Copper tolerances of Adenophlebia auriculata (Eaton) 1884 (Insecta: Ephemeroptera) and Burnupia stenochorias Cawston 1932 (Gastropoda: Ancylidae) in indoor artificial streams

Copper tolerances of two potential African model species for toxicity testing, the mayfly Adenophlebia auriculata (Eaton) 1884 (exposed to 10 different concentrations in the range of 0.02–65 mg l−1) and the limpet Burnupia stenochorias Cawston 1932 (exposed to eight different concentrations in the range of 0.02–3 mg l−1) were determined in continuous flow-through indoor artificial streams. The following parameters were monitored daily: Cu, pH, temperature, oxygen, survival and location of each individual in the channels. Behavioural effects after 96 h exposure on the mayflies were measured with impedance conversion technique. B. stenochorias (LC50: 0.36 mg l−1 (24 h), 0.10 mg l−1 (48 h), 0.07 mg l−1 (72 h)) was more sensitive to copper than A. auriculata (LC50: 1.78 mg l−1 (24 h), 0.79 mg l−1 (48 h), 0.18 mg l−1 (96 h)). A. auriculata occurred most frequently under the stones, however moved up to the top of the stones just before death at ≥0.5 mg Cu l−1. With increasing exposure time the mayflies significantly preferred the stones close to the outflow (P=0.016). B. stenochorias reacted to Cu-exposure by moving out of the water (P=0.009) and towards the inflow or outflow of the channels at ≥0.06 mg l−1. After 96 h of exposure, Cu-exposed mayflies ventilated more than the controls (P<0.05). A dose-dependent sequence of different behaviours was seen with increasing Cu-concentrations: increased abdomen undulations (≥0.046 mg l−1), increased locomotion (escape) at ≥0.231 mg l−1 and increased ventilation (≥0.277 mg l−1) combined with increased variance in the data sets. In both species the Cu body burdens increased proportionally with copper exposure.