Dreissenids’ breaking loose: differential attachment as a possible driver of the dominance shift between two invasive mussel species

Abstract Ponto-Caspian dreissenids are notorious freshwater invaders. Recently, widespread observations show a dominance shift from the early invader, Dreissena polymorpha, to its successor, bugensis . These likely reflect congeneric species differences in physiological and behavioural traits. Here, we assessed mussel attachment strength, rate, mode of byssal failure as trait that could potentially contribute shifts. The traits were measured field laboratory experiments. Fouling plates deployed Rhine-Meuse river delta collected acclimatised 60 L non-aerated tanks. Attachment strength was positively correlated with shell size. D. significantly greater compared slower growing polymorpha individuals dreissenid assemblage. This corresponded superior thread morphology (i.e. higher number two times wider threads). Moreover, our results indicated threads stronger than those , latter ruptured more often. Additionally, had lower rate Having gives an advantage when it comes withstanding currents predators. On other hand, not being attached allows individual actively move around. would allow them away fast changing unfavourable environmental conditions. indicate competitive benefits for over therefore possibly contributing