Update of marine alien species in Hellenic waters

The list of marine alien species in Hellenic waters is updated taking into account new findings (published and unpublished data). According to the present work, the number of these species has increased from 90 (known until end 2003) to 128. Most of them are zoobenthic species followed by fish and macroalgae. An interannual analysis revealed an important increase of alien species during the last years. The study of their geographic distribution showed that their majority is present in the southeastern Aegean. More than 55% of them are well established, while about 40% are casual records. Their main pathway of introduction seems to be the Suez Canal followed by shipping, whereas the Straits of Gibraltar, aquaculture and the Straits of Dardanelles appear to play a less important role in their invasion of Hellenic waters. These findings are discussed considering environmental and anthropogenic factors.