An oil spill affecting coral reefs and mangroves on the caribbean coast of Panama

Abstract

In April 1986, more than 50,000 barrels of medium weight crude oil were spilled into the largest complex of coral reefs and mangroves on the central Caribbean coast of Panama. Considerable amounts of oil came ashore at Punta Galeta, where a long-term environmental sciences program of the Smithsonian Tropical Research Institute provided extensive baseline information for investigating the effects of the oil spill. Immediate mortality was most apparent for organisms living at the seaward edge of the reef flats and on drying substrata above mean water level. By June 1986, a number of reef species were reduced in abundance, and a bloom of microalgae grew over much of the reef flat that had been directly exposed to the oil at low tide. The abundances of some fast-growing algae appeared to have recovered by September 1986, but the slower-growing corals, zoanthids, and calcareous algae were at the lowest abundances recorded. Defoliation and mortality of mangroves, particularly Rhizophora mangle, was severe on windward coasts, and other areas where the oil penetrated into sediments around the mangrove roots. Oysters and other organisms living on mangrove roots also suffered severe mortality, The types of habitats and organisms affected were obviously dependent on the particular weather conditions during the oil spill. Studies are continuing to follow succession and other changes in seagrass meadows, coral reefs, mangrove forests, and associated habitats that were affected by the oil.