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 Coral Bleaching Tropical coral reefs are given their color by tiny algae called dinoflagellates. The algae are essential for the corals to build their calcium carbonate skeleton, and in turn the coral provides nutrition for the algae. Coral bleaching is a phenomenon in which coral appears white - essentially this means that the dinoflagellates are missing. Scientists believe that the bleaching is caused by abnormally high ocean temperatures, such as those caused by El Niņo. The high temperature stresses the relationship between that coral the algae in some way, so that the algae either leave the coral or lose their pigment. Observations of bleached coral in the Florida Key suggest that bleached coral can quickly recover when the temperature drops again. The danger for coral reefs is not just bleaching however: the same lack of nutrients that affect the fish population also starves the coral animals. In the 1982-83 El Niņo, corals off Costa Rica, Panama, Colombia, and the Galapagos Islands suffered losses ranging from 50 to 97 percent. Peter Glynn of the University of Miami said "It will take decades, if not centuries, for these reefs to fully recover’. The 1997-98 El Niņo episode is already resulting in the death of corals off Mexico, Costa Rica and Panama.
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