Fish assemblage patterns in a subtropical estuary in southern Brazil / Padrões da assembleia de peixes em uma baía subtropical do sul do Brasil

Abstract: In this study, the relationship between fish assemblage structure and environmental factors was analyzed in a bay in southern Brazil. Fish were collected every two months between February and December 2002 at six sampling sites using bottom trawl nets. Abiotic data (salinity, temperature, rainfall, and depth) and biotic data (number of individuals, biomass, and total length of individuals from each species) were obtained. In total, 56 fish species representing 27 families were collected. Assemblage structure varied with seasonality, as was evidenced by the variation in temperature and rainfall in each season. Catches showed a high abundance of demersal fishes, particularly Genidens genidens, Eucinostomus gula, and E. argenteus.

Resumo: Neste estudo, a relação entre a estrutura da assembleia de peixes e fatores ambientais foi analisada em uma baía no sul do Brasil. Os peixes foram coletados a cada dois meses entre fevereiro e dezembro de 2002 em seis locais de amostragem usando redes de arrasto de fundo. Dados abióticos (salinidade, temperatura, precipitação e profundidade) e dados bióticos (número de indivíduos, biomassa e comprimento total de indivíduos de cada espécie) foram obtidos. No total, 56 espécies de peixes representando 27 famílias foram coletadas. A estrutura da assembleia variou com a sazonalidade, conforme evidenciado pela variação da temperatura e precipitação em cada estação. As capturas mostraram grande abundância de peixes demersais, principalmente Genidens genidens, Eucinostomus gula e E. argenteus.

Variability in nearshore fish biodiversity indicators after a mining disaster in eastern Brazil.

The rupture of the Fundão mining dam (Doce river basin, Brazil) caused a wide range of negative impacts. Yet, assemblage-level implications to estuarine and coastal fishes remain unclear, partly due to the lack of pre-disaster information. Based on monthly otter trawl surveys, we analyzed spatial and seasonal variability in univariate (total biomass, biomass of species vulnerable to exploitation, rarefied richness and evenness) and multivariate (species composition and trophic composition) indicators of fish biodiversity in the Doce river delta, eastern Brazil. We determined the independent and interactive effects of environmental, seasonal and spatial variables on species composition to test whether environmental alterations provoked by mine tailings could affect assemblage's organization. Most indicators present idiosyncratic spatiotemporal patterns, suggesting they have complementary roles in revealing changes in fish biodiversity. Environmental variables, including those affected by the Fundão dam collapse such as turbidity, dissolved oxygen and pH, were much more important than seasonal and spatial predictors in explaining the variation in fish species composition. These findings highlight the potential from mine tailings to disrupt local ichthyofauna and indicate a preponderant role of environmental conditions in assemblage structuring. Given the lack of data prior to rupture, our results may be used as a baseline against which to assess temporal trends in fish biodiversity relative to changes detected in less disturbed estuarine and coastal assemblages.

Marine fish assemblages of Eastern Brazil: An update after the world's largest mining disaster and suggestions of functional groups for biomonitoring long-lasting effects.

When the Fundão dam collapsed in Brazil, 50 million m3 of iron ore tailings were released into the Doce river, resulting in the world's largest mining disaster. The contaminated mud was transported 668 km downstream of the Doce river and reached the Atlantic Ocean 17 days after the collapse. Seven months later, there was evidence that the tailings had reached the largest and richest coral reef formation in the South Atlantic Ocean. This study provides the first description of species composition, abundance, and diversity patterns of fish assemblages in estuaries, coastal areas, and coral reefs affected by the rupture of the mining dam in the Doce river. A linear mixed model (GLMM) was used to evaluate the influence of salinity on fish abundance across estuarine and coastal ecosystems. In addition, based on functional traits related to habitat use and feeding habits, this study identified fish species suitable as bioindicators of the long-lasting effects of this major mining disaster. Bottom trawls were used to sample five estuaries and their respective coastal areas, and a visual census was employed to sample five reef areas, representing an impact gradient. A total of 269 species were recorded in all three habitats, but only seven were shared among them. The results showed lower similarity in assemblages among estuarine areas compared to the coastal and reef areas. Species composition among estuaries and reef ecosystems was more heterogeneous. In contrast, coastal habitats exhibited high homogeneity. Salinity had no statistically significant effect on fish abundance either in estuaries (p = 0.22) and along the coast (p = 0.14). Twelve fish species were identified as suitable bioindicators for evaluating the long-lasting effects of resuspension of contaminated sediments. These species are commonly found in the ecosystems under the influence of the disaster inhabiting potentially contaminated substrates and substrate-associated benthic preys.

