Parasite introduction with an invasive goby in Belgium: double trouble?

Non-indigenous species may have negative impacts
on the native fauna in their competition for food and
habitat, but they can also introduce non-indigenous parasite
species, with sometimes devastating consequences. Cointroduction
of parasites should therefore be carefully monitored,
but this aspect is mostly overlooked. The round goby
Neogobius melanostomus (Pallas, 1814) and the tubenose goby
Proterorhinus semilunaris (Heckel, 1937), both known for
their invasiveness, have recently been discovered in Belgium.
Here, we morphologically and genetically document the cointroduction of the Ponto-Caspian Gyrodactylus proterorhini Ergens, 1967, originally described on tubenose goby in southern Slovakia. Because of their direct life cycle and extraordinary reproductive capacities, gyrodactylid monogenean parasites can readily invade new areas together with the host. Moreover, G. proterorhini has a wide host range and might therefore represent a threat to other gobiid fishes. The Gyrodactylus parasite found on the Belgian round goby population is probably acquired through secondary infection from local fish, as suggested by molecular phylogenetic analysis.