Estudo das potenciais respostas ecológicas às alterações hidrológicas ocorridas no baixo trecho do Rio Paraguaçu-Ba

Abstract

The integrity of aquatic and riparian ecosystems and floodable areas is conditioned by the flow regime, so that the implementation of dams in riverbeds leads to several ecological impacts, especially in the downstream section, where there is a change in the hydrological regime. The aim of the work was to study the potential ecological responses, with an emphasis on ichthyofauna as an environmental indicator, to the hydrological changes assessed in the lower stretch of the Paraguaçu River influenced by the presence of the Pedra do Cavalo dam. The analysis was carried out using the IHA (Indicators of Hydrologic Alteration) software, studying the five components of river flow critical to ecological processes: magnitude, duration, frequency, periodicity and rate of change. Furthermore, information on local ichthyofauna contained in the Inema/UFBA report (2013) was considered. It was found that all components of the flow underwent changes, the main one was the regularization of flows, among their potential ecological responses, according to the literature, are: losses in reproductive processes and recruitment, changes in the set of species, increase of non-native species and loss of sensitive species. The diagnosis of the local ichthyofauna, carried out by INEMA/UFBA (2013), presented aspects such as changes in species composition and the presence of introduced species, which are pointed out in the literature as consequences of changes in magnitude, periodicity and rate of change. Therefore, the need to establish an environmental hydrograph is evident so that ecological demands are met in the different locations of the stretch.