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 1 0 different concentrations in the range of 0.02-65 mg l(-1)) and the l impet Burnupia stenochorias Cawston 1932 (exposed to eight different c oncentrations in the range of 0.02-3 mg l(-1))were determined in conti nuous flow-through indoor artificial streams. The following parameters were monitored daily: Cu, pH, temperature, oxygen, survival and locat ion of each individual in the channels. Behavioural effects after 96 h exposure on the mayflies were measured with impedance conversion tech nique. 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. auricul ata (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, howev er moved up to the top of the stones just before death at greater than or equal to 0.5 mg Cu l(-1). With increasing exposure time the mayfli es 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 greater than or equal to 0.06 mg l(-1). After 96 h of exposure, Cu-exposed ma yflies ventilated more than the controls (P < 0.05). A dose-dependent sequence of different behaviours was seen with increasing Cu-concentra tions: increased abdomen undulations (greater than or equal to 0.046 m g l(-1)), increased locomotion (escape) at greater than or equal to 0. 231 mg l(-1) and increased ventilation (greater than or equal to 0.277 mg l(-1)) combined with increased variance in the data sets, In both species the Cu body burdens increased proportionally with copper expos ure. (C) 1998 Elsevier Science B.V.