SPATIAL AND TEMPORAL VARIABILITY DURING PERIODS OF RECOVERY AFTER MASS BLEACHING ON WESTERN ATLANTIC CORAL REEFS

Western Atlantic coral reefs were differentially affected by a mass bleaching (discoloration) event in 1987. We periodically assessed the ''appearance'' of zooxanthellate organisms between December 1987 and June 1988 at nine conspicuously affected sites in the Bahamas, Florida, St. Croix, and Venezuela, using a standardized point-count technique. Three to four months after the local initiation of the event, the ''bleached'' state was still present in one to three of the most abundant reef coral taxa and in a few of the less common species (n = 5 sites). ''Recovery'' occurred somewhat faster at shallower depths, at least in the Bahamas and Florida. Scleractinian corals which were ''prolonged bleachers'' had foliaceous or massive, rather than branching, morphologies. ''Bleached'' points disappeared from the point counts after +6 to +8 months. Long-term field data on spatial and temporal variability in the dynamics of zooxanthellate organisms would help us to understand the ecological consequences of bleaching. More generally, we need to distinguish anthropogenic changes in the structure and functioning of reef ecosystems from those which occur naturally. Point-count techniques are well suited for collaborative studies involving rapid quantification of coloration states and health in reef corals.