MONITORING BEHAVIORAL-RESPONSES TO METALS IN GAMMARUS-PULEX (L) (CRUSTACEA) WITH IMPEDANCE CONVERSION

An impedance conversion technique was used to study the behaviour of G ammarus pulex (L.) exposed to acutely toxic concentrations of Pb (0.01 , 0.05, 0.1 and 0.5 mg Pb 1(-1)) and to field concentrations of Cu (le ss than or equal to 0.05 mg Cu 1(-1)). Initial stress responses were s tudied during short-term exposure(1 h) and sublethal toxic effects wer e monitored during 7 (Ph) and 35 days (Cu), respectively. Exposure to Pb caused 30 % mortality and resulted in a bioconcentration factor (BC F) of 2700 at 0.5 mg. Pb 1(-1) after 168 h. Exposure to Cu polluted st ream water caused no mortality within 35 days and uptake was low (BCF 5.8). Gammarus pulex reacted with initial stress responses to metal ex posure within 30 min. (Cu) or 1 h (Pb). The reactions consisted of inc reased ventilation and decreased locomotion. Sublethal concentrations of Pb and Cu caused toxic effects on the behaviour of G. pulex after s everal days of exposure, consisting of increased ventilation and decre ased locomotion. Impedance conversion is an appropriate method for det ecting stress responses to metals and can be used in ''early warning'' biomonitoring systems as well as for acute and chronic behavioural to xicity resting.