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.

Brook Trout Salvelinus fontinalis
Signal Grayfish Pacifastacus leniusculus
Reed Mannagras Glyceria maxima
American waterweed Elodea canadensis
Grayfish Plague, As- and Ps1-types,  Aphanomyces astaci (As, Ps1)

Potentially invasive alien species

a Crayfish* Orconectes limosus
Prussian Carp Carassius aurelius gibelio
Peled Coregonus peled
Common Carp Cyprinus carpio
Pink Salmon Oncorhynchus gorbuscha
Rainbow Trout Onchorhynchus mykiss
Lake Trout Salvelinus namaycush
Round Goby Neogobius melanostomus
Danube Grayfish Astacus leptodactylus
Chinese Mitten Crab Eriocheir sinensis
Amur Sleeper* Perccottus glenii
an Amphipoda* Gmelinoides fasciatus
Marmorkrebs* Procambarus sp.
Tropical Hornworth Ceratophyllum submersum
a waterweed* Elodea nuttalii
Fringed Water-lily* Nymphoides peltata
a parasitic nematode worm Anguillicola crassus

Other invasive alien species


Brown Bullhead Ameiurus nebulosus
Brook Stickleback Culaea inconstans
Moderlieschen Leucaspius delineatus
Marsh Frog Pelophylax ridibundus
Sweet Flag Acorus calamus
a peritrich ciliate Cothurnia variabilis


Prorocentrum minimum
This indicator will be checked in early 2011 after the national strategy on invasive alien species has been published.

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