WASHINGTON (Reuters) - Extremely warm waters in the Pacific Ocean caused by the El Nino wea-ther phenomenon are bleaching coral reefs in the Galapagos Islands, the National Oceanic and Atmospheric Administration said on Tuesday. The agency, part of the U.S. Commerce Department, said it had used satellite data to identify Galapagos "hot spots": places where water temperatures were 3 to 5 degrees Fahrenheit (2 to 3 degrees Celsius) higher than the maximum temperatures normally expected. Corals at the Galapagos thrive as long as temperatures remain at or below 81 F (27 C) -- the normal maximum sea surface temperature there -- but a small increase in water temperatures can be deadly to these animals, agency oceanographers said in a statement. Coral bleaching occurs as coral tissue expels a type of algae essential to the coral's survival. Corals normally recover unless ocean temperatures rise too high or high temperatures last too long. During the 1997-98 El Nino, the agency has also confirmed coral bleaching at sites in the Florida Keys, Baja California, the Pacific coast of Panama, the Yucatan coast of Mexico, the Cayman Islands and the Netherlands Antilles. It said its satellite data had been confirmed by reports from its buoys in the water.