Population Density, Distribution and Consumption Rates of Three Corallivores at Cabo Pulmo Reef, Gulf of California, Mexico

Abstract

Abstract. The influence of corallivores on coral community structure of eastern Pacific reefs has been considered less important then that of abiotic oceanographic factors. The data that support this assumption, however, are only available for Central American reefs. To assess the role of predation on hermatypic corals in a different regional reef environment, the abundance, spatial distribution and consumption rate of three corallivores: the echinoid Eucidaris thouarsii (Valenciennes), the asteroid Acanthaster planci (Linnaeus) and the teleostean fish Arothron meleagris (Bloch & Schneider), were estimated at Cabo Pulmo reef, Gulf of California, México (23°25′ N, 109°25′ W). Statistically, the abundances of the species did not change in any sections of the reef (mean values: E. thouarsii, 0.17 indiv. · m−2; A. planci, 1.9 indiv. · m−2; A. meleagris, 39 indiv. · ha−1). The average daily individual consumption rates of coral were calculated at 1.83 g CaCO3· m−2 for E. thouarsii, 118.4 cm2 for A. planci, and 16.38 g CaCO3· m−2 for A. meleagris, and were lower than those reported for Central American reefs. Considering the mean estimated carbonate production (7.9 kg CaCO3· m−2· a−1), corallivores eliminate less than 4% of the coral standing stock of Cabo Pulmo reef. The low corallivore population density and consumption rates, together with high local coral cover, indicate that corallivores are not key factors determining scleractinian abundance in this marginal reef.