Ictiofauna em três reservatórios do Rio Apodi-Mossoró, semiárido brasileiro, antes da transposição do Rio São Francisco

Ichthyofauna in Three Reservoirs of the Apodi-Mossoró River, Brazilian Semiarid, Before the Transposition of the São Francisco River

Abstract

The São Francisco River Transposition Project may impact receiving reservoirs due to changes in environmental characteristics and the potential introduction of new species, leading to biotic homogenization and alterations in water features. This study aimed to analyze fish composition in three reservoirs (Santa Cruz, Umari, and Pau dos Ferros) in the Apodi-Mossoró River basin before transposition. Quarterly sampling at various locations was conducted using gillnets. Fish were identified and assessed based on their origin (native, allochthonous, or exotic). Species accumulation curves were generated for each reservoir to evaluate the capture methodology's effectiveness, estimating species richness over months. Twenty-two species belonging to 11 families and three orders were recorded, with 81.82% being native, 13.64% allochthonous, and 4.54% exotic. Characiformes was the most representative order, followed by Perciformes and Siluriformes. The most diverse families within these orders were Characidae, Cichlidae, and Loricariidae. Similarity in abundance was observed among native, allochthonous, and exotic species across reservoirs. Considering the scarcity of taxonomic composition studies in semi-arid ecosystems, this research provides a significant reference for future studies on native fish conservation.