Temporal and spatial variation of rocky shores intertidal benthic communities in Southeast Brazil

The relationships between environmental factors and temporal and spatial variations of benthic communities of three rocky shores of the state of Espírito Santo, Southeast Brazil, were studied. Sampling was conducted every three months, from August 2006 to May 2007, using intersection points. Chthamalus bisinuatus (Pilsbry, 1916) (Crustacea) and Brachidontes spp. (Mollusca) were the most abundant taxa, occupying the upper level of the intertidal zone of the rocky shore. The species richness was higher at the lower levels. The invasive species Isognomon bicolor (C. B. Adams, 1845) (Mollusca) occurred at low densities in the studied areas. The clustering analysis dendrogram indicated a separation of communities based on exposed and sheltered areas. According to the variance analyses, the communities were significantly different among the studied areas and seasons. The extent of wave exposure and shore slope influenced the species variability. The Setibão site showed the highest diversity and richness, most likely due to greater wave exposure. The communities showed greater variation in the lower levels where environmental conditions were less severe, relative to the other levels

Temporal and spatial variation of rocky shores intertidal benthic communities in Southeast Brazil Variação espaço-temporal das comunidades bentônicas do entremarés de costões rochosos no Sudeste do Brasil

The relationships between environmental factors and temporal and spatial variations of benthic communities of three rocky shores of the state of Espírito Santo, Southeast Brazil, were studied. Sampling was conducted every three months, from August 2006 to May 2007, using intersection points. Chthamalus bisinuatus (Pilsbry, 1916) (Crustacea) and Brachidontes spp. (Mollusca) were the most abundant taxa, occupying the upper level of the intertidal zone of the rocky shore. The species richness was higher at the lower levels. The invasive species Isognomon bicolor (C. B. Adams, 1845) (Mollusca) occurred at low densities in the studied areas. The clustering analysis dendrogram indicated a separation of communities based on exposed and sheltered areas. According to the variance analyses, the communities were significantly different among the studied areas and seasons. The extent of wave exposure and shore slope influenced the species variability. The Setibão site showed the highest diversity and richness, most likely due to greater wave exposure. The communities showed greater variation in the lower levels where environmental conditions were less severe, relative to the other levels.<br>Foram realizadas amostragens das comunidades bentônicas de médiolitoral em três costões rochosos do estado do Espírito Santo com o objetivo de estudar a variação espaço-temporal, relacionando com os fatores abióticos. Efetuaram-se coletas trimestrais entre agosto de 2006 e maio de 2007, utilizando o método de pontos de interseção. Chthamalus bisinuatus Pilsbry, 1916 (Crustacea) e Brachidontes spp. (Mollusca) foram os táxons mais abundantes, ocupando os níveis superiores da zona entremarés dos costões. Nas zonas inferiores ocorreu um maior número de espécies. A espécie invasora Isognomon bicolor (C.B. Adams, 1845) (Mollusca) ocorreu em baixa cobertura nas áreas estudadas. O dendrograma indicou a separação das amostras das áreas expostas e abrigadas. Segundo os resultados das análises de variância, as comunidades foram significativamente diferentes entre as áreas e as estações do ano. O grau de exposição às ondas e a inclinação do costão influenciaram a variabilidade de espécies. Setibão apresentou os maiores índices de diversidade e de riqueza, provavelmente devido à maior exposição às ondas. As comunidades apresentaram maiores variações nos níveis inferiores, onde as condições ambientais são menos estressantes em relação aos outros níveis

Gastropod communities associated with Ulva spp. in the littoral zone in southeast Brazil

Phytal communities are characterized by spatial and temporal variation and are influenced by fluctuating biological and physical parameters. This study aimed to describe and compare the gastropods associated with Ulva spp., at three sites of the Espirito Santo coast with ferruginous laterite substrate and different modes of wave exposure. Camburi is characterized by the presence of iron ore particles. Samples were collected bimonthly. At each site, five sampling quadrats were launched at random in the intertidal region. Individuals of Ulva spp. were collected (2964 individuals) and 53 taxa were found. In Camburi the dominant species was Amphitalamus vallei (Barleeidae), while in Capuba and Manguinhos Eulithidium affine (Phasianellidae) predominated. The analyses indicated that Camburi is distinct from the other sites. The lesser wave impacts and the more complex structure of the algae in Camburi, due to the presence of iron ore, may explain this variation

Differential organotin sensitivity in two Leucozonia species from a ship traffic area in southeastern Brazil

Tributyltin exposure is the primary cause of imposex development in gastropods, making them excellent bioindicators. The present research represents the first examination of butyltin (BT) contamination in surface sediments associated with imposex in Leucozonia nassa and L. ocellata in a harbour complex area in Espirito Santo, southeastern Brazil. The objectives of this study were to evaluate the organotin pollution in the area and to assess the sensitivity of both species to BT pollution through imposex development. Specimens were collected between 2007 and 2010 and the sediments were sampled in 2007. Imposex intensity was evaluated based on the percentage of imposexed females, the relative penis length index (RPLI) and the average value of the vas deferens sequence index (VDSI). BTs were analysed using gas chromatography equipped with a pulsed flame photometric detector (PFPD). The results demonstrated the occurrence of elevated concentrations of BTs in the sediment ranging from 383.7 to 7172.9 ng Sn g(-1), indicating a severe contamination of the area, which was confirmed by the biological monitoring results. Our findings also indicated that L. ocellata is a less sensitive species than L. nassa and that this differential sensitivity plays a key role in the distributions of the populations of both species in the studied area