Copper toxicity to Ceriodaphnia dubia Richard, 1894 under increased mineralization and high organic matter content
A.M. Sheromov, R.A. Lozhkina, A.S. Olkova
Section: Ecotoxicology
The variability in toxicity of the same hazardous substance across different environments due to the influence of additional factors is a key challenge in bioassay. This study aimed to evaluate the effect of water mineralization and organic matter content on copper toxicity to the cladoceran Ceriodaphnia dubia Richard, 1894. Test organisms were exposed to waters amended with CuSO4·5H2O (0.005, 0.01 and 0.025 mg/L Cu2+). Sodium chloride (0.5, 1.0 and 2.0 g/L) and potassium humate (0.5, 1.0 and 2.5 %) were added to the above solutions to assess the effect of mineralization and organic matter. The effect of mineralization on copper toxicity was twofold. A moderate increase in mineralization (0.5 g/L NaCl) significantly reduced copper toxicity, as evidenced by decreased C. dubia mortality at 0.005 and 0.025 mg/L Cu2+ (p < 0.05). Conversely, high mineralization (2.0 g/L NaCl) combined with a high copper content (0.025 mg/L) resulted in 100 % mortality. Furthermore, C. dubia fertility showed a consistent negative correlation with increasing mineralization. Organic matter addition reduces mortality and enhances reproductive output in C. dubia. This effect was most pronounced at the highest Cu2+ concentration (0.025 mg/L). Specifically, Ceriodaphnia brood size in treatments supplemented with 0.5 %, 1 % and 2.5 % potassium humate was 6.9, 6.7 and 3.2 times higher than in the corresponding control, respectively.
ISSN 1995-4301
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