Nycthemeral and Monthly Occupation of the Fish Assemblage on a Sheltered Beach of Baía Norte, Florianópolis, Santa Catarina State, Brazil

Interpreting fish community records is challenging for several reasons, including the lack of past ichthyofauna data, the cyclical temporal variations in the community, and the methodology employed, which usually underestimates fish assemblages. The objective of this study was to describe short-scale and meso-scale (nycthemeral period and months, respectively) temporal variations in the ichthyofauna composition and structure of a sheltered beach of Baía Norte (Florianópolis, Santa Catarina state, Brazil), using a capéchade net. Samples were collected monthly for a period of 48 hours. During the period from December 2010 to November 2011, a total of 19,302 individuals belonging to 89 species and 39 families were captured. The number of individuals that were sampled during the day and/or night was dependent on the sampling month. On average, the daytime assemblage was more abundant and different in structure and composition than the nighttime assemblage. Of the eight species that had the highest Index of Relative Importance (%IRI), five had higher variations (ANOVA F) between the day and night than between the months. This finding reinforced the need for sampling during both the day and night. The capéchade net effectively captured demersal and pelagic individuals in a broad range of sizes

Potencial atrator de peixes ósseos em recife artificial no litoral norte do estado do Rio de Janeiro, Brasil Attractor potential of osteichthyes in artificial reef on the northern coast of Rio de Janeiro State, Brazil

<abstract language="eng">Artificial reefs have become an important and popular resource enhancement technique by concentrating fishes and by increasing natural production of biological resources. In order to increase the necto-benthic colonization potencial, an artificial reef was installed on the northern coast of Rio de Janeiro (21º27'S, 41ºOO'W), an area with typically low relief bottom. Measuring nearly 1500 m², the reef consisted of four sets of different materials randomly disposed: concrete pipes (N = 12); tires structures (N = 20); and cement tanks (N = 7) and pre-made blocks (N = 4). ln order to determine the artificial reef effects on the teleost community, trammel nets were used for monthly sampling the reef site (RA) and on a control area (AC) with sandy bottom. During the 23-month survey from April/96 to March/98, were recorded: a) Chaetodipterus faber (Broussonet, 1782) and Haemulon aurolieatum (Cuvier, 1829) as exclusive species of the RA; b) higher values of species richness and abundance on the RA, at least in 5 of 8 periods; c) increase on the fish abundance on summer months. Correlation analysis indicated that salinity and precipitation were the most significant environmental factors correlated with the temporal fish community variation. This results highlight the importance of rainfall periodicity and the influence of Paraíba do Sul River on the nekton assemblage distribution. It is suggested that the functional role of the artificial reef might be related to higher availability of local shelter and food resources

Temporal and spatial variation on heavy metal concentrations in the bivalve Perna perna (LINNAEUS, 1758) on the northern coast of Rio de Janeiro State, Brazil

Heavy metal (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) concentrations were studied in Perna perna from three beaches (Barra do Furado, Buena and Ponta do Retiro) on the northern coast of Rio de Janeiro State by ICP-AES. The average concentration was 0.3 ± 0.04 (Cd); 1.9 ± 0.6 (Cr); 6.1 ± 0.7 (Cu); 1,130 ± 113 (Fe); 22 ± 3.2 (Mn); 9.3 ± 4.6 (Ni); 0.4 ± 0.2 (Pb); 44 ± 5.8 (Zn) µg.g-1 dry weight. There were no significant difference for almost all the studied metals in relation to sex. Although, significant spatial variations (p < 0.05) occurred for Cr, Pb and Ni with higher values for Barra do Furado. Temporal variations were significant (p < 0.05) at the three beaches, however, no trends of accumulation were observed. The metal concentrations were similar to areas under low pollution impact, except for Fe, which was probably due to the local substrates enriched in iron oxides.<br>Este trabalho descreve as concentrações de Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn em Perna perna das praias de Barra do Furado (BF), Buena (B) and Ponta do Retiro (PR) na costa Norte do Estado do Rio de Janeiro. As concentrações dos metais foram determinadas em ICP-AES. As concentrações médias foram 0.3 ± 0.04 (Cd); 1,9 ± 0.6 (Cr); 6,13 ± 0.7 (Cu); 1.130 ± 113 (Fe); 22 ± 3,2 (Mn); 9.3 ± 4,6 (Ni); 0.4 ± 0.2 (Pb); 44 ± 5,8 (Zn) µg.g-1 de peso seco. Não ocorreram diferenças significativas para a maioria dos metais, em relação ao sexo. Variações espaciais significativas (p < 0.05) ocorreram para Cr, Pb e Ni com os maiores valores em BF. Variações temporais significativas (p < 0.05) ocorreram nas três praias, contudo, nenhuma tendência sazonal de acumulação foi observada. As concentrações dos metais foram similares aquelas áreas descritas sob baixo impacto de poluição por metais pesados, exceto para o Fe, cujos altos valores provavelmente estão associados a presença de substratos locais ricos em óxido de Fe