Étude hydrobiologique de la retenue du Rupt-de-Mad

Hydrobiological survey of the reservoir of the Rupt-de-Mad

¹ Hydrobiologie-Algologie, Université Nancy I, 54506 Vandoeuvre Cedex
² Laboratoire d'Hygiène et de Recherche en Santé Publique, 11 bis, rue Gabriel-Péri, BP 88, 54515 Vandoeuvre-lès-Nancy Cedex

Résumé

Etude des variations de la physico-chimie et de la microbiocénose d'une retenue d'eau à potabiliser de la région de Metz (Moselle, France). Ce milieu de type mésotrophe abrite une flore algale diversifiée mais rarement abondante. A côté d'algues banales il apparaît sporadiquement des espèces caractéristiques de fleurs d'eau (Microcystis oeruginosa Kuetz, Oscillatoria agardhii Gomont ou Stephanodiscus hantzschii Grun). Ce risque potentiel suggère un contrôle biologique préventif dans certaines conditions d'environnement.

Abstract

A great part of needs in water of Greater Metz (department of Moselle, France) comes from Rup-de-Mad, affluent of the left side of Moselle River. In order to provide a regular supply, a damming was built on this river upstream Arnaville, with a volume of 355 000 m³ and a surface of 25 ha. Between 1987 and 1990, a study of physic al, chemical and biological parameters of the network has been realized. Except from deep waters of the damming, the characteristics of waters are up to the standards of water quality to make drinkable. The environment, of a mesotroph type, contains a varied flora of algoe (over 200 taxons) but rarely abundant. The diatoms are well represented as well at the level of the specific richness as for the number of individuals, the typical species being Asterionella formosa Hassall, Melosira varians Ag. and Stephanodiscus hantzschii Grun. The chlorophycean algoe belong to species more often met in environnments and are devoid of a particular ecological meaning; the small number of sampling does not allow to precise their supply, the verno-estival period being, in a whole, propitious to them. The cyanophycean algoe (cyanobacteria) never reach a development likely to set problem, meanwhile the presence of Microcystis oeruginosa Kütz., well-know as toxic, has to be noted. A proliferation, source of nuisance, about the establishment of favourable environmental conditions, cannot be excluded. This potential risk of toxicity suggest the utility of preventive supervision of the attitude of the algal flora.