Thermal niches and climate change reshape marine invasion risk worldwide

Marine biological invasions and climate change are two major drivers of biodiversity loss, yet their interactions remain poorly understood. Here, we used correlative ecological niche models (ENMs) to characterise the thermal niches of 80 globally invasive marine species and project their thermal suitability from 2020 to 2100 under multiple Shared Socioeconomic Pathway scenarios. Our models, based on Minimum Volume Ellipsoids fitted to sea surface and bottom temperatures, revealed substantial differences across species' thermal affinities. Tropical and subtropical invaders are projected to experience widespread declines in thermal suitability, suggesting that warming at low latitudes may approach their physiological thermal limits and redistribute thermally suitable conditions toward higher latitudes (25° to 35° N/S). Temperate species exhibited lower magnitudes of thermal suitability change, consistent with their broader thermal tolerances, although increases in thermal suitability at higher latitudes (50° to 60° N/S) suggest potential emerging invasion risks as polar barriers weaken. Climate change is expected to reshape marine invasion patterns by altering the spatial distribution of thermally suitable conditions, amplifying risks at mid-to-high latitudes while constraining some tropical invaders. While our findings provide a baseline for understanding thermal constraints on marine bioinvasions, caution is warranted: realised niches may underestimate species' full thermal tolerances, and key factors like biotic interactions, functional characteristics, and other environmental variables were not included. Nonetheless, thermal niches emerge as a strong predictor of potential invasion risk, identifying regions with high thermal suitability for invasive species and informing early detection and management strategies.