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

A interpretação dos registros da comunidade ictíica têm se mostrado um desafio por diversos motivos, entre eles a falta de dados pretéritos, existência de variações temporais cíclicas na comunidade e pelos métodos utilizados que geralmente subamostram a assembleia. Neste sentido, o objetivo do presente trabalho foi descrever o padrão de variação temporal (nictemeral e mensal) na composição e na estrutura da ictiofauna de uma praia abrigada da Baía Norte de Florianópolis, usando uma rede capéchade. Coletas foram realizadas mensalmente, integrando um período de 48 horas/mês. Durante os meses de dezembro de 2010 a novembro de 2011, 19302 indivíduos distribuídos em 89 espécies e 39 famílias foram capturados. O número de indivíduos capturados durante o dia e/ou noite foi dependente do mês de coleta. Em média, a assembleia foi mais abundante durante o dia, diferindo em estrutura e composição do período da noite. Das oito espécies com maior Índice de Importância Relativa (IRI%), cinco apresentaram maior variação (F ANOVA) entre o dia e a noite do que a verificada entre os meses, o que reforça a necessidade de amostragens durante o dia e a noite. A rede capéchade foi eficiente na captura de indivíduos demersais e pelágicos com ampla faixa de tamanho.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

Variação temporal de peixes em diferentes fases ontogenéticas em uma praia abrigada da Baía Norte, Sul do Brasil

In beach environment daily shifts of fishes have been related to their physiological and ecological needs. On the other hand, the effect of ontogenetic changes in diurnal movement of fish fauna in this region is poorly known. The objective of this study was to evaluate the diel and seasonal variation of three ontogenetic stages of the ichthyofauna in a sheltered beach of the Baía Norte of Florianópolis. A capéchade net was armed and set for 48 hours (within one month periods) at a depth of 0.5 m to 2 m, in each sampling, with harvests performed twice at both dawn and dusk, totaling four monthly samples during an annual cycle. The results indicate that ontogenetic changes did not influence the diel occupancy of most species. The Índio beach showed high richness and juvenile abundance, with the largest number of juvenile fishes in the summer and fall. Adults were abundant in spring and summer. Among the species with highest juvenile catch, Genidens barbus, Micropogonias furnieri, Sphoeroides testudineus and Selene vomer showed residence all year round, with an increase in the mean abundance in the hottest period of the year. The increase in the mean abundance of adults was positively correlated with rainfall and seems to coincide with the spawning period of most speciesKeywords: ichthyofauna, temporal cycles, juvenile fishes.Nos ambientes praiais, os deslocamentos diários dos peixes têm sido relacionados às suas necessidades fisiológicas e ecológicas. Por outro lado, o efeito das mudanças ontogenéticas na movimentação diuturna da ictiofauna nesta região ainda é pouco conhecido. O objetivo deste trabalho foi avaliar a variação diuturna e sazonal da ictiofauna em três estágios ontogenéticos em uma praia abrigada da Baía Norte de Florianópolis. Uma rede capéchade foi armada em uma profundidade de 0,5 m a 2 m e permaneceu por 48 horas/mês em cada uma das coletas, com despescas realizadas no amanhecer e no anoitecer, totalizando duas amostras diurnas e duas noturnas, ou seja, quatro amostras mensais ao longo de um ciclo anual. Os resultados obtidos indicam que mudanças ontogenéticas não influenciaram o padrão de ocupação diuturno da maioria das espécies. A praia do Índio apresentou elevada riqueza e abundância de juvenis, com maior número destes no verão e no outono. Adultos foram abundantes na primavera e no verão. Das espécies capturadas em maior número no estágio juvenil, Genidens barbus, Micropogonias furnieri, Sphoeroides testudineus e Selene vomer apresentaram permanência anual, com elevação nas médias de abundância no período mais quente do ano. A elevação nas médias de abundância dos adultos, provavelmente coincidindo com o período de desova da maioria das espécies, correlacionou-se positivamente com a pluviosidade.Palavras-chave: ictiofauna, ciclos temporais, peixes juvenis

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

Comparison of the temporal and taxonomic patterns of ichthyofauna captured with a fyke net in two sheltered environments in southern Brazil

We use two taxonomic indexes to assess the variability of the taxonomic structure and diversity of the ichthyofauna of two low-energy environments in southern Brazil and to compare the temporal patterns of these two ichthyofaunas. Sampling was conducted in the infralittoral zones of Maciel (Paranagua Bay, PR) and Indio Beach (Norte Bay of Florianopolis, SC). A fyke net was set up at a depth of 0.5 to 2.0 m and left in place for 48 h for each of the samplings. A total of two diurnal and two nocturnal samplings were conducted monthly per one year. The ichthyofaunas at the two sites exhibited similar temporal dynamics, with their abundance and biomass presenting a tendency to increase with increasing temperature during the spring and summer months. A total of 113 species were captured, of which 47 were present at both sites. Harengula clupeola, Sphoeroides testudineus and S. greeleyi were especially abundant at both sites. The co-occurring species displayed similar day and night occupancy trends. In all seasons, the obtained values for the average taxonomic distinctness and variation in taxonomic distinctness were within the confidence intervals. The seasonal reproduction and recruitment patterns led to slight changes in taxonomic distinctness during the year, which were within the expected intervals