Studies on two migratory fish from lower Tocantins River before closure of Tucurui dam

Migratory fish species are generally the most important species for the fishing industry as well as for artesanal fishing. In the lower Tocantins, two species of migratory fish dominate the captures: the mapará (Hypophthalmus marginatus) and the curimatã (Prochilodus nigricans). These two species were studied before the daming of this river by the Tucuri hydroelectric dam as part of a larger study of commercial fisheries encompassing the Tocantins basin from the mouth to Marabá (Pará). Based principally on landing records, this study describes the migration cycles of the two species. A classical and simple pattern of migration can be recognized: an upstream movement of immature and adults in the upper part of the distribution area, and then, the reverse or downstream movement of larvae and adults in a dispersion phase. The main difference between these two species lies in the size of distribution area. The mapará is limited to part of the river downstream from the hydroelectric dam of Tucurui, and so, would not be affected by its presence. The curimatã has a much larger geographic range in the Tocantins basin. The part of population living downsteam will probably be profundly pertubed by the dam due to the blockage of its migratory route

Colonização ictiofaunística do Reservatório de Itaipu e áreas adjacentes Ichthyofaunistic colonization of the Itaipu Reservoir and vicinity áreas

<abstract language="eng">Samples were taken from November 1983 to October 1989 in sites along the main body of the Itaipu reservoir and its area of influence to evaluate the impacts of this reservoir on ichthyofauna and to provide information about the colonization process in the dammed area. The ichthyofaunistic similarity between the sites was analysed during the studied period. Spatial and temporal variations of the ichthyofaunistic diversity were also done, using Shannon-Winer Index of Diversity, eveness and species richness, comparing the results with those obtained before the damming. After Itaipu Reservoir formation, it was observed significative alteration in specific abundance and ichthyofauna structure of the Paraná River, with an increase in species number in ali tributaries of the reservoir, and a high replacement in species. Diversity and species richness were higher in the dammed stretch of the Paraná river and in its tributaries of the left side after the Itaipu reservoir formation. Among the sampled sites, the highest values of the diversity index were registered in Paraná River upstream and downstream the reservoir, Iguatemi river and Arroio Guaçu. Based on information of similarity in species composition and abundance in the sampled area, five site groups could be identified

Variation in floristic composition, demography and above-ground biomass over a 20-year period in an Amazonian monodominant forest

Background: Previous work has shown that Amazonian tropical forests have experienced two widespread changes in dynamics over recent decades, increases in both tree stem turnover and above-ground biomass. However, data from an Amazonian monodominant forest dominated by Peltogyne gracilipes have shown that the above-ground biomass of this forest type has declined slightly (&lt;5%) over an 11-year period. Aims: To determine whether the tree communities in three types of forest, with or without Peltogyne gracilipes (Peltogyne-rich forest (PRF), Peltogyne-poor (PPF) and forest without Peltogyne (FWP)) on Maracá Island, Roraima, have experienced a change in structure and floristic composition over a 20-year period. Methods: We have quantified the variation in the occurrence and abundance of tree species, the above-ground biomass (AGB) and change in total stand biomass from mortality, recruitment and growth for trees, palms and large lianas, ≥10 cm diameter at breast height, in three plots of 0.25 ha in each of the three forest types. Results: Floristic composition showed little change, with no shift in the rank abundance amongst the 10 most important tree species, although in FWP there was a reduction in species richness from 51 to 43. Recruitment is shown to offset the losses caused by mortality in PRF and FWP. The annual mean mortality rates were low, at around 1%. In 2011 AGB in the three forest types varied from 434 Mg ha-1 (PPF) to 363 Mg ha-1 (FWP). PRF experienced an AGB decline of 4.1%, associated with the death of large trees, while FWP showed a slight increase in biomass (2.6%). Conclusions: Over the last 20 years Maracá forest stands appear to have been stable in terms of their floristic composition and structure, some showing a persistent monodominance by Peltogyne gracilipes. © 2014 Copyright 2013 Botanical Society of Scotland and Taylor &amp; Francis

Catfishes of the genus Auchenipterichthys (Osteichthyes: Siluriformes: Auchenipteridae): a revisionary study

The Neotropical auchenipterid catfish genus Auchenipterichthys is reviewed and found to include four species. Auchenipterichthys thoracatus, formerly considered to be widely distributed throughout the Amazon River basin, is found to be restricted to the upper Madeira River basin. The widespread Amazonian species that had been misidentified as A. thoracatus is, instead, A. coracoideus; a species that also occurs in the upper Essequibo River. Auchenipterichthys longimanus, the most widely distributed species of the genus, is found through much of the Amazon and Orinoco River basins. The fourth species of the genus, A. punctatus (and its junior synonym A. dantei), is found in the upper portions of the Orinoco and Negro River basins in Venezuela and the central portions of the Amazon River basin in Brazil. All four species of Auchenipterichthys are redescribed and illustrated, and a key to the species is provided