Alien species

Non-native species have been introduced into the Kvarken archipelago deliberately, as well as unintentionally. These alien species might have negative effects on the sensitive ecosystem, since alien species may outcompete native species, spread diseases or parasites. An example of an alien species that, at some pont in the future, may have a negative effect on the Kvarken ecosystem, is the zebra mussel (Dreissena polymorpha) that spreads in large colonies and outcompetes native species in the same area for nutrients and physical space. Still, some alien species may have positive effects on the ecosystem, as the sea worm Marenzelleria which counteracts eutrophication by oxygenating the sea floor sediments through its burrowing.

Picture: Zebra mussel (Dreissena polymorpha)


Lundberg, C. et al (2012). Undervattensmiljö i Norra Östersjön – Viktigt att tänka på vid havsnära planering. Närings-, trafik- och miljöcentralen, Helsingfors.