Combined effect of temperature and a reference toxicant (KCl) on Daphnia middendorffiana (Crustacea, Daphniidae) in a high-mountain lake

Climate change has direct effects on aquatic systems where increased water temperature leads to range shifts and changes in the distribution of organisms. The climate ecosystems are expected all biomes, Alpine environments particular. Anthropogenic pressure (e.g., chemical pollution) besides impact state quality which environmental contaminants can interact. To better understand effect increases pollution high-mountain lakes, we performed an ecotoxicological assay Daphnia middendorffiana collected during summer 2021 a lake (Upper Balma Lake, Cottian Alps, 2212 m a.s.L.). Samples were exposed two values (15 °C 20 °C), potassium chloride (KCl) as reference toxicant, D. magna model organism for comparison. Findings showed immobilization after exposure KCl both species, but non-optimal (20 15 magna, respectively) enhanced this effect. mean half-maximal effective concentration (EC50; 24 h) was significantly lower than that recorded (46.9 mg/L vs 255 mg/L). A higher EC50 (273.4 mg/L; compared (EC50 50.6 h). Our findings suggest combined may severely affect occurrence middendorffiana, occupies central position food webs lakes Alps.