Microplastics in Aquatic Ecosystems: Sources, Transport Mechanisms, and Ecological Impacts

Review Article

Abstract

Microplastics have emerged as one of the most pervasive contaminants in aquatic ecosystems, posing significant environmental and ecological challenges worldwide. These plastic particles, generally smaller than 5 mm, originate from both primary sources, such as industrial microbeads and synthetic pellets, and secondary sources resulting from the degradation of larger plastic debris. Rivers, lakes, estuaries, coastal waters, and marine environments act as major reservoirs and transport pathways, facilitating the widespread distribution of microplastics across diverse ecosystems. Their persistence, buoyancy, and resistance to degradation enable long-distance transport through hydrological processes, atmospheric deposition, and biological interactions. The increasing accumulation of microplastics has raised concerns regarding their impacts on aquatic organisms, biodiversity, food webs, and ecosystem functioning. Numerous studies have demonstrated that microplastics can be ingested by organisms at different trophic levels, causing physical injury, physiological stress, altered feeding behavior, reproductive impairment, and reduced growth. Furthermore, microplastics act as carriers of toxic chemicals, heavy metals, and pathogenic microorganisms, amplifying their ecological risks through bioaccumulation and trophic transfer. Recent advances in analytical techniques, remote sensing, numerical modelling, and artificial intelligence have improved the detection, monitoring, and prediction of microplastic pollution, providing valuable insights into their environmental dynamics. This review summarizes the major sources of microplastics, their transport mechanisms within aquatic environments, and their ecological consequences. It also highlights current monitoring approaches, emerging mitigation strategies, and future research directions aimed at reducing microplastic contamination and protecting aquatic ecosystems.