Goethe University Frankfurt am Main, Department of Aquatic Ecotoxicology, Faculty of Biological Sciences, Max-von-Laue-Straße 13, 60438 Frankfurt am Main, Germany.
Norwegian University of Science and Technology, Department of Biology, Høgskoleringen 5, Realfagbygget, 7491 Trondheim, Norway.
Sci Total Environ. 2020 May 20;718:137253. doi: 10.1016/j.scitotenv.2020.137253. Epub 2020 Feb 13.
Human-induced changes in the environment have increased the number of stressors impacting aquatic organism. In the light of climate change and plastic pollution, thermal stress and microplastics (MP) have become two of the most intensively studied stressors in aquatic ecosystems. Previous studies, however, mostly evaluated the impacts of thermal and MP stress in isolation, thereby neglecting joint effects. To examine the combined effects of both, we exposed the freshwater mussel Dreissena polymorpha to irregular polystyrene MP (6.4, 160, 4000, 100,000 p mL) at either 14, 23 or 27 °C for 14 days and analyzed mortality, mussel activity and clearance rate, energy reserves, oxidative stress and the immunological state. Further, we exposed the mussels to diatomite (natural particle equivalent, 100,000 p mL) at each of the three water temperatures to compare MP and natural particle toxicity. An increase in water temperature has a pronounced effect on D. polymorpha and significantly affects the activity, energy reserves, oxidative stress and immune function. In contrast, the effects by MP are limited to a change in the antioxidative capacity without any interactive effects between MP and thermal exposure. The comparison of the MP with a diatomite exposure revealed only limited influence of the particle type on the response of D. polymorpha to high concentrations of suspended particles. The results indicate that MPs have minor effects on a freshwater mussel compared to thermal stress, neither alone nor as interactive effect. Limited MP toxicity could be based on adaptation mechanism of dreissenids to suspended solids. Nonetheless, MP may contribute to environmental impacts of multiple anthropogenic stressors, especially if their levels increase in the future. Therefore, we suggest integrating MP into the broader context of multiple stressor studies to understand and assess their joint impacts on freshwater ecosystems.
人为改变环境增加了影响水生生物的应激因素数量。在气候变化和塑料污染的背景下，热应激和微塑料（MP）已成为水生生态系统中研究最集中的两个应激因素。然而，以前的研究大多单独评估热和 MP 应激的影响，从而忽略了联合效应。为了研究这两种应激因素的联合效应，我们将淡水贻贝多形光壳炱暴露于不规则聚苯乙烯 MP（6.4、160、4000、100000 p mL）中，温度分别为 14、23 或 27°C，持续 14 天，并分析死亡率、贻贝活动和清除率、能量储备、氧化应激和免疫状态。此外，我们在三种水温下将贻贝暴露于硅藻土（天然颗粒当量，100000 p mL）中，以比较 MP 和天然颗粒的毒性。水温升高对多形光壳炱有明显影响，显著影响其活动、能量储备、氧化应激和免疫功能。相比之下，MP 的影响仅限于抗氧化能力的改变，而 MP 与热暴露之间没有相互作用。将 MP 与硅藻土暴露进行比较，仅发现颗粒类型对高浓度悬浮颗粒下贻贝反应的影响有限。结果表明，与热应激相比，MP 对淡水贻贝的影响较小，无论是单独作用还是相互作用都较小。MP 的有限毒性可能基于多形光壳炱对悬浮固体的适应机制。尽管如此，MP 可能会对多种人为应激因素对环境的影响做出贡献，特别是如果它们的水平在未来增加的话。因此，我们建议将 MP 纳入多应激因素研究的更广泛背景中，以了解和评估它们对淡水生态系统的联合影响。
