The rising temperature of the waters begins a process that is called bleaching . In an attempt to cool themselves off the coral reefs expel algae's from there bodies. This accretion forms a white spot on the coral. Coral can recover from small bleaching attacks, but constant bleaching makes it nearly impossible for coral to recover from. Another factor contributing to the deaths of coral reefs is the areas where they are usually located.
Coral is found in shallow coastal areas.
These coastal zones often are not the most healthy of areas because of agricultural runoff, and waste products from industrialized areas. This man made waste is not exactly healthy for the coral reefs. Another disease that kills coral is called Black Band Disease. This is a complex process that involves numerous layers of algae. Each layer of algae is different and the bottom layer of algae secretes a harmful substance that deteriorates and kills the coral.