COCOS ISLAND (PACIFIC OF COSTA-RICA) CORAL-REEFS AFTER THE 1982-83 EL-NINO DISTURBANCE

Cocos Island coral reefs were adversely affected by the 1982-83 El Nino warming event. Surveys made in 1987 indicated dramatic coral mortality at all depths (1-24m). Live coral cover on three studied coral reefs was 2.6, 2.9 and 3.5%. Population densities of the corallivores Acanthaster planci and Arothron meleagris were relatively high with their feeding activities concentrated on the few surviving colonies. Density of Diadema mexicanum was also high, being responsible for the erosion of large reef framework areas. It is predicted that recovery of the original reef-framework thickness is in the order of centuries.