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首页> 外文期刊>Estuarine Coastal and Shelf Science >Toxic effects of isoproturon on periphyton communities - a microcosm study
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Toxic effects of isoproturon on periphyton communities - a microcosm study

机译：异丙隆对周围植物群落的毒性作用-微观研究

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Coastal and estuarine ecosystems are increasingly exposed to herbicide contamination. To study the potential risks of these pollutants, the establishment of periphyton communities under exposure of a concentration series of isoproturon in a range of 0.0024-0.312 mg L~(-1) was investigated in a microcosm study. After two weeks of growth, chronic effects on biomass development, measured as Chl a fluorescence, taxonomic composition and photosynthetic capacity of PS II of attached microalgae were analysed using a pulse-amplitude modulated (PAM) fluorescence-based method. Algal classes were differentiated according to their pigment systems using four excitation wavelengths. Biomass remained constant up to pre-exposure concentrations of 0.02 mg L~(-1) isoproturon but decreased within one order of magnitude at the highest test concentration. Algal classes shifted from diatoms to chlorophytes at pre-exposure concentrations of 0.02-0.39 mg L~(-1). Community structure of diatoms representing the dominant group of attached algae at lower test concentrations was studied by microscopic analysis revealing that species numbers were highest at lowest test concentrations as compared to controls. At higher test concentrations Navicula halophila dominated with 89% of the diatom biomass but was abnormally shaped. Pollution-induced community tolerance (PICT) of periphyton to isoproturon was determined by short-term inhibition tests of photosynthesis. Pre-exposed communities increased their effect concentrations (EC_(50)) up to threefold within the 0.039 mg L~(-1) pre-treatment. Our results suggest that attached microalgal communities have a high potential of tolerance development to isoproturon at lower levels of contamination due to the replacement of sensitive species by more tolerant algae, although these species seemed to be affected too. We conclude that herbicide concentrations in river basins, estuaries or coastal zones may change community structure and primary production of microphytobenthos even when the contamination does not exceed levels of acute toxicity.
机译：沿海和河口生态系统越来越受到除草剂污染。为了研究这些污染物的潜在风险，在微观研究中研究了在浓度范围为0.0024-0.312 mg L〜（-1）的异丙隆浓度下暴露的围生植物群落的建立。生长两周后，使用基于脉冲幅度调制（PAM）的荧光方法分析了对附着生物的PS II的荧光，生物分类组成和PS II的光合能力，对生物量发育的长期影响进行了测量。使用四个激发波长，根据其色素系统区分藻类。直到暴露前的浓度为0.02 mg L〜（-1）异丙肾上腺素，生物量仍保持恒定，但在最高测试浓度下，生物量下降了一个数量级。暴露前浓度为0.02-0.39 mg L〜（-1）时，藻类从硅藻转变为绿藻。通过显微镜分析研究了在较低测试浓度下代表附着藻类优势群的硅藻的群落结构，结果显示与对照组相比，物种数在最低测试浓度下最高。在较高的测试浓度下，Navicula halophila占硅藻生物量的89％，但形状异常。通过光合作用的短期抑制试验确定了污染引起的周生植物对异丙隆的群落耐受性（PICT）。在0.039 mg L〜（-1）的预处理范围内，暴露前的社区将其效应浓度（EC_（50））增加到三倍。我们的结果表明，由于敏感物种被更耐受的藻类替代，因此附着的微藻群落在较低污染水平下对异丙隆的耐受性发展潜力很大，尽管这些物种似乎也受到了影响。我们得出的结论是，即使污染程度不超过急性毒性水平，流域，河口或沿海地区的除草剂浓度也可能会改变微底栖底栖动物的群落结构和初级生产。

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