|
2P Modelling ecotoxic effects (MOP/145) Development and validation of a chronic Zn-BLM for the rainbow trout Oncorhynchus mykiss. Vermaercke, Sigrid 1, Deschamphelaere, Karel1, Janssen, Colin1, 1 Ghent University, Laboratory of Aquatic Ecology and ecotoxicology, Ghent, East-Flanders, Belgium ABSTRACT- Ghent, Belgium. Ecotoxicology, University of Ghent, Belgium. The biotic ligand model (BLM) concept which has recently been developed for some metals (e.g. copper and silver) is currently the most developed practical applicable technique to assess the ecotoxicity of metals on a site-specific basis: i.e. taking into account differences in the physico-chemical characteristics of the surface water. The BLM is based on the hypothesis that toxicity is not simply related to the total metal concentration, but is depending of the metal complexation and interaction processes at the site of toxic action (i.e. the Biotic Ligand, BL). The individual effects of Ca2+, Mg2+, Na+ and H+ on the chronic toxicity of Zn to O. mykiss was determined in a number of univariate experiments. Beside the experiments in standard test media, chronic toxicity tests will be performed in five different surface waters representing various European regions. The results of these tests allow to validate the developed model and to evaluate the effect of dissolved organic carbon on chronic zinc bioavailibility and toxicity to O. mykiss. Based on the observed (linear) relationships between exposure period and relevant endpoints (dose-response), stability constants to the BL for Zn and relevant ion species will be derived according to the methodology as proposed by De Schamphelaere and Janssen (2001). Secondly, the measurement data on ion gill concentrations will allow the derivation of stability constants to the gill and develop a chronic BLM assuming that the gill is the main BL for chronic Zn-toxicity (cf. Di Toro et al., 2001; Santore et al., 2001). Combining the gained knowledge generated with both approaches, a chronic Zn-BLM for the fish O. mykiss will be established. Key words: rainbow trout, ecotoxicology, Biotic Ligand Model, zinc |
