Overland long distance dispersal (LDD) (A), short distance dispersal (SDD) (B), and ‘stepping stone’ dispersal (C) of invasive bivalve species (dot clusters) between isolated (e.g., hydrologically unconnected) freshwater sites via possible zoochorous vectors. Equally, when sites are hydrologically connected (D) (e.g., streams) additional aquatic vectors, such as fish species, may facilitate LDD, SDD or stepping stone dispersal. Moreover, zoochorous vectors may intensify invader spread across large aquatic areas (e.g., large lakes). Dashed lines indicate water current.