Exotic species in Lesina and Varano lakes new guest in Lesina and Varao lakes: Gargano National Park (Italy)

1. Introducing more or less voluntary alien species is now recognized worldwide as one of the most 1 - serious biological threats to biodiversity. The brackish-water lakes of the Lesina and Varano (Apulia, Adriatic Sea), where in recent years (2000-2007) the presence of exotic species is increasingly reported by local fishermen, have not been spared this phenomenon. 2. The two biotopes are connected with the Adriatic Sea by two artificial channels. In this paper a list 2 - of alien species found in the two brackish basins in recent years was described. 3. The following 6 species were reported: Oreochromis niloticus niloticus (Linnaeus, 1758) 3 - (Actinopterygii, Perciformes, Cichlidae), Callinectes sapidus (Rathbun, 1896) (Arthropoda, Crustacea, Decapoda, Portunidae), Procambarus clarkii (Girard 1852) (Arthropoda, Crustacea, Decapoda, Cambaridae), Musculista senhousia (Benson in Cantor,1842) (Mollusca, Bivalvia, Mytilidae), Rapana venosa (Valenciennes, 1846) (Mollusca, Gastropoda, Muricidae), Dyspanopeus sayi (Smith, 1869) (Arthropoda, Crustacea, Decapoda, Xanthidae). 3. The presence of Oreochromis niloticus niloticus and Procambarus clarkii seemed to be linked to the 4 - accidental release from aquaculture activities present in the sourronding land, while the presence of Musculista senhousia, Rapana venosa and Dyspanopeus sayi was probably due to the introduction into the lake of the juvenile mussels coming from the northern Adriatic sea. The place of origin of other species is not clear.