Alien species in the Mediterranean Sea by 2010. A contribution to the application of European Union’s Marine Strategy Framework Directive (MSFD). Part I. Spatial distribution

Abstract

The state-of-art on alien species in the Mediterranean Sea is presented, making distinctions among the four subregions defined in the EU Marine Strategy Framework Directive: (i) the Western Mediterranean Sea (WMED); (ii) the Central Mediterranean Sea (CMED); (iii) the Adriatic Sea (ADRIA); and (iv) the Eastern Mediterranean Sea (EMED). The updated checklist (December 2010) of marine alien species within each subregion, along with their acclimatization status and origin, is provided. A total of 955 alien species is known in the Mediterranean, the vast majority of them having being introduced in the EMED (718), less in the WMED (328) and CMED (267) and least in the Adriatic (171). Of these, 535 species (56%) are established in at least one area.Despite the collective effort of experts who attempted in this work, the number of introduced species remains probably underestimated. Excluding microalgae, for which knowledge is still insufficient, aliens have increased the total species richness of the Mediterranean Sea by 5.9%. This figure should not be directly read as an indication of higher biodiversity, as spreading of so many aliens within the basin is possibly causing biotic homogenization. Thermophilic species, i.e. Indo-Pacific, Indian Ocean, Red Sea, Tropical Atlantic, Tropical Pacific, and circum(sub)tropical, account for 88.4% of the introduced species in the EMED, 72.8% in the CMED, 59.3% in the WMED and 56.1% in the Adriatic. Cold water species, i.e. circumboreal, N Atlantic, and N Pacific, make up a small percentage of the introduced species, ranging between 4.2% and 21.6% and being more numerous in the Adriatic and less so in the EMED.Species that are classified as invasive or potentially invasive are 134 in the whole of the Mediterranean: 108 are present in the EMED, 76 in the CMED, 53 in the Adriatic and 64 in the WMED. The WMED hosts most invasive macrophytes, whereas the EMED has the lion’s share in polychaetes, crustaceans, molluscs and fish.

DNA barcoding reveals a cryptic nemertean invasion in Atlantic and Mediterranean waters

“…The presence of the same haplotypes in different invaded areas and in its natural distribution range suggests several invasion events. The Mediterranean Sea is one of the world's regions most affected by biological invasions (Galil 2009;Zenetos et al 2010), mainly since the opening of the Suez Canal. However, the presence of C. simula from the eastern Mediterranean Sea has not been reported, and the invasion of Atlantic localities cannot be explained by the hypothesis of a Lessepsian migration to the Mediterranean Sea.…”

New Mediterranean Biodiversity Records (December 2012)

“…On the other hand, the occurrence of ovigerous females supports that P. gibbesi is established in Cyprus. The blue crab (Callinectes sapidus Rathbun, 1896) is one of the most invasive aquatic species in the Mediterranean Sea (Zenetos et al, 2010). The first record in Hellenic waters dates back to 1947-1948(Serbetis, 1959, but Nehring (2011) suggested that the species was present as early as 1935 in the Gulf of Thessaloniki.…”

On the occurrence of Uronema marinum Womersley (Chaetophorales, Chlorophyta) in the north-western lagoons of the Adriatic Sea, Mediterranean Sea (Italy)

“…Thalli were attached to other alien algae, such as Gracilaria vermiculophylla, Agardhiella subulata and Soleria filiformis, which most likely were introduced by aquaculture (Zenetos et al, 2010;Sfriso et al, 2012). Later, U. marinum was also recorded in Venice Lagoon and in Pialassa della Baiona in Emilia-Romagna as an epiphyte on many other species, mostly Cladophorales.…”

“…Farnham and the concentration of reactive phosphorus (Table 1). Both G. vermiculophylla and A. subulata originate from the Pacific Ocean (Zenetos et al, 2010). Uronema marinum, probably has the same origin and may have been introduced simultaneously with one (or both) of these species.…”

“…The latest lists of alien species in the Mediterranean Sea (Zenetos et al, 2010(Zenetos et al, , 2012 place this region amongst the most affected by biological invasions. In December 2010, the inventory of marine non indigenous species (NIS) included 955 taxa (except phytoplankton).…”