Population structure of the invasive bivalve Isognomon bicolor on rocky shores of Rio de Janeiro State (Brazil)

The aim of this study was to compare the population structure of the invasive bivalve Isognomon bicolor in three different areas on the coast of Rio de Janeiro State and to verify its temporal variation. All the areas presented high densities, reaching more than woo live individuals per too cm. The number of dead individuals and recruits was higher in Ilha do Brandito (Angra dos Reis) than in the other areas. The individuals sampled at Praia Vermelha (Rio de Janeiro) presented the highest maximum and mean sizes, compared to those found at Ilha do Brandao. In this area, vermetid molluscs are dominant and build a complex reef structure where only a few individuals of I. bicolor can really grow.