Environmental Risk of Zinc and Cadmium Mixture: Developmental Toxicity Assessment in Water Flea, Daphnia magna Through Acute and Chronic Toxicity

Daphnia magna (D. magna) is a microcrustacean widely used as an indicator organism in the assessment of metal toxicity. Therefore, the aim of the study was to evaluate the acute (48 hours) and chronic (21 days) toxicity of cadmium (Cd²⁺) and zinc (Zn²⁺) on D. magna with different concentrations under Elendt M4 medium. The results of the evaluation of the mortality rate of D. magna acute exposure to 40mL Cd²⁺ (10.00 – 125.00μg.L^–1) and 40mL Zn²⁺ (300.00 – 1,800.00μg.L^–1) showed that Cd²⁺ is more toxic than Zn²⁺ with 50% effect concentration (EC₅₀) of test organisms at 75.30 and 1,274.80μg.L^–1, respectively. For the Cd²⁺ – Zn²⁺ (300.00 – 1,800.00μg.L^–1) mixture containing 75.30μgCd.L^–1, the EC₅₀ value was 1,833.50μg.L^–1 higher than the single metal indicating that Zn²⁺ has a protective role in D. magna against Cd²⁺ toxicity. In the chronic toxicity test, D. magna was exposed to Cd²⁺ (0 – 9.50μg.L^–1) and Zn²⁺ (0 – 200.00μg.L^–1) with EC₅₀ of 1.80 and 126.90μg.L^–1, respectively. The mixture of Cd²⁺ – Zn²⁺ containing 1.80μgCd.L^–1 was toxic to D. magna at the end concentrations of the trial with a mortality rate of up to 81.50% of individuals. At the concentration range of 0 – 140.00μgZn.L^–1, the organism is protected from chronic toxicity of Cd²⁺, hence it does not affect the maturation and reproduction of D. magna. The research results are the basis for studying the toxicity of other metals on microcrustaceans to assess the quality of aquatic ecosystems and human health.