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© Nicolas Borel
© Nicolas Borel
© Lionel Wibail, CRNFB
Elodea canadensis - Canadian waterweed

Synonym: Anacharis canadensis
French name:  Elodée du canada
Dutch name: Canadese waterpest
Family: Hydrocharitaceae
Group: Vascular plants
Origin: North America
Habitat: freshwater
Introduction:  aquariums and ponds
ISEIA Score : 12
Naturalization in Belgium
First observation in the wild: 1860
Invasion stage: regression
Spatial distribution: widespread
Reproduction in the wild: yes
Dispersion potential: high
Natural habitats: high
More on invasiveness: Elodea canadensis thrives in various types of freshwater habitats, from still to slow-flowing systems and from very shallow to deep waters. It is most frequent in clear, nutrient-rich and alkaline waters. Elodea aggressively invaded the waterways of Europe in the 19th Century. After spectacular vigour and dispersal, there was a subsequent decline and replacement by other non-native water weeds. But new invasions and explosive growth are still occurring in some parts of Europe.
Distribution in Belgium
Established populations
absent from district
isolated populations (1-5 localities per district)
widespread (>5 localities per district)
Endangered areas
low risk
medium risk
high risk

Endangered Natura 2000 habitats ():
freshwater habitats: 313031503260
Impacts on Species
Predation / Herbivory: low
Competition: high
Disease transmission: low
Genetic effects: low
Impacts on Ecosystems
Nutrient cycling: high
Physical alteration: high
Natural successions: likely
Food web alteration: low
More on impacts: As observed for most non-native Hydrocharitaceae species, this submerged perennial aquatic plant makes dense monospecific populations which often colonise all of water bodies, restrict water movement, cut off light, produce anoxic conditions and trap sediments in the system. Canadian waterweed has been reported to outcompete native aquatic plants. Dense beds provide a poor habitat for aquatic animals. They interfere with recreation activities and increase the risk of adjacent land flooding.
Data Source & References
Authors: Branquart Etienne, Stiers Iris, Triest Ludwig, Vanderhoeven Sonia, Van Landuyt Wouter, Van Rossum Fabienne, Verloove Filip
Published on:  22 November 2007
Last update:  14 December 2010
Barrat-Segretain, M.H. (2004)
Growth of Elodea canadensis and E. nuttallii in monocultures and mixture under different light and nutrient conditions.
Arch. Hydrobiol. 161: 133-144.
Bowmer, K.H., Jacobs, S.W.L. & Sainty, G.R. (1995)
Identification, Biology and Management of Elodea canadensis, Hydrocharitaceae.
Journal of Aquatic Plant Management 33: 13-19.
CPS-SKEW (2006)
Elodea canadensis & Elodea nuttallii
From online fact sheets of the Swiss Commission for Wild Plants Conservation
Centre for Aquatic Plant Management (2004)
Information sheet 7: Canadian waterweed.
Centre for Ecology and Hydrology.
Denys, L., Packet, J. & Van Landuyt, W. (2004)
Neofyten in het Vlaamse water : signalement van vaste waarden en rijzende sterren.
Natuur.focus 3(4): 120128.
Erhard, D. & Gross, E.M. (2006)
Allelopathic activity of Elodea canadensis and Elodea nuttallii against epiphytes and phytoplankton.
Aquatic Botany 85: 203-211.
Essl, F. & Rabitsch, W. (2003)
Neobiota in Osterreich.
Umweltbundesamt, 432 pp.
Lambinon, J., Delvosalle, L. & Duvigneaud, J. (2004)
Nouvelle fore de la Belgique, du Grand-Duché de Luxembourg, du Nord de la France et des régions voisines.
Editions du Patrimoine du Jardin botanique national de Belgique, Meise.
Larson, D. & Willen, E. (2007)
The relationship between biodiversity and invasibility in central Swedish lakes invaded by Elodea species.
In: F. Gherardi (Ed.), Biological invaders in inland waters: profiles, distribution and threats, Springer: 423-433.
Muller, S. (2004)
Plantes invasives en France : état des connaissances et propositions d'actions.
Publication scientifique du Museum d'Histoire naturelle, Patrimoines naturels n°62.
Simpson, D.A. (1990)
Displacement of Elodea canadensis Michx. by Elodea nuttallii (Planch.) St. John in the British Isles.
Watsonia 18: 173-177.
Spicer, K.W. & Catling, P.M. (1988)
The biology of Canadian weeds. 88. Elodea canadensis Michx.
Canadian Journal of Plant Science 68:1035-1051
Thiébaut, G. (2007)
Non-indigenous aquatic and semiaquatic plant species in France.
In: F. Gherardi (Ed.), Biological invaders in inland waters: profiles, distribution and threats, Springer: 209-229.
Thiébaut, G. (2005)
Does competition for phosphate supply explain the invasion pattern of Elodea species?
Water research 39: 3385-3393.
Toussaint, B. & Bedouet, F. (2005)
Les espèces végétales invasives des milieux aquatiques et humides du bassin Artois-Picardie.
Agence de l'Eau Artois-Picardie, 38 pp.
Van Landuyt, W., Hoste, I., Vanhecke, L., Van den Bremt, P. Vercruysse, W. & De Beer, D. (2006)
Atlas van de Flora van Vlaanderen en het Brussels gewest.
Nationale Plantentuin en het Instituut voor Natuur- en Bosonderzoek i.s.m. Flo.Wer vzw.
Verloove, F. (2006)
Catalogue of the Neophytes in Belgium (1800-2005).
Scripta Botanica Belgica 39, 89 pp.
Wittenberg, R. (2005)
An inventory of alien species and their threat to biodiversity and economy in Switzerland.
CABI Bioscience Switzerland Centre report to the Swiss Agency for Environment, Forests and Landscape. The environment in practice no. 0629: 155p.
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