Lindane raises catfish electrodetection threshold.

The detection threshold of the electric sense in catfish, Ictalurus nebulosus, was assessed psychophysically in order to investigate the effects of the organic toxicant lindane. In tapwater the detection threshold for ac-stimuli of 1Hz at 18 degrees C was 8.5 mu V/cm. In 0.1\% DMSO in tapwater the threshold was 14 mu V/cm. In 50 mu g/l lindane dissolved in 0.1\% DMSO in tapwater the threshold went up to 1000 mu V/cm. After clearing, the threshold returned to 36 mu V/cm. The results demonstrate that catfish ampullary electroreceptors are susceptible to exposure to sublethal doses of organic pesticides. Since ampullary electroreceptor organs are known to respond also to heavy metal pollution, the electric sense seems a promising system to monitor the cumulative pollution of aquatic habitats.