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In 2014 and 2015, the brown rice coral in Hawaii was completely bleached, but the blue rice coral recovered quickly after bleaching, and blue coral was unaffected by the elevated ocean temperatures.
Researchers from the Smithsonian Conservation Biology Institute, U.S., have now decoded the reason for this resilience. Hawaiian blue rice corals have a deep blue pigment derived from algae called zooxanthellae that live inside the coral tissue. The researchers found that these algae produce sunscreen for the coral. This pigment has a protein named chromoprotein which filters out harmful UV radiation The findings of this study were published this week in Scientific Reports.
After the 2014 and 2015 Hawaii bleaching events, the blue rice coral was found to have exceptional reproductive vigour at 90% motility. But the brown coral's motility was only half this. A key factor in the blue rice coral's ability to reproduce successfully might be its sunscreen pigment, which the coral may retain even if it bleaches.
Lead author Mike Henley, explains in a release that by studying blue rice corals' reproductive successes, we can better understand how other corals weather climate change and ocean warming.