7790

• UCREFRP Catalog Number: 7790
• Author: Tyus, H. M., W. P. Dwyer and S. Whitmore.
• Title: Feasibility of Preventing Further Invasion of the Zebra Mussel into the Western United States.
• USFW Year: 1993.
• USFW - Doc Type: \
• Copyright Material: NO

Once established, the zebra mussel
is a prolific colonizer. Maturing within
12 to 18 months in favorable environ-
ments, it may spawn more than once a
year, and production of over 1 million
eggs per season is possible from one
female (Miller et al. 1992). Fertilized
eggs develop into free-swimming
larvae (veligers) that can remain
suspended in the water for a month.
Larvae attach to hard surfaces and
transform into the hard-shelled form
(post-veligers). Up to 700,000 post
veligers/m' have been reported to settle
in raw water systems during a single
spawning season (Miller et al. 1992;
McMahon et al. 1993). In Lake St.
Clair, the striped, yellowish-brown
mussels grow nearly an inch in the first
year, reach a size of 1.5 to 2 inches, and
live about 3 years (Mackie 1993).