Toxicity and bioaccumulation of copper in the oribatid mite Oppia nitens (Acari: Oribatida)

To determine the toxicity and bioaccumulation of copper, adult oribatid soil mites Oppia nitens were exposed for 28 days to LUFA 2.2 soil spiked at concentrations of 0–6400 mg Cu kg⁻¹ dry soil. Effects on survival and reproduction were related to total and available (0.01 M CaCl₂ extractable and pore water) concentrations in the soil and concentrations in the animals. The mites showed a concentration-dependent uptake of copper, which, however, decreased at toxic concentrations. Overall bioaccumulation factors were low, suggesting a low tendency for copper bioaccumulation. The estimated median lethal concentration (LC50) values were 3251 mg Cu kg⁻¹ dry soil, 1130 mg Cu kg⁻¹ dry soil, 1977 mg Cu L⁻¹ pore water, and 592 mg Cu kg⁻¹ dry body weight, and the estimated 50 % effective concentrations (EC50) for effects of copper on reproduction were 589 mg Cu kg⁻¹ dry soil, 116 mg Cu kg⁻¹ dry soil, 78.5 mg Cu L⁻¹ pore water, and 413 mg Cu kg⁻¹ dry body weight, based on measured soil total concentrations, 0.01 M CaCl₂ extractable, porewater, and internal concentrations, respectively. The results show that the mite O. nitens is a suitable test organism for measuring metal bioavailability and toxicity in soil.