Molluscs associated with the macroalgae of the genus Gracilaria (Rhodophyta): importance of algal fronds as microhabitat in a hypersaline mangrove in Northeastern Brazil/Moluscos associados a macroalgas do gênero Gracilaria (Rhodophyta): importância das frondes algais como microhabitat em um manguezal hipersalino no Nordeste do Brasil

In this study, the authors characterized the malacofauna associated with the macroalgae Gracilaria domingensis (Kutzing) Sonder ex Dickie 1874 and Gracilaria cuneata Areschoug 1854 of a hypersaline mangrove on the northern coast of the state of Rio Grande do Norte, Northeastern Brazil. The first alga dominates in the rainy season and it is substituted by second one in the dry period. A total of 1,490 molluscs were surveyed, representing 56 species in 29 families: 1,081 were associated with G. domingensis and 409 with G. cuneata, the latter showing the greater diversity. Columbellidae, Neritidae, Pyramidellidae and Cerithiidae were among the most representative families in the number of species and individuals. The micromolluscs were dominant in the algal microhabitat, constituting 74.63% of the malacofauna recorded. The columbellid Parvanachis obesa was the dominant species followed by the neritid Neritina virginea in both algae. In spite of the annual alternated succession of the algae species, at least 15 mollusc species are common for these algae.