Density-dependent growth and grazing effects of juvenile queen conch Strombus gigas L. in a tropical seagrass meadow

Abstract

A field experiment with 1-yr-old queen conch Strombus gigas L. in a seagrass meadow of the Exuma Cays, Bahamas, indicated that growth rates and mortality were density-dependent and related to food limitation. Juvenile queen conch were important consumers of macrodetritus including particles identified as dead seagrass blades. Herbivory on living macrophytes was minimal. Enclosure/exclosure treatments showed that the natural field density of juvenile conch (2 · m −2) reduced significantly the standing crop of senescent seagrass blades and macrodetritus but not that of living seagrass. Grain size, organic content and chlorophyll of sediments were not influenced by the presence of juvenile conch. Removal of seagrass detritus by conch, however, may have a major influence on the abundance and species composition of other benthic invertebrates that use detritus as a source of food or shelter.