Abstract

Landings of Concholepas concholepas, a carnivorous gastropod and valuable fishery resource, appear disproportionately high compared with herbivores or suspension feeding mussels. The species has been previously described as feeding on a great variety of prey, the most important being barnacles, mussels, and tunicates. To quantitatively evaluate published information on the diet of C. concholepas, an analysis of the stomach contents of 925 individuals was performed, representing a wide size-range, broad geographical distribution (29°30?S to 32°08?S), and different community types (variety of potential prey choices). The diet was based principally on suspension feeders, such as barnacles (Balanus laevis and juveniles of Austromegabalanus psittacus) (75%) and the ascidian Pyura chilensis (16%). An additional sampling, in which abundance of prey in the habitat and microhabitats occupied by the gastropod was determined, showed that the gastropod positively selects these prey species, the ascidian being the most preferred. The rest of the diet was made up of Calyptraea trochiformis and mytilid bivalves. According to the literature, intertidal individuals of this species only feed at night. To confirm this behavior for subtidal populations, two 24-h samplings (analyzing digestive tract contents) were performed at a single location. No distinct circadian cycle of feeding for subtidal populations was found, most animals feeding most of the time. This, together with the characteristics of diet, made mainly by suspension feeders, which transfer energy from primary productivity in the water column which varies along the coast, to benthic carnivores, help to explain the high productivity of the gastropod and its variability along the coast of Chile.