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

Abstract

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.