Current status of aquatic introductions in Italy

Italy is a crossroads for non-indigenous species introductions into the Mediterranean, both for marine species coming from the Red Sea, favoured by the warm climate of Southern Italy, and for species that find good opportunities in the eutrophic Adriatic Sea. It is also affected by the recent severe invasion in the Mediterranean involving the green algae, Caulerpa spp., that are supplanting the native phanerogams constituting the submarine landscape. In the last 40 years, many publications on aquatic species invasions have appeared in the literature; a summary is drawn from scattered material of this overlooked phenomenon. In total 108 non-indigenous aquatic species are know from Italian waters. Also in fresh waters the incidence of introductions is high, as testified by the well-documented cases of fishes, crayfish and zebra mussel. In some cases (the infralittoral beds of Caulerpa and the brackish waters of the Lagoon of Venice), the ecological consequences of the invasions have been investigated in more detail, shedding light on the impact of introductions on the Italian aquatic communities. An increasing awareness of the importance of species invasions is slowly emerging from the academic to the legislative and diplomatic arena.