Coral Bleaching around the Addu Atoll in the Maldives. Algae living in the corals are released as a stress reaction caused by warmer water temperatures, thus turning the coral white. The corals can only revitalise once lower water temperatures return. If this does not happen, they die. In February and March of 2016, water temperatures of 32 degrees celsius were measured over several days around the Addu Atoll, possibly a result of El Nino.