AS2 Alien inland water species

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Invasive alien species

Altogether 25 alien species have been recorded from Finland's inland waters. These species have spread to natural water habitats thanks to human actions. Seven of these may be considered invasive and 12 potentially invasive. Six other alien species are not known to be invasive.

The number of alien inland water species has increased steadily thoughout the whole 20th century as well as the first decade of the 21st century. No similar peak during the past two decades can be seen as in the case of alien Baltic Sea species. As large a share as as two thirds of the species have been brought to Finland intentionally. Introductions of new species were done up to the 1970s after which this practice has been given up.

Clearly the greatest number of alien species has been recorded from the southwestern parts of the country. Here also natural species diversity is at its highest as is the magnitude of human actions, intentional and unintentional introductions included. Apart from northern Lapland, all other inland water regions host approximatley ten alien species each.

Potentially invasive alien species

Other invasive alien species