Corals may not recover from bleaching

August 4th, 2008 - 2:31 pm ICT by IANS  

Sydney, Aug 4 (IANS) Coral communities in Australia’s Great Barrier Reef might not be able to recover from bleaching as easily as previously presumed, says a new study. A two-year study by a University of Queensland team has found that contrary to perception, it is not possible for bleached corals to recover or become more resistant to bleaching by taking up more heat tolerant species of their micro-algae partners.

All corals have a symbiotic relationship with single-celled dinoflagellates, commonly referred to as zooxanthellae. The coral provides a habitat for the zooxanthellae, which in turn produce essential nutrients for the corals.

Under stressful conditions like high or low water temperatures, the symbiotic zooxanthellae are expelled from their host, causing a whitening of the coral tissue or bleaching.

Coral bleaching events have caused significant mortality of corals worldwide and the frequency as well as intensity of bleaching events is predicted to increase as a result of climate change.

Eugenia Sampayo, a research scholar, said past research had suggested that bleached corals could take up new, more tolerant symbionts, which would make them less susceptible to future bleaching events.

“Our research, however, shows that this may not be possible for all corals,” she said.

“This study is one of few that follows individual colonies over a two-year period and shows that individual colonies of the stony coral, Stylophora pistillata, do not change their symbionts as a response to temperature stress,” Sampayo said.

These findings have been published in the Proceedings of the National Academy of Sciences.

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