Reproductive strategies of two Curimatidae species in a Mogi Guacu impoundment, upper Parana River basin, São Paulo, Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Structure and composition of the stream ichthyofauna of four tributary rivers of the upper Rio Parana basin, Brazil

The ichthyofauna of 24 stretches of streams, all of 100 m length and of fifth or lower order and most of second and third order, were sampled along four left bank tributaries (Rio do Peixe, Rio Aguapei, Rio Sao Jose dos Dourados, lower Rio Tiete of the main channel of the Rio Parana in the state of São Paulo, southeastern Brazil. Sampling of the fish fauna at each of the six sites in the four basins incorporated a standardized fish collecting methodology and a standardized documentation of environmental data serving as the basis for a comparative analysis of the collecting locations. The 8,189 fish specimens collected represented six orders, 18 families, 42 genera, and 56 species, with a total biomass of 28.8 kg. Approximately 52% of the collected species were characiforms, 28% siluriforms, 9% gymnotiforms, 5% cyprinodontiforms, 4% perciforms, and 2% synbranchiforms. The most abundant of the species were the characiforms Astyanax altiparanae (15% of total) and Knodus moenkhausii (12% of total). The two species with the largest overall biomasses were A. altiparanae (34% of total biomass) and the siluriform Hypostomus sp. (8% of total biomass). Analysis of the trophic structure of the studied ichthyofauna indicated that the 10 numerically dominant species across the 24 sampled streams can be grouped into five guilds that are in decreasing order of numerical importance: omnivores, insectivores, insectivores/invertivores, periphytivores, and algivores. Species richness in the sampled stream stretches varied from six to 20 species with an average richness of 14. The species richness estimated by extrapolation for all 24 sampled stream stretches was 67 species. The Characidae are predominant among the collected specimens with approximately 50% of both individuals and biomass, a fact hypothesized to be a function of several attributes typical of the family. Six of the 56 collected species were new to science and six other species are of indefinite taxonomic status and require further analysis in order to determine their identity.

Hisonotus piracanjuba, a new species of Hypoptopomatinae (Siluriformes: Loricariidae) from the rio Paranaiba, upper rio Parana system, central Brazil

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

Neoplecostomus (Teleostei : Loricariidae) from the upper Rio Parana basin, Brazil, with description of three new species

Neoplecostomus paranensis was the only Neoplecostomus species known from the upper Rio Parana basin, and it was diagnosed from its congeners mainly by the absence or reduction of the adipose fin. In this study we describe three new Neoplecostomus species. All of them are promptly differentiated from N. paranensis by having a well-developed adipose fin. Furthermore, the new species are differentiated from congeners by morphometric and meristic traits, in addition to color pattern. Neoplecostomus paranensis is redescribed. We also provide an identification key to all Neoplecostomus species.

A new Hemigrammus Gill from upper rio Parana system, Southeastern Brazil (Characiformes : Characidae)

Hemigrammus parana is described from the upper rio Parana system, in the area of influence of the Ilha Solteira reservoir in states of Mato Grosso do Sul, Minas Gerais and São Paulo, southeastern Brazil. The new species differs from all congeners by the combination of the following characters: absence of humeral spot; presence of a roughly triangular or rectangular conspicuous black caudal spot, extending from base to tip of middle caudal-fin rays, its greatest depth at base of caudal-fin rays; and anal-fin rays iii-iv, 18-23.

Deglaciation sequences in the Permo-Carboniferous Itarare Group, Parana Basin, southern Brazil

The Late Carboniferous-Early Permian Itarare Group is a thick glacial unit of the Parana Basin. Five unconformity-bounded sequences have been defined in the eastern outcrop belt and recognized in well logs along 400 km across the central portion of the basin. Deglaciation sequences are present in the whole succession and represent the bulk of the stratigraphic record. The fining-upward vertical facies succession is characteristic of a retrogradational stacking pattern and corresponds to the stratigraphic record of major ice-retreat phases. Laterally discontinuous subglacial tillites and boulder beds occur at the base of the sequences. When these subglacial facies are absent, deglaciation sequences lie directly on the basal disconformities. Commonly present in the lowermost portions of the deglaciation sequences, polymictic conglomerates and cross-bedded sandstones are generated in subaqueous proximal outwash fans in front of retreating glaciers. The overlying assemblage of diamictites, parallel-bedded and rippled sandstones, and Bouma-like facies sequences are interpreted as deposits of distal outwash fan lobes. The tops of the deglaciation sequences are positioned in clay-rich marine horizons that show little (fine-laminated facies with dropstones) or no evidence of glacial influence on the deposition and likely represent periods of maximum ice retreat. (c) 2006 Elsevier Ltd. All rights reserved.

Radioactivity distribution in some Permian sediments from the Irati and Corumbatal formations of the Parana basin, southeastern Brazil

in the city of Limeira, southeastern Brazil, an important exposure of Permian sediments of the Parana basin was revealed by an open pit mine that exploits limestone for production of soil correction compounds and raw materials for the ceramic industry. The radioactivity of these sediments was investigated in some detail and the results provided a general view of the vertical distributions of uranium, thorium and potassium concentrations and of the element ratios U/K, U/Th and Th/K. In general, the concentrations of the main natural radioactive elements are low, with uranium being enriched in some limestone and shale levels. In addition the results showed that the U-238 series is in radioactive disequilibrium in many of the analyzed samples. Although the origin of the observed disequilibrium has not been investigated, the results suggest that it is due to weathering processes and water interaction with the rock matrix. (C) 2003 Elsevier Ltd. All rights reserved.

