Fish feeding and dynamics of soft-sediment mollusc populations in a coral reef lagoon

Abstract

Large coral reef fish were excluded from enclosed plots to examine their effect on the dynamics of soft sediment mollusc populations from One Tree Lagoon (Great Barrier Reef). Three teleost fish which feed on benthic molluscs, Lethrinus nebulosus, Diagramma pictum and Pseudocaranx dentex, were common in the vicinity of the cages. The densities of 10 common species of prey were variable between locations and among times. Only two species exhibited an effect attributable to feeding by fish, and this was at one location only. A number of the molluscs exhibited annual cycles in abundance, with summer peaks due to an influx of juveniles but almost total loss of this cohort in winter. While predation by fish is clearly intense, it does not have significant effects on the demography of these molluscs. -from Authors