Gittenberger, A., Rensing, M., Stegenga, H. & Hoeksema, B., 2010
Gittenberger, A., Rensing, M., Stegenga, H. & Hoeksema, B. (2010). Native and non-native species of hard substrata in the Dutch Wadden Sea. Nederlandse faunistische Mededelingen No. 33: 21-75.
In the summer of 2009 a rapid assessment was done of marine algae and macrofauna of hard substrata in the Dutch Wadden Sea. During a three week survey in July- August, 83 localities were searched for native and non-native species. The survey was carried out with a variety of methods: snorkeling, using a Remotely Operated Vehicle (rov), checking fouling plates, and turning over rocks at low tide. The distributions and salinitiy ranges were recorded for 129 species, 29 of which were cryptogenic or of non-native origin. In addition, an inventory was made of published and unpublished records. Eleven species and one subspecies were found to be new to the Dutch Wadden Sea. One red alga (Ceramiaceae sp.) is probably a new species to Europe. The sea-squirt Molgula socialis is recorded as new for the Netherlands. It is probably widespread, may even be native and misidentified in the past as the non-native American species M. manhattensis. The total number of non-native species in the Dutch Wadden Sea has been raised to 64. The relatively high number of species that was recorded as new for the area within only three weeks of fieldwork, may be at least partly a consequence of the fact that the ongoing biodiversity research in this unesco World Heritage Site is not focusing on hard substrata. However, it is also possible that several species have settled relatively recently.