Benthic macroinvertebrates in streams in the North of France as good indicator of freshwater quality. Correlation between metallic and organic contaminations and biocenotic index

This work concerned the evaluation of the metallic and organic contaminatio n of the Canal a Grand Gabarit (Northern France) and the consequences on th e benthic macro-invertebrates communities. Several parameters (Al, Cd, Cu, Fe, Pb, Zn, TOC, P, TKN) were measured in sediments taken from the Canal a Grand Gabarit, and the Aa river. The data showed a strong contamination of the canals localized in the Bassin Minier. The communities of the benthic m acroinvertebrates collected with artificial substrates showed to be in good agreement with the values found for the sediments parameters. CPA showed t hat biocenotic index values were negatively correlated with the Cd, Zn, Ph and Cu levels of the sediments. Organic parameters seem to have no effect o n biocenotic index values.