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This study investigated the community structure and functional traits of the mollusk fauna associated with macroalgae with different thallus morphologies in a reef environment in Northeastern Brazil. A total of 15 individuals of each species of macroalgae adhered to natural substrate and 15 individuals of Padina gymnospora detached from the substrate were collected. The structural complexity of algal habitats was measured and the associated malacofauna screened and identified. All three macroalgae differed significantly in the complexity of their habitat, with Sargassum polyceratium being the most complex. A total of 823 specimens of mollusks belonging to 22 species and 11 families were recorded, of which Columbellidae was the most represented with six species. The functional trait "size" revealed that micromollusks smaller than 10 millimeters were predominant in the community; however, individuals of larger sizes (up to 24.54 millimeters) belonging to young stages of other species were also present. Eight functional trophic groups were identified, of which "carnivorous" stood out with seven species. Six functional groups of microhabitats were identified, with intra-specific variation in habitats, while habitat expansion was documented for species not yet recorded in association with macroalgae. The structure of the molluskan community differed among the three algae species with the greatest richness, abundance, and diversity of mollusks and functional traits occurring with S. polyceratium. Community structure differed between algae adhered to natural substrate and detached algae, with the latter having lower mollusk richness and diversity, but with greater abundance of some species that remained on algal fronds after release from the reef environment. This study reinforces the importance of algal habitat for marine invertebrate fauna, especially for micromollusks that spend their entire life cycle, or part of it, in association with macroalgae. K E Y W O R D SDictyopteris justii, malacofauna, Padina gymnospora, phytal ecosystem, Sargassum polyceratium

Rhodolith beds formed by non-articulated calcareous algae have been recognized as important habitats for a range of organisms. The Brazilian coast is home to one of the largest beds of the Southwestern Atlantic, but the lack of faunal studies in these habitats represents one of our major gaps in the knowledge of Brazilian biodiversity. This study compares the composition, abundance and diversity of echinoderm species associated with rhodoliths in three different isobaths (10, 15 and 20 m) along the coast of the State of Paraíba, Northeastern Brazil. These rhodolith beds provided 2,855 specimens, representing 32 species from four Classes, of which Ophiuroidea was the most numerous. The echinoderm community was significantly different considering the abundance of individuals (F=452.86, p=0.001) and the number of species (F=45.14, p=0.006) among the three depths analyzed. Abundance and species numbers decrease with increasing depth. Rhodolith beds in the State of Paraíba are an important habitat for echinoderms, harboring a high diversity and abundance of associated species. Richness and diversity records exceed those found in other coastal areas around the world, indicating that these banks are of special relevance for the conservation of echinoderms in Brazil.

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What do we know about Cassis tuberosa (Mollusca: Cassidae), a heavily exploited marine gastropod? ABSTRACTCassis tuberosa is a key species in reefs and sandy beaches, where it plays an essential role as a predator of sea urchins and sand dollars. Due to the beauty of its shell, it is one of the most exploited species for trade as marine souvenirs throughout its distribution in the Western Atlantic. Despite its ecological importance, there is little available information about population and biological data or the impacts of its removal from its natural habitats. Considering the economic and ecological importance of this species, this study provides a short review of existing studies and highlights research and conservation needs for this highly exploited marine gastropod.