Ichthyofauna in the inner continental shelf next to the Paranaguá estuarine complex, southern Brazil / Fauna de peixes da plataforma continental interna próxima do complexo estuarino de Paranaguá, sul do Brasil

The composition and structure of fish assemblages in the inner continental shelf of the Paraná State are affected by cold fronts and the rainfall regime. Data from fishing activities in this region, as well as the analysis of environmental characteristics, are the main tools available for understanding fish dynamics, under influence of increasing human activities. In order to better understand patterns and temporal variations in fish assemblages in the inner continental shelf of the Paraná State, a total of 24 double trawls were performed with an otter trawl between August 2000 and July 2001, in two sampling areas, the North area in front of the northern mouth of the Paranaguá Estuary Complex, and the South area, in front of the Leste beach. A total of 45,277 fish specimens belonging to 35 families and 97 species were caught. Sciaenidae was the most abundant family, with 37.1% of the total number of individuals caught, and with the highest richness (18 species). Statistical analyses evidenced significant differences in environmental characteristics and in fish fauna, and that both areas disturbances were observed in the fish assemblages during the dry and wet season, being more intense in the Southern area, disturbances that would be related to the shrimp fishing present in the two areas sampled in this study.

A composição e estrutura das assembleias de peixes na plataforma continental interna do Paraná são afetadas pelas frentes meteorológicas frias e pelo regime de chuvas. Os dados das atividades pesqueiras da região, bem como a análise das características ambientais, são a principal ferramenta disponível para o entendimento da dinâmica dos peixes, sob a influência de atividades antropogênicas crescentes. Para melhor entender os padrões de assembleia de peixes e suas variações temporais na plataforma continental interna do Estado do Paraná, foram realizados 24 arrastos duplos com rede de arrasto de porta entre agosto de 2000 e julho de 2001, em duas áreas de amostragem, a área norte em frente da entrada norte do complexo estuarino de Paranaguá e a área sul em frente a praia de Leste. Um total de 45.277 indivíduos de peixes foram capturados, pertencentes a 35 famílias e 97 espécies. Sciaenidae foi a família mais abundante, com 37,1% do número total de indivíduos capturados e com a maior riqueza (18 espécies). As análises estatísticas evidenciaram diferenças significativas nas características ambientais e na fauna de peixes, e em ambas as áreas foram evidenciadas perturbações nas assembleias de peixes durante a estação seca e chuvosa, sendo mais intenso na região sul, perturbações que estariam relacionados com a pesca do camarão presente nas duas áreas amostradas neste estudo.

Ichthyofauna in the inner continental shelf next to the Paranaguá estuarine complex, southern Brazil / Fauna de peixes da plataforma continental interna próxima do complexo estuarino de Paranaguá, sul do Brasil

The composition and structure of fish assemblages in the inner continental shelf of the Paraná State are affected by cold fronts and the rainfall regime. Data from fishing activities in this region, as well as the analysis of environmental characteristics, are the main tools available for understanding fish dynamics, under influence of increasing human activities. In order to better understand patterns and temporal variations in fish assemblages in the inner continental shelf of the Paraná State, a total of 24 double trawls were performed with an otter trawl between August 2000 and July 2001, in two sampling areas, the North area in front of the northern mouth of the Paranaguá Estuary Complex, and the South area, in front of the Leste beach. A total of 45,277 fish specimens belonging to 35 families and 97 species were caught. Sciaenidae was the most abundant family, with 37.1% of the total number of individuals caught, and with the highest richness (18 species). Statistical analyses evidenced significant differences in environmental characteristics and in fish fauna, and that both areas disturbances were observed in the fish assemblages during the dry and wet season, being more intense in the Southern area, disturbances that would be related to the shrimp fishing present in the two areas sampled in this study.(AU)

