Role of the artificial structures on biodiversity: the case of arthropod fauna in the North Adriatic lagoons

The lagoons of the North Adriatic region are site of several anthropic activities, which express themselves also with the abundance of artificial structures like the wooden poles (bricole). These become suitable substrate for the colonization of numerous species that, in their absence, would not find an opportune substrate in the natural soft bottoms of the lagoon. Using the arthropod taxocoenosis as study-case, in this work we provide evidence that the presence of artificial hard substrates has a double effect on the biodiversity of this taxon, as they promote the settlement of (i) a much larger pool of species than the one of the surrounding soft bottoms and (ii) of species which are new for the Adriatic transitional environments. In particular, an amphipod already known in the Mediterranean but new for the Adriatic, Ampithoe ferox (Chevreux), has been recorded on the artificial hard substrates of the Sacca di Goro (Po delta). In order to facilitate the identification of this scarcely known species, we provide a key to distinguish it from the more common congener Ampithoe ramondi Audouin.