Electric methods have been tested and considered as possible proactive controls. Some research has been directed towards killing the mussels using electricity. Other research has attempted to find methods that do not necessarily kill mussels, but that will affect their behavior. These latter studies examined direct or alternating currents applied over a wide range of voltage intensities (e.g., pulse power and cathodic protection approaches). Although these studies produced inconsistent results, some were promising.
Smythe et al. (1995) stated that electric fields can stun post-veligers and affect the settlement behavior of the zebra mussels. Peak pulse power direct current (DC) signals of 15.75 and 26.2 V/cm appeared to have had a reasonably large and significant effect on mussel settlement behavior with settlement reduction between 78 and 88 percent and 83 to 88 percent, respectively. Alternating current (AC) voltages higher than 39 V/cm produced reductions in settlement as high as 35 percent. Fears and Mackie (1995) tested the efficacy of systems which use low-voltage AC for preventing settlement and attachment by zebra mussels. They found that 3 V/cm with steel rods on both wood and concrete surfaces and with steel plate trash bars completely prevented settlement of both new recruits and translocators. Partial prevention of settlement at 2 V/cm with steel rods on both wood and concrete surfaces and steel plates was observed. In contrast, EPRI (1992) reported on previous studies indicating that to be effective, voltage should be in the 700 to 800 V/cm range. Lange et al. (1993) reported that field strengths of up to 17 V/cm with a corresponding veliger exposure time of 0.1 sec had little or no effect on zebra mussel attachment.
Investigations have focussed on the prevention of colonization by young zebra mussels using a modified impressed current cathodic protection. Lewis and Pawson (1993) found that current densities of approximately 20, 40, and 50 mA/m2 did not provide complete protection from zebra mussel settlement, though significant protection was accomplished at approximately 50 mA/m2. Additional tests at higher electric current densities are being conducted.