A composição e estrutura das assembleias de peixes na plataforma continental interna do Paraná são afetadas pelas frentes meteorológicas frias e pelo regime de chuvas. Os dados das atividades pesqueiras da região, bem como a análise das características ambientais, são a principal ferramenta disponível para o entendimento da dinâmica dos peixes, sob a influência de atividades antropogênicas crescentes. Para melhor entender os padrões de assembleia de peixes e suas variações temporais na plataforma continental interna do Estado do Paraná, foram realizados 24 arrastos duplos com rede de arrasto de porta entre agosto de 2000 e julho de 2001, em duas áreas de amostragem, a área norte em frente da entrada norte do complexo estuarino de Paranaguá e a área sul em frente a praia de Leste. Um total de 45.277 indivíduos de peixes foram capturados, pertencentes a 35 famílias e 97 espécies. Sciaenidae foi a família mais abundante, com 37,1% do número total de indivíduos capturados e com a maior riqueza (18 espécies). As análises estatísticas evidenciaram diferenças significativas nas características ambientais e na fauna de peixes, e em ambas as áreas foram evidenciadas perturbações nas assembleias de peixes durante a estação seca e chuvosa, sendo mais intenso na região sul, perturbações que estariam relacionados com a pesca do camarão presente nas duas áreas amostradas neste estudo.(AU)

Spatial structure variation of the demersal ichthyofauna captured with botton trawl in the Pinheiros Bay, PR / Variação da estrutura espacial da ictiofauna demersal capturada com rede de arrasto de porta na Baía dos Pinheiros, PR

Spatial changes in the demersal ichthyofauna structure in the Pinheiros Bay, PR, were monitored between May 2003 and April 2004. Three bottom trawls were monthly performed at four points along an axis between the access inlet and inner areas of the Bay. The number of captured species, Shannons diversity index and Margalefs Richness Index were significantly different between inner and outer areas of the Bay. Average capture, expressed by individual total catch, did not differ significantly among the four areas, but spatial separation patterns were observed for some species. The analysis of the spatial structure of species sizes revealed differences in individual total length average values among the studied areas. Some species presented spatial differences in number of individuals caught among the four areas. Cathorops spixii showed preference for more internal areas and Isopisthus parvipinnis, Stellifer rastrifer and Stellifer brasiliensis, for the most external area of the Pinheiros Bay.

No período de maio de 2003 a abril de 2004 foram monitoradas as mudanças espaciais da estrutura da ictiofauna demersal da Baía dos Pinheiros, Paraná, através de três arrastos de fundo realizados mensalmente em quatro áreas ao longo de uma radial entre a barra de acesso e as áreas mais internas da Baía. Foram significativamente diferentes o número de espécies capturadas, o índice de diversidade de Shannon-Wiener e o Índice de Riqueza de Margalef entre as áreas internas e externas da Baía. As capturas médias em número total de exemplares não foram significativamente diferentes entre as quatro áreas, observando-se a existência de padrões de separação espacial de algumas espécies. A análise da distribuição espacial da estrutura de tamanho por espécie revelou diferenças no comprimento total médio dos exemplares entre as áreas pesquisadas. Algumas espécies apresentaram diferenças espaciais de captura em número de exemplares nas quatro áreas, havendo preferência da espécie Cathorops spixii pelas áreas mais internas e de Isopisthus parvipinnis, Stellifer rastrifer e Stellifer brasiliensis pela área mais externa da Baía dos Pinheiros.

