These authors noted that Galician Rias’ ecosystems are subjected to a high frequency of introductions of alien species, which is likely due to the importation and further culturing in mussel-rafts of clams and oysters from the Adriatic Sea. Greater clarity in our understanding of the mode of introduction and the niche opportunities (as defined by Shea and Chesson 2002) for the establishment and spreading of X.securis in the Galician Rias will help us to focus on the potential impact of this invader.