Fatores responsáveis pela variação dos componentes da diversidade beta na assembleia de peixes em riachos de cabeceira.

Abstract

Fish assemblage composition varies across time and space, and beta diversity has been a valuable tool for quantifying this variation and understanding associated mechanisms. Understanding which factors determine the action of these mechanisms is fundamental for headwater stream management and conservation projects. Therefore, was evaluated which component of total beta diversity (species replacement or difference in richness) is most representative for the fish assemblage between streams, identified the scale of effect of land use on this assemblage, and evaluated the relative influence of land use, local environment and distance between collection points on beta diversity components. The study was carried out in 12 headwater streams close to and located in the municipality of Maringá, Paraná, Brazil. The percentage of land use classes was measured at 11 spatial scales, five buffers from the sampled section and six from the water network upstream of the sampled section. The data was analyzed using Redundancy Analysis based on distance and variance partition. The results showed that species replacement was the most important component for total beta diversity, with land use in buffers 100 and 500 meters from the sampled section considered the scale of effect for the variation of the components. Land use and local environmental variables were more representative for total beta diversity and richness differences and the distance between collection points for species replacement. It was concluded that land use and local environmental variables select fish species, reducing richness in urban areas, while the dispersal limit acts on species replacement. Therefore, it is suggested that management and conservation projects should be focused on land use, conserving or restoring riparian forest, which would improve the local quality of streams, mainly urban streams, which are the most altered.