Abstract
The occurrence of three exotic decapods is reported from the Lagoon of Bizerte (northern Tunisia) based on records gathered from local fishermen. These three species are the Atlantic blue crab Callinectes sapidus Rathbun, 1896, the blue swimming crab Portunus segnis (Forskal, 1775), and the Lessepsian shrimp Trachysalambria palaestinensis (Steinitz, 1932). Our sightings confirm the establishment of C. sapidus and P. segnis in the Lagoon of Bizerte and widen the known distribution of T. palaestinensis to northern Tunisia. The updated distribution maps of C. sapidus and P. segnis in the Mediterranean Sea confirm the rapid expansion and colonizing behaviour of these two invasive portunid species. Finally, the potential impacts of these two latter species on the local ecosystem were discussed.