Distribution, ecology and impact of a small invasive shellfish, Hemimysis anomala in Alsatian water
Fiche publication
Date publication
mars 2010
Auteurs
Membres identifiés du Cancéropôle Est :
Dr MULLER Christian
Tous les auteurs :
Dumont S, Muller CD
Lien Pubmed
Résumé
The dissemination of Hemimysis anomala (H. anomala) in Europe and more recently in North America highlights the problem of proliferation of invasive species able to form large colonies. Concern relates mainly to competition for food, in particular the zooplankton that H. anomala feeds on at the juvenile stage and that could be lacking for many other species, like young fish. A recent study describes the spread of H. anomala towards the south of France by the Rhne River (Wittmann and Ariani in Biol Invasions, 7 pp, 2008). We have also found it near the Marne east of Paris, as well as in an increasing number of rivers and gravel pits in Alsace. We confirm here that H. anomala is very prolific, reproducing three times a year, in March/April, June/July and September/October. During the winter, we observed gatherings of thousands of individuals in open water from mid-December until March/April, with females carrying eggs in March when water reaches 7-8A degrees C. The tracking of the population of H. anomala in an Alsatian gravel pit during three consecutive years shows a marked reduction in the number of individuals after a period of strong growth, which could be explained by substantial predation by perch and other predators. Finally, the ecological impact of the establishment of H. anomala was evaluated indirectly by the study of alevin and hydra populations, chosen for their nutritional dependence on zooplankton. Combined with the decrease of the H. anomala population observed over the period studied, our data suggest that a major impact on the aquatic community by H. anomala is unlikely at least in the studied area.
Référence
Biol Invasions. 2010 Mar;12(3):495-500