SHORT-TERM ECOLOGICAL CONSEQUENCES OF A MAJOR OIL-SPILL ON PANAMANIAN SUBTIDAL REEF CORALS

A major oil spill (8,000,000 liters; 50,000 barrels) occurred in Bahia Las Minas on the Caribbean coast of Panama in April 1986, and oil slicks from the refinery landfill and mangroves were still common there after 2 1/2 years. We studied short-term effects of the spill on common shallow subtidal reef corals, at the individual, population, and community levels. Numbers of corals, total coral cover, and species diversity based on cover decreased significantly with increased amounts of oiling. Cover of the large branching coral Acropora palmata decreased most. Frequency and size of recent injuries on massive corals increased with level of oiling, particularly for Siderastrea siderea. Growth of three massive species (Porites astreoides, Diploria strigosa, and Montastrea annularis, but not S. siderea) was less at oiled reefs in the year of the spill than during the 9 previous years. Subtidal coral reefs, particularly those along protected coasts, may suffer extensive damage from chronic exposure after major oil spills.