Microplastics and invasive crayfish: emerging interactions and ecological implications from three coexisting species in a subalpine lake.

Microplastics (MPs) and invasive species are two of the most pressing threats to freshwater ecosystems, yet their interactions remain underexplored. This study presents the first comparative analysis of MP uptake among three coexisting invasive crayfish species (Faxonius limosus, Pacifastacus leniusculus, and Procambarus clarkii) from Lake Maggiore, a large subalpine lake subjected to intense anthropogenic pressure. A total of 90 individuals were analyzed for biometric traits and MP occurrence in intestinal content, with species identification confirmed via molecular analysis. No significant interspecific differences or correlations with biometric traits were found, though F. limosus showed the highest average concentration. Most MPs were < 1 mm polyester or polyacrylate fibers, suggesting a dominant domestic source. Additionally, this work provides the first evidence of MP uptake in F. limosus, filling a key knowledge gap. Beyond documenting MP ingestion, our findings support the potential of invasive crayfish as agents of MP removal, suggesting an ecological role with important implications for environmental monitoring and ecosystem management. These results also highlight the need for further research on trophic transfer and organ-level accumulation of MPs, especially in widely distributed invasive species that are increasingly relevant for environmental risk assessment.