CESAM and Department of Biology, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
Chemosphere. 2010 Jan;78(3):241-8. doi: 10.1016/j.chemosphere.2009.10.066. Epub 2009 Dec 8.
Risk assessment of toxic substances under ecologically-relevant scenarios which include the presence of natural stressors is essential to understand their indirect toxic effects and to improve prediction of the impacts of contamination on community structure and ecosystem function. Here, we study the effects of the pesticide imidacloprid on the responses of Daphnia magna to a combination of predator-release kairomones from trout and alarm cues from conspecifics, simulating different levels of perceived predation risk. The joint effects of simultaneous exposure to both types of stressors were assessed both by traditional analysis of variance and by employing conceptual models for the evaluation of contaminant mixture exposures. Results demonstrated that pesticide exposure can significantly increase the costs of inducible antipredator defences and impair life-history responses of daphnids to fish predation pressure. Since trait-mediated effects are well-known to play a key role in population dynamics, the combined direct and indirect effects of sub-lethal concentrations of pesticides could induce maladaptive responses in zooplankton populations in the field, reducing their long-term viability.
在包括自然胁迫因素的生态相关情景下，对有毒物质进行风险评估对于理解其间接毒性作用以及提高对污染对群落结构和生态系统功能的影响的预测至关重要。在这里，我们研究了杀虫剂吡虫啉对大型溞（Daphnia magna）对来自鳟鱼的捕食者释放信息素和同种警报信号的组合反应的影响，模拟了不同程度的感知捕食风险。通过传统的方差分析和用于评估污染物混合物暴露的概念模型，评估了同时暴露于这两种胁迫因素的联合效应。结果表明，农药暴露会显著增加诱导性防御捕食者的成本，并损害水蚤对鱼类捕食压力的生活史反应。由于性状介导的效应在种群动态中起着关键作用，因此亚致死浓度的杀虫剂的直接和间接联合作用可能会导致田间浮游动物种群产生适应性不良反应，降低其长期生存能力。
