Abstract：
Emerging pollutants, such as pharmaceuticals and microplastics have become a pressing concern due to their widespread presence and potential impacts on ecological systems. To assess the ecosystem-level effects of these pollutants within a multi-stressor context, we simulated real-world conditions by exposing a near-natural multi-trophic aquatic food web to a gradient of environmentally relevant concentrations of fluoxetine and microplastics in large mesocosms over a period of more than three months. We measured the biomass and abundance of different trophic groups, as well as ecological functions such as nutrient availability and decomposition rate. To explore the mechanisms underlying potential community and ecosystem-level effects, we also performed behavioral assays focusing on locomotion parameters as a response variable in three species: Daphnia magna (zooplankton prey), Chaoborus flavicans larvae (invertebrate pelagic predator of zooplankton) and Asellus aquaticus (benthic macroinvertebrate), using water from the mesocosms. Our mesocosm results demonstrate that presence of microplastics governs the response in phytoplankton biomass, with a weak non-monotonic dose-response relationship due to the interaction between microplastics and fluoxetine. However, exposure to fluoxetine evoked a strong non-monotonic dose-response in zooplankton abundance and microbial decomposition rate of plant material. In the behavioral assays, the locomotion of zooplankton prey D. magna showed a similar non-monotonic response primarily induced by fluoxetine. Its predator C. flavicans, however, showed a significant non-monotonic response governed by both microplastics and fluoxetine. The behavior of the decomposer A. aquaticus significantly decreased at higher fluoxetine concentrations, potentially leading to reduced decomposition rates near the sediment. Our study demonstrates that effects observed upon short-term exposure result in more pronounced ecosystem-level effects following chronic exposure.
摘要：
新兴污染物，如药物和微塑料已成为一个紧迫的问题，因为它们的广泛存在和对生态系统的潜在影响。为了在多压力源背景下评估这些污染物的生态系统水平影响，我们通过在三个多月的时间内将近自然的多营养水生食物网暴露于大型中观中环境相关浓度的氟西汀和微塑料的梯度来模拟现实条件。我们测量了不同营养类群的生物量和丰度，以及生态功能，如养分利用率和分解率。为了探索潜在的群落和生态系统水平效应的潜在机制，我们还进行了行为测定，重点是运动参数作为三个物种的响应变量：大型水蚤（浮游动物猎物），Chaoborusflavicans幼虫（浮游动物的无脊椎动物中上层捕食者）和Asellusaquaticus（底栖大型无脊椎动物），利用中观宇宙中的水。我们的中观结果表明，微塑料的存在控制着浮游植物生物量的响应，由于微塑料和氟西汀之间的相互作用，具有弱的非单调剂量反应关系。然而,暴露于氟西汀引起浮游动物丰度和植物材料微生物分解率的强烈非单调剂量反应。在行为分析中，浮游动物猎物D.magna的运动表现出类似的非单调反应，主要由氟西汀诱导。它的捕食者C.flagicans，然而,显示出由微塑料和氟西汀控制的显着非单调反应。在较高的氟西汀浓度下，分解剂A.aquaticus的行为显着降低，可能导致沉积物附近分解速率降低。我们的研究表明，短期暴露后观察到的影响会导致长期暴露后更明显的生态系统水平影响。
