RESPONSES OF AMERICAN BULLFROG, LITHOBATES CATESBEIANUS, AND SOUTHERN LEOPARD FROG, LITHOBATES SPHENOCEPHALUS, TO LOW VOLTAGES IN UNIFORM AQUATIC ELECTRICAL FIELDS

摘要

Extensive research has described the behavioral response of fishes to electrofishing, but few investigations have measured the response of frogs. As electricity continues to be used as a tool to conduct frog and other amphibian surveys, and because frogs inhabit many of the same environments where electrofishing surveys are conducted for fish species, documenting the response of frogs to electricity is important. We measured the voltage gradient and power density thresholds that resulted in immobilization of early life stages of American bullfrog, Lithobates catesbeianus, and Southern leopard frog, Lithobates sphenocephalus, for a range of pulse frequencies (15-120 Hz) and ambient water conductivities (250-1,381 mu S/cm). Voltage gradients of 0.40-1.00 V/cm at power densities of 58-1,461 mu W/cm(3) induced immobility. The lowest power densities causing immobilization were at pulse frequencies of 60 and 120 Hz; more power was required at lower frequencies and in water with a higher conductivity.