Navegando por Palavras-chave "Microcosm"

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    Dynamics of fipronil in Oleo Lagoon in Jatai Ecological Station, São Paulo-Brazil
    (Elsevier B.V., 2010-03-01) Peret, Andre Moldenhauer [UNIFESP]; Oliveira, Luciana Fontes [UNIFESP]; Bianchini, Irineu [UNIFESP]; Regali Seleghim, Mirna Helena [UNIFESP]; Peret, Alberto Carvalho [UNIFESP]; Mozeto, Antonio Aparecido [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Fipronil is a phenylpyrazole pesticide widely used to protect sugar-cane crops from insect pests. After reaching the environment, this insecticide may have several fates. This research aimed to propose a kinetic model to describe the fate of commercial fipronil Regent 800WG (R) in the sediment-water interface of the Oleo Lagoon in the Mogi-Guacu river floodplain, situated within the Jatai Ecological Station, by means of a microcosm scale experiment. Results showed that a small fraction of the pesticide is quickly dragged to the sediment while most of it remains in the water column. Biodegradation proves to be an important fipronil degradation route, especially when microorganisms capable of using fipronil as sole carbon source increase their population, as a function of exposure time. Biodegradation rates were higher in the sediment than in the water column. (C) 2009 Elsevier B.V. All rights reserved.
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    Is the microcosm approach using meiofauna community descriptors a suitable tool for ecotoxicological studies?
    (Academic Press Inc Elsevier Science, 2018) Santos, Anna Carolina Chaaban; Choueri, Rodrigo Brasil [UNIFESP]; Pauly, Guacira de Figueiredo Eufrasio; Abessa, Denis Moledo de Souza; Gallucci, Fabiane [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The usual approaches used in ecological risk assessment have been based on individual and population level standard procedures. Although these have been important tools to assess adverse effects on ecosystems, they are generally simplified and therefore lack ecological realism. Microcosm studies using meiobenthic communities offer a good compromise between the complexity of the ecosystem and the often highly artificial settings of laboratory experiments. An experiment was designed to investigate the potential of the microcosm approach using meiofauna as a tool for ecotoxicological studies. The experiment tested the ecological effects of exposure to sewage-impacted pore water simultaneously at the community level using meiofauna microcosms and at the individual level using laboratory fecundity tests with the copepod Nitokra sp. Specifically, the experiment tested the toxicity of pore water from three sites according to a contamination gradient. Both approaches were efficient in detecting differences in toxicity between the less and more contaminated sites. However, only multivariate data from community analysis detected differences in the gradient of contamination. In addition to information about toxicity, the community level microcosm experiment gave indications about sensitive and tolerant species, indirect ecological effects, as well as raised hypothesis about contamination routes and bioavailability to be tested. Considering the importance of meiofauna for benthic ecosystems, the microcosm approach using natural meiobenthic communities might be a valuable addition as a higher tier approach in ecological risk assessment, providing highly relevant ecological information on the toxicity of contaminated sediments.