Abstract
Abstract: The Araguaia River basin has the highest fish biodiversity within the Cerrado biome (Brazilian savannah), with many endemic and threatened species by human activities. Despite growing efforts to catalog Neotropical freshwater fish biodiversity, many regions are still undersampled. Our objective is to complement the information about stream fish in two hydrographic basins in the Cerrado. We sampled 72 streams with 50 m stretch in the Upper Araguaia (n = 32) and Middle Rio das Mortes (n = 40) basins. We collected 14,887 individuals distributed in 137 species, 81 genera, 30 families, and six orders. Characidae, Loricariidae, and Cichlidae were the families richer in species. We found a high diversity of rare fish species in the streams sampled, ca. 71.5% of the species had at least five individuals collected, and 18 species had only one collected specimen. The most frequent species were Astyanax cf. goyacensis, Knodus cf. breviceps, and Characidium cf. zebra. Both basins shared around 43% of the species. We caught 76 species in Upper Araguaia and 120 species in Middle Rio das Mortes. Seventeen exclusive fish species occurred in Upper Araguaia, whereas 61 were found in the Middle Rio das Mortes basin. Our analysis showed lower diversity of fish in Upper Araguaia than in the Middle Rio das Mortes basin. Considering the exclusive fish species of both basins, the human threats in those regions, and the few existent protected areas, we need a better look at the aquatic biodiversity conservation of this ecosystem.
Highlights
The Cerrado is a Brazilian biome considered one of the global biodiversity hotspots due to its high species riches, endemic rates, and human threats to its biodiversity (Myers et al 2000)
Among the river basins originating within the Cerrado, the Araguaia River basin harbors more considerable fish diversity (Dagosta et al 2020), with more than 320 currently described species and many with a restricted distribution that mainly occupies the headwaters (Latrubesse et al 2019)
We sampled a total of 72 streams ranging from first to fourth order according to Strahler’s (1957) classification in the Upper Araguaia and Middle Rio das Mortes basin, belonging to the Tocantins–Araguaia ecoregion (Figure 1, Table 1)
Summary
The Cerrado is a Brazilian biome considered one of the global biodiversity hotspots due to its high species riches, endemic rates, and human threats to its biodiversity (Myers et al 2000). The origins of large South American rivers (Amazonica, Tocantins-Araguaia, Paraná, and São Francisco basin) are inserted into this biome, which is informally entitled the Brazilian “berço das águas” (water cradle). The water bodies of Cerrado (e.g., rivers, lakes, and streams) harbor about 1200 cataloged fish species (ICMBio 2020), corresponding to 25% of South American freshwater fish species. It is important to highlight that many of the Cerrado fishes are endemic and represent more than 42% (n = 131) of the threatened Brazilian fish species (Latrubesse et al 2019). Among the river basins originating within the Cerrado, the Araguaia River basin harbors more considerable fish diversity (Dagosta et al 2020), with more than 320 currently described species and many with a restricted distribution that mainly occupies the headwaters (first to third order) (Latrubesse et al 2019). Agriculture plantations or pastures replace native vegetation, and water bodies are being dammed for hydropower dam construction and agricultural irrigation intensification (Coe et al 2011, Latrubesse et al 2019)
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