Consultant's Report - Minnesota State Legislature

Technological Controls
MINNESOTA DEPARTMENT OF NATURAL RESOURCES
Feasibility Study to Limit the Spread of Zebra Mussels from Ossawinnamakee Lake
As outlined above, technological control methods include acoustic, chemical, electrical, and
physical treatments. Acoustic control methods can be utilized at high frequencies to induce
mortality, or at lower frequencies to prevent settlement and typically affect all life stages.
Electrical control methods have a similar effect at high and low frequencies, although most of
these methods are most effective in controlling juvenile and adult mussels. Most ofthe physical
control methods are utilized to prevent all zebra mussel life stages from spreading to particular
locations, and subsequently induce mortality. Chemical control methods are generally utilized to
induce mortality, but there are several that only prevent substrate attachment. Each of these
control method categories and specific alternatives are described in detail below.
Acoustic Deterrents
Cavitation, sound treatment, and vibration are three acoustic treatments that can be utilized to
control zebra mussel populations. The impacts and effectiveness ofthese treatments are not fully
proven, especially in high-flow areas, but they are fairly low maintenance technologies that have
a low likelihood ofharming nontargeted organisms. There is a possibility that resident fish may
be affected by cavitation, but migratory fish should not be affected at short exposure times. In
addition, acoustic control methods are environmentally friendly and do not have associated
safety issues. Although acoustic technology is still under investigation, there is evidence
suggesting that sound energy could be an attractive alternative to chemical or electrical
treatment. In order to implement acoustic treatment options, site considerations are required for
constructability and periodic maintenance access. In addition, electrical service is required for
signal generation and amplification. Figure V-I demonstrates a conceptual view of a cavitation
or sound treatment deterrent system.
Figure V-1. General Schematic of an Acoustic Deterrent System
V-3
Review oCPotential Control Methods