Abstract
Abstract: 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.
Highlights
Freshwater ecosystems have been negatively impacted by various anthropogenic actions (Dudgeon et al 2006)
We studied how threats influencing the conservation status of Brazilian threatened fish species are distributed across hydrographic regions and taxonomic groups
Habitat loss or degradation are by far the biggest threats to fish, affecting all representative taxonomic groups and hydrographic regions of Brazil
Summary
Freshwater ecosystems have been negatively impacted by various anthropogenic actions (Dudgeon et al 2006). Freshwater biota has suffered higher extinction rates than terrestrial and marine in the last decades (Jenkins 2003, Dirzo et al 2014). The effects of these major threats are derived from human impacting activities (i.e. fine-scale threats) (Venter et al 2016) whose impacts are context-dependent, since their occurrences and intensities show geographic variability (Vörösmarty et al 2010). Intrinsic (i.e. biological traits) and extrinsic factors (e.g. type of impact) are important drivers of species vulnerability (Olden et al 2007)
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