The massive 'bleaching' (loss of zooxanthellae) and death of reef corals that occurred in one area (Gulf of Chiriquí) on the Pacific side of Panamá and in the Galápagos Islands during February-April 1983 continued in these areas until September-October 1983, resulting in a catastrophic disturbance. Similar episodes have been reported subsequently throughout much of the tropical eastern Pacific region (Costa Rica, the entire Pacific coast of Panamá, and Colombia), in the central and western Pacific Ocean, in parts of the western Atlantic Ocean (Caribbean coasts of Costa Rica, Panamá, and Colombia), and in the Florida Keys and Bahama Islands. By the end of the disturbance, late in 1983, eastern Pacific coral reefs as a whole had lost 70%-95% of their living coral cover to depths of 15-18 m, and some reefs had experienced drastic reductions and local extinctions of certain species. Both hard and soft corals (octocorals) were affected on Panamic Caribbean reefs, but total coral mortality was significantly less (about 2%), and effects were more pronounced, at shallow depths (< 10 m), on Caribbean as compared with Pacific reefs of Panamá. Attention is drawn to the strong correlation (in space and time) between coral mortality in the eastern Pacific and the abnormally high sea-water temperatures which accompanied the severe 1982-1983 El Niño event. Much evidence indicates that prolonged ocean warming, with mean temperatures of 30-32°C, can cause bleaching and death of corals. In Panamá, in a non-upwelling environment (Gulf of Chiriquí), corals were first affected in February-March, 2-3 months after ocean warming (mean temperatures of 30-31°C); in an upwelling environment (Gulf of Panamá) corals were not affected until June-July, 2-3 months following upwelling and the warming period. The warm period persisted in the Gulf of Panamá, to at least 10 m depth, for 9 months. Some of the shallow-water coral mortality that occurred in the central and western Pacific could have been caused by sea-level recessions (and associated suboptimal conditions) that often accompany El Niño events. Coral-reef recovery in the eastern Pacific could take many years or decades because: (a) the chief frame-building corals produce few planulae; (b) some coral species have been severely reduced in numbers or locally exterminated; (c) corallivores are still abundant and are expected to concentrate on surviving corals; and (d) bioerosion is high, causing coral skeletal breakdown and possibly the loss of parts of reef-frames.
ASJC Scopus subject areas
- Water Science and Technology
- Nature and Landscape Conservation
- Management, Monitoring, Policy and Law
- Health, Toxicology and Mutagenesis