Abstract
Abstract: The Amazonas River basin comprises the world’s highest fish species diversity. Anthropogenic interferences in aquatic environments represent a pressure over the maintenance of ecological stability and biodiversity. We inventoried the ichthyofauna of 13 disturbed/modified tributaries of Urubu and Amazonas rivers in the region of the middle Amazon River, between June 2018 and March 2019. A total of 164 species were captured, represented by 11 orders, 37 families and 96 genera. Characiformes was the richest order, followed by Cichliformes and Siluriformes. The most representative families in number of species were Cichlidae, Serrasalmidae, and Characidae. Hemigrammus levis was the most abundant species, and Acarichthys heckelii the most common, registered in all sampled sites. In the present study, species with economic interest were collected, as well as many species recently described and one still waiting for formal description, identified provisionally as Moenkhausia aff. colletii. Therefore, the high fish diversity registered, even in disturbed environments in Middle Amazonas River, denotes the makeable ecological importance of this region for fishes resources and supports the necessity of evaluation of other aquatic environments in the region, as well as the potential impacts on composition, maintenance, and survival of ichthyofauna in environments directly affected by human activities.
Highlights
The Amazonas River basin is the world’s largest watershed (Goulding et al 2003), and has an area over 8.000.000 km2 (Sioli 1984)
During the rain forest annual flooded pulse, the combination of flat terrain and variable rivers and streams discharge allows the presence of large areas of wetlands and floodplain forest (Junk 1970), resulting in a dynamic complex of seasonally flooded areas with marked ecological importance (Junk et al 2011)
The orders with the highest number of species were Characiformes (56.7%, 93 species) followed by Cichliformes (17.1%, 28 species) and Siluriformes (16.4%, 27 species)
Summary
The Amazonas River basin is the world’s largest watershed (Goulding et al 2003), and has an area over 8.000.000 km (Sioli 1984). The associated channels and wetlands support high values of primary and secondary productivity (Junk 2013). This complex landscape harbors the highest diversity of freshwater fishes in the world, with more than 2,700 species currently considered valid (Dagosta & Pinna 2019). During the rain forest annual flooded pulse, the combination of flat terrain and variable rivers and streams discharge allows the presence of large areas of wetlands and floodplain forest (Junk 1970), resulting in a dynamic complex of seasonally flooded areas with marked ecological importance (Junk et al 2011). The structure and function of Amazon freshwater ecosystems are being increasingly impacted by crescent human activities and territorial modifications (Castello et al 2013). The main impacts evidenced are roads construction and expansion (Jones et al 2000, Barber et al 2014, Smith et al 2018), deforestation (Renó et al 2011, Barber et al 2014, Inomata et al 2018), construction and installation of hydroelectric dams (Junk et al 2007, Alho 2015, Hurd et al 2016, Reis et al 2016, Inomata et al 2018), pollution (Castello et al 2013), and overfishing (Alho 2015, Inomata et al 2018)
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