Schür Christoph, Beck Joana, Lambert Scott, Scherer Christian, Oehlmann Jörg, Wagner Martin
Department of Environmental Toxicology, Eawag, Überlandstrasse 133, 8600 Dübendorf, Switzerland; Department Aquatic Ecotoxicology, Faculty of Biological Sciences, Goethe University, Frankfurt am Main, Max-von-Laue-Str. 13, 60438 Frankfurt am Main, Germany.
Department Aquatic Ecotoxicology, Faculty of Biological Sciences, Goethe University, Frankfurt am Main, Max-von-Laue-Str. 13, 60438 Frankfurt am Main, Germany.
Sci Total Environ. 2023 Dec 10;903:166521. doi: 10.1016/j.scitotenv.2023.166521. Epub 2023 Aug 26.
The toxicity of microplastics on Daphnia magna as a key model for freshwater zooplankton is well described. While several studies predict population-level effects based on short-term, individual-level responses, only very few have validated these predictions experimentally. Thus, we exposed D. magna populations to irregular polystyrene microplastics and diatomite as natural particle (both ≤63 μm) over 50 days. We used mixtures of both particle types at fixed particle concentrations (50,000 particles mL) and recorded the effects on overall population size and structure, the size of the individual animals, and resting egg production. Particle exposure adversely affected the population size and structure and induced resting egg production. The terminal population size was 28-42 % lower in exposed compared to control populations. Interestingly, mixtures containing diatomite induced stronger effects than microplastics alone, highlighting that natural particles are not per se less toxic than microplastics. Our results demonstrate that an exposure to synthetic and natural particles has negative population-level effects on zooplankton. Understanding the mixture toxicity of microplastics and natural particles is important given that aquatic organisms will experience exposure to both. Just as for chemical pollutants, better knowledge of such joint effects is essential to fully understand the environmental impacts of complex particle mixtures. ENVIRONMENTAL IMPLICATIONS: While microplastics are commonly considered hazardous based on individual-level effects, there is a dearth of information on how they affect populations. Since the latter is key for understanding the environmental impacts of microplastics, we investigated how particle exposures affect the population size and structure of Daphnia magna. In addition, we used mixtures of microplastics and natural particles because neither occurs alone in nature and joint effects can be expected in an environmentally realistic scenario. We show that such mixtures adversely affect daphnid populations and highlight that population-level and mixture-toxicity designs are one important step towards more environmental realism in microplastics research.
微塑料对大型溞（作为淡水浮游动物的关键模型）的毒性已有充分描述。虽然有几项研究根据短期的个体水平反应预测了种群水平的影响，但只有极少数研究通过实验验证了这些预测。因此，我们让大型溞种群在50天内接触不规则聚苯乙烯微塑料和作为天然颗粒的硅藻土（两者均≤63μm）。我们在固定颗粒浓度（50,000个颗粒/毫升）下使用两种颗粒类型的混合物，并记录其对总体种群大小和结构、个体动物大小以及休眠卵产生的影响。颗粒暴露对种群大小和结构产生了不利影响，并诱导了休眠卵的产生。与对照种群相比，暴露种群的最终种群大小降低了28 - 42%。有趣的是，含有硅藻土的混合物比单独的微塑料产生的影响更强，这突出表明天然颗粒本身的毒性并不比微塑料小。我们的结果表明，接触合成颗粒和天然颗粒会对浮游动物产生负面的种群水平影响。鉴于水生生物会同时接触到微塑料和天然颗粒，了解微塑料和天然颗粒的混合毒性很重要。就像化学污染物一样，更好地了解这种联合效应对于全面理解复杂颗粒混合物的环境影响至关重要。
虽然基于个体水平的影响，微塑料通常被认为具有危害性，但关于它们如何影响种群的信息却很匮乏。由于后者对于理解微塑料的环境影响至关重要，我们研究了颗粒暴露如何影响大型溞的种群大小和结构。此外，我们使用了微塑料和天然颗粒的混合物，因为它们在自然界中都不是单独存在的，并且在环境现实场景中可能会产生联合效应。我们表明，这种混合物会对水蚤种群产生不利影响，并强调种群水平和混合毒性设计是使微塑料研究更具环境现实性的重要一步。
