Biological pollution as a driver of change in marine environments: what about the Taranto seas?

In the last years, the introduction of alien species registered a considerable expansion worldwide, often ascribed to the increase of globalized transoceanic trade, which favoured the shifting of these species outside their natural distribution range, through several kind of vectors. Alien species have become a serious trouble for marine ecosystems, since some of them can establish in the new environment, posing severe threaten for biodiversity, structure and functioning of the receiving system, productive activities and human health. Those species, which proved to have negative effects on the recipient ecosystem, are called invasive and their negative effects are collectively named as biological pollution. Port zones and mussel farming areas seem to be the most exposed to this emerging menace. The Taranto seas are seat of many activities predisposing to the introduction of alien species and more than forty species, belonging to all the phyla, have been recorded since the first decades of the last century. Starting from the beginning of the 2000s, more and more comprehensive studies have been performing on this issue and a continuous monitoring of new introductions is in progress nowadays. Particular consideration has been paying to algal aliens, both micro and macro-algae, which gather the highest number of newly introduced species in Mar Grande, Mar Piccolo and Gulf of Taranto. Since now, none of them proved harmful for these environments, but the danger for a forthcoming invasiveness is real, so we must be alert to this.