Energetics of a Predator-Prey Interaction: Corals and Coral-feeding Fishes

Abstract

Various hypotheses have been proposed to account for defense of a feeding territory by coral-feeding fishes. However, before the adaptive significance of feeding territories can be fully understood, energetics of the predator/prey relationship must be quantified. Energetics of the interaction between the coral Pocillopora meandrina and the territorial coral-feeding damselfish Plectroglyphidodonjohnstonianus were examined to determine the minimum energetic requirement of the predator and the effect of predation on productivity of the prey. Coral productivity for colonies exposed (experimental) and not exposed (control) to predation, and metabolic rates of the fish were determined. Fish required 240 cal /day, while corals produced 0.2 1 cal/cm2/day. A typical colony of P. meandrina did not produce enough energy to sustain a fish. Data presented here indicate that territories of two or more colonies should provide sufficient energy. Predation by an individual P. johnstonianus did not have a measurable effect on coral primary productivity.