763 resultados para hidrelétrica e macrófitas aquáticas


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Located in the Pantanal of Miranda-Abobral, the Baía da Medalha is the largest pond close to the Base de Estudos do Pantanal of the Universidade Federal de Mato Grosso do Sul. The Baía da Medalha has been a study site for several didactic and scientific projects for years. Nevertheless, its fish fauna has never been inventoried. Based on data collected from the beginning of the 1990s up to 2011, we provide a list of fish species from the Baía da Medalha. A total of 97 species were recorded, corresponding to about 40% of the species stated for the Pantanal. Characiformes and Siluriformes were the most species-rich orders, being Characidae and Cichlidae the families with the highest number of species. Regional seasonal flood dynamics and the abundance of aquatic macrophytes may be associated with this high diversity. The representative richness found in this lagoon highlights the importance of such taxonomic surveys to preserve the diversity of aquatic habitats within the Pantanal ecosystem.

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

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This study aimed to evaluate feed preference and control efficacy of grass carp (Ctenopharyngodon idella) on the aquatic macrophytes Ceratophyllum demersum, Egeria densa and Egeria najas. An experiment was carried out at mesocosms conditions with 2,000 liters capacity and water residence time of 2.8 days. C. demersum, E. densa e E. najas biomasses were offered individually with sixty g and coupled in similar quantities of 30 g of each species, evaluated during 81 days, envolving 6 treatments. (1 - C. demersum, 2 - E. najas, 3 - E. densa, 4 - C. demersum + E. najas, 5 - C. demersum + E. densa and 6 - E. najas + E. densa). When offered individually, E. najas and C. demersum presented the same predation rate by grass carp, which was higher than E. densa predation rate. When plants were tested in pairs, the order of feed preference was C. demersum > E. najas > E. densa. E. najas and C. demersum percentage control ranged from 73 to 83%. No relation between biomass consumption and grass carp body weight gain was observed, probably due to differences in nutritional quality among macrophyte species according to fish necessities. Therefore, it is concluded that the use of grass carp is one excellent technique to control submersed macrophytes in Brazil.

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In the present investigation we studied the feeding habits of the fishes associated with aquatic macrophytes in the Rosana Reservoir, southeastern Brazil. Twenty fish species were collected during four field trips, regularly distributed across the dry and wet seasons. Focal snorkeling observations of the fishes were made over a total of six hours. Nine species were present in abundances of more than 1% and, therefore, had their feeding habits analyzed. Hemigrammus marginatus, Roeboides paranensis, Hyphessobrycon eques, Astyanax altiparanae, Serrasalmus spilopleura, and Bryconamericus stramineus were predominantly invertivores, with predominance of aquatic insects (Diptera, Ephemeroptera, and Trichoptera immatures) among their food items. The predominantly algivores were Apareiodon affinis, Serrapinnus notomelas, and Satanoperca pappaterra, with high frequency of filamentous blue-green algae, diatoms, clorophyts, and periderm. The different microhabitat exploitation plus diet composition suggests partitioning of resources and absence of food competition among the most representative fish species in the studied community, indicating the importance of the naturalistic approach to fish ecology studies.

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

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Agronomia (Produção Vegetal) - FCAV

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The Dipteryx alata is a tree specie with possibility of use in human and animal nutrition, and in the pharmaceutical industry. For reclamation of degraded areas, the revegetation has been an alternative, however, requires fertilizer addition. The objectives of this study were to evaluate the nutritional status and growth of Dipteryx alata seedlings, introduced in degraded soil under recovery process, with residues (organic and agroindustrial), compared to collected seedlings in preserved Cerrado, and evaluate the residues impact on soil chemical properties. In this work the degraded soil received the incorporation of residues, organic - RO (macrophytes) and agroindustrial - RA (ash derived from burning bagasse from sugarcane), with the following doses: 0, 16 and 32 t ha- 1 and 0, 15, 30 and 45 t ha-1 respectively. Within three months of incorporation of residues into the degraded soil, the D. alata seedlings were introduced in the experimental area, and 12 months later were evaluated for height, stem diameter, chlorophyll content and leaf contents of N, P, K, Ca, Mg, S, B, Cu, Fe, Mn and Zn. For purposes of comparison, the foliar concentration of those elements was determined in Dipteryx alata seedlings collected in preserved Cerrado area. Concomitant with the collect of leaves, at Cerrado and experimental area, soil was collected (0.0 - 0.20m deep) for evaluation of chemical parameters (P, OM, pH, K, Ca, Mg, H + Al, Al, Cu, Fe, Mn and Zn). Comparing the seedlings collected in the Cerrado with the seedlings from experimental area it is observed that the leaf concentration of N, P, K and Mg was higher in seedlings from preserved Cerrado in relation to those introduced in the experimental area. Fe, Mn and Zn, have lower foliar concentration in plants collected in the Cerrado, in the case of Mn the worst results occur in the absence of macrophytes indicating the importance of organic residue. The foliar concentration of Ca, S and Cu was similar in...

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The planting of seedlings, the establishment and maintenance of the natural regeneration process, or the combination thereof, are methods used in the recovery of degraded or disturbed environments, however, often require the addition of soil conditioners. This study aimed to evaluate the influence of conditioners, introduced in degraded soil on growth and nutritional status of Astronium fraxinifolium seedlings. To conduct the experimentation were used as degraded soil conditioner, ash from sugarcane bagasse (CZ) and macrophytes (MC), at the doses of 0, 15, 30 and 45 t ha-1 and 0, 16 and 32 t ha-1 respectively, which combined produced 12 treatments, with three replications, and for field installation, was used the experimental randomized block design. Astronium fraxinifolium (Gonçalo Alves) seedlings, native tree species in cerrado, were introduced in the experimental area and, after 12 months, were evaluated for leaf concentration of nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, copper, iron, manganese and zinc (N, P, K, Ca, Mg, S, B, Cu, Fe, Mn and Zn, respectively). Seedlings and adult plants of A. fraxinifolium were collected in preserved cerrado reserve were also analyzed for nutrients foliar concentration to perform a comparative analysis. The leaves collection in the preserved cerrado and experimental area, was accompanied by soil sampling (0.0 - 0,20 m deep), which was analyzed for phosphorus, OM (organic matter), pH, K, Ca, Mg, Al+H (potential acidity), Al (aluminum), Cu, Fe, Mn and Zn. The results show that the applied residues contributed to raise the foliar concentration of Cu and Fe. The foliar concentration of nutrients was higher in A. fraxinifolium seedlings from preserved cerrado, except for B, which was similar between areas, besides Cu and Fe with higher levels in the seedlings from experimental area. The combined addition of residues (MC and CZ), led to increase the plants height and diameter. This...

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pós-graduação em Agronomia (Produção Vegetal) - FCAV

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A distribuição e a abundância das macrófitas aquáticas são determinadas por diversos fatores que limitam a ocorrência e o crescimento destes vegetais. Vários estudos sobre ecologia de macrófitas aquáticas têm sido realizados na bacia hidrográfica do Rio Itanhaém devido à grande abundância e riqueza de espécies de macrófitas aquáticas de água doce e salobra com diferentes formas de vida nos trechos de rios localizados na planície costeira, A macrófita aquática alvo deste estudo é a Limnobium laevigatum (Humb. & Bonpl. Ex Willd.) Heine que pode crescer enraizada nas margens dos rios ou flutuantes livres em locais com maior profundidade.Os objetivos deste trabalho são: (a) gerar um mapa de distribuição de L. laevigatum na planície costeira da bacia do rio Itanhaém; (b) verificar a existência de diferenças na abundância de L. laevigatum nos diferentes bancos desta espécie; (c) identificar quais são as variáveis abióticas responsáveis pela distribuição e a abundância de L. laevigatum na planície costeira. Para gerar o mapa de distribuição os principais rios da planície costeira foram percorridos em fevereiro de 2013 e em abril de 2015 e os locais de ocorrência foram georreferenciados. Nos locais de ocorrência foram coletadas amostras do vegetal para determinação da biomassa e teores de nitrogênio e fósforo na biomassa. Além disso foram feitas medidas de temperatura, pH, condutividade elétrica, oxigênio dissolvido e turbidez e coletas de água e sedimento para a determinação de nitrogênio e fósforo totais. Aos valores de biomassa foi aplicada uma Análise de Variância para verificar a existência de diferenças significativas entre os locais de ocorrência. Aos valores das variáveis abióticas foi aplicada uma Análise de Componentes Principais e aos dados bióticos uma Análise de Componentes Principais. Os resultados obtidos mostraram maior quantidade de locais de ocorrência em 2015 (10) em...

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)