Next step of the colonization of the Balearic Islands (Spain) by invasive Atlantic blue crab, Callinectes sapidus Rathbun, 1896 (Crustacea: Decapoda: Portunidae)

The arrival of invasive alien species represents key threats to native biodiversity worldwide becoming an important and growing concern. The Mediterranean Sea is a quasi-enclosed body of water connected to the Atlantic and Indian Oceans that makes it very susceptible to being affected by the arrival of invasive species. The Atlantic blue crab, Callinectes sapidus, with a native range along the American east coast, is a reported alien species found in Mallorca and Menorca (Balearic Islands, Spain). The current report describes the first appearance of C. sapidus from the Ibiza and Formentera islands (Balearic Islands). Crabs, predominantly female, were collected from high salinity waters (25-32 parts per thousand), which could be related to the biological cycle.