bleaching of coral reefs across Barbados in 2012.
This was confirmed by Marine Biologist of the Coastal Zone Management Unit (CZMU), Angelique Brathwaite, who said, while there were not quantitative assessments carried out last year, visual surveys showed that the levels of bleaching were not on the scale of the events of 2005 and 2010.
Ms. Brathwaite explained that coral bleaching is caused by higher than average temperatures affecting the reef for a period of time. This causes the coral to become stressed, and it expels its algae (zooxanthellae).?? Zooxanthellae live within corals and provide energy, food and colour for their hosts.?? When the zooxanthellae are lost, the corals lose these attributes; [and] they become white and can starve.
"We had a minor coral bleaching event in 1998 which was our first one. [Then] we had major coral bleaching in 2005 where over 90 per cent of our corals bleached, and around 26 per cent of them died as a result," she said.
Ms. Brathwaite added that there was another bleaching event in 2010, which saw about 50 per cent of corals being bleached.
She noted that in 2005 high temperatures between 30 and 31 degrees Celsius essentially "sat" on the reef for about three months, while the duration of similar temperatures on the reefs was reduced in 2010 due to hurricane activity. "The action created by the hurricanes stirred up the water so that it moved around and did not remain on the reefs for an extended period of time. It was really just for a month, so the bleaching was a lot less," the Marine Biologist pointed out.
She explained that the reduced bleaching last year could be linked to hurricanes or high wave energy occurring within the region. "This is normal, but having such calm for long periods as in 2005 is extremely unusual," she said.
Ms. Brathwaite added that if there were no bleaching events this year, it would give the coral a longer time to recover from bleaching episodes. But, she stressed, coral were also affected by land based sources of pollution and physical damage, so recovery might not be so much.
Coral bleaching episodes are monitored jointly by the Marine Research Section at the CZMU and the Centre for Resource Management and Environmental Studies of the University of the West Indies.