Community Structure and Intertidal Zonation of the Macroinfauna on the Atlantic Coast of Uruguay

Five sandy beaches, covering a complete range of dissipative-reflective categories, were studied at the Atlantic coast of Uruguay. The objective of this study was to analyze the species richness, abundance and zonation of the intertidal macroinfauna in relation to beach textural characteristics. The most distinctive features of the macroinfauna studied were: (a) maximum species richness (17), densities and biomass occurred at a long dissipative beach (Barra del Chuy) of fine sands and a flat slope, while the lowest values of community parameters occurred at a truly reflective beach (Manantiales), with coarse sands and a steep slope: (b) polychaete worms were mostly collected from the long dissipative beach; (c) cirolanid isopods showed a distinct pattern of distribution, with Excirolana brasiliensis as the dominant cirolanid in coarse sands and Excirolana armata in fine sands; and (d) faunistical zones were not easy to distinguish: they were recognized at Arachania and Punta del Diablo (two belts), and Barra del Chuy (three belts).