Microplastics as Ecological Infrastructure: A Review from a Systems Perspective on Microbial Connectivity, Carbon Cycling, and Ecosystem Resilience

Microplastics are increasingly recognized not only as persistent pollutants but also as novel microbial habitats capable of influencing ecological processes across aquatic ecosystems. Although the plastisphere has been extensively described, its broader ecological significance remains poorly integrated within ecosystem theory. Here, we propose the Ecological Infrastructure Framework (EIF), which considers colonized microplastics as persistent mobile substrates that may support microbial communities, create opportunities for biological connectivity and redistribute microbial functional potential across environmental boundaries. The framework integrates material persistence, eco-corona formation, microbial succession, environmental selection and dispersal to examine how plastic-associated communities develop and interact with receiving environments. We further introduce Ecological Filter Compression as a testable hypothesis whereby additional particle-mediated dispersal may modify the relative contributions of dispersal limitation and environmental selection to microbial community assembly. Rather than assuming that colonized particles transport intact functional consortia, the EIF distinguishes physical transport from microbial survival, establishment and the realization of ecological functions. We also examine how microplastics may influence carbon cycling through experimentally demonstrated effects on microbial activity, aggregation and sinking behavior, while considering the additional contribution of mobile microbial functional capacity as a hypothesis requiring direct validation. Potential consequences for ecosystem resilience are similarly expected to depend on environmental context, community composition and disturbance characteristics. By integrating plastisphere ecology with metacommunity theory and ecosystem functioning, this review provides a systems-level framework for evaluating when persistent synthetic particles may contribute to ecological connectivity and generates testable predictions concerning microbial dispersal, community assembly, biogeochemical processes and ecosystem resilience.