Efeitos a jusante da UHE Balbina na ecologia trófica de Cichla temensis Humboldt, 1821, na bacia do rio Uatumã, Amazonas, Brasil

Abstract

The Amazon basin has suffered from the impacts of human activities. Plans to build a series of hydroelectric plants in the Amazon basin are an imminent risk to the Amazonian aquatic environments. The Balbina Hydroelectric Dam was built more than 30 years ago on the Uatumã River and caused several environmental and social impacts in the Uatumã River basin that are still not understood. Cichla temensis sport fishing is one of the main sources of income in the Uatumã Sustainable Development Reserve. However, downstream impacts of the dam on the ichthyofauna were not considered. Thus, this study aimed to evaluate the downstream impacts of Balbina Dam on the trophic ecology of Cichla temensis in the Uatumã river during the late high water to early low water period in 2020. Through the analysis of stable isotopes of carbon and nitrogen from muscle tissue, we determined the downstream effects of the damming of the Uatumã River on the niche width, carbon prey sources, and trophic position of Cichla temensis. Furthermore, from the analysis of stable isotopes from multiple tissues with different turnover rates, we examined the degree of individual specialization in two subpopulations of Cichla temensis. Our results suggest that the isotopic niche of the species was altered by the damming during the analyzed period and that unfragmented river provide better conditions to promote individual specialization than fragmented rivers. This study contributes to understanding how specific characteristics of the life history of populations of generalist predators are impacted by fragmentation in megadiverse environments such as the Amazon environment.