Oil exploitation poses a significant threat to freshwater biodiversity, and future plans to develop petroleum leases in the Amazon Basin should be seem with caution. A series of oil spills have significantly affected biodiversity and human activities in some Amazonian basins, indicating that disturbances by petroleum activities will increase in the region, particularly in upper basins and river headwaters. Measures are needed to reduce the risk of spills and to minimize their impacts. More fundamentally, changes in decision making are needed that give proper weight to these impacts.
Summary
Length–weight relationships (LWR) were estimated for seven fish species from the Napo River and its main tributaries, Arabela and Curaray rivers, Amazon basin, Peru. A total of 652 specimens were sampled between 2012 and 2014 using seines and gillnets. This study reports new maximum total length for four species and new LWR and maximum total weight records for three and five species, respectively.
Summary
The length‐weight relationships (LWRs) are described for 29 fish species in the region of the Tucuruí Reservoir, located in the Tocantins/Araguaia Basin, northern Brazil. Fishes in fourteen sites were sampled seasonally for 10 years, from 2001 to 2010. Significant differences between sexes were found for two species, while 27 species had similar LWRs for males and females. The relationship of standard length and total length is presented for all species as well as the minimum and average size of reproductive females and seasonality of occurrence. No information on LWRs of these 29 species was heretofore available in FishBase.
A new species of Poptella is described from the Rio Juma, a tributary of the lower Rio Aripuanã, Rio Madeira basin, Amazonas, Brazil. The new species is distinguished from all congeners, except P. brevispina, by having a lower number of scale rows between the lateral line and dorsal-fin origin (7 vs. 8-10). The new species can be readily distinguished from P. brevispina by the lower number of branched dorsal-fin rays (9 vs. 10). This is the first description of a new species of Poptella since the revisionary study of the Stethaprioninae, published 30 years ago.
Brachychalcinus reisi, a new species of characid fish, is described from the rio Curuá, tributary of rio Iriri, rio Xingu basin, Serra do Cachimbo, Pará State, Brazil. The new species can be distinguished from its congeners by the presence of a series of longitudinal black wavy stripes on the entire body and by a lower number of longitudinal scale rows between dorsal-fin origin and lateral line (7-8 vs. 8-12). Additionally, the new species differs from B. copei, B. parnaibae, and B. retrospina by the lower number of branched dorsal-fin rays (9 vs.10). This is the first description of a new species of the subfamily since the revisionary study of Stethaprioninae, published almost 30 years ago.
A new species of Brachychalcinus is described from the Rio Trombetas basin, Brazil. It differs from congeners by possessing a conspicuous rounded second humeral spot. Additionally, our new species differs from Brachychalcinus nummus, B. orbicularis and B. reisi by having a higher number of branched dorsal‐fin rays, and from Brachychalcinus parnaibae by having a lower head depth.
The ribeirão Sucuri, a tributary of the rio Tietê, and part of the upper rio Paraná basin, is located in the municipality of Pongaí, São Paulo state. The ichthyofauna of ribeirão Sucuri was sampled at nine collection sites in May 2018. Our study captured 408 specimens representing five orders, 11 families, and 35 species. Among the species collected, two have not been previously reported from the rio Tietê basin: Eigenmannia guairaca Peixoto, Dutra & Wosiacki, 2015 and Hoplias misionera Rosso, Mabragaña, González-Castro, Delpiani, Avigliano, Schenone & Días de Astarloa, 2016. Additionally, four species were found that are non-native: Hoplias misionera, Poecilia reticulata Peters, 1859, Roeboides descalvadensis Fowler, 1932, and Satanoperca sp. This study represents the first fish inventory of a tributary on the left margin of the Tietê-Batalha sub-basin and only the second for this portion of the rio Tietê. Our results increase to 55 the number of species recorded from this sub-basin and add data on the putative morphological variation in several species.
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