Monitoring behavioural responses to metals inGammarus pulex (L.) (Crustacea) with impedance conversion

An impedance conversion technique was used to study the behaviour ofGammarus pulex (L.) exposed to acutely toxic concentrations of Pb (0.01, 0.05, 0.1 and 0.5 mg Pb l(-1)) and to field concentrations of Cu ( ≤ 0.05 mg Cu l(-1)). Initial stress responses were studied during short-term exposure (1 h) and sublethal toxic effects were monitored during 7 (Pb) and 35 days (Cu), respectively.Exposure to Pb caused 30 % mortality and resulted in a bioconcentration factor (BCF) of 2700 at 0.5 mg Pb l(-1) after 168 h. Exposure to Cu polluted stream water caused no mortality within 35 days and uptake was low (BCF 5.8).Gammarus pulex reacted with initial stress responses to metal exposure within 30 min. (Cu) or 1 h (Pb). The reactions consisted of increased ventilation and decreased locomotion.Sublethal concentrations of Pb and Cu caused toxic effects on the behaviour of G.pulex after several days of exposure, consisting of increased ventilation and decreased locomotion.Impedance conversion is an appropriate method for detecting stress responses to metals and can be used in "early warning" biomonitoring systems as well as for acute and chronic behavioural toxicity testing.