Geoscience Reference
In-Depth Information
Figure 7-50.
Public awareness about zebra mussels is
crucial in i ghting this pest. Display on back of pickup
truck of the Kansas Department of Wildlife and Parks.
Photo by J.S. Aber.
Figure 7-49.
Cluster of zebra mussels (
Dreissena
polymorpha
) from the Deûle canalisée, Lambersart,
northern France. Shells are up to 2 inches (5 cm) long.
Modii ed from original photograph by F. Lamiot;
obtained from Wikimedia Commons
investigation, but so far none is available (U.S.
Geological Survey 2008). For chemical control,
water-treatment plants may inject peroxide at
the point of water intake to prevent zebra
mussels from entering the plant. Molluscicides
could be used to kill adult and veliger zebra
mussels. However, zebra mussels are so tena-
cious that any effective chemical control would
kill everything else in the water. Unfortunately,
“once zebra mussels become established in a
water body, they are impossible to eradicate with
the technology currently available” (National
Atlas 2009). At this point, the best strategy is to
prevent, or at least slow, the spread of zebra
mussels through public education and manda-
tory inspection programs (Figs. 7-50 and 51).
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http://
commons.wikimedia.org/
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.
Lake Huron, presumably from the fresh-water
ballast of a transatlantic ship (U.S. Army Corps
of Engineers 2002). Zebra mussels have many
natural enemies in their native eastern European
habitat, but few of these are present in North
America. In effect, zebra mussels are unchecked
by existing predators, parasites or benthic com-
petitors in North America. They have spread
rapidly and are now found throughout the Great
Lakes, Mississippi, and most other eastern drain-
age basins. Zebra mussels are transported pri-
marily in the free-swimming larval (veliger)
stage in the bilge water of boats, i shing buckets,
and any l owing water body
-
creeks, rivers,
canals, etc. According to the U.S. Army Corps
of Engineers (USACE), “the zebra mussel has
become the most serious nonindigenous bio-
fouling pest ever to be introduced into North
American freshwater systems” (USACE 2002).
Potential means to control zebra mussels fall
into three general categories
-
physical, biologi-
cal and chemical (USACE 2002). The problem is
to control both adult and veliger stages in situ
and in transport. Physical controls to remove
adult mussels include high-pressure water
jetting, freezing, scraping and desiccation.
Many possible biological controls are under
7.5 Summary
Wetlands are some of the most productive eco-
systems in the world and are home to a diverse
variety of invertebrate and vertebrate animals.
Protecting this wildlife has been the primary
inspiration for preserving and restoring wetland
habitats worldwide. Aquatic animals must deal
with low oxygen levels and other constraints,
just as the plants must. In relation to wetlands,
animals fall into three general categories. First
are those that are wholly adapted for wetlands
through their morphology and behavior; they
spend most, if not all, of their life cycles in
wetlands. Second are animals that frequent wet-
lands to take advantage of the rich resources,
