PARENT SESSION

2A - Mixture toxicity
Poster Hall
8:30 AM - Monday, 28 April 2003
Chair: Hermens, J.¹, ¹
Co-chair: Toy, R.², Backhaus, T.³, ^{2 3}

(MOP/73) Assessment of Whole Effluent Toxicity with aquatic snails in bioassay and in situ.

Coeurdassier, Michaël¹, de Vaufleury, Annette¹, Lovy, Christiane¹, Badot, Pierre-Marie¹, ¹ University of Franche-Comté, Besançon, France, France

ABSTRACT- The freshwater gastropod Lymnaea palustris was used to assess the toxicity of an industrial effluent containing high levels of metals in chronic bioassay and in situ by using an active biomonitoring approach in the receptor stream. The bioassays were performed on adults exposed during four weeks to different dilutions of the effluent at three successive treatment steps (crude effluent, after physico-chemical and after biological treatments). Dose-dependent responses reflecting exposure (bioaccumulation of Cr, Zn and Fe) and effects on fecundity, survival and on oxidative stress (measured by malondialdehyde) were investigated. Results showed that Cr and Zn were highly accumulated in snails while Fe was regulated. However, body concentrations of Cr and Zn decreased along the effluent treatment gradient, particularly after the physico-chemical one. Between controls and treatments, no effect were observed on malondialdehyde production. However, the reduction of effluent toxicity along the treatment process was shown by the responses of fecundity and survival. Snails were also caged in the receptor river, upstream and downstream of effluent discharge (after biological treatment). Two types of caging were developped: a floating one to integrate only the contamination of the water and a second one in contact with the sediment. There was no difference between Cr, Zn and Fe concentrations in the water at the studied stations while the sediment was highly contaminated in the downstream station. After two weeks, no effect was noted on malondialdehyde concentration, fecundity and mortality at all stations. Bioaccumulation of Cr and Zn in snails exposed to sediment was significantly higher in the downstream station, reflecting the contamination of the receptor stream by the effluent.

Key words: bioassay, whole effluent toxicity, biomonitoring, freshwater snails