Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal.
TOXRUN-Toxicology Research Unit, CESPU, University Institute of Health Sciences (IUCS), 3810-193 Gandra, Portugal.
Sci Total Environ. 2023 Jun 1;875:162556. doi: 10.1016/j.scitotenv.2023.162556. Epub 2023 Mar 3.
Freshwater benthic environments are among the major sinks of microplastics (MPs, < 5 mm) sourced on inland anthropogenic activities. The ecotoxicological effects of MPs on benthic macroinvertebrates have been assessed preferably in collectors, shredders, and filter-feeders, but resulting in insufficient knowledge on the potential trophic transfer and its effects on macroinvertebrates with predator behaviour such as planarians. This work evaluated the behavioural (feeding, locomotion), physiological (regeneration) and biochemical responses (aerobic metabolism, energy reserves, oxidative damage) of the planarian Girardia tigrina after consuming contaminated live prey Chironomus riparius larvae previously exposed to microplastics of polyurethane (PU-MPs; 7-9 μm in size; 375 mg PU-MPs/kg). After the feeding period (3 h), planarians consumed 20 % more contaminated prey than uncontaminated prey, probably related to increased curling/uncurling movements of larvae (that might be more appellative to planarians). Histological analysis revealed planarians' limited intake of PU-MPs, mainly detected near the pharynx. The consumption of contaminated prey (and intake of PU-MPs) did not result in oxidative damage but slightly increased the aerobic metabolism and energy reserves which show that the consumption of more prey was sufficient to cope with the potential adverse effects of internalized MPs. Moreover, no effects were observed in the locomotion of planarians in good agreement with the hypothesis of sufficient energy acquired by the exposed planarians. Despite the previous, it seems that the energy acquired was not allocated for planarians' regeneration since a significant delay in the regeneration of the auricles was observed for planarians feeding on contaminated prey. Therefore, further studies should be performed considering the potential long-term effects (i.e., reproduction/fitness) and the effects of MPs that might result from continuous feeding on contaminated prey, representing a more realistic exposure scenario.
淡水底栖环境是内陆人为活动中微塑料（MPs，<5 毫米）的主要汇。已经评估了 MPs 对底栖大型无脊椎动物的生态毒理学影响，最好是在收集者、撕食者和滤食者中进行评估，但对具有捕食者行为的大型无脊椎动物（如涡虫）的潜在营养转移及其影响的了解仍然不足。本工作评估了食性（摄食、运动）、生理（再生）和生化反应（有氧代谢、能量储备、氧化损伤）在食用受污染活猎物摇蚊幼虫后，涡虫 Girardia tigrina 的行为变化，这些幼虫先前暴露于聚氨酯微塑料（PU-MPs；大小为 7-9 微米；375 毫克 PU-MPs/kg）中。在摄食期（3 小时）后，涡虫比食用未受污染的猎物多消耗 20%的受污染猎物，这可能与幼虫卷曲/伸展运动增加有关（这可能对涡虫更有吸引力）。组织学分析显示涡虫对 PU-MPs 的摄入量有限，主要在咽附近检测到。食用受污染的猎物（和摄入的 PU-MPs）并没有导致氧化损伤，但略微增加了有氧代谢和能量储备，这表明食用更多的猎物足以应对内化 MPs 的潜在不利影响。此外，涡虫的运动没有受到影响，这与暴露的涡虫获得足够能量的假设一致。尽管如此，似乎获得的能量并没有分配给涡虫的再生，因为食用受污染猎物的涡虫的耳瓣再生明显延迟。因此，应该进行进一步的研究，考虑到潜在的长期影响（即繁殖/适应力）和可能由连续食用受污染猎物引起的 MPs 影响，这代表了更现实的暴露情况。
