Migration, transformation, and ecological effects of microplastics in aquatic ecosystems

Microplastics (MPs) are an emerging environmental contaminant of increasing concern due to their complex behavior and biological impacts in aquatic ecosystems. This review summarizes key advances in understanding their characteristics, sources, environmental fate, and ecological effects. MPs originate from primary production and secondary fragmentation and enter water bodies via runoff, atmospheric deposition, and marine activities. Their transport is shaped by hydrodynamics, physicochemical properties, and biological vectors, producing dynamic spatiotemporal patterns. Once released, MPs undergo physical abrasion, photochemical aging, and biological degradation, processes that reshape surface properties and influence their function as carriers of co-occurring pollutants. At the organism level, MPs can trigger oxidative stress, inflammation, neurotoxicity, and genotoxicity, while mixtures with metals, antibiotics, and other contaminants often display enhanced toxicity. At the ecosystem level, MPs alter species interactions, disrupt microbial communities, and interfere with biogeochemical processes, threatening ecosystem functions. Although detection technologies have advanced, major gaps persist in understanding chronic toxicity under realistic conditions, trophic transfer pathways, and multi-stressor effects. Future research should integrate multi-omics tools, improve in situ monitoring, and develop multi-factor risk assessment models to better predict ecological risks and inform effective management strategies.