Coral mortality outside of the eastern Pacific during 1982-1983: relationship to El Nino

1982-83 witnessed the most widespread coral bleaching and mortality in recorded history. In early 1982 coral bleaching and subsequent mortality was reported from the Great Barrier Reef (GBR). These reports were followed in early 1983 with observations of coral bleaching and mortality in the Java Sea, Tokelau Islands, French Polynesia, Galapagos Islands, and on the Pacific coast of Panama and in mid-1983 with bleaching in the SW Indian Ocean, S Japan and the Caribbean. In the C Pacific ENSO-related anomalies included an increase in the frequency of cyclones and a lowering of sea level that were directly responsible for the extensive coral mortality observed there. In other regions, where the signal of ENSO is less well defined, a causal relationship between ENSO and coral death is more difficult to establish. On GBR, high temperatures and high light may have played a role in the bleaching, but the proximal cause of bleaching is not known, and ENSO-related anomalies that were observed in the area during 1982-83 did not coincide with the bleaching event. On the Caribbean coast of Panama (San Blas Islands), elevated water temperatures are thought to have led to the observed bleaching. Analysis of available meteorological and oceanographic data failed to reveal a mechanism for the onshore warming nor is there a clear link between the bleaching and the ENSO. -from Authors