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© T. Pennington
© T. Pennington
© Bill Haller, Center for Aquatic Invasive Plants
© Emmanuel Delbart, FUSAGx
© T. Pennington
© T. Pennington
© T. Pennington
Egeria densa - Brazilian waterweed

Synonym: Elodea densa
French name:  Egéria
Dutch name: Egeria
Family: Hydrocharitaceae
Group: Vascular plants
Origin: South America
Habitat: freshwater
Introduction:  aquariums and ponds
ISEIA Score : 12
Naturalization in Belgium
First observation in the wild: 1999
Invasion stage: spread
Spatial distribution: isolated
Reproduction in the wild: yes
Dispersion potential: high
Natural habitats: high
More on invasiveness: The Brazilian waterweed as a very wide ecological amplitude. It thrives in various types of freshwater habitats, from acid to eutrophic environments. It prefers flowing systems but may also be found in still waters. This aquatic weed is not light demanding and is able to develop in deep and turbid waters.
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: 3260
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: Egeria densa is highly competitive in meso-eutrophic waters. 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. The Brazilian waterweed has been reported to outcompete native aquatic plants and to adversely affect fish communities. 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
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.
ISSG (Invasive Species Specialist Group) (2006)
Online fact sheets
Global Invasive Species Database, IUCN.
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.
Mony, C.,Koschnick, T.J., Haller, W.T. & Muller, S. (2007)
Competition between two invasive Hydrocharitaceae (Hydrilla verticillata (L.f.) (Royle) and Egeria densa (Planch)) as influenced by sediment fertility and season.
Aquatic Botany 86: 236–242.
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.
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.
Verloove, F. (2006)
Catalogue of the Neophytes in Belgium (1800-2005).
Scripta Botanica Belgica 39, 89 pp.
Washington State Department of Ecology (2003)
Technical information about Egeria densa (Brazilian Elodea).
Water Quality Program: Non-Native Freshwater Plants.
Weber, E. (2003)
Invasive plant species of the world: a reference guide to environmental weeds.
CABI Publishing, Cambridge, Massachusetts, 548 pp.

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