Untitled - CNR

Marine research at CNRFigure 2: Dreissena polymorpha (Pallas), commonly known as “Zebra mussel”, is anEuro-Asiatic bivalve mollusc that was introduced into North American Great Lakes inthe early 80s. It causes huge damages both to industries, since it grows in the aspirationpipes of cooling plants, and to the ecosystem, competing with local fish species. (Photowww.wildlifedepartment.com/ images/mussel2.jpg)Figure 3: Ballast waters of cargo ships are a very efficient vector for the introduction ofmany exotic species of viruses, bacteria, algae and animals. (Picture www.imo.org)2 The arrival and spreadingof NISThe most common way of intentional introductionof exotic species is the importof organisms to be farmed [10]. In thiscase the carrier is man. Anyway, in manycases the arrival of NIS is accidental or unintentional.In particular, for the marineenvironment, one of the main vectors foraccidental arrivals are just these importedorganisms that can “transport” individualsof other species as parasites, epibionts orsymbionts. For example, even if a EUDecision of the 14th November 2003 expresslyforbids this procedure, importedmolluscs are often maintained in the seawater until they can be sold, releasing inthis way possible “guests” [11]. (Table 1)Moreover, merchant cargos transport exoticspecies both on their hulls and in ballastwaters, that are charged in specifictanks to ensure the stability and the structuralintegrity of the ship during the navigation[12, 13] (Figure 4).This latter vector is particularly important2127