Comparison between the macroinfauna of urbanized and protected beaches in Rio de Janeiro State, Brazil

The intertidal macroinfauna of five sandy beaches with similar morphodynamics conditions was studied to compare composition and structure between beaches near urbanized centers and protected beaches located in Rio de Janeiro State. The beaches were sampled in winter 1996 and summer 1997 according to a systematic design with stratification. A total of nine species were identified with the crustaceans being the most abundant and frequent animals. Species richness showed little variation between beaches while density of some species such as Emerita brasiliensis (Crustacea) and Phaleria testacea (Insecta) were lower at urbanized beaches when compared to protected ones. At the most urbanized beaches, Pseudorchestoidea brasiliensis was absent during both sampling periods. The negative relationships between human recreational activities (e.g., trampling) and density of macroinfaunal species was recently gained support and in Barra da Tijuca beach these relation is very clear. In the developed and most-visited sector, Barra (Alvorada), the amphipod Pseudorchestoidea brasiliensis was never collected whereas in the protected portion, Barra (Reserva), the same species occurred in high densities. Thus, our results suggested that the amphipod Pseudorchestoidea brasiliensis is more vulnerable to trampling than are other species.