Abstract The presence of non-native species is one of the primary drivers of biodiversity loss, disrupting the ecological processes that sustain complex interactions among organisms. Their expansion in freshwater environments is an alarming phenomenon, demanding continuous investigation to map spatiotemporal patterns, assess ecological impacts, forecast future scenarios, and identify strategic areas for intervention to prevent uncontrolled invasions. In the Triângulo Mineiro and Alto Paranaíba (TMAP) region of Minas Gerais, Brazil, non-native species pose an increasing threat. In freshwater systems such as the upper Paraná River basin, the introduction of non-native species is known to alter ecological interactions, disrupt trophic networks, and compromise the persistence of native ichthyofauna. The major tributaries of this basin in the TMAP region, the Paranaíba and Grande rivers, are potentially facing these significant ecological threats. This study investigates the occurrence patterns and spatiotemporal distribution of non-native fish species in the TMAP rivers over the past five decades. We compiled an inventory of non-native fish species in the Paranaíba and Grande rivers, whose tributaries traverse the TMAP, and analyzed geospatial patterns to identify rivers with the highest spatial densities and the temporal trends in species expansion over time. Our inventory revealed 45 non-native fish species present in TMAP rivers, with particularly high occurrences of Cichla spp. (peacock bass), Oreochromis niloticus (Nile tilapia), and Poecilia reticulata (guppy), all characterized by wide spatial distributions and high densities. Our analysis also identified invasion hotspots in key tributaries of the Paranaíba and Grande rivers. Among them, the Araguari, Uberabinha, and lower Tijuco (Paranaíba), and the Claro and São João (Grande) emerged as epicenters of invasion in the TMAP. Although historical records show fluctuations in the abundance of non-native species over the past five decades, a marked trend of rapid expansion, particularly since the 2000s, has been observed. In light of this scenario, conserving the native ichthyofauna of the TMAP requires effective control strategies for non-native species and sustained scientific monitoring in critical areas, especially in the identified invasion hotspots of the Paranaíba River Basin.
Ranuzi et al. (Fri,) studied this question.