Diet of fish fauna from Franco stream, Mato Grosso do Sul, Brazil. The aim of this study was to characterize the diet of the most abundant fish species in the Franco stream (Ivinhema, MS). Fish were captured monthly, from March 2006 to February 2007. To infer the diet of species that feed on macroscopic items, the stomach contents of each individual was removed, weighed (g) and subsequently analyzed under stereomicroscope. The data obtained for each species in each sampling unit were analyzed with the following methods: Frequency of Occurrence, Volumetric Analysis Index and Index of Importance. We collected 17 species of fish, the vast majority Characiformes, with ten species, two species of Siluriformes, two of Perciformes, two of Gymnotiformes and one of Synbranchiformes. The diet of two species of the genus Astyanax was based mainly on items of plant origin; Serrapinnus notomelas fed up of plant items, mainly from algae; Hemigrammus marginatus showed a mainly insectivorous feeding habits of alien origin, Corydoras aeneus and Eigenmannia trilineata fed up primarily of aquatic insects; sediment was the main food item of Hypostomus ancistroides, followed by algae and macrophytes; Crenicichla britiskii fed mainly on terrestrial insects.

In this study, it was examined the reproductive biology of Astyanax. altiparanae, in streams with different levels of environmental disturbance in the Ivinhema river basin (Mato Grosso do Sul State, Brazil). Samplings were conducted between July 2001 and November 2011, at 101 sites, using sieves, seining nets, gill nets and electrofishing. Streams were classified into three levels of environmental integrity. We analyzed 735 specimens, 410 females and 325 males. Females predominated in impacted streams and both sexes presented nearly the same pattern of length distribution in the three levels of environmental integrity. Females reached gonadal maturity with greater lengths (L 50 = 55.67mm) in altered and impacted streams and had higher reproductive activity between October and December. The species showed higher Condition Factor and higher reproductive intensity in the impacted streams. Our results evidenced that in impacted sites the species exhibited a good ability to allocate a significant portion of its energy to reproduction, probably due to the greater supply of food.

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–  The aim of this study was to describe and quantify the effect of aquatic pollution on the fish assemblage structure of the Corumbataí River (Brazil), by comparing two sites with different water quality characteristics. The results revealed that abundance of individuals was low at the polluted site (B). However, the two sites did not differ significantly in species richness (total and average). This fact contradicts theories stating that portions where the transverse area of the channel is larger should present a higher biological richness. It was also observed that the ichthyofauna of site B had higher evenness, and, consequently, a tendency to a higher diversity than that at site A. This demonstrates that diversity estimates should be used cautiously in environmental impact studies, as they do not necessarily indicate better conditions of communities living in more preserved environments.

ABSTRACT. This study analyzed physicochemical characteristics of the water, degradation of the surroundings and the influence of these factors on the diet of two fish species of Astyanax in Tarumã stream microbasin, central western Brazil. Fish were collected in eight sites between 2007 and 2010, using gillnets and sieves. Environmental variables were evaluated by a principal component analysis and the diet based on Spearman's correlation. The variables width, type of riparian vegetation, pH, conductivity, total dissolved solids, temperature, oxidation and reduction potential, presence of waste, and altitude have separated the sampling sites into two groups: 'less impacted' and 'more impacted'. The two characid species presented omnivorous habit, typical of disturbed environments. The consumption of food resources was different over the space: terrestrial plants and sediment were more important in the most impacted sites for both species. And specifically to Astyanax altiparanae the order of importance of the food was distinct between most and less impacted sites. These data indicated that the diet of these species is a suitable tool for analyzing the environmental quality of the studied sites.Keywords: environmental degradation, streams, ichthyofauna, food.Influência da qualidade ambiental na dieta de Astyanax em uma microbacia do CentroOeste do Brasil RESUMO. Este trabalho teve como objetivo analisar as características físico-químicas da água, degradação do entorno e a influência destes fatores na biologia alimentar de duas espécies de Astyanax na microbacia Touro-Tarumã, Centro-Oeste do Brasil. Os peixes foram coletados em oito locais, de 2007 a 2010, utilizando redes de espera e peneirões. As variáveis ambientais foram avaliadas por análise multivariada e a dieta pela correlação de Spearman. As variáveis ambientais largura, tipo de mata ciliar, pH, condutividade, sólidos totais dissolvidos, temperatura, potencial de oxidação e redução, presença de lixo e altitude permitiram diferenciar os locais de coleta em "mais impactados" e "menos impactados". As duas espécies de caracídeos estudadas apresentaram comportamento onívoro, que é típico de ambientes alterados. Os recursos alimentares consumidos pelas espécies diferiram espacialmente: vegetais terrestres e sedimento apresentaram maior importância nos locais mais impactados para as duas espécies. Especificamente para A. altiparanae a ordem de importância do alimento consumido diferiu entre os locais mais e menos impactados. Estes dados indicam que o estudo da dieta destas espécies mostrou-se uma ferramenta adequada para análise da qualidade ambiental destes locais.Palavras-chave: degradação ambiental, riachos, ictiofauna, alimentação.

Recebido em: 24/07/2016-Aprovado em: 02/12/2017-Disponibilizado em: 30/12/2017 RESUMO Estudo comparativo entre riachos distintos da bacia do rio Paraná pela aplicação de Protocolo de Avaliação Rápida (PAR). Sendo contemplados nove parâmetros e gradiente de estresse, classificado nas categorias: "ótima" (nota 16 a 20), "boa" (nota 11 a 15), "regular" (nota 6 a 10) e "péssima" (nota 0 a 5), sendo este último o mais alto nível de estresse. O PAR foi aplicado por dois avaliadores e as notas atribuídas a partir da inspeção visual das condições físicas do ambiente, calculou-se a média dos valores de cada parâmetro e a nota final pela somatória dos parâmetros. O PAR revelou que riachos inseridos em Unidades de Conservação apresentam-se melhores preservados. Enquanto que os riachos urbanos apresentaram a pior qualidade dos elementos físicos e estado crítico quanto aos aspectos propostos no PAR. Medidas recomendadas foram: implantação de plano de gestão ambiental para preservação dos recursos hídricos; aplicação do PAR a outros trechos; a utilização dos dados para sensibilização da população regional, considerando ser o PAR uma ferramenta útil para categorizar as condições ambientais de riachos e a qualidade de habitats. Palavras-chave: Condições ambientais. Unidade de conservação. Avaliação de habitats. Microbacias urbanas. ABSTRACT Comparative study among different streams of the Paraná River basin by applying a Rapid Assessment Protocol (RAP). It is contemplated nine parameters and stress gradient rated in the categories: excellent (score 16-20), good (score 11-15), regular (score 6-10) and poor (score 0-5). RAP was applied by two raters and the scores were assigned based on visual inspection of the physical condition of the environment; the value of each parameter was obtained by averaging the values assigned by the raters and the final score by the sum of the parameters. In a gradient, RAP revealed that water bodies within conservation units were better preserved. It"s necessary the implementation of an environmental management plan aimed at conserving water resources in the watershed; the application of RAP to other stretches; the use of data to raise awareness in the regional population, considering RAP as a useful tool to categorize the environmental conditions of the streams and habitat quality.