Microplastics disrupt microbial functions in aquatic ecosystems

Understanding the biological effects of microplastics (MPs, <5 mm) in natural environments is complex, due in part to the heterogeneous physicochemical properties of MPs and the various environmental factors that influence their interactions. Research has shown that planktonic and benthic microbial communities in water and sediment interact with MPs, much like they do with natural substrates (i.e ., clay, wood), rapidly forming biofilms known as the 'Plastisphere'. Studies suggest that MPs and their associated plastispheres can serve as carriers for opportunistic pathogens, harmful cyanobacteria, and micropollutants (i.e ., pesticides, and pharmaceuticals). Furthermore, MPs influence key aquatic ecosystem functions such as nitrification-denitrification, photosynthesis, and the trophic state of water. Surface water plays a crucial role in transporting plastic waste into oceans and deep-sea environments. However, substantial research gaps remain regarding the effects of MPs in surface water ecosystems, particularly in the presence of oils or other hazardous substances. This review aims to provide a comprehensive overview of the effects of MPs on microbial functions in water and sediment ecosystems and highlights critical knowledge gaps in the impacts of MPs on water and sediment environments.