Microfibers, which are sourced from textiles and some products from the fishery industry, are the biggest contributors to microplastic pollution in aquatic ecosystems. In addition to these synthetic microfibers, naturally derived microfibers can also be found in aquatic environments. However, there are limited studies on the ecotoxicity of natural microfibers. To shed light on this topic, this study assessed and compared the toxicity of natural and synthetic microfibers on Daphnia magna, using lyocell, polyester (PET) and polypropylene (PP) microfibers. To evaluate the adverse effect of microfibers on D. magna, after effects including depuration, food intake, growth, mortality, and immobilization rate were continually observed for up to 96 h after the initial 48 h of exposure to the microfibers. Immobilization rate decreased in the following order: PP, PET, and lyocell. However, the depuration of microfibers in the lyocell and PET treatment groups was similar, with higher mortality rates than in the PP treatment group. Furthermore, despite the high rates of food intake following exposure, the lyocell and PET exposed groups exhibited growth inhibition during the same period. This growth inhibition corresponded with, and was likely due to, reductions in the length of gut microvilli, probably an expression of gut damage, which is believed to have reduced nutrient absorption in the affected individuals. Based on the results of this study, it was confirmed that even natural microfibers, and not just synthetic microfibers, can have adverse effects on aquatic organisms. This study confirmed not only the toxicity of microfibers, but also the consequences of their after effects. These results could be the basis for future research on the after effects of microplastics on aquatic organisms and provide directions for further microplastic ecotoxicity studies.

来自纺织品和一些渔业产品的超细纤维是水生生态系统中微塑料污染的最大贡献者。除了这些合成超细纤维，在水生环境中也可以找到天然衍生的超细纤维。然而，关于天然微纤维的生态毒性的研究有限。为了阐明这一主题，本研究使用莱赛尔、聚酯 (PET) 和聚丙烯 (PP) 超细纤维评估并比较了天然和合成超细纤维对大型水蚤的毒性。为了评估超细纤维对 D. magna 的不利影响，在最初接触超细纤维 48 小时后，持续观察长达 96 小时的后效应，包括净化、食物摄入、生长、死亡率和固定率。固定率按以下顺序降低：PP、PET 和莱赛尔。然而，lyocell 和 PET 治疗组的微纤维净化相似，死亡率高于 PP 治疗组。此外，尽管暴露后的食物摄入率很高，但在同一时期，lyocell 和 PET 暴露组表现出生长抑制。这种生长抑制对应于并且可能是由于肠道微绒毛长度的减少，这可能是肠道损伤的一种表现，据信这减少了受影响个体的营养吸收。根据这项研究的结果，证实即使是天然超细纤维，而不仅仅是合成超细纤维，也会对水生生物产生不利影响。这项研究不仅证实了超细纤维的毒性，还证实了它们的后遗症。