DNA barcode of Parodontidae species from the La Plata river basin - applying new data to clarify taxonomic problems

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Reproductive migration of fish and movement in a series of reservoirs in the Upper Parana River basin, Brazil

AbstractThis study evaluates the effectiveness of two fish passes at two hydropower dams (Canoas I and II) in the Upper Parana basin, which form part of a cascade of three reservoirs. Fish from 12 migratory species (3089 specimens) were captured during their ascending, reproductive migration and were tagged with hydrostatic tags. The recapture data (294 specimens over two consecutive years) showed that there is a strong tendency for the maintenance of ascending migration through reservoirs with fish passes but with differences in migratory activity within the same species. No eggs, larvae or juveniles of these species were found in samples collected over 5 years in the reservoirs above the fish passes. These data suggest that fish passes have contributed to the restoration of the migratory routes of adult fish but that in the absence of suitable spawning or nursery habitats for these species; they probably act as ecological traps and do not contribute to the recruitment of the species.

Trends in planktonic copepod diversity in reservoirs and lotic stretches in a large river basin in South America

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The fish fauna in tropical rivers: The case of the Sorocaba river basin, Sao Paulo, Brazil

A survey was carried out on the fish species in the Sorocaba. River basin, the main tributary of the left margin of the Tiete River, located in the State of Sao Paulo, Brazil. The species were collected with gill nets. After identification of the specimens, their relative abundance, weight and standard length were determined. Up to the present moment there are not any studies that focus this subject in this hydrographic basin. Fifty-three species, distributed in eighteen families and six orders were collected. Characiformes were represented by twenty-eight species, Siluriformes by seventeen species, the Gymnotiformes by three species, Perciformes and Cyprinodontiformes by two species, and the Synbranchiformes by one species. Among the collected species there were two exotic. The most abundant species were Astyanax fasciatus and Hypostomus ancistroides. In relation to total weight the most representative species were Hoplias malabaricus and Hypostomus ancistroides. Cyprinus carpio, Prochilodus lineatus, Schizodon nasutus and Hoplias malabaricus were the most representative species in relation to average weight. Largest standard length were recorded for Sternopygus macrurus, Steindachnerina insculpta, Eigenmannia aff. virescens and Cyprinus carpio.

Life-history strategies associated to reproduction of three Hyphessobrycon species (Characidae) in lentic environments of upper Paraná River basin

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The stream fish fauna from three regions of the Upper Paraná River basin

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Identification guide to some Diaptomid species (Crustacea, Copepoda, Calanoida, Diaptomidae) of "de la Plata" River Basin (South America)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Erosion rates and landscape evolution of the lowlands of the Upper Paraguay river basin (Brazil) from cosmogenic Be-10

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Pb-210 and compositional data of sediments from Rondonian lakes, Madeira River basin, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Regulation of the abundance and turnover of copepod species by temperature, turbidity and habitat type in a large river basin

Freshwater copepods were sampled in the La Plata River basin to identify the processes that affect beta diversity and to determine the main factors influencing their geographical distribution and patterns of endemism. Beta diversity patterns exhibited strong dissimilarity between locations; the turnover process was predominant and indicated a replacement of species along the basin. Redundancy analysis indicated the presence of two large sets of species separated geographically by a boundary zone, with several associated variables. Northern species were associated with water transparency and temperature, mean air temperature, mean air temperature during winter and minimum air temperature of coldest month, indicating that these species are not tolerant to low temperatures and are abundant in reservoirs that are common in the upper stretch of the Paraná River basin. Southern species were related with amplitude of air temperature, turbidity, total phosphorus and total suspended matter, indicating that these species are polythermic and have adapted to live in river stretches. From 20 environmental variables analyzed in our study, partial least squares analysis indicated four variables with increased retention of effects on copepod abundance: air temperature, minimum temperature of coldest month, turbidity and transparency. Because almost all of the species found in this study occurred across a wide range of habitat types, the cause of the separation between river and reservoir species could be considered to be more anthropogenic than natural, and it primarily affected species abundance. For certain members of the northern group of copepod species, distribution was dependent on high temperatures, whereas the distribution of the southern group indicated that the species were polythermic.

Knodus dorsomaculatus (Characiformes: Characidae), a new species from Teles Pires River, Tapajos River basin, Brazil

Knodus dorsomaculatus, a new species, is described from Teles Pires River, a tributary of the Tapajos River, Brazil. It can be distinguished from its congeners by the presence of a conspicuous dark blotch on the base of the first five branched dorsal fin rays and the presence of ii,9 dorsal fin rays. Additional comparisons between K. dorsomaculatus and its congeners are presented.

Peat palynomorphs from Eugenio de Melo, middle valley of Paraiba do Sul River, Sao Paulo, Brazil.

Peat palynomorphs from Eugenio de Melo, middle valley of Paraiba do Sul River, Sao Paulo, Brazil. This paper presents palynomorphs identified in the peats of the Eugenio de Melo region, the middle valley of the Paraiba do Sul River, Sao Paulo State. The samples were collected at intervals of 10 cm from a core with 3.90 m deep, aged between 11400-11220 and 490-290 cal. years B.P. Three types of algae were identified and presented, and ten spores, two gymnosperm pollen grains and thirty-nine angiosperms were described, with their own ecological information.

Heavy metal distribution in recent sediments along the Tiete River basin (Sao Pauro, Brazil)

The distribution of heavy metals in recent sediments deposited along the Tiete River, a highly polluted river in southeast region of Brazil was studied. Around the metropolitan area of Silo Paulo city (25 million people), the pollution is related to municipal wastes and industrial effluents with reinforced downstream by agricultural activities. The observed increase of heavy metal concentrations is particularly important for Zn in the upper basin and Cu, Co and Cr at mouth. Geo-accumulation index calculation, related to the regional background, showed that the sediments along the basin are seriously polluted by heavy metals of anthropogenic origin, mainly Cu, Co, Cr and Zn. Calculated index suggests medium to very strongly pollution.

A new species of the catfish genus Trichomycterus from the La Plata River basin, southern Brazil, with comments on its putative phylogenetic position (Siluriformes: Trichomycteridae)

The genus Trichomycterus is a highly diverse group of Neotropical catfishes that encompass almost 60% of all the currently recognized species of the Trichomycteridae. A new species of this genus, T. perkos, is herein described from tributaries of the Paranapanema and Uruguai River basins, southern Brazil. The new species exhibits a remarkable ontogenetic change in its pigmentation, having a unique color pattern when adult. The adult pigmentation consists of three wide dark brown stripes, located in an inner skin layer of trunk and caudal peduncle, combined with a superficial light brown freckled pattern on the dorsum and caudal peduncle. Small, presumably juvenile specimens lack the superficial freckles but already have the dark stripes, thus resembling the color pattern of a few other congeners. Nevertheless, several unequivocal morphological features distinguish both juveniles and adults of T. perkos from these congeners. In spite of the difficulties in estimating phylogenetic relationships within Trichomycterus, the new species is tentatively proposed as being the sister-taxon of a small group of species composed by T. crassicaudatus, T. igobi, and T. stawiarski.