The spread of Styela clava Herdman, 1882 (Tunicata, Ascidiacea) in European waters

The alien ascidian Styela clava now invading the Sea of Marmara (Tunicata: Ascidiacea)

“…It reaches maturity at a size of 5 to 7.5 cm after ten months of settlement (Davis and Davis 2007). It is a hermaphroditic species and has a pelagic lecithotrophic larva that rarely travels more than a few centimeters according to Davis et al (2007), but probably travels much father due to currents. It is known to tolerate temperatures ranging from -2 to +23 °C and salinity from 20 to 32 psu (Davis and Davis 2007).…”

Anthropogenic spread of the immigrant sea-spider Ammothea hilgendorfii (Arthropoda: Pycnogonida: Ammotheidae) in UK waters

“…Climatically, the UK is amenable to a species originating in Japan, as can be seen from the current distribution of the (Davis & Davis, 2004). It appears to have taken A. hilgendorfi some two decades to spread from Southampton to Poole Harbour (where it has since proliferated), and three decades to reach the southern North Sea coast of England; the main dispersion (so far) of this species in the UK seems to have occurred during the past decade.…”

The impact of the ascidian Styela clava Herdman on shellfish farming in the Bassin de Thau, France

“…On mainland Europe S. clava have been reported as widespread in the Limfjord (Lützen and Sørensen, 1993) and in the Kattegat (Lützen, 1999) in Denmark. To the South, it has been reported in the ports of Ostend, Belgium (Eneman, 1995); Dunkerque, France (Davoult et al., 1993), Pornichet, Pornic and La Rochelle in France (Davis and Davis, 2004); Ría de Ferrol, in northwest Spain (Vázques and Urgorri, 1992); Santander, Gijon, Muros and Sada in northeast Spain (Davis and Davis, 2004); and Leixões (Porto), Cascais and Lisboa in Portugal (Davis and Davis, 2005). It is now well established in European waters but we have not recorded any populations in fifty Mediterranean harbours that we have surveyed (Davis et al., 2007).…”