Preconcentration and determination of Cu(II) in a fresh water sample using modified silica gel as a solid-phase extraction adsorbent

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

Revegetation on a Removed Topsoil: Effect on Aggregate Stability

The construction of a large reservoir on the Parana River (Selviria, MS, Brazil) disturbed the soil of an extensive agricultural area in which between 5 and 8m of topsoil were removed. In this area, a restoration process was carried out using revegetation with green manure without or with amendments (for 4 years), crops (2 years), and Brachiaria decumbens cultivation for 6 years. The following treatments were used: control plots, T0 (residual subsoil) and T1 (soil tillage without culture); plots with green manure and without amendments: T2 (velvet bean) and T3 (pigeon pea); plots with green manure and with amendments: T4 (limed + velvet bean), T5 (limed + pigeon pea); T6 (limed + gypsum + velvet bean) and T7 (limed + gypsum + pigeon-pea). They were arranged in randomized blocks. After 13 years of rehabilitation process, when the soil was cultivated with brachiaria, the structural stability in three depths was evaluated. Organic-matter content and others chemical properties did not show any relationship with the stability of aggregates of the experimental area as measured by mean weight diameter (MWD). Significant differences between depths were found for MWD and the other parameters measured. Nevertheless, there were no significant differences observed between treatments, independent of the adopted system of revegetation. By taking an absolute value of MWD, the stability of superficial layer was observed in the following sequence: T7 T5 T6 T1 T2 T3 T4 T0. The control plot (T0) gave the lowest value of MWD (1.76mm) in relation to the plots in restoration process. Treatment T7 was the most effective in recovering the stability of aggregates (2.63mm). However, treatments T5 and T6 displayed a similar value. After 13 years of revegetation practices, a slight recovery of the stability was observed, although this is still lower than stability in soils of similar edaphic conditions in the original topsoil of experimental area.

Revegetation and Soil Management Effects on Chemical Properties of a Saprolite Resulting from Deep Soil Removal

During the building of a hydroelectrical power plant at Ilha Solteira in the Parana River (Brazil), materials of a highly weathered soil Oxisol were extracted from a depth between 5 and 8 m for engineering works. This resulted in an abandoned depression area. The topsoil was not salvaged and the open pit was not backfilled, and as result vegetation hardly or not at all recovered. on the residual saprolite materials, an experimental field was established to assess different soil rehabilitation treatments. Field experiments were initiated in 1992. After soil tillage, two different crops and three different liming strategies were compared, giving six combinations. In addition, two uncropped control treatments, tilled and no-tilled, were established so that a total of eight treatments were assessed. The experimental design consisted of four randomized experimental blocks, which included a total of 32 plots with a plot area of 100 m(2). This experiment was used to study the effectiveness of the soil-reclamation treatments after a 9-year period. Soil samples were taken at three different depths (0-10, 10-20, and 20-40 cm), and they were analyzed routinely for pH, organic-matter content, and cation exchange capacity (CEC). Revegetation of the abandoned saprolite material increased soil organic-matter content and cation exchange capacity (CEC), and to some extent small differences between treatments were evidenced. Exchangeable calcium (Ca) and magnesium (Mg) recovered faster than organic-matter content. A significant linear relationship was found between organic-matter content and CEC, suggesting continued addition of organic material will further approach the value of these parameters to those levels corresponding to natural soils under "Cerrado" vegetation.

Genetic diversity in Egeria densa and E. najas in Jupia Reservoir, Brazil

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

XX : XY sex chromosome system with X heterochromatinization: an early stage of sex chromosome differentiation in the Neotropic electric eel Eigenmannia virescens

An early stage of sex chromosome differentiation is reported to occur in the electric eel Eigenmannia virescens (Pisces, Sternopygidae) from populations of two tributaries of the Parana river system (Brazil). Cytogenetic studies carried out in the two populations showed that the Mogi-Guacu population is characterized by 2n = 38 chromosomes and undifferentiated sex chromosomes and the Tiete population presents 2n = 38 both for males and females and an XX:XY sex chromosome system. The X-chromosome is acrocentric, easily recognized by the presence of a conspicuous heterochromatin block in its distal portion; the Y-chromosome is probably one of the medium sized acrocentrics present in the male karyotype. BrdU induced R-bands of the two populations did not reveal any difference in the euchromatic regions of the chromosomes. AluI and HaeIII restriction enzyme digestion patterns and chromomycin A3 staining of the X-chromosome are presented. The possible role of heterochromatinization in the evolution of sex chromosomes in fish is discussed.

Detection of hybrids and genetic introgression in wild stocks of two catfish species (Siluriformes: Pimelodidae): The impact of hatcheries in Brazil

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

5S rDNA chromosomal mapping and COI sequence analysis reveal differentiation among distinct populations of a characid fish Serrapinnus notomelas

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

Fishes of the Atlantic Rainforest of Boraceia: testimonies of the Quaternary fault reactivation within a Neoproterozoic tectonic province in Southeastern Brazil

The upper portion of the Rio Guaratuba, located in the Serra do Mar coastal range of Southeastern Brazil, shows biological and geological evidences of being captured and diverted away from its original course in the direction of the Parana River Basin to become a coastal river due to the Quaternary activity of NW-trending faults. Despite draining directly to the Atlantic Ocean, the upper portion of the Guaratuba still maintains an ichthyofauna that is typical of the adjoining Parana River Basin rather than the characteristic fish fauna of the Brazilian coastal drainages. The fish fauna of the upper Guaratuba is an evident testimony of the tectonic process that allowed the faunal interchange between the upland basins and the coastal drainages that probably has been taking place in Southeastern Brazil throughout the long geological history of the passive Brazilian continental margin.

