Department of Biological Sciences, Limnology Laboratory, Middle East Technical University, Ankara, Turkey; Earth System Science, Graduate School of Natural and Applied Science, Middle East Technical University, Ankara, Turkey.
Department of Biological Sciences, Limnology Laboratory, Middle East Technical University, Ankara, Turkey; Ecosystem Research and Implementation Centre, Middle East Technical University, Ankara, Turkey.
Sci Total Environ. 2022 Aug 25;836:155407. doi: 10.1016/j.scitotenv.2022.155407. Epub 2022 Apr 22.
The ubiquitous presence of microplastics (MP) in aquatic ecosystems can affect organisms and communities in multiple ways. While MP research on aquatic organisms has primarily focused on marine ecosystems and laboratory experiments, the community-level effects of MP in freshwaters, especially in lakes, are poorly understood. To examine the impact of MP on freshwater lake ecosystems, we conducted the first in situ community-level mesocosm experiment testing the effects of MP on a model food web with zooplankton as main herbivores, odonate larvae as predators, and chironomid larvae as detritivores for seven weeks. The mesocosms were exposed to a mixture of the most abundant MP polymers found in freshwaters, added at two different concentrations in a single pulse to the water surface, water column and sediment. Water column MP concentrations declined sharply during the first two weeks of the experiment. Contrary to expectations, MP ingestion by zooplankton was low and limited mainly to large-bodied Daphnia, causing a decrease in biomass. Biomass of the other zooplankton taxa did not decrease. Presence of MP in the faecal pellets of odonate larvae that fed on zooplankton was indicative of a trophic transfer of MP. The results demonstrated that MP ingestion varies predictably with MP size, as well as body size and feeding preference of the organism, which can be used to predict the rates of transfer and further effects of MP on freshwater food webs. For chironomids, MP had only a low, short-term impact on emergence patterns while their wing morphology was significantly changed. Overall, the impact of MP exposure on the experimental food web and cross-ecosystem biomass transfer was lower than expected, but the experiment provided the first in situ observation of MP transfer to terrestrial ecosystems by emerging chironomids.
微塑料（MP）在水生生态系统中普遍存在，可能通过多种方式影响生物和群落。虽然 MP 对水生生物的研究主要集中在海洋生态系统和实验室实验，但对淡水，尤其是湖泊中 MP 的群落水平效应知之甚少。为了研究 MP 对淡水湖泊生态系统的影响，我们进行了首次原位群落水平中观实验，以浮游动物为主要草食动物、蜻蜓幼虫为捕食者、摇蚊幼虫为碎屑食者的模式食物网为对象，测试了 MP 的影响，实验持续了七周。中观实验将最常见的两种淡水 MP 聚合物混合物以单一脉冲的形式添加到水面、水柱和沉积物中，暴露在不同浓度的 MP 中。在实验的头两周，水柱中的 MP 浓度急剧下降。与预期相反，浮游动物对 MP 的摄入量很低，主要局限于大型的 Daphnia，导致生物量减少。其他浮游动物类群的生物量没有减少。以浮游动物为食的蜻蜓幼虫的粪便中存在 MP，表明 MP 发生了营养转移。结果表明，MP 的摄入量可根据 MP 尺寸、生物体的体型和摄食偏好进行预测，这可用于预测 MP 对淡水食物网的转移速率和进一步影响。对于摇蚊而言，MP 对其出蛹模式只有短期、低水平的影响，但其翅膀形态发生了显著变化。总的来说，暴露于 MP 对实验食物网和跨生态系统生物量转移的影响低于预期，但该实验首次原位观察到了出蛹的摇蚊将 MP 转移到陆地生态系统的情况。
