19 resultados para microcrustacean


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Potassium permanganate is a chemical compound widely used in aquaculture for the control and removal of parasites, and in the prevention of diseases caused by bacteria and fungi. However, this compound can be toxic to fish, being a strong oxidant. Moreover, there is no consistent information in the literature about its toxicity to non-target organisms. The purpose of this study was to evaluate the acute toxicity (LC50;96h) of potassium permanganate for tilapia, Oreochromis niloticus, and to determine its toxic effects on nontarget organisms using ecotoxicological assays performed with the microcrustacean Ceriodaphnia dubia and with the green microalgae Pseudokirchneriella subcapitata. The results showed that the concentration of 1.81 mg L-1 of potassium permanganate caused acute toxic effect in tilapia fingerlings. The ecotoxicological assays demonstrated that concentrations above 0.12 mg L-1 can cause chronic toxic effects on non-target organisms, indicating possible deleterious effects on the food chain of the aquatic ecosystem that may receive the discharge of effluents released by fish cultures treated with this chemotherapy. All toxic concentrations determined in this study were below those recommended in the literature for the use of this chemotherapy in fish cultures, demonstrating that this type of therapy should be more carefully considered in order to avoid damage to the treated fish and to the environment. (C) 2011 Elsevier B.V. All rights reserved.

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Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas

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Contaminant driven genetic erosion reported through the inspection of selectable traits can be underestimated using neutral markers. This divergence was previously reported in the aquatic system of an abandoned pyrite mine. The most sensitive genotypes of the microcrustacean cladoceran Daphnia longispina were found to be lacking in the impacted reservoir near the entrance of the metal rich acid mine drainage (AMD). Since that divergence could be, at least partially, accounted for by mutagenicity and genotoxicity of the AMD, the present study aimed at providing such a characterization. The Allium cepa chromosomal aberration assay, using root meristematic cells, was carried out, by exposing seeds to 100, 10, 1, and 0.1 % of the local AMD. Chromosomal aberrations, cell division phases and cell death were quantified after the AMD exposure and after 24 and 48 h recovery periods. The AMD revealed to be mutagenic and genotoxic, even after diluting it to 1 and 0.1 %. Dilutions within this range were previously found to be below the lethality threshold and to elicit sublethal effects on reproduction of locally collected D. longispina clonal lineages Significant mutagenic effects (micronuclei and chromosomal breaks) were also found at 0.1 % AMD, supporting that exposure may induce permanent genetic alterations. Recovery tests showed that AMD genotoxic effects persisted after the exposure. © 2013 Springer Science+Business Media New York.

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This study aimed to estimate the acute toxicity of teflubenzuron (1-(3,5-dichloro-2,4-difluorophenyl)-3-(2,6-difluorobenzoyl)urea) (TFB) for Daphnia magna, Lemna minor and Poecilia reticulata, in the absence and presence of sediment; evaluate the effect of sediment on the TFB bioavailability; and to classify this insecticide according to its environmental poisoning risk for agricultural and aquaculture uses. The tests of TFB acute toxicity were conducted in static system in a completely randomized design with increasing TFB concentrations, and a control group. The TFB has been classified according to the estimated values of EC50 and LC50 by its acute toxicity and environmental risk. The sediment significantly reduced toxicity and bioavailability of TFB in water column. Therefore, the insecticide can be classified as being highly toxic to Daphnia magna, which means the agricultural and aquacultural uses of TFB pose a high risk of environmental toxicity to non-target organisms. However, it was practically non-toxic to L. minor and P. reticulata. © 2013 Copyright Taylor and Francis Group, LLC.

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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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Pós-graduação em Química - IQ

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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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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Ensuring availability of quality water for human consumption causes becomes an increasing number of studies for the analysis of effluent before and after treatment, so that its release into receiving bodies do not cause significant changes in the river water and on the biological communities related to them. The biomarkers of toxicity have long been used to verify the potential toxic effluent and its correlation with the treatment efficiency of them. In this context, the cladoceran Ceriodaphnia dubia stands out because it is a benthic aquatic organism highly sensitive to environmental changes. In this study, to evaluate the interference of the release of treated wastewater of oil refinery in Rio Atibaia, we sought to determine the toxicity on population dynamics of Ceriodaphnia dubia microcrustacean in water samples upstream and downstream from the launch site, compared with samples from Rio Jaguarí at the point of capture by the company itself and treated effluent. We have studied the number of offspring produced in 10 replicates, each starting with a test individual of up to 24 hours for each sample and correlated the results with physical-chemical and microbiological tests performed by a laboratory technician. For most tests, the results indicate that the treated effluent gives sub-lethal toxicity to the microcrustacean, as delay the onset of the reproductive cycle of the same

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The aims of this research were to evaluate the acute toxicity (LC/EC50) and the environmental risk of toltrazuril (TOL) and florfenicol (FFC) for plant Lemna minor, snail Pomacea canalicuta, fish Piaractus mesopotamicus and Hyphessobrycon eques and the microcrustacean Daphnia magna. The organisms were acclimated in room bioassay with controlled temperature according to standard to each one. They were exposed at nominal concentrations in static system. For environmental risk (RQ) was used the estimated environmental concentration (EEC) that is the dosage indicate to treatment and the lethal or effective concentration (LC/CE50) from each drug in acute exposure. FFC showed LC50;7d of 97.03 mg L-1 for L. minor; >100.0 mg L-1 for P. mesopotamicus and H. eques and EC50;48h > 100.0 mg L-1 for P. canaliculata and D. magna, and it was classified low risk (RQ = 0.01) for all bioindicators. TOL howed LC50;7d >100.0 mg L-1 for L. minor, 3.72 mg L-1 for P. mesopotamicus; 6.22 mg L-1 for H. eques and CE50;48h of 7.59 mg L-1 for P. canaliculata and 18.57 mg L-1 for D. magna, and it was classified low risk (RQ = 0.01) for L. minor and high risk for P. mesopotamicus (RQ = 2.68), H. eques (RQ = 6.22), P. canaliculata (RQ = 1.31) and D. magna (RQ = 0.53). Lemna minor was the bioindicator indicating of FFC toxicity and H. eques, bioindicator of the TOL. FFC is safety however and the use of TOL necessaries cautions to treat the wastewater before discard on the environment.