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Aim The present study uses marine prosobranchs from shallow waters (down to 200 m) as a model to determine biogeographical units along the Brazilian coast and to investigate changes in assemblages along the Western Atlantic.Location Western Atlantic Ocean.Methods The composition and species distribution of prosobranchs were determined using secondary data and information gathered from Brazilian scientific collections. The similarities among the areas were calculated using the Sørensen, Simpson and Ochiai Indices, and were illustrated using dendrograms constructed by unweighted pair group method using arithmetic averages. Ordination analysis was performed using non-metric multi-dimensional scaling based on the similarity matrices.Results As a result of the compilation performed, 700 marine prosobranch species distributed in 81 families from shallow waters were recorded in Brazil.The results show a clear correlation between geographic distance between areas and their faunal similarity. There is a gradual latitudinal variation in marine prosobranch assemblages along the Brazilian coastline. The coastal areas sustain richer gastropod assemblages than the oceanic islands.Main conclusions Considering the results of cluster and ordination analyses, this study proposes to divide the Brazilian coast into four regions: (1) Guyanese Province (Amap a state), (2) North-eastern Brazil Area (from the mouth of the Amazon to southern Bahia, Brazil), (3) South-eastern Brazil Area (from southern Bahia to Santa Catarina, Brazil, transition zone), and (4) Argentinian Province (Rio Grande do Sul state). The North-eastern and South-eastern Brazil Areas belong to the Brazilian Province. The Brazilian insular areas are biogeographical units distinct from the other regions studied. Each island has its own composition of marine prosobranchs from shallow waters, while they share species with other coastal and island environments.

A B S T R A C TSessile organisms that live in consolidated substrates frequently compete for space. Coral species have many strategies to face this competition, including harming their opponents or hindering their growth. In the present study, the competitive interactions between three species of zoanthids were investigated in the intertidal zone of a sandstone reef environment in northeastern Brazil. The competitive abilities of the three species were evaluated by periodic observation of the natural fringes of contact and experimental evaluation of their growth rate through removal of 100 cm 2 of colonies of each species. Palythoa caribaeorum and Zoanthus sociatus had similar growth rates, and both species grew faster than Protopalythoa variabilis. The recolonization strategy seems to differ among species. The contact fringes between P. caribaeorum and Z. sociatus remained unchanged over time, without any type of aggressive interaction between them, suggesting that stand-off was the strategy used by these organisms. Palythoa caribaeorum and Z. sociatus grew among the polyps of P. variabilis, often killing its colonies. The coexistence of zoanthids reveals a capacity for survival in the face of competition for limited resources such as free substrate, which led to the colonization and establishment of zoanthids in intertidal environments. R E S U M OA competição por espaço é comum em organismos sésseis que vivem em substrato consolidado. Os corais apresentam muitas estratégias para competição por espaço, incluindo danos ao oponente ou inibição do crescimento. No presente estudo, as interações competitivas entre três espécies de zoantídeos foram investigadas em um ambiente de recifes de arenito no nordeste brasileiro. As habilidades competitivas dos zoantídeos foram analisadas por observações periódicas das margens de contato entre as colônias em ambiente natural e avaliação experimental da taxa de crescimento, através da remoção de uma área de 100 cm 2 de colônias de cada espécie. Palythoa caribaeorum e Zoanthus sociatus apresentaram taxa de crescimento similar, crescendo mais rápido que Protopalythoa variabilis. A estratégia de colonização parece ser diferente entre as espécies. As margens de contato entre P. caribaeorum e Z. sociatus permaneceram inalteradas ao longo do tempo, sem qualquer interação agressiva entre as colônias, sugerindo que a inibição do crescimento foi a estratégia utilizada. Palythoa caribaeorum e Z. sociatus cresceram entre os pólipos de P. variabilis, muitas vezes sufocando e matando suas colônias. A coexistência entre os zoantídeos revela uma capacidade de sobrevivência frente a recursos limitados, como substrato livre, o que levou ao sucesso na colonização e estabelecimento de zoantídeos em ambientes intertidais.

