CHECKLIST OF INTRODUCED PLANTS IN THE MED ITERRANEAN - ORIGINS AND IMPACT ON THE ENVIRONMENT AND HUMAN ACTIVITIES

This review addresses the problem of recently introduced plants in the Mediterranean in order to analyse their vectors, the dispersal proces ses and the possible ecological and economic consequences. Ninety-five cases (94 macroscopic algae and one seagrass) are listed and discusse d. Three major routes of access into the Mediterranean are indicated: shipping, the Suez canal and aqua-culture. The recent introduction of Caulerpa taxifolia along our coasts has called attention to a new pote ntial source: aquaria. Among the successful acclimatizations, cold-tem perate Pacific and Atlantic species remain confined to the north of th e Mediterranean (Gulf of Lions, Adriatic), whereas some tropical or su b-tropical plants colonize large areas. Some introduced algae prolifer ate to the detriment of the indigenous Mediterranean vegetation. In co ntrast with some terrestrial introductions, no population crash has be en observed in the Mediterranean, although some notable fluctuations s eem to occur in coastal lagoons. From an economic point of view, the t wo activities most affected by this phenomenon are aquaculture and fis hing. With the gradual disappearance of European frontiers, the worldw ide development of marine cultures and the multiplication of giant Sea worlds, the transfer of live marine organisms will become routine and the risk of new introductions will considerably increase in the Medite rranean. Only international legislation, established by the countries of the littoral, will be able to control these problems.