A Comparative Study Of Intertidal Molluscan Communities In Sandy Beaches, São Sebastião Channel, São Paulo State, Brazil

Abstract

The aim of this work was to study the molluscan communities in two intertidal environments and their relationship with selected environmental variables. The study areas are located along São Francisco and Engenho d'Agua beaches (São Sebastião Channel, São Paulo State, Brazil). These sites are structurally similar with sediments of coarse sand and pebbles that facilitate settlement of molluscan species. The area was subdivided into low, intermediate and high intertidal levels where the samples were taken. Temperature, salinity, grain size, organic matter, and calcium carbonate content were analyzed as environmental variables. The high species diversity recorded in the study sites was due to the occurrence of organisms on consolidated and unconsolidated substrates. However, differences in the specific composition of the two areas were associated with local differences in sediment constituents and the presence of urban waste water in São Francisco. 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