Le specie alloctone animali nelle acque interne italiane.

One of the leading causes of biodiversity loss in inland waters is the introduction of species. We compiled a list of the allochthonous species occurring today in the Italian inland waters, including the species that require freshwater systems to complete their life-cycle. We analyzed their native range, the date of their first introduction into the wild, their current distribution in Italy, and modes, vectors and pathways of their first introduction. Xenodiversity amounts to 112 species, which contribute for about 2% to the inland water fauna in Italy. Northern and central regions are most affected, and Asia, North America, and the rest of Europe are the main donor continents. The large majority of allochthonous species entered Italy as a direct or indirect effect of human intervention. Accidental transport, in association with both fish (for aquaculture or stock enhancement) and crops, has been the main vector of invertebrate introductions, whereas vertebrates were mostly released for stocking purposes. Additional research is needed to provide criteria for prioritizing intervention against well established invaders and identify which new potential invader should be targeted as “unwanted”.