Movements and habitat use of the invasive blue crab Callinectes sapidus in Mediterranean coastal lagoon

Abstract The Atlantic blue crab ( Callinectes sapidus ), an invasive and ecologically impactful decapod species, has rapidly proliferated across the Mediterranean Sea, prompting concerns over its effects on native ecosystems and local economies. Despite its growing presence, knowledge of its behavioural ecology in Mediterranean coastal systems remains limited. This study presents the first acoustic telemetry-based assessment of C. sapidus within its invasive range, focusing on movement patterns, activity levels, and habitat preferences in Biguglia Lagoon, Corsica (Northwestern Mediterranean). In 2023, 31 adult crabs (20 males, 11 females) were tagged and tracked over four months. Accelerometer data revealed distinct diel activity patterns, with females exhibiting significantly higher walking and swimming behaviours, while males were more sedentary, particularly at night. Salinity preferences varied by sex: females occupied higher-salinity zones, likely linked to reproductive behaviour, while males favoured lower salinity areas. Females also travelled greater distances and had larger, more variable home ranges, with some individuals extending into adjacent marine environments. Although no berried females were tagged, detections at sea suggest early seaward migrations by non-ovigerous and potentially ovigerous females. These findings underscore the species’ behavioural plasticity and sex-specific ecological strategies. The integration of telemetry and environmental data offers critical insights into the spatial ecology of C. sapidus , informing targeted management strategies. This research directly supported Corsica’s first Territorial Control Plan for marine invasive species and provides a framework for adaptive management across other Mediterranean regions facing similar ecological challenges. Highlights First telemetry study of blue crab in Mediterranean invasive range Females showed higher activity and larger home ranges than males Crabs displayed sex-specific salinity and depth preferences Some females migrated to sea, suggesting early reproductive movement Findings informed Corsica’s first invasive species control plan