Intracolonial variation in toxicity in scleractinian corals.

Single colonies of the scleractinian corals Lobophyllia corymbosa, Favites abdita, Favia matthaii, Favia stelligera, Platygyra daedalea, Leptoria phrygia, Cyphastrea serailia, Hydnophora exesa and Astreopora myriophthalma were permanently marked with buoys on the reef flat at Heron Island. Great Barrier Reef. Portions of colonies were removed up to seven times at intervals of two or three months. Aqueous extracts of the colony portions were assayed using six bioassay regimes namely, toxicity to mice, toxicity to a coral and a hydroid, cytolytic activity on sheep erythrocytes and sea urchin ova and for antimicrobial activity on eight bacterial species. The incidence of one type of bioactivity in an extract was not correlated with the incidence of any other type of activity in that extract. Although each coral colony provided extracts that affected at least two of the bioassay systems, different activity profiles were obtained from successive extracts of each colony. Thus there is a temporal component to the idiosyncratic nature of bioactivity within a given colony of scleractinian coral.