Sedimentation of the Cretaceous Bauru Group in São Paulo, Parana Basin, Brazil

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

Natural radionuclides in major aquifer systems of the Parana sedimentary basin, Brazil

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

A comparative study of aquifer systems occurring at the Parana sedimentary basin, Brazil: major hydrochemical trends

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

Uranium speciation in groundwaters from Parana basin, Brazil

This paper describes the results of a regional study involving the sampling of 60 pumped tubular wells drilled at the Parana sedimentary basin, Brazil, which was carried out with the purpose of evaluating the U speciation in the Botucatu-Piramboia aquifer. Uranium proved to be intensively dissolved even under the enhanced reducing conditions occurring at the most confined zones of the aquifer, and Eh-pH diagrams were utilized to evaluate the influence of temperature and pressure on the migration of the U-species within the aquifer.

Collection of Fafia [Pfaffia glomerata (Spreng.) Pedersen] in northwestern state of Parana-Brazil

Interviews were conducted with fafia (Pfaffia glomerata (Spreng.) Pedersen) collectors from the municipal districts of Querencia do Norte and Porto Rico, where enterprises and buyers of this plant are concentrated. The results allowed us to conclude that both the adults and children make collection. Each adult collects from 50 to 150 kg of roots/day, depending on the collection area, for about 8 months/year. Collections mostly occur all over the year, but the activity becomes more intense from May to August. All families are not exclusively dedicated to fafia collection and also develop other rural activities. They have been collecting fafia for 2 to 13 years, indicating that an intensive exploitation has been present in the region for over a decade. During collection, no plant part is used for replanting the species. The roots are commercialised by regional buyers. The price of the roots varies from US $ 0.07 to US $ 0.13/kg and average gain is about US $ 2,055/family/year, representing a considerable profit for the collectors.

Temporal distribution and composition of the ichthyoplankton from Leopoldo's Inlet on the Upper Parana River floodplain (Brazil)

Temporal distribution and composition of ichthyoplankton and their relationships with some environmental variables of Leopoldo's Inlet (Ressaco do Leopoldo) on the upper Parana River floodplain, southern Brazil, were analysed. Samples were taken from February 1991 to February 1992, and 3480 larvae were collected. The highest density of larvae was observed in November 1991 (36.79 larvae/ 10 m(3)) at night (night/day ratio 7: 1). Species composition showed a predominance of Characiformes (80%). There was a high density (4.28 larvae/10 m(3)) of Bryconamericus stramineus throughout almost the whole study period, the majority of the species were more frequently collected at night. Pearson's correlation indicated a relationship between larval density, temperature, and pluviometric index. Leopoldo's Inlet, whose ichthyofauna is mainly composed of grazing and resident species. shows favourable conditions for fish reproduction and development.

Genetic structure of Blastocerus dichotomus populations in the Parana River basin (Brazil) based on protein variability

The population structure of 147 marsh deer (Blastocerus dichotomus) from three areas in the Parana River basin, Brazil, was studied by observing protein polymorphism at 17 loci. Six loci were polymorphic and 11 monomorphic. The proportion of polymorphic loci (P) was 35.29% and the average heterozygosity (H) was 6.31%. Wright's F-ST indicated that only 4.9% of the total variation in allelic frequencies was due to genetic differences between the three groups. The high value of F-IS (0.246) indicated inbreeding in the marsh deer. Genetic distance values (D = 0.014-0.051) showed little divergence between the three areas. We suggest that probable mechanisms accounting for the genetic structure are female phylopatry and polygyny and also that inbreeding has resulted from decreasing areas of wetland leading to isolation, overhunting, and diseases transmitted by cattle.

Thermotectonic and fault dynamic analysis of Precambrian basement and tectonic constraints with the Parana basin

The Precambrian crystalline basement of southeast Brazil is affected by many Phanerozoic reactivations of shear zones that developed during the end of the Neoproterozoic in the Brasiliano orogeny. These reactivations with specific tectonic events, a multidisciplinary study was done, involving geology, paleostress, and structural analysis of faults, associated with apatite fission track methods along the northeastern border of the Parana basin in southeast Brazil.The results show that the study area consists of three main tectonic domains, which record different episodes of uplift and reactivation of faults. These faults were brittle in character and resulted in multiple generations of fault products as pseudotachylytes and ultracataclasites, foliated cataclasites and fault gouges.Based on geological evidence and fission track data, an uplift of basement rocks and related tectonic subsidence with consequent deposition in the Parana basin were modeled.The reactivations of the basement record successive uplift events during the Phanerozoic dated via corrected fission track ages, at 387 +/- 50 Ma (Ordovician); 193 +/- 19 Ma (Triassic); 142 +/- 18 Ma (Jurassic), 126 +/- 11 Ma (Early Cretaceous); 89 +/- 10 Ma (Late Cretaceous) and 69 +/- 10 Ma (Late Cretaceous). These results indicate differential uplift of tectonic domains of basement units, probably related to Parana basin subsidence. Six major sedimentary units (supersequences) that have been deposited with their bounding unconformities, seem to have a close relationship with the orogenic events during the evolution of southwestern Gondwana. (c) 2005 Elsevier Ltd. All rights reserved.