Checklist of the ichthyofauna of the Rio Negro basin in the Brazilian Amazon

Abstract

This study presents an extensive review of published and unpublished occurrence records of fish species in the Rio Negro drainage system within the Brazilian territory. The data was gathered from two main sources: 1) litterature compilations of species occurrence records, including original descriptions and revisionary studies; and 2) specimens verification at the INPA fish collection. The results reveal a rich and diversified ichthyofauna, with 1,165 species distributed in 17 orders (+ two incertae sedis), 56 families, and 389 genera. A large portion of the fish fauna (54.3% of the species) is composed of small-sized fishes < 10 cm in standard length. The main groups are Characiformes (454 species; 39.0%), Siluriformes (416; 35.7%), Gymnotiformes (105; 9.0%), and Cichliformes (102; 8.8%). The species composition differs between the main aquatic environments, such as: main channel (159 species), lakes (296), tributary rivers (596), small streams (234), seasonal beaches (186), and rapids (41). Part of the ichthyofauna is shared with adjacent basins, such as the Orinoco, rivers of the Guiana Shield, lower Solimões/Amazonas and upper Amazonas, which contributes to the remarkable ichthyofaunal diversity of the basin. A high rate of species endemism was observed in Characidae (24), Loricariidae (18), Cichlidae (18) and Callichthyidae (18), totalling 156 species (13.4%) endemic to the basin. An estimation of the species richness for the Rio Negro basin, considering 23 published references, resulted in 1,466 and 1,759 species (Jackknife 1 and 2, respectively), which seems reasonable when considering the large number of morphotypes left out of the present list and the low sampling effort in many areas of the basin. The results presented herein provide an additional tool for environmental managers and decision makers for conservation purposes of one of the richest and most well-preserved sub-basins of the Rio Amazonas system.

Vulnerability of the biota in riverine and seasonally flooded habitats to damming of Amazonian rivers

“…For fishes, the highest diversity values are reported in Andean‐foreland basins and, also, in the Negro and lower Amazon cratonic basins (Figure 1), which agrees with recent findings (Beltrão, Zuanon, & Ferreira, 2019; Oberdorff et al, 2019). Trees exhibit a clear east‐to‐west gradient of increasing diversity, reaching the highest diversity value in the Marañon basin.…”

A Review on Fish Sensory Systems and Amazon Water Types With Implications to Biodiversity

“…Such organs may differ depending on water type not only in size, but also in the density of Merkel cells, or even in cell sensitivity. Interestingly, a higher diversity of Amazon catfishes occurs in white waters (Queiroz et al, 2013;Dagosta and de Pinna, 2019) and in the deeper portions of the Amazon's aquatic habitats (e.g., Beltrão et al, 2019) where underwater light is scarce, further stressing the importance of the mechanosensory system in this group. It is therefore unfortunate that the role of touch among species that inhabit black, clear, and white water types has not been investigated.…”

Length‐weight relationship of 16 fish species from the Negro River basin (Amazonas state, Brazil)

“…To date, 1,165 species are known to inhabit the Negro River (Beltrão et al., 2019), but studies on the length‐weight relationships have been performed mainly for ornamental fish species (Barros et al., 2018; Lemos et al., 2015; Santos et al., 2012), which are historically exploited in the Rio Negro basin, mainly in the upper and middle Rio Negro stretches, where fishing occurs more intensely, and represent just over 90% of the species exported by the state of Amazonas (Anjos et al., 2009).…”