Benthic macroinvertebrates in the Paranapanema reservoir cascade (southeast Brazil)

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

Ontogenetic shifts in the digestive tube and diet of Bryconamericus stramineus Eigenmann, 1908 (Osteichthyes, Characidae)

Aim: Studies on feeding of early life stages are very important to the understanding of the biology and trophic ecology of fish species. Therefore, the aim of this work is to describe the development of the digestive tube, and to characterize the diet of larvae and juveniles of Bryconamericus stramineus Eigenmann, 1908 of the upper Parana River floodplain; Methods: Larvae were obtained from, monthly samples during nychthemeral cycles with four-hour interval between samplings from February/91 to February/92, utilizing a conical-cylindrical plankton net; Results: At the preflexion stage, larvae at approximately 4.00 mm SL, showed a morphologically undifferentiated straight tube, with the anterior region more dilated. At the flexion stage a differentiation in the anterior region of the digestive tube occurs, with the intestine wall getting thicker (8.30 mm SL). The formation of pyloric caeca occurs at 9.00 mm SL. At the postflexion stage the first loop is formed at 9.25 mm SL and the second loop at about 10.00 mm SL. Bryconamericus stramineus consumed mainly cladocerans, also ingesting copepods, rotifers, nematodes, algae, insects and inorganic particles. Along the development, there was an increase in the number of food items and a diversification in the number of consumed taxa; Conclusions: Changes in the diet of B. stramineus larvae were not observed, being them zooplanktivores during all the initial development. However, an increase of large preys, such as insects larvae, was observed at the end of the larval period and in juveniles, suggesting a tendency towards invertivory. Larvae and juveniles preferentially fed during the night.

Considerações sobre a reprodução de duas espécies de raias (Myliobatiformes, Potamotrygonidae) na região do Alto Rio Paraná, Sudeste do Brasil

This article presents preliminary information about the reproduction of two species of freshwater stingrays of the genus Potamotrygon, found in the Upper Parana River (Southwest Brazil), where these animals are exotic. Males of P. motoro and P. falkneri become sexually mature around 270 mm and 260 mm of disc width (DW), respectively. Females become sexually mature around 330 mm of DW in P. motoro and 325 mm in P. falkneri. In both species, females are bigger and heavier than males, reaching about 700 mm of DW and 20 kg. Copulating has not been recorded, but one courtship ritual has been observed during the dry season. Mature males present a different dentition from females and young males, which is probably related to their reproductive behavior instead of to their feeding habit. The female fertility has varied from one to three offspring. A miscarriage has been observed at different stages of embryonic development always when pregnant females were captured. In spite of the great history of anthropization of the study area, it seems that hydrological cycles are related to the reproduction of stingrays. Nevertheless, it would be necessary to conduct deeper studies to verify or not this influence.

Influence of forest cover and mesohabitat types on functional and taxonomic diversity of fish communities in Neotropical lowland streams

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

A fish-based biotic integrity index for assessment of lowland streams in southeastern Brazil

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

Larval Contracaecum sp (Nematoda : Anisakidae) in Hoplias malabaricus and Hoplerythrinus unitaeniatus (Osteichthyes : Erythrinidae) of economic importance in occidental marshlands of Maranhao, Brazil

This work describes the presence of Contracaecum sp. larvae (Nematoda: Anisakidae) found in food fish of economic importance captured in occidental marshlands in the State of Maranhao, Brazil. Hoplias malabaricus (Erythrinidae) and Hoplerythrinus unitaeniatus (Erythrinidae), commonly called traira and jeju, respectively, were examined. All H. malabaricus were infected with a mean intensity of 24.6 +/- 38.3 (1-137 parasites per host) while eighty percent of H. unitaeniatus showed a mean intensity of 10.4 +/- 9.2 (2-31) parasites. Nematodes were most similar to larvae of a type 2 described by Moravec, Kohn and Fernandes [Moravec, F., Kohn, A., Fernandes, B.M.M., 1993. Nematode parasites of fishes of the Parana River, Brazil. Part 2. Seuratoidea, Ascaridoidea, Habronematoidea and Acuarioidea. Folia Parasitol. 40, 115-134], but differed in having a longer intestinal caecum and greater caecum/ventricular appendix ratio. Larval measurements and a description of their Brazilian fish hosts are presented. (C) 2004 Elsevier B.V. All rights reserved.

Hematology of free-living marsh deer (Blastocerus dichotomus) from Southeast Brazil

This work reports basic hematologic values of a sample of a population of free-living marsh deer (Blastocerus dichotomus) living by the Parana River in Southeast Brazil. Hematologic values are presented separately for male, female, and young animals as well as for anesthetized and nonanesthetized cervids. Nonanesthetized deer restrained by physical means had significantly higher erythrocyte indices and total leukocyte counts. Comparisons of blood parameters of anesthetized animals of different ages and gender differed slightly, with only two significant differences observed: young animals had significantly higher red blood cell counts than adult males and a lower blood total protein content when compared to adult females. Results indicate that two main reference ranges for blood values should be considered for marsh deer, for blood obtained from anesthetized or physically restrained individuals.