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© John Coyne, Central Fisheries Board
© Iris Stiers (VUB)
© Iris Stiers (VUB)
© Klaus van de Weyer, Lanaplan
© Vic Ramey, Center for Aquatic and Invasive Plants
© John Coyne, Central Fisheries Board
Lagarosiphon major - Curly waterweed

Synonym: Elodea crispa
French name:  Elodée à feuilles alternes
Dutch name: Verspreidbladige waterpest
Family: Hydrocharitaceae
Group: Vascular plants
Origin: Africa
Habitat: freshwater
Introduction:  aquariums and ponds
ISEIA Score : 12
Naturalization in Belgium
First observation in the wild: 1993
Invasion stage: spread
Spatial distribution: isolated
Reproduction in the wild: yes
Dispersion potential: high
Natural habitats: high
More on invasiveness: Lagarosiphon major preferably develops in clear still and slow-flowing water systems, where it can grow down to 3 meters. It can live in a wide range of trophic conditions providing that silty or sandy bottom rich in nutrients is available. It best grows in temperate alkaline waters and prefers well-lit environments.
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: 313031403150
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: high
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 (siltation increase). The curly waterweed is known to take the water pH up to value over 10 and to deplete dissolved CO2 concentrations, creating stressful conditions for other aquatic organisms. It has been reported to outcompete native aquatic plants (e.g. Charophytes, Myriophyllum spp., Potamogeton spp.) and to affect associated populations of aquatic invertebrates and vertebrates, especially in alkaline waters. Dense beds provide a poor habitat for aquatic animals and are not consumed by fish. 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:  11 December 2013
Caffrey, J. et al. (2009)
Research and Control Programme for Lagarosiphon major in Lough Corrib 2008.
Centre for Aquatic Plant Management (2004)
Information sheet: Lagarosiphon major.
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.
Gavin L., Lucy F.E. & Caffrey J.M. (2007)
The quantitative abundance of Lagarosiphon major in Lough Corrib, Ireland.
In: A. bij de Vaate (Ed), 15th International Conference on Aquatic Invasive Species, Nijmegen.
ISSG (Invasive Species Specialist Group) (2006)
Online fact sheets
Global Invasive Species Database, IUCN.
James C., Eaton J.W. & Hardwick K. (1998)
Competition between three submerged macrophytes Elodea canadensis, Elodea nuttallii and Lagarosiphon major.
In: A.T. Monteiro et al. (Eds), Proceedings of the 10th EWRS International Symposium on Aquatic Weeds: 79-82.
Keenan, E., Baars, J.-R. & Caffrey, J.M. (2009)
Changes in littoral invertebrate communities In Lough Corrib in response to an invasion by Lagarosiphon major.
Aquatic Weeds 2009, Proc., 12th European Weed Res. Soc. Symp., Aug. 24-28, Rep. Finn. Environ. Inst., Jyvaskyla.
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.
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.
Ramey V. (2001)
non-native invasive plants in the US: Lagarosiphon major.
Centre for Aquatic and Invasive plants, University of Florida.
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.
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.
Other Internet Links

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