Use of oligochaete communities for assessment of ecotoxicological risk in fine sediment of rivers and canals of the Artois-Picardie water basin (France)
Utilisation des communautés d'oligochètes pour l'évaluation du risque écotoxicologique dans les sédiments des cours d'eau ou des canaux d'Artois Picardie (France)
Résumé
This study had a purpose to validate different tools based on the oligochaetes for the evaluation of the biological quality of sediments within a surveillance network. Biological data (IOBS index, percentage of Tubificidae with and without hair setae, worm densities), physical data (granulometrics) and chemical data (Cd, Cu, Cr, Hg, Ni, Pb, Zn, PCBs, PAHs) have been studied with co-inertia analysis. These analyses show an opposition between IOBS index and metals, a correlation between metals and percentage of tubificidae without hair setae, and an association between PAHs, low index values, high densities and high percentage of Tubificidae with hair setae. For 24 sites, biological and chemical data gave similar information. In 11 cases on 36 they are conflicting. The use of metal speciations, according to the method of Teissier et al. (1979), show that the organic matter content seems tohave an important role by sorbing metals leading to lower availability. Macrophyte cover could also explain some conflicting results. Granulometrics does not play a determinating role in the present case. As a conclusion, a table allowing the classification of river sediments is proposed for monitoring assessment.This table takes into account IOBS index values, the worm densities and the percentage of Tubificidae without hair setae.
Le but de cette étude est de valider différents outils basés sur les oligochètes pour évaluer la qualité biologique des sédiments. Des données biologiques (IOBS) , des données physiques (granulométrie) et des données chimiques (Cd, Cu, Cr, Hg, Ni, Pb, PCB, PAH) ont été étudiées.