Projected Habitat Expansion of the Invasive Striped Eel Catfish Plotosus lineatus in the Mediterranean Sea Under Future Climate Conditions

The striped eel catfish Plotosus lineatus is a venomous Indo-Pacific species that has rapidly expanded within the Mediterranean Sea following its Lessepsian migration through the Suez Canal. Understanding its current distribution and future invasion potential is essential for evaluating ecological risks under ongoing climate change. In this study, ensemble species distribution models were applied to predict the present and future habitat suitability of P. lineatus across the Mediterranean Sea under the CMIP6 SSP2-4.5 climate scenario. Georeferenced occurrence records were compiled from published literature and validated databases. A total of 21 environmental variables were initially evaluated, and after multicollinearity filtering using Pearson correlation (|r| < 0.7) and Variance Inflation Factor (VIF < 10) analyses, 11 environmental predictors obtained from the Bio-ORACLE v3 database were retained for modelling. Nine modelling algorithms were initially evaluated, and six high-performing models were integrated into the final unweighted ensemble model based on predefined AUC and TSS performance criteria. Minimum seawater temperature was identified as the dominant factor controlling habitat suitability, indicating that winter thermal conditions currently represent the principal ecological barrier limiting the Mediterranean distribution of the species. Current projections identified the Levantine Basin as the principal invasion hotspot. Future projections, based on mean environmental conditions for the 2020–2100 period under the CMIP6 SSP2-4.5 scenario, indicated a substantial increase in suitable habitats toward the central Mediterranean, including southern Italy and the Aegean region. These findings suggest that future climatic conditions may facilitate the expansion of P. lineatus into additional areas of the Mediterranean Sea, highlighting the need for continued monitoring and regional management.