In the Coral Reef Conservation Research Lab at RSMAS we are conducting experiments on coral bleaching and recovery. Coral bleaching is the breakdown of the relationship between corals and the symbiotic algae that live inside their tissues and provide them with energy through photosynthesis. As the corals lose the algae they also lose their color, hence the term, ‘bleaching.’
In our study, over 600 small coral ‘cores’ were drilled out of larger coral colonies and then experimentally ‘bleached’ by exposure to seawater at 32°C. The different coral cores were bleached to different levels of severity to simulate mild and severe bleaching events in nature.
The corals were then allowed to recover at two different cooler temperatures (24°C and 29°C) for several months, where they regained their algae and their color. As corals recovered, the photosynthetic performance and density of their symbiotic algae was monitored in order to see how both bleaching severity and recovery temperature might affect the speed of recovery, and the types of symbiotic algae they recover with. Some of the corals recovered after the first bleaching experiment with different kinds of symbiotic algae known to be more tolerant to high heat. Now they are being exposed to high heat again to observe how past bleaching history and changes in symbiont communities affect bleaching sensitivity.
– Ross Cunning, RSMAS graduate student
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