Mediterranean coastal wetlands, including lagoons and saltmarshes, are critical biodiversity hotspots and provide essential ecosystem services such as nursery habitats, nutrient cycling, and water filtration. These fragile ecosystems are increasingly threatened by climate change, anthropogenic pressures, and biological invasions. The blue crab Callinectes sapidus, a decapod crustacean native to the western Atlantic, has recently established stable populations in several Mediterranean regions, including the Stagnone di Marsala lagoon and the Trapani saltmarshes (western Sicily, Italy). This species displays high ecological plasticity and reproductive capacity, enabling rapid expansion in brackish and shallow environments, where it may outcompete native communities. Within the framework of FAO-GFCM project, we conducted a multidisciplinary study combining monitoring of some ecological variables, habitat characterization and a systematic literature review to assess the potential impacts of C. sapidus on local biodiversity and ecosystem functioning. Our results confirmed a stable and reproducing population, with a marked presence of ovigerous females and juvenile stages, particularly in spring, indicating active recruitment and successful settlement. Habitat analyses revealed the blue crab’s preference for structurally complex and productive environments, such as vegetated lagoon areas, where it may exert top-down pressure on native invertebrate communities and disrupt key ecological processes. Given the ecological relevance and protected status of these sites (Natura 2000), the spread of C. sapidus poses a tangible threat to long-term conservation goals and the provision of vital ecosystem services. Moreover, its presence may compromise traditional artisanal fisheries and the ecological balance of these transitional environments. We highlight the importance of adopting integrated ecosystem management strategies that combine early detection, continuous monitoring, stakeholder engagement and the exploration of controlled commercial exploitation as a complementary mitigation tool. Our study underscores the need to align invasive species control with broader conservation objectives, ensuring the ecological integrity and resilience of Mediterranean coastal wetlands in the face of ongoing global change.

Keywords: Coastal wetlands, Biological invasions, Blue crab, Habitat conservation, Mediterranean lagoons.