Abstract
In the mid-19thcentury, European and North American shellfish farmers began the search for "new" bivalves of potential commercial interest, suitable for farming and more resistant to epi-demics. Some of these imports have had great success (like the Japanese oyster or the Philippine clam), but often this kind of trade has caused serious problems: the introduction of a species in a "new" environment is, in fact, a high ecological risk action. It is, in fact, clear that the continuous transport of stocks of living organ-isms from a production area to another, practically all over the world, favours the spread of pests and the diffusion of invasive species which may cause damage to economic activities and in par-ticular to aquaculture. Moreover, in the Mediterranean Sea, the Su-ez Canal has facilitated the spread of numerous molluscs which, over time, have created stable Mediterranean populations, entering sometimes in competition with the native flora and fauna.
In freshwaters, the most famous case is the diffusion in Western Europe and North America of the zebra mussel, an invasive bivalve which causes very serious economic problems, obstructing indus-trial and civil pumping water stations in lakes and rivers.
Keywords: Anadarainaequivalvis, Brachidontes pharaonis, Dreissena, Crep-idula fornicata, epizootic diseases, export, import, invasive molluscs, Lessepsian migration, Potamocorbula amurensis, quagga mussel, Rapanavenosa, zebra mus-sel.
