Microplastic pollution in marine ecosystems: sources, impacts, and stakeholder-based solutions

Microplastics (MPs) are plastic particles of anthropogenic origin with a size range of 1-5000 μm. Marine MP pollution is increasingly recognized as a significant global environmental challenge. MPs, which enter marine ecosystems from land- and marine-based sources, pose physical, chemical, and biological risks due to the adsorption of various pollutants and the formation of biofilm layers. MPs are found in various organisms from lower to higher trophic levels of the marine food web. The negative effects of MPs on marine organisms depend on their abundance, their characteristics, and the exposure time of organisms to MPs. MPs can adversely affect various vital functions of marine organisms, including survival rate, photosynthesis, growth rate, body composition, reproduction, feeding, and mobility. This review presents the major sources of MPs in the marine environment, as well as their quantities and characteristics. In addition, studies focusing on the potential of MPs to adsorb and transport pollutants, and the levels of accumulation observed in marine organisms, are evaluated. Finally, the responsibilities of stakeholders in mitigating marine MP pollution to maintain marine ecosystem health are discussed. This paper provides a comprehensive review of marine MP pollution, highlighting the main sources of MPs, the pathways through which MPs enter marine ecosystems, the interactions of MPs with coexisting pollutants, their abundance and characteristics in marine organisms, the negative effects of MPs on various marine organisms, and the roles of stakeholders in mitigating MP pollution.