Coastal reef environments support a great diversity of benthic species, which are physically arrayed according to their adaptations to biotic factors such as competition and to abiotic factors such as salinity and desiccation. Few studies have described adaptive strategies on rocky shores in tropical regions. This contribution deals with the spatial distribution of three species of zoanthids (Palythoa caribaeorum, Protopalythoa variabilis and Zoanthus sociatus) on flat sandstone reefs in northeastern Brazil. Zoanthid distribution and abundances were determined as the percentage of cover along six transects, where 50 × 50 cm quadrats were sampled. Biotic data (influence of macroalgal cover) and abiotic data (relief, substrate type, temperature and salinity) were also taken along the transects to attempt to explain the zoanthid distribution. These species tended to colonize the middle and low intertidal zones, which are least exposed to air. Zoanthus sociatus apparently resists desiccation better than P. caribaeorum. Protopalythoa variabilis showed the highest abundance and frequency, occurring in the entire middle intertidal zone and colonized areas with high proportions of unconsolidated sediment. Desiccation was the main factor limiting the spatial distributions of the three species, although substrate composition and probably interspecific competition with macroalgae were also important. The results suggest that the zoanthids use a variety of these adaptive strategies, which account for their success on consolidated substrates. Continuous monitoring of changes in distribution patterns can be useful for indicating human impacts on marine biodiversity, providing insights for monitoring and conservation programmes.

The use of antifouling paints containing the biocide compound tributyltin (TBT) has been shown as an inductor of imposex in neogastropods mollusks. Imposex is characterized by the development of male features in females, mainly the appearance of a no functional vas deferens and penis. Samples of Thais rustica were collected in eight sites in the metropolitan area of Natal city, Rio Grande do Norte state, northeast Brazil, and examined for occurrence of imposex, which was found in many females. The higher imposex levels were presented by samples from sites near city harbor.
A utilização de tintas antiincrustrantes contendo o composto biocida tributilestanho (TBT) tem induzido moluscos neogastrópodes ao imposex. O imposex é caracterizado pelo surgimento de caracteres sexuais masculinos, sobretudo, pênis e vaso deferente não funcionais em fêmeas desses moluscos. Foram coletadas amostras de Thais rústica em oito estações ao longo da costa da cidade de Natal no Rio Grande do Norte. Esses animais foram analisados quanto a presença e o grau de imposex que apresentavam. Os níveis mais elevados de imposex foram observados na estação mais próxima ao porto

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Some marine animals have a dynamic mutualistic association involving heterotrophic coral animals (hosts) and autotrophic dinoflagellate endosymbionts in the genus Symbiodinium, known as zooxanthellae, which are directly involved in their physiology. Currently, there is limited knowledge of the Symbiodinium diversity associated with zoanthids from the Brazilian coast. Hence, this study assessed the diversity of zooxanthellae associated with Palythoa caribaeorum, Zoanthus sociatus and Protopalythoa variabilis commonly found on the northeast coast. Zoanthids samples were collected from sandstone reefs, and the total DNA from the samples was extracted. Diversity was assessed by denaturing gradient gel electrophoresis (DGGE) and ITS region cloning library. Data from ITS region sequences showed that zoanthids hosted two phylogenetic subclades or subgenus (C1 and A3) closely related to Symbiodinium from previous studies. Subclade C1 was found in Pa. caribaeorum, Pr. variabilis and Z. sociatus, while subclade A3 was found exclusively in Z. sociatus. This suggests that Pa. caribaeorum and Pr. variabilis are extremely selective, whereas Z. sociatus shows greater flexibility in the selection of its symbionts, and these differences may be involved with living in different reef environments. Knowledge of zooxanthellae diversity associated with zoanthids can explain their large distribution in Brazilian coast and contribute to a better understanding of zoanthid's sensitivity to thermal stress.

Most of the scyphozoans and cubozoans recorded for the Brazilian coast are presumed to be distributed over the entire coastline, but little information on precise records is available. This paper presents the first published records for the Ceará state (northeastern region) of the cubozoan Chiropsalmus quadrumanus, and the scyphozoans Chrysaora lactea, Linuche unguiculata (polyp), Lychnorhiza lucerna, Nausithoe sp. (polyp), Phyllorhiza punctata, and Stomolophus meleagris. The medusoid species have been known by local fishermen and non-specialists for a long time in the area. A maioria das cifomedusas e cubomedusas registradas para o litoral brasileiro é presumivelmente distribuída por toda a costa; porém poucos registros precisos estão disponíveis. Este estudo apresenta os primeiros registros publicados para o estado do Ceará (região Nordeste) da cubomedusa Chiropsalmus quadrumanus, e dos cifozoários: Chrysaora lactea, Linuche unguiculata (pólipo), Lychnorhiza lucerna, Nausithoe sp. (pólipo), Phyllorhiza punctata and Stomolophus meleagris. As espécies de medusas são conhecidas de longa data por pescadores locais e não-especialistas no grupo. Cifomedusas, cubomedusas, águas-vivas, Chirodropidae, Coronatae, Semaeostomeae, Rhizostomeae Biota Neotropica v6 (n2) -http://www.biotaneotropica.org.br/v6n2/pt/abstract?inventory+bn01406022006 Palavras-chave: