Diversidade e fatores estruturadores de uma assembleia de peixes em uma bacia inserida em unidades de conservação

Abstract

The rivers comprise less than 0.01% of the existing fresh water. Despite its small extension compared to other ecosystems, such as terrestrial for example, the continental waters shelter about 15 thousand species of fish that occupy these ecosystems occasionally or exclusively. Despite their importance as a direct source of water and high biodiversity, these ecosystems are among the most affected globally by anthropic actions. However, protected areas directed to the preservation of freshwater ecosystems are rare. Therefore, describing diversity patterns and understanding the ecological and evolutionary processes that shape this diversity, in addition to the anthropic influences in these ecosystems, is of paramount importance for the maintenance of their ecological services. In this sense, our study was carried out in the Pandeiros river basin, located in the northern mesoregion of the state of Minas Gerais, which is inserted in two Conservation Units, whose main objective is the maintenance of the ichthyofaunistic diversity and the aquatic ecosystem as a whole . We sought to evaluate how the fish assemblage structure responds to the abiotic factors at different spatial scales, to evaluate how the spatial diversity of the ichthyofauna varies in the fluvial longitudinal gradient, and to determine the effectiveness of the Conservation Units through the degree of antropic disturbance in the lotic stretches of the basin. Our results demonstrated that local variables of physical habitat are the ones that most influence the structuring of fish assemblages. We conclude that in basins with a low degree of disturbance the local characteristics of physical habitat and the longitudinal gradient of these lotic systems are the main factors in the structuring of fish assemblages, and that these are indirectly affected by the environmental quality.