Blenniidae along the Italian coasts of the Ligurian and the Tyrrhenian Sea: Community structure and new records of Scartella cristata for northern Italy

The assemblages of blenniid fishes were studied by underwater visual method s at 15 rocky shore sites of the coast of Liguria (northern Italy) in 1998 and 10 sites along the Ligurian and Tyrrhenian Sea (west coast of Italy) in 1989 and 1990. A total of 12 species was found, with little variation in s pecies composition among sites. Fish density ranged from 0.4 to 0.9 individ uals/m(2). Similarity among the sampling sites of Tyrrhenian Sea followed a geographical latitudinal gradient (north-south). The study at a smaller sp atial scale in the Ligurian Sea showed that both geographical distance and environmental features influence the similarity among sites. The presence o f Scartella cristata at 21 out of 25 sampling stations indicate that this s pecies, which formerly did not occur in the northern Mediterranean, is now firmly established in the coastal waters of Italy. These findings provide a dditional evidence of a notable and rapid biological modification in coasta l fish communities, probably related to temperature increase of the Mediter ranean Sea.