|Settlement and possible competition for space between the invasive violet tunicate Botrylloides violaceus and the native star tunicate Botryllus schlosseri in The Netherlands|
|Gittenberger, A.; Moons, J.J.S. (2011). Settlement and possible competition for space between the invasive violet tunicate Botrylloides violaceus and the native star tunicate Botryllus schlosseri in The Netherlands. Aquat. Invasions 6(4): 435-440. dx.doi.org/10.3391/ai.2011.6.4|
|In: Aquatic Invasions. European Research Network on Aquatic and Invasive Species: St. Petersburg. ISSN 1818-5487, more|
Competition; Introduced species; Salinity; Tunicata [WoRMS]; Marine
Settlement and competition for space of two colonial sea squirts, the non-native violet tunicate Botrylloides violaceus and the native golden star tunicate Botryllus schlosseri, were compared in The Netherlands. In each year, from March 2006 to March 2010, 125-150 grey, 14 x 14 cm, PVC plates were deployed along the Dutch coast at 13 localities, at a depth of 1 m, and checked for species after three and six months. New plates were deployed every three months. While comparing plates with only one species represented to plates with both species represented, it appeared that Botrylloides violaceus outcompeted Botryllus schlosseri for space. Botryllus schlosseri is nevertheless expected to remain abundant along the Dutch coast because it can inhabit places with low or fluctuating salinities where Botrylloides violaceus is at a disadvantage. Settlement and the interactions between these species in The Netherlands resembled the situation in North America where both of them are considered non-native. The interactions between the two species seemed to be independent of their being native or introduced in a particular area.