SUMMARY:The invertebrate fauna associated with colonies of the bryozoan Schizoporella errata was studied at two sites differing in hydrodynamism in southeastern Brazil. Patterns of species distribution, abundance, and diversity were similar at both sites. Polychaetes dominated the assemblages, both in number of individuals and species, with 70 species distributed in 20 families. Decapod crustaceans were also abundant, mainly anomuran crabs and caridean shrimps. Cluster analysis separated the samples from each site, and further analysis indicated that an interaction between water movement and trophic structure could explain these differences. At the site with low water movement, more muddy sediments were found inside the colonies, and a greater proportion of deposit-feeders was found. At the other site, higher hydrodynamism resulted in less sediments within the colonies, and favoured the occurrence of more filter-feeders. The trophic structure of faunal assemblages can help understand the structure of assemblages associated with biogenic substrata, as already demonstrated for benthic communities.

The crustacean species composition in the intertidal zones of 13 sheltered unconsolidated marine beaches in south-eastern Brazil is described. Fifty-three crustacean species were collected, adding 46 species to the total reported by previous studies in the same region. Decapods dominated the community, in contrast to exposed sandy beaches where peracarids normally predominate. The species were distributed irregularly among the beaches. Richness varied markedly among sites, and was positively related to a combination of factors such as ¢ne sand grains, high organic matter content, and relatively low siltĉ lay content. The presence of rock fragments enabled both rocky shore and sandy beach crustaceans to occur on the same beaches. Richness and abundance of crustaceans showed no clear relationship to sediment grain size and slope, in contrast to the norm for exposed sandy beaches. The dominance of the tanaid Kalliapseudes schubarti in some areas may be a result of organic matter pollution in the region. These beaches showed higher species richness than typical sheltered and exposed sandy beaches, indicating that this sheltered, highly heterogeneous seascape is an important area for conservation.

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O conceito de que a temperatura constitui um fator limitante, essencial na distribuição, tem sido amplamente aceito. No entanto, fixar áreas limítrofes e distinguir conjuntos faunísticos com precisão, tem se mostrado extremamente diffcil. Uma análise dos numerosos estudos sôbre a oceanografia do Atlântico Sul e da costa brasileira, acompanhada de uma revisão cronológica da literatura sobre a zoogeografia dessa região, foi efetuada por PALÁCIO (1982).No litoral do Estado de São Paulo, a região de Ubatuba é uma das mais estudadas, havendo um razoável número de trabalhos sobre a sistemática e a ecologia de anelídeos poliquetos de substrato mole: