Crustáceos associados à macroalga Ulva spp. em praias com diferentes características ambientais Crustacean species associated with Ulva spp. on beaches with different environmental characteristics

Communities associated with macroalgae are known to host a diverse and abundant fauna. Despite the ecological importance of this environment, studies with macroalgae present at the rocky shores are relatively scarce and mostly conducted with structurally more complex species. The main goal of this study was to analyze the crustacean species associated with the green macroalga Ulva spp. present in rocky shores at Cigarras Beach and Araca Bay, both situated in Sao Sebastiao, Northern coast of the state of Sao Paulo. Nine samples were taken from each area. At Araca bay, three sampling zones could be distinguished (subtidal, intertidal and upper tidal) and three samples were collected at each zone. Amphipods and isopods were the dominant group in both areas; however the amphipod Parhyale hawaiensis was present in great number only in Araca. The mean abundance of crustacean species associated with Ulva spp. was four times higher in Araca bay than in Cigarras Beach. No difference in the Shannon-Wienner index was detected between the areas or among the zones in Araca bay. The higher density of crustacean species in Araca bay may be associated with the absence of other macroalgae species that could be used as a biological substrate and the low hydrodynamic forces acting in this area.