Anthropogenic environmental changes are the main cause of species extinction during the Holocene. Species have been exposed to major source of threats, such as habitat loss and fragmentation, pollution, introduced species, and harvesting, many of which are derived from specific anthropogenic activities, such as urbanization, agriculture, and damming (i.e. fine-scale threats). However, the importance of these threats on the species conservation status in a given region depends on the type of impacts they are exposed to and the susceptibility of species to these impacts. In this study, we used a database of threatened Brazilian freshwater fish species to test whether the major source of threats and the specific anthropogenic impacts to species vary across hydrographic regions and taxonomic groups. Our results showed that habitat loss is a ubiquitous major threat jeopardizing the conservation status of the Brazilian fish species. However, different fine-scale threats mediate this process across hydrographic regions and taxonomic groups. The combination of impacts from agriculture, deforestation, and urbanization affects most of the threatened species in the basins of the Northeast, South, and Southeast, including the species of the most threatened order, the Cyprinodontiformes. Damming is the main human activity affecting threatened species of Siluriformes, Characiformes, Gymnotiformes, and Cichliformes, especially in northern basins (Amazon and Tocantins-Araguaia). Therefore, we found that specific fine-scale threats influencing threatened species vary across hydrographic regions and taxonomic groups, probably due to geographic variability in the incidence of human activities and differential niche requirements and vulnerability of species to these activities.

The Araguaia River is an important watercourse located in Central Brazil and well known for its diversity of fish fauna. Differences between landscape and resources in the distinct environments existing in a floodplain can determine the success of a species. This study presents a list of ichthyofauna species found in lentic and lotic environments in the floodplain of the Araguaia River basin, bordering Mato Grosso and Goiás States. We carried out sampling in July 2019, during the dry season, using diverse fish collection strategies, such as waiting nets, trawl, cast net and fishing rods. Were distributed 12 sampling points between lentic and lotic environments and we captured a total of 168 individuals of 42 species, 19 families and six orders. The predominant orders were Characiformes, Siluriformes and Cichliformes, while the families were Serrasalmidae, Characidae, Triportheidae, Curimatidae and Anostomidae. The genera Triportheus, Psectrogaster and Moenkhausia were the most abundant, while Pimelodus was the most dispersed. Results showed greater abundance and diversity in the lentic environment than in the lotic one, with top-of-the-chain species in both. The variance between environments and the presence of species that are endemic, recently described, of undefined taxonomic status, and bioindicators, highlight the importance of conserving and further studying the ichthyofauna in the Araguaia River basin.