Abstract
Daphnia magna and Ceriodaphnia quadrangula were exposed to 50 or 10% of the EC super(50) of organophosphate pesticides, carbamate pesticides, or pyrethroid pesticides to determine the effects of exposure on the heart beat of the organisms. The higher concentration of organophosphates and the lower concentration of the pyrethroids increased and decreased the heart rates, respectively. No change in heart rate was noted for the carbamates, or for the other concentrations of pyrethroids or organophosphates. A heart beat chart was developed that could be used in a screening bioassay to differentiate exposure to the three classes of pesticides.