The Riverine Plastisphere: Current Knowledge, Ecological Implications, and Research Needs

This is the authors' abstract. We don't add key points for this paper.

Plastic debris in river ecosystems provides persistent surfaces for microbial colonization, forming complex plastic-associated biofilm communities known as the riverine plastisphere. Despite the growing number of studies on plastic-associated microorganisms, current knowledge remains strongly biased toward marine environments, whereas riverine plastisphere communities are still comparatively understudied. This mini-review critically examines the current state of knowledge on the riverine plastisphere, focusing on microbial community composition, ecological drivers, biofilm development, ecological significance, and microbiological aspects related to pathogens and antibiotic resistance genes (ARGs). Current evidence indicates that riverine plastisphere communities are influenced by a complex interplay of environmental conditions, anthropogenic pressures, and substrate-related factors. The available literature suggests that these plastic-associated biofilms may support distinct microbial assemblages and microbial traits linked to nutrient cycling, pollutant transformation, pathogen occurrence, and ARG persistence. However, current knowledge remains largely focused on community composition and occurrence patterns, whereas evidence linking plastisphere communities to ecosystem-level processes remains limited. Recent studies have also highlighted the importance of considering the plastisphere as a biofilm system developing at the interface between plastic substrates and the surrounding environment, where biological, chemical, and physical processes interact. Information on ecological relevance, microbial viability, virulence, and gene mobility remains comparatively scarce. The mini-review also highlights the challenges associated with methodological heterogeneity, limited comparability among studies, and the absence of harmonized indicators capable of supporting robust ecological and public health risk assessments. Overall, the riverine plastisphere represents a rapidly developing research field that offers new opportunities to investigate the interactions among plastic pollution, microbial ecology, and lotic ecosystem processes. Future progress will depend on methodological harmonization and on the development of approaches capable of linking microbial occurrence to ecosystem processes and translating occurrence data into ecologically meaningful information and comparable risk assessments.