Bleaching Induced Mortalities in Reef Corals from La Parguera, Puerto Rico: A Precursor of Change in the Community Structure of Coral Reefs?

Goenaga, Carlos; Vicente, Vance; Armstrong, R

An unprecedented Caribbean bleaching event occurred in the summer of 1987. Preliminary of observations revealed extensive tissue discoloration in zooxanthellate cnidarians at all depths of reef front environments at La Parguera, southwestern Puerto Rico. These included scleractinians, zoanthids, encrusting and arborescent octocorals, anemones, and hydrocorals. Zooxanthellate sponges were also affected. Recovery by all taxa, except for a few species within the Scleractinia, has been almost complete. A grid extending from the reef crest to the reef base on Cayo Enrique, La Parguera, was photographed before and after the event to determine the extent to which scleractinians had been affected. Four months after the event: 1) 22% of the observed colonies (n=326) were white or pale, 2) 44% of those that were white or pail showed tissue neurosis within or near the discolored tissues and, 3) bleaching was unrelated to depth. The large majority of the affected colonies (78%) belong to Montastrea annularis. The data suggests that a light related phenomenon was responsible for the bleaching event. Over 60% of the affected colonies were bleached only on their upper surfaces. We hypothesize that exceptionally calm seas coupled with high water transparency and increased water temperature were a major factor causing the expulsion of zooxanthellae. It is possible that the 1987 coral bleaching event, together with other recent, large scale events, will modify the structure of Caribbean coral reefs.

Bleaching Induced Mortalities in Reef Corals from La Parguera, Puerto Rico: A Precursor of Change in the Community Structure of Coral Reefs?

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