Relações entre diversidade íctia e fatores hidrodinâmicos de um riacho na bacia do rio Uruguai

Abstract

Relationship between ichthyofaunal diversity and hydrodynamic factors in a stream of Uruguay river basin. Biota Neotrop., 9(1): http://www.biotaneotropica.org.br/v9n1/en/ abstract?article+bn00809012009.Abstract: Physical, chemical and environmental factors in watercourses can exert influence on the structure and diversity of species of aquatic biota. Among the physical factors there are hydrodynamic conditions. Disposal variations result into complex dynamics of fish populations and communities. This study aims at assessing the correlation between hydrodynamic variables in the Fortaleza stream, affluent of Uruguay River, and species diversity. The methodology included the collection of hydrodynamic (average depth of the water column, average water flow speed and discharged water in the pluvial metric section) and biological (fish collection in the areas of influence on pluvial metric sections) data. Shannon diversity indices, equitability and the similarity index were calculated with biological data. It has been collected a sample with 527 fishes. There were 25 species, being 4 exotic ones and 4 species not-yet-classified. Such species included 4 orders, 7 families and 13 genera classified. The Shannon index ranged from 1.43 to 2.68 nats/individual. The equitability index was always above 0.8 indicating that individuals are well distributed among different species. The similarity index of Jaccard ranged between 20 and 80%. The lowest figures were obtained from the sample area located near the source. The correlations between the Shannon index and hydrodynamic features resulted in R 2 coefficients ranging between 0.59 and 0.83. These results show that diversity of species is influenced by the hydrodynamic characteristics. Nevertheless, either depth of water column or discharge average speed is not significant enough to explain the spatial variability of the diversity of species. Keywords: streamflow, fish diversity, biologic indexes. KAUFMANN, V. & PINHEIRO, A.Relações entre diversidade íctia e fatores hidrodinâmicos de um riacho na bacia do rio Uruguai. Biota Neotrop., 9(1): http://www.biotaneotropica.org.br/v9n1/pt/ abstract?article+bn00809012009.Resumo: Fatores físicos, químicos e ambientais em um curso de água podem influenciar a estrutura e a diversidade das espécies da biota aquática. Entre os fatores físicos têm-se as condições hidrodinâmicas. Variações do escoamento resultam em dinâmicas complexas das populações e comunidades de peixes. Este trabalho tem por objetivo avaliar as correlações entre as variáveis hidrodinâmicas no Arroio Fortaleza, afluente do rio Uruguai, e a diversidade das espécies. A metodologia compreendeu a coleta de dados hidrodinâmicos (profundidade média da coluna de água, velocidade média do escoamento e vazão escoada na seção fluviométrica) e biológicos (coleta de peixes nas áreas de influência das seções fluviométricas). Com os dados biológicos foram calculados os seguintes índices: o de diversidade de Shannon, o de equitabilidade e o de similaridade. Coletaram-se 527 exemplares, d...

<b>Influence of an artificial dam on the fish assemblage of a Neotropical stream

“…and Bryconamericus iheringii). The low species richness in P1 may have been caused by lower values of depth and flow rate, which reduces the possibility of new habitats, microhabitats, and reproduction sites (Kaufmann & Pinheiro, 2009). However, the dam can be considered responsible for the lower richness upstream, also verified in P3, because these units does not receive species from the Água Feia River, where the Chumbeiro Stream ends.…”