Rapid assessment of the marine alien megabiota in the shallow coastal waters of the Greek islands, Paros and Antiparos, Aegean Sea

The shallow seabed off the Greek islands Paros and Antiparos was surveyed for the presence of alien megabiota during July 2011. Fourteensites were surveyed by snorkeling at depths between 0 and 10 m. Eight alien species were recorded: Caulerpa racemosa var. cylindracea,Halophila stipulacea, Pinctada radiata, Percnon gibbesi, Cassiopea andromeda, Aplysia dactylomela, Siganus luridus and Fistulariacommersonii. The first four species are new records for the islands; all eight species established populations in the study area. Siganusluridus was present in high numbers in all sites and may be considered as highly invasive. Cassiopea andromeda reappeared in the AegeanSea after a hiatus of 55 years, reaching densities >20 individuals/m2 at one site.JRC.H.5-Rural, water and ecosystem resource