Caracterização e influência dos fatores ambientais nas assembléias de peixes de riachos em duas microbacias urbanas, Alto Rio Paraná

Abstract

Abstract:To quantify the influence of environmental descriptors on fish diversity and abundance in two small urban sub-basins in the Upper Paraná basin, we carried out two sampling series in the dry season (June and July) and two in the wet season (November and December), by means of a sieve (80 × 120 cm) and a standardized effort (20 throws) per site. We collected 1,667 fish belonging to 20 species. Serrapinnus notomelas was the most abundant species, followed by Oligosarcus pintoi. The variations in species richness and evenness were explained by water electrical conductivity, stream depth, and stream width. The Cluster Analysis results showed a clear differentiation among the sites, with significant spatial differences and no seasonal variation in species composition. The first two axes of the Canonical Correspondence Analysis (CCA) explained 55% of the variation in species abundance, and the main determinants of species distribution were stream width and water conductivity and turbidity. Keywords: water quality, freshwater fish, urban streams, water contamination. Resumo: Com o objetivo de quantificar a influência das características ambientais sobre a diversidade e abundância de peixes em duas microbacias urbanas na bacia do Alto Rio Paraná, foram realizadas duas amostragens no período de seca (junho e julho) e duas no período de chuva (novembro e dezembro) utilizando uma peneira (80 × 120 cm), com esforço padronizado em 20 lances por local. Foram coletados 1.667 indivíduos, distribuídos em 20 espécies. A espécie mais abundante foi Serrapinus notomelas, seguida de Oligosarcus pintoi. A variação na riqueza de espécies e na equitabilidade foram explicadas pela condutividade, profundidade e largura dos riachos. Os resultados da análise de agrupamento e da ANOSIM mostraram diferença espacial significativa e ausência de variação temporal na composição de espécies. Os dois primeiros eixos da Análise de Correspondência Canônica (ACC) explicaram 55% da variação na abundância das espécies e os principais determinantes na distribuição das espécies foram a largura dos riachos, condutividade elétrica e turbidez da água. Palavras-chave: qualidade da água, peixes de água doce, riachos urbanos, contaminação da água.

Diet and trophic guilds of fish assemblages in two streams with different anthropic impacts in the northwest of Paraná, Brazil

“…Thus, any qualitative or quantitative changes modify the structure of biotic communities, including the trophic chain (PUSEY & ARTHINGTON 2003). In degraded environments, the use of large quantities of items such as detritus as a food source is well documented, though mainly by introduced species tolerant to environmental disturbances and generalists, such as P. reticulata (CUNICO et al 2006, FERREIRA & CASATTI 2006, FELIPE & SÚAREZ 2010. This species was present in the sampled streams, particularly in Morangueiro, which is more degraded as a function of receiving a large load of urban pollution.…”

Composition and diversity of the fish assemblages under influence of a gradient river/dam of Taquari River, São Paulo, Brazil

“…Rare species generate a great number of null values impairing the establishment of biological associations. Thus, these species were eliminated in the ordination [20]. The species matrix was composited by 19 species in 11 samplings, the environmental matrix was composited by nine numeric variables (abiotic factors) and one categorical variable (month) in 11 samplings.…”

Ichthyofauna of tributaries of the Vermelho River, upper Paraguay River basin, region of Rondonópolis, state of Mato Grosso, Brazil

“…As shown by Sala et al (2000), changes in riparian zones can lead to increased input of nutrients, sediments and contaminants, significantly impacting the communities who live there. As a result of these factors, Dudgeon et al (2006) and Felipe and Súarez (2010) reported that the significant drop in water quality leads to loss of aquatic biodiversity due to the disintegration of the physical and chemical environment and changes in the natural dynamics of biological communities. Therefore, it is urgent to study the taxonomic and systematic composition as well as the ecological parameters of the streams that house this unknown ichthyofauna (Castro 1999).…”