El Nino of 1997-98 is believed to have been the most severe recorded in over 600 years. In the 1983 and 1998 mass bleaching disasters, record El Nino s occurred in conjunction, but it must be noted that once El Nino disappeared so did the high land-sea surface temperatures. Changes in sea level endanger coral reefs by overexposure to sunlight that occurs when the sea level drops. The rise in sea level decreases the amount of sunlight available for photosynthesis. The rise in sea level can be attributed to thermal expansion of the ocean and the melting of polar ice caps caused by global warming.
Coral reefs are home to much marine wildlife.
Many varieties of fish, shrimps, and crabs depend on the shelter sponges provide that are part of the reef s ecosystem. The many crevices within the coral reef provide shelter and protection for crustaceans and eels. Octopus, squid, snails, and other mollusks live on or near the reef. Individual and schools of fish are vital for the reef s ecosystem, as they are both predators and prey. As a result of the reef s diverse ecosystem, the local populous depends on its survival for economic and dietary reasons.