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The present work describes sightings of two groups of Tursiops truncatus, one with six and one with fifteen individuals, including four specimens identified by photograph and video, besides personal communications and records by other researchers. The presence of calves in the observed groups and the constant tactile interaction among the individuals suggest they may be using the area for socialization purposes. All the observations were taken on the north-western portion of the atoll which is the most sheltered throughout the year. The sightings of T. truncatus in the REBIO Atol das Rocas contribute to the knowledge about this species in Brazilian oceanic waters and highlight the importance of this area for the conservation of cetaceans.

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The present study examines habitat selection and grazing pressure of the periwinkle Nodilittorina lineolata (Gmelin, 1791) on the rocky shore of Arraial do Cabo, RJ, Brazil (lat. 23°S, long. 43°W). Transfer experiments suggest that periwinkles actively select the mid intertidal, where the cirripede Chthamalus bisinuatus Pilsbry is the dominant sessile invertebrate. We also conducted a caging experiment in the middle intertidal, manipulating grazers and light, to assess the impact of grazing upon microalgal density. Grazing pressure significantly reduced microalgal abundance at the midintertidal level, suggesting that food availability plays an important role in the habitat selection of periwinkles on the studied shore.Key words: Brazil, habitat selection, intertidal, Littorinidae, microalgae. RESUMO Seleção de hábitat de gastrópodes Littorinidae e seu impacto sobre populações de microalgasO presente estudo examina seleção do hábitat e pressão de herbivoria pelo gastrópode Nodilittorina lineolata (Gmelin, 1791) no costão rochoso de Arraial do Cabo, RJ, Brasil (lat. 23°S, long. 43°W). Experimentos de transferência sugerem que os gastrópodos selecionam ativamente a região do médio-litoral, em que o cirripédio Chthamalus bisinuatus Pilsbry é o invertebrado séssil dominante. Nós também conduzimos um experimento de exclusão, com gaiolas, no médio-litoral, manipulando os herbívoros e luz, para acessar o impacto da herbivoria sobre a densidade de microalgas. A pressão de herbivoria reduziu significativamente a abundância de microalgas no médiolitoral, sugerindo que a disponibilidade de alimento exerce um papel importante na seleção do hábitat dos gastrópodos estudados.Palavras-chave: Brasil, Littorinidae, microalgas, seleção de hábitat.

In this reply, we address the criticism directed recently to our work by Galil et al. (2016) dismissing the hypothesis that the Suez Canal can act as a revolving door allowing marine species to move both ways between the Red Sea and the Mediterranean Sea. We reiterate that the presence in the Red Sea of the Indo-West Pacific sea slug Chelidonura fulvipunctata Baba, 1938 is most parsimoniously explained by an invasion from the Mediterranean and highlight several recent studies combing morphology and molecular phylogenetics where established views about the presence of alien Indo-Pacific / Red Sea species in the Mediterranean were proven wrong. Caution is suggested when assuming the conspecificity of species between these realms based solely on external features.