Investigating the feasibility to remove SHP Pandeiros: lessons from fish fauna

Abstract

The presence of hydroelectric power plants in rivers causes severe impacts on the aquatic environment around the world. Although the impacts are inherent to dams, the identification of the type of change suffered varies according to each system in which the plant is inserted. The difficulty of measuring and assessing the magnitude of these changes is even more critical for tropical aquatic environments. Even if the impacts are identified, after the construction of a hydroelectric power plant these are rarely mitigated. However, in the last decades, as part of river and basin restoration programs mainly in the United States of America and some countries in Europe, the physical removal of these dams has been adopted as a management measure to reestablish the natural characteristics before the plants. In this context, this thesis aims to identify the possible impacts from the hydroelectric plant present in the Pandeiros River located in the São Francisco River basin, Brazil in order to create subsidy for the decision making of its removal. First, an approach is taken to the scenario of hydroelectric production and conservation of aquatic environments in developing countries with a focus on Brazil, demonstrating the impacts of hydroelectric power plants and the difficulties of mitigating such impacts, raising the possibility of using the technique of physical dams removal As a management measure to restore aquatic environments (Article 1). Second, it is an empirical evaluation of the effects on the fish community (richness, abundance and composition) separated by a hydroelectric plant (Article 2). The third, is evaluation of the variation of the fish assemblages along the river Pandeiros from the perspective of the trophic dynamics and influence of the dam in this dynamic (Article 3). To reach the objectives it’s were used two-year (2014-2016) sampling data at eight sampled sites along the river, comprising a longitudinal gradient considering the influence of the dam. In general, the results found emphasize the changes in the community and in the trophic dynamics of the ichthyofauna caused by the SHP Pandeiros. In the three approaches we discuss the possible effects of the removal of the dam on the Pandeiros River, emphasizing that the ichthyofauna present in certain sites of the river it’s caused by the dam. Concluding that it is expected that after the removal occurs a restructuring of the community of fishes possibly resulting in the similar dynamics prior to the SHP Pandeiros.