Opsanus brasiliensis Rotundo, Spinelli & Zavalla-Camin, 2005 (Teleostei: Batrachoidiformes: Batrachoididae), sinônimo- júnior de Opsanus beta (Goode & Bean, 1880), com notas sobre a ocorrência da espécie na costa brasileira / Opsanus brasiliensis Rotundo, Spinelli & Zavalla-Camin, 2005 (Teleostei: Batrachoidiformes: Batrachoididae), a junior synonym of Opsanus beta (Goode & Bean, 1880), with notes on its occurrence in the Brazilian coast

Neste trabalho, dois exemplares de Opsanus coletados na costa do Paraná, e que representam os primeiros registros do gênero no sul do Brasil, foram identifcados como Opsanus beta (Goode & Bean, 1880). Uma comparação mais detalhada entre estes exemplares e a série-tipo de Opsanus brasiliensis Rotundo, Spinelli & Zavalla-Camin, 2005 (descrita originalmente do litoral de Santos, São Paulo), além de informações da literatura, indicou que Opsanus brasiliensis é sinônimo-júnior de Opsanus beta e que os representantes de Opsanus aqui encontrados são exóticos. É aqui levantada a possibilidade de que O. beta invadiu a costa brasileira através de água de lastro de navios que teriam zarpado das áreas naturais de ocorrência desta espécie.

In this paper, two individuals of Opsanus caught in the coast of Paraná (the first records of this genus in the southern Brazil) were identified as Opsanus beta (Goode & Bean, 1880). Such speciemens were compared with the type series of Opsanus brasiliensis Rotundo, Spinelli & Zavalla-Camin, 2005 (originally described from the coast of Santos, São Paulo), and with the literature data. As a result, Opsanus brasiliensis is herein regarded as a junior synonym of O. beta, and so the exemplars of Opsanus found at the Brazilian coast are exotic. It is herein postulated that O. beta would have invaded the Brazilian coast through ballast water released by vessels that sailed from the natural areas of occurrence of such species.

Spatial structure variation of the demersal ichthyofauna captured with botton trawl in the Pinheiros Bay, PR / Variação da estrutura espacial da ictiofauna demersal capturada com rede de arrasto de porta na Baía dos Pinheiros, PR

Spatial changes in the demersal ichthyofauna structure in the Pinheiros Bay, PR, were monitored between May 2003 and April 2004. Three bottom trawls were monthly performed at four points along an axis between the access inlet and inner areas of the Bay. The number of captured species, Shannons diversity index and Margalefs Richness Index were significantly different between inner and outer areas of the Bay. Average capture, expressed by individual total catch, did not differ significantly among the four areas, but spatial separation patterns were observed for some species. The analysis of the spatial structure of species sizes revealed differences in individual total length average values among the studied areas. Some species presented spatial differences in number of individuals caught among the four areas. Cathorops spixii showed preference for more internal areas and Isopisthus parvipinnis, Stellifer rastrifer and Stellifer brasiliensis, for the most external area of the Pinheiros Bay.

No período de maio de 2003 a abril de 2004 foram monitoradas as mudanças espaciais da estrutura da ictiofauna demersal da Baía dos Pinheiros, Paraná, através de três arrastos de fundo realizados mensalmente em quatro áreas ao longo de uma radial entre a barra de acesso e as áreas mais internas da Baía. Foram significativamente diferentes o número de espécies capturadas, o índice de diversidade de Shannon-Wiener e o Índice de Riqueza de Margalef entre as áreas internas e externas da Baía. As capturas médias em número total de exemplares não foram significativamente diferentes entre as quatro áreas, observando-se a existência de padrões de separação espacial de algumas espécies. A análise da distribuição espacial da estrutura de tamanho por espécie revelou diferenças no comprimento total médio dos exemplares entre as áreas pesquisadas. Algumas espécies apresentaram diferenças espaciais de captura em número de exemplares nas quatro áreas, havendo preferência da espécie Cathorops spixii pelas áreas mais internas e de Isopisthus parvipinnis, Stellifer rastrifer e Stellifer brasiliensis pela área mais externa da Baía dos Pinheiros.