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(70-16) Effects of AMD on Gambusia holbrooki (Pisces, Poeciliidae) and Daphnia manga (Crustacea). Gerhardt, A.*,1,2, Janssens de Bisthoven, L.1,2, Guhr, K.1,2, Soares, A.2, 1 LimCo International, Ibbenbueren, Germany2 University of Aveiro, Aveiro, Portugal ABSTRACT- The abanonded S. Domingos mine (Portugal) offers a natural pH and metal gradient of the drainage water, an ideal model for toxicity studies in situ. Short-term toxicity bioassays were performed in artificial flow-through systems with water from the AMD (pH 6.4, 5.5, 5.0, 4.4 and 3.3) and 2 local control sites and the site of origin of the respective test species in the laboratory and in situ. Survival of 10-20 organisms per pH condition with the Multispecies Freshwater Biomonitor (MFB). Condition parameters (sizes, DW) and metal burdens in the organisms were measured at the end of the experiments. Simultaneously the following elements were measured in the water: metals: As, Cd, Co, Cr, Cu, Fe, Mn, Pb and Zn, other elements: Ca, K, Mg, Na, Cl and S. Gambusia holbrooki (local species) and Daphnia magna (standard species) did not show pH-dependent changes in metal burdens, except for Fr. Gambusia holbrooki showed increasing Fe burdens at low pH and generally contained more Fe compared to Daphnia magna. The behavioural stress responses of Gambusia holbrooki consisted of two phases, (locomotion: 2 h, ventilation: 2-10 h), and followed the Stepwise Stress Model. Daphnia magna had longer response times (locomotion: 10 h). Daphnia magna (LC50-24h: pH 6.4/metals) was more sensitive than Gambusia holbrooki (LC50-24h: pH 5.5/metals). Daphnia magna survived better and was more active in the laboratory than in situ, no significant differences were found for Gambusia holbrooki. Key words: Multispecies Freshwater Biomonitor, toxicity, stress behaviour, metal pollution |
