Callinectes sapidus (Rathbun, 1896), native to the western Atlantic Ocean and the Gulf of Mexico, is a highly invasive species known for its adaptability and aggressive predatory behaviour. Its growing presence in the Mediterranean over the past decade has raised concerns regarding potential ecological and economic impacts. The species thrives in both marine and brackish environments, with its life cycle closely influenced by salinity and temperature. Juveniles and adults occupy estuarine and brackish waters, while females migrate to high-salinity areas for spawning and larval development. The ANNOTATE project monitored the environmental DNA (eDNA) of C. sapidus during summer and fall across six inland tributaries of the Marano and Grado lagoon (Northern Adriatic), where the species has been established since the early 2000s. Results achieved showed variations in temperature and salinity across the sites, and C. sapidus was detected in all surveyed tributaries, including locations far upstream. This confirms the species’ ability to tolerate a wide range of environmental conditions. These findings highlight the euryhaline and eurythermal nature of C. sapidus and underscore the importance of monitoring its populations in freshwater ecosystems. Despite the ecological significance of these habitats, knowledge of the blue crab’s impacts in such environments remains limited, emphasizing the need for further research and management efforts.
