36 resultados para CYANOBACTERIAL BLOOMS


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

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A variação espacial e temporal de rotíferos foi analisada em um reservatório pequeno, raso e eutrófico, com intensas florações de algas Cyanobacteria, em sete pontos de amostragem durante 17 meses (março/2002 a julho/2003). Foram identificados 52 táxons em 16 famílias, sendo Brachionidade, Conochilidae, Synchaetidae, Lecanidae, Collothecidae, Trichocercidae e Gastropodidae as mais frequentes. Collotheca sp. foi abundante no inverno (período seco), enquanto Conochilus coenobasis Skorikov, 1914 e Keratella cochlearis Gosse, 1851 apresentaram baixas abundâncias. Brachionus mirus var. reductus (Koste, 1972), Filinia longiseta (Ehrenberg, 1834) e Keratella lenzi (Hauer, 1953) apresentaram picos de abundância no verão (período chuvoso), e Kellicottia bostonensis (Rousselet, 1908), Ploesoma truncatum (Levander, 1894), Polyarthra remata (Skorikov, 1896), Polyarthra vulgaris Carlin, 1943 e Ptygura sp. no inverno, entretanto, relacionados a chuvas atípicas. Diferenças significativas do número de táxons e da abundância total dos rotíferos ocorreram entre os meses amostrados. A análise de correspondência canônica explicou 46% da relação da abundância dos rotíferos e variáveis ambientais, correlacionados com a pluviosidade, nitrito, temperatura da água, nitrogênio orgânico, nitrato e temperatura do ar. Houve flutuações na abundância dos rotíferos um mês após oscilações na abundância do fitoplâncton. A maior parte das correlações entre as abundâncias de espécies de rotíferos e do fitoplâncton foi positiva. Alguns táxons como Filinia longiseta, Keratella lenzi e K. cochlearis apresentaram variação temporal definida e semelhante a outros reservatórios eutróficos. A ausência de padrões claros de distribuição em algumas espécies foi atribuída a hidrodinâmica do reservatório, o qual foi construído recentemente, e as condições climáticas adversas durante o período de estudo, como as chuvas intensas no inverno.

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Oceanic disposal systems of domestic sewage, or submarine sewage outfalls, have been historically used around the world as a solution for urban effluents, in special due to economic aspects. However, release into the ocean, in shallow or deep waters, may induce a set of negative environmental impacts, as eutrophication, toxic algal blooms, pathogenic microorganisms introduction and contamination by chemical substances which are capable of causing toxic effects to the biota and bioaccumulation. Thus, the release of untreated sewage into the sea does not constitute an adequate environmental practice; then, urban effluents should be treated in order to remove nutrients, contaminants and pathogenic organisms and avoid environmental degradation.

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Pós-graduação em Ciências Biológicas (Biologia Vegetal) - IBRC

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Pós-graduação em Ciências Biológicas (Biologia Vegetal) - IBRC

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Pós-graduação em Educação - IBRC

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Pós-graduação em Ciência Animal - FMVA

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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In extensive animal husbandry, natural or artificial ponds allow direct access of cattle to water but result in degradation of water quality and in increased health risks. Under such circumstances eutrophication occurs and consequently algal bloom, among them toxigenic cyanobacteria. The present study aimed to report the occurrence of cyanobacteria in the drinking water of cattle and to describe their physical and chemical parameters, as pH, temperature and dissolved oxygen. Nineteen samples of natural ponds or water troughs formed predominantly as result of rainfall from six farms located in the Southeast and Midwest regions of Brazil were analyzed for the presence of cyanobacteria, and pH, temperature and dissolved oxygen was measured. Microcystis and/or Merismopedia were detected in two ponds; one of them was covered with intense flowering. The values of pH, temperature and dissolved oxygen in 19 collections were pH 7.2-9.7, 31-34ºC and 7.8-30mg/l respectively. Also non-pathogenic algae of several genera were detected besides the occurrence or not of cianogenics. Under these conditions, the common practices of drinking water supply for extensively raised cattle and the possibilities of eutrophication and cyanobacterial growth bring potential risks for animal health.

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Algae bloom is one of the major consequences of the eutrophication of aquatic systems, including algae capable of producing toxic substances. Among these are several species of cyanobacteria, also known as blue-green algae, that have the capacity to adapt themselves to changes in the water column. Thus, the horizontal distribution of cyanobacteria harmful algae blooms (CHABs) is essential, not only to the environment, but also for public health. The use of remote sensing techniques for mapping CHABs has been explored by means of bio-optical modeling of phycocyanin (PC), a unique inland waters cyanobacteria pigment. However, due to the small number of sensors with a spectral band of the PC absorption feature, it is difficult to develop semi-analytical models. This study evaluated the use of an empirical model to identify CHABs using TM and ETM+ sensors aboard Landsat 5 and 7 satellites. Five images were acquired for applying the model. Besides the images, data was also collected in the Guarapiranga Reservoir, in São Paulo Metropolitan Region, regarding the cyanobacteria cell count (cells/mL), which was used as an indicator of CHABs biomass. When model values were analyzed excluding calibration factors for temperate lakes, they showed a medium correlation (R²=0.81, p=0.036), while when the factors were included the model showed a high correlation (R²=0.96, p=0.003) to the cyanobacteria cell count. The empirical model analyzed proved useful as an important tool for policy makers, since it provided information regarding the horizontal distribution of CHABs which could not be acquired from traditional monitoring techniques.

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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)