Establishment of the blue crab Callinectes sapidus (Rathbun, 1896) in a Mediterranean hypersaline basin: evidence of ecological plasticity and range expansion

A central aspect of ecology is the understanding of how environmental factors influence species distribution, population structure, and dynamics, ultimately highlighting species’ capacity to adapt to environmental shifts. This study investigates the population structure and environmental drivers influencing Callinectes sapidus (Rathbun, 1896) within a hypersaline basin (Stagnone di Marsala, Sicily, Italy), highlighting the species’ adaptability to Mediterranean hypersaline coastal ecosystems. The presence of both sexes at various developmental stages indicates the full establishment of the population within the Stagnone, confirming that ecological opportunism, high salinity tolerance, and thermal preference enable C. sapidus to invade areas encompassing a wide range of environments. Two sampling methods were adopted: baited traps and gillnets. The nets captured larger, more mobile males, while traps were effective for a broader size range and included more female individuals. Population structure varied across different sectors of the basin, with the Center–North area showing the highest abundance, likely due to favorable habitat conditions and limited water exchange with the sea. These results emphasize the ability of C. sapidus to complete its life cycle under hypersaline conditions and its preference for stable, sheltered environments. The findings have significant implications for managing C. sapidus populations and mitigating their ecological impact. Adaptive management strategies, such as targeted harvesting and monitoring of salinity and temperature, are key to controlling this invasive species and protecting Mediterranean coastal ecosystems.