Environmental typology of rivers from the Brazilian semiarid as a first step for the application of the index of biotic integrity: The case of the Chapada Diamantina

Abstract

Defining environmental river types is an essential step in the development of accurate fish‐based methods (IBI, Index of Biotic Integrity) to assess the environmental quality of aquatic ecosystems. In this study, the environmental typology of the rivers and streams in the region of Chapada Diamantina was developed. Thirty‐five sampling sites representative of the upper Paraguaçu River and its main tributaries were characterized to characterize the fish assemblages and abiotic environmental descriptors. A cluster analysis based on fish species CPUE was performed to define a first biological typology. Then, a discriminant analysis model was developed to select the environmental descriptors that explained the fish‐based river types. The model selected 11 environmental variables and classified 91% of the cases. The river typology defined in this study will be used for the development of an IBI to assess the ecological status of the Chapada Diamantina rivers. It is expected that both the typology developed here and the future IBI will provide important and useful tools to develop and apply nature conservation‐oriented management schemes in the Chapada Diamantina aquatic ecosystems.