In contrast to marine ecosystems, the toxicity impact of microplastics in freshwater environments is poorly understood. This contribution reviews the literature on the range of effects of microplastics across and between trophic levels within the freshwater environment, including biofilms, macrophytes, phytoplankton, invertebrates, fish and amphibians. While there is supporting evidence for toxicity in some species e.g. growth reduction for photoautotrophs, increased mortality for some invertebrates, genetic changes in amphibians, and cell internalization of microplastics and nanoplastics in fish; other studies show that it is uncertain whether microplastics can have detrimental long-term impacts on ecosystems. Some taxa have yet to be studied e.g. benthic diatoms, while only 12% of publications on microplastics in freshwater, demonstrate trophic transfer in foodwebs. The fact that just 2% of publications focus on microplastics colonized by biofilms is hugely concerning given the cascading detrimental effects this could have on freshwater ecosystem function. Multiple additional stressors including environmental change (temperature rises and invasive species) and contaminants of anthropogenic origin (antibiotics, metals, pesticides and endocrine disruptors) will likely exacerbate negative interactions between microplastics and freshwater organisms, with potentially significant damaging consequences to freshwater ecosystems and foodwebs.

与海洋生态系统相比，微塑料在淡水环境中的毒性影响知之甚少。该贡献回顾了有关微塑料在淡水环境中的营养级之间和营养级之间的影响范围的文献，包括生物膜、大型植物、浮游植物、无脊椎动物、鱼类和两栖动物。虽然有证据支持某些物种的毒性，例如光合自养生物的生长减少，一些无脊椎动物的死亡率增加，两栖动物的遗传变化，以及鱼类体内微塑料和纳米塑料的细胞内化；其他研究表明，尚不确定微塑料是否会对生态系统产生有害的长期影响。一些分类群尚未研究，例如底栖硅藻，而只有 12% 的关于淡水中微塑料的出版物，展示食物网中的营养转移。鉴于这可能对淡水生态系统功能产生的级联不利影响，只有 2% 的出版物关注由生物膜定殖的微塑料这一事实令人非常担忧。包括环境变化（温度升高和入侵物种）和人为污染物（抗生素、金属、杀虫剂和内分泌干扰物）在内的多种额外压力因素可能会加剧微塑料与淡水生物之间的负面相互作用，对淡水生态系统和食物网造成潜在的重大破坏性后果。