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small fish, may inhibit the larger, predatory fish from finding
their food. This thicker plant growth can also interfere with
boaters, anglers and swimmers. Zebra mussel infestations may also
promote the growth of blue-green algae, since they avoid consuming
this type of algae but not others.
Zebra mussels attach to the shells of native mussels in great
masses, effectively smothering them. A survey by the Corps in the
East Channel of the Mississippi River at Prairie du Chien revealed a
substantial reduction in the diversity and density of native mussels
due to Zebra Mussel infestations. The East Channel provides habitat
for one of the best mussel beds in the Upper Mississippi River.
Future efforts are being considered to relocate such native mussel
beds to waters that are less likely to be impacted by zebra mussels.
Financial impacts have been significant to Wisconsin's water
utilities and to power plants, where these animals congregate on and
clog intake and distribution pipes. In 2001, for example, Wisconsin
Electric Power Company reported that they were spending $1.2 million
per year in the control of zebra mussels on their Lake Michigan
power plants. Lock and dam operators on the Mississippi River and
raw water users have also incurred costs. The estimated annual cost
of controlling zebra mussels in the Great Lakes now range from $100
to $400 million, according to NOAA Great Lakes Environmental
Research Laboratory Director Dr. Stephen Brandt.
CONTROLLING ZEBRA MUSSELS: Once zebra mussels are established in a
water body, very little can be done to control them. It is therefore
crucial to take all possible measures to prevent their introduction
in the first place. Be sure to follow the four-step procedure in
preventing the spread of aquatic hitchhikers. In addition to these
measures, boaters can take specific precautions in protecting their
motors from zebra mussels.
Infestation of raw water intake pipes and structures can seriously
limit water flow into hatcheries, drinking water treatment plants,
industrial facilities, and cooling
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systems of power plants. Virtually all control initiatives have
stemmed from such utility or industrial infestations, thus
cost-effectiveness and mechanical functioning are the primary goals.
Control measures can include physical removal, industrial vacuums,
backflushing, chemical applications (chlorine, bromine, potassium
permanganate), and even oxygen deprivation. An ozonation process is
under investigation (patented by Bollyky Associates Inc.) which
involves the pumping of high concentrations of dissolved ozone into
the intake of raw water pipes. This method only works in controlling
veligers, and supposedly has little negative impacts on the
ecosystem. Further research on effective industrial control measures
that minimize negative impacts on ecosystem health is needed.
No selective method has been developed that succeeds in controlling
zebra mussels in the wild without also harming other aquatic
organisms. To a certain extent, ducks and fish will eat small zebra
mussels, but not to the point of effectively controlling their
populations. Water draw-downs may yield positive results in some
situations, as the mussels are killed by deep freezing during
winter. They are also susceptible to the scouring and freezing of
winter ice along the shores of the Great Lakes. As of yet, no
practical and effective controls are known, again emphasizing the
need for research and prevention.
Welcome Aboard! New Members of
the LLFC
LaVerne & Ruth Immel
Corey Ficht
Michael Sabby
Jeff Plank
Mark & Coni LaBarbera
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