On the benthic molluscs of Banco Inglés (Río de la Plata, Uruguay)

Abstract

We describe the specific richness and community structure of benthic molluscs on a shallow-water sandy bank (Banco Inglés) in the Río de la Plata estuary. From a total of 25 macroinvertebrate taxa collected, that included one ophiuroid, one bryozoan, fourcrustaceans and four polychaete species, molluscs were the dominant taxon, with 15 species recorded. These were one species of Polyplacophora, eight Bivalvia and six Gastropoda (one exotic), representing 11families and 11 genera. In terms of mean relative abundance, the molluscan assemblage was dominated by the deposit-feeder bivalve Corbula caribaea, averaging ca. 30% of the individuals of the macroinfauna. The alien species Rapana venosa was noted in two stations, represented by one and four specimens. We used null model analysis to test for nonrandomness in the structure of the molluscan communities of the area. The analysis supported the null hypothesis that co-occurrence patterns could not be distinguished from those that might arise by random processes.