Effect of natural zooplankton feeding on the tissue and skeletal growth of the scleractinian coral Stylophora pistillata

Laboratory experiments were designed to estimate the ingestion rates of the scleractinian coral Stylophora pistillata under varying prey concentrations and feeding regimes and to assess the effect of feeding on the tissue and skeletal growth. Six sets of corals were incubated under two light (80 and 300 mumol photons m(-2) s(-1)) and three feeding levels (none, fed twice, and fed six times per week) using freshly collected zooplankton. Results showed that the number of prey ingested was proportional to prey density, and no saturation of feeding capability was reached. Capture rates varied between 0.5 and 8 prey items 200 polyp(-1) h(-1). Corals starved for several days ingested more plankton than did fed corals. Fed colonies exhibited significantly higher levels of protein, chlorophyll a, and chlorophyll c(2) per unit surface area than starved colonies. Feeding had a strong effect on tissue growth, increasing it by two to eight times. Calcification rates were also 30% higher in fed than in starved corals. Even moderate levels of feeding enhanced both tissue and skeletal growth, although the processes involved in this enhancement remain to be determined.