O efeito de barragens hidrelétricas sobre populações de peixes de rios de águas pretas na Amazônia: uma abordagem com o uso de marcadores biogeoquímicos e moleculares

Abstract

A widely studied effect of the hydroelectric dams is the habitat fragmentation due the physical barrier originated by their construction. These barriers could be an obstacle to the migratory movements of fish species, which need to realize them to complete their life cycle. The most the studies were developed to understand the dam’s effects on these migratory species and few studies were done taking non-migratory species as target species. The conservation of populational genetic variability is fundamental to the conservation of fish species, including non-migratory ones, and, as consequence, to the maintenance of healthy ecosystems. This study evaluated the effect of the Balbina hydroelectric dam on the movement dynamics and genetic structure of the population of Cichla temensis, to answer a central question “Is the Balbina hydroelectric dam on the Uatumã river a physical and ecological barrier to fish movement and gene flow among C. temensis population?”. To reach this question were performed biogeochemical analyzes based on isotopic signatures of 87Sr/86Sr of otoliths, scales and waters, by mass spectrometry with plasma source and multicoletor, with laser ablation (MC-LA-ICPMS), and molecular analyzes to determine population parameters from biological samples (pelvic fin fragment) using a genomic tool using SNP's, applying the RADseq methodology. Were effectively analyzed 88 otoliths, 20 scales, 78 fin samples from C. temensis and 4 water samples from the Uatumã River. Biogeochemistry allowed us to observe the direct impacts of the fragmentation of the Uatumã river, due to the implementation of the Balbina Hydroelectric Dam, on the behavioral patterns related to the dispersal movements of the population originating from C. temensis of the Uatumã river, especially those inhabiting the area directly under dam influence. The genomics analysis showed that the dam forced a structuring of the C. temensis populations, dividing it into two populational units, one upstream and another downstream. It is hoped that this research will serve as subsidies for further studies, aiming that the fishery resources can be properly managed the environmental effects of hydroelectric projects deeply understood.