INVERTEBRATE COMMUNITY RESPONSES TO PHYSICAL AND CHEMICAL FACTORS AT THE RIVER AQUIFER INTERACTION ZONE .1. UPSTREAM FROM THE CITY OF LYON

A survey was undertaken from April to June 1991 in seven sites of the Rhone River and the Ain River, southeastern France. A variety of physi cal and chemical factors were measured in an attempt to assess the imp ortance of each in determining the distribution of species and the com munity structures at the surface/aquifer interaction zone. Metal (zinc and copper) impact was more precisely considered. Two investigation m ethods (multivariate statistical community analysis and community para meters such as abundance, richness, diversity indices) revealed that t he structures of the surface and interstitial communities were partly related to some of the chemical factors and to variations in metal con centrations in the water or in the sediments. Variables such as magnes ium, sulfate, potassium, oxygen, and metal contents appeared to be dis criminant factors which could be associated with specific faunistic as semblages. Moreover, sites contaminated by zinc or copper generally ha d a low number of individuals and low number of taxa. Taxonomic groups were differently affected by metals. However, the potential use of ep igean and especially hypogean invertebrate species in biomonitoring tr ace metal contamination at the river/aquifer interaction zone is as ye t premature.