Assessment of the long term impacts of alien aquatic macrophytes on native plant communities: Example of freshwater lakes and ponds of the coastline of Aquitaine (South West France) - INRAE - Institut national de recherche pour l’agriculture, l’alimentation et l’environnement Access content directly
Conference Poster Year : 2009

Assessment of the long term impacts of alien aquatic macrophytes on native plant communities: Example of freshwater lakes and ponds of the coastline of Aquitaine (South West France)

Etude des impacts à long terme des communautés de macrophytes exotiques sur les espèces indigènes : Exemple de lacs et étangs du littoral aquitain

Abstract

The development of alien exotic aquatic macrophytes in all types of aquatic water bodies induces structural and functional disturbances on the native plant communities, directly linked with the characteristics of the colonization and the abundance of these invaders. These disturbances are especially raised in stagnant water bodies as lake or ponds where the physical features of the ecosystem rarely constitute a natural factor of regulation of this colonization. They are generally the consequences of the interspecific competition for light or nutrients. Alien species are very competitive with an important production of biomass and a high capacity of colonization of several biotopes. For the native species the competition causes, first, a rapid loss of biomass production and, second, a decrease of the richness of the communities. Since three decades, about fifteen freshwater shallow lakes and ponds of the coastline of the Aquitaine are the place of successive invasions of amphiphytes as Ludwigia grandiflora (Mich.) Greuter & Burdet, subsp. hexapetala (Hook. & Arn) Nesom & Kartesz, Myriophyllum aquaticum (Vell.) Verdc., and hydrophytes as Lagarosiphon major (Ridley) Moss and Egeria densa Planch. All communities of native hydrophytes can be in competition with these alien species, from the shallow biotopes of shore to the deepest zones of the lakes. Among these plants, protected species like Isoetes boryana, Littorella lacustris and Lobelia dortmanna are present: these species disappear when their biotopes are colonized by the alien species and when organic matter covers the sediments. Some species of Potamogeton, like P. natans, P. polygonifolius and P. crispus, two species of Myriophyllum, M. alterniflorum and M. spicatum, regressed in several sites. The small size helophytes (height below 40 cm) such as Eleocharis palustris or Schoenoplectus pungens can also disappear in the zones colonized by Ludwigia. To our knowledge, this competition doesn't cause the extinction of indigenous species in these lakes and ponds. The control and the management of Ludwigia by mechanical extraction or hand pulling allow new installations of hydrophytes in the cleaned biotopes. For this species, the frequent hand pulling management operations can allow the conservation of the native shoreline species in good conditions. Finally, the investigations of the structure and the dynamics of the communities, on the water and sediment quality and on the physical features of the biotopes, allow to present a first assessment of the ecological impacts of these invasive species in this particular ecological context.

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hal-02592941 , version 1 (15-05-2020)

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Vincent Bertrin, Alain Dutartre, Christophe Laplace-Treyture. Assessment of the long term impacts of alien aquatic macrophytes on native plant communities: Example of freshwater lakes and ponds of the coastline of Aquitaine (South West France). 12th EWRS International Symposium on Aquatic Weeds, Aug 2009, Jyväskylä, Finland. 2009. ⟨hal-02592941⟩

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