Plastic pollution meets biological invasions: a systematic review of emerging interactions

Plastic pollution and biological invasions are two of the most pervasive and persistent drivers of ecological change. Although both have been widely studied in isolation, their potential interactions remain poorly understood. This review synthesises 146 peer-reviewed scientific articles published up to December 2024, providing the first global assessment of research at the intersection between plastic pollution and biological invasions. We found that the literature is taxonomically narrow, geographically skewed and methodologically fragmented. Research focuses on aquatic invertebrates, especially Mollusca and Arthropoda and is largely restricted to microplastics, with limited attention to mesoplastics, nanoplastics or terrestrial systems. Most studies use standardised ecotoxicological assays under laboratory or field conditions, leaving broader ecological processes, such as context-dependent interactions at the population, community and ecosystem levels, habitat modification by non-native species interacting with plastic debris and plastic-driven disruptions to ecosystem functioning and services, largely underexplored. Despite these limitations, we identified three recurrent pathways through which plastics and biological invasions interact: (1) non-native species dispersal and colonisation via plastic debris; (2) altered biotic interactions and (3) the experimental use of non-native species to assess plastic toxicity, with a focus on species-specific physiological responses. These interactions may influence bioaccumulation dynamics, contaminant transfer across trophic levels and compromise the resilience of invaded ecosystems. Our findings highlight key research gaps that include the limited integration of ecological responses in natural ecosystems, the under-representation of many taxonomic groups and the lack of comparative analyses exploring how non-native species may act as vectors for plastic transport and bioaccumulation. This situation implies the need for more mechanistic, context-sensitive and cross-disciplinary approaches. We also emphasise the urgent need to incorporate plastic pollution into non-native risk assessments and management frameworks. Strengthening methodological standardisation and public engagement, for instance through citizen science, will be critical for addressing the combined impacts of these two global stressors and mitigating their impacts.