As an emerging contaminant, microplastics (MPs) are widely distributed in freshwater ecosystems and pose potential threats to aquatic organisms, attracting significant attention from both the scientific community and the general public. However, there is still uncertainty regarding the mechanisms of MPs transfer within aquatic biota and how particle size and food availability influence their transport patterns. In this study, zebrafish (Danio rerio) were selected as a model organism to investigate the uptake and elimination of fluorescent polyethylene (PE) MPs under different exposure scenarios (waterborne or trophic transfer, with or without food) and varying particle sizes (ranging from 10-300 μm at concentrations of 0.1, 2, and 300 mg/L). Additionally, water fleas (Daphnia magna) were provided as prey for the fish. The dynamic accumulation of PE-MPs sized between 10-20 μm at a concentration of 25 mg/L by daphnia was also determined along with its impact on animal feeding behavior. The results demonstrated that both organisms were capable of ingesting PE-MPs during exposures lasting up to 24 hours for daphnia and up to 72 hours for zebrafish. Furthermore, rapid elimination rates were observed within just 30 minutes for daphnia and between 6-12 hours for zebrafish. The presence of food reduced MPs uptake and removal by daphnia but significantly increased MP elimination by fish. Zebrafish showed a preference for ingesting larger-sized MPs that they could easily recognize; however, trophic transfer from daphnia to fish was found to be the primary route of ingestion specifically for PE-MPs sized between 10-20 μm. The findings suggest that while fish directly ingest fewer invisible MPs from the water column, they still accumulate these particles through predation on contaminated prey organisms. Therefore, it is imperative to prioritize the ecological risks associated with the transfer of MPs from zooplankton to fish.

中文翻译：

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淡水模式生物对荧光聚乙烯微塑料的吸收、去除和营养转移：颗粒大小和食物供应的影响


微塑胶 （MP） 作为一种新兴污染物，广泛分布在淡水生态系统中，对水生生物构成潜在威胁，引起了科学界和公众的极大关注。然而，关于 MP 在水生生物群中转移的机制以及颗粒大小和食物供应如何影响它们的运输模式仍然存在不确定性。在本研究中，选择斑马鱼 （Danio rerio） 作为模式生物，研究荧光聚乙烯 （PE） MP 在不同暴露情景（水源或营养转移，有或没有食物）和不同粒径（范围为 10-300 μm，浓度为 0.1、2 和 300 mg/L）下的吸收和消除。此外，水跳蚤 （Daphnia magna） 被作为鱼的猎物。还测定了水蚤在 25 mg/L 浓度下大小在 10-20 μm 之间的 PE-MPs 的动态积累及其对动物取食行为的影响。结果表明，这两种生物体都能够在水蚤长达 24 小时和斑马鱼长达 72 小时的暴露期间摄入 PE-MPs。此外，水蚤在短短 30 分钟内观察到快速消除率，斑马鱼在 6-12 小时内观察到快速消除率。食物的存在减少了水蚤对 MP 的吸收和去除，但显著增加了鱼类对 MP 的消除。斑马鱼表现出偏爱摄入它们很容易识别的较大尺寸的 MP;然而，发现从水蚤到鱼类的营养转移是主要的摄入途径，特别是 10-20 μm 大小的 PE-MP。 研究结果表明，虽然鱼类从水柱中直接摄入的不可见 MP 较少，但它们仍然通过捕食受污染的猎物生物来积累这些颗粒。因此，当务之急是优先考虑与 MP 从浮游动物转移到鱼类相关的生态风险。