Barbosa Miguel, Inocentes Núrya, Soares Amadeu M V M, Oliveira Miguel
Department of Biology & CESAM - Centre for Environmental and Marine Studies, University of Aveiro, Campus Universitário Santiago, 3810-193 Aveiro, Portugal; Centre for Biological Diversity, School of Biology, University of St Andrews, East Sands, St Andrews KY16 8LB, Fife, United Kingdom.
Department of Biology & CESAM - Centre for Environmental and Marine Studies, University of Aveiro, Campus Universitário Santiago, 3810-193 Aveiro, Portugal.
Aquat Toxicol. 2017 Dec;193:268-275. doi: 10.1016/j.aquatox.2017.10.017. Epub 2017 Nov 8.
Increased variability in water temperature is predicted to impose disproportionally greater fitness costs than mean increase in temperature. Additionally, water contaminants are currently a major source of human-induced stress likely to produce fitness costs. Global change models forecast an increase in these two human-induced stressors. Yet, in spite the growing interest in understanding how organisms respond to global change, the joint fitness effects of water pollution and increased variability in temperature remain unclear. Here, using a multigenerational design, we test the hypothesis that exposure to high concentrations of fluoxetine, a human medicine commonly found in freshwater systems, causes increased lifetime fitness costs, when associated with increased variability in temperature. Although fluoxetine and variability in temperature elicited some fitness cost when tested alone, when both stressors acted together the costs were disproportionally greater. The combined effect of fluoxetine and variability in temperature led to a reduction of 37% in lifetime reproductive success and a 17.9% decrease in population growth rate. Interestingly, fluoxetine and variability in temperature had no effect on the probability of survival. Freshwater systems are among the most imperilled ecosystems, often exposed to multiple human-induced stressors. Our results indicate that organisms face greater fitness risk when exposed to multiple stressors at the same time than when each stress acts alone. Our study highlights the importance of using a multi-generational approach to fully understand individual environmental tolerance and its responses to a global change scenario in aquatic systems.
预计水温变异性增加所带来的适应性成本将比温度平均升高带来的成本高得多。此外，水污染物目前是人为造成压力的主要来源，很可能会产生适应性成本。全球变化模型预测这两种人为压力源都会增加。然而，尽管人们越来越有兴趣了解生物体如何应对全球变化，但水污染和温度变异性增加对适应性的综合影响仍不清楚。在此，我们采用多代设计，来检验以下假设：当与温度变异性增加相关联时，接触高浓度氟西汀（一种在淡水系统中常见的人类药物）会导致终生适应性成本增加。虽然单独测试时，氟西汀和温度变异性都会引发一些适应性成本，但当两种压力源共同作用时，成本会高得多。氟西汀和温度变异性的综合作用导致终生繁殖成功率降低37%，种群增长率下降17.9%。有趣的是，氟西汀和温度变异性对生存概率没有影响。淡水系统是最濒危的生态系统之一，经常受到多种人为压力源的影响。我们的研究结果表明，生物体同时暴露于多种压力源时面临的适应性风险比每种压力单独作用时更大。我们的研究强调了采用多代方法来全面了解个体环境耐受性及其对水生系统全球变化情景反应的重要性。
