Ecotoxicological biotests as tools for continuous monitoring of water quality in dam reservoir

Ecotoxicological biotests were applied in order to evaluate their suitability as early warning systems in the continuous monitoring of lowland shallow dam reservoirs located in Central Europe. The following biotests were used: Daphtoxkit FTMmagna, Algaltoxkit FTM, Ostracodtoxkit F, Phytotoxkit and MARA Test. The experiment was conducted from July 2010 to December 2012 in Goczalkowice Reservoir (the Vistula River, Poland), serving as a model. For the analysis, 41 out of 52 measured water indices were used to assess its toxicity to living organisms. The results of biotests were correlated with 41 hydrochemical indices of water quality. The pattern of relationships among the result of biotest and hydrochemical indices as well as Factor Analysis (FA) and Primary Component Analysis (PCA) revealed that:i) signs of ecotoxicity detected with biotests were associated with either low flow periods or spring surface runoff of water; ii) single events of increased ecotoxicity in the depression areas behind saddle dam pump stations appeared after high flow periods;iii) elevated toxicity was accompanied by high concentrations of dissolved and suspended substances;iv) FA and PCA demonstrated correlations among the results of biotests and damming parameters, water conductivity, alkali and transitory metal metals (Ca, Fe, Cu, Zn), and several forms of nitrogen phosphorous and carbon compounds concentration.The relationships suggest that batteries of biotests may serve as a cost-effective tool for continuous monitoring of water quality in dam reservoirs and can detect effects of extreme hydrologic events, local toxic discharges, and signs of the trophic status of the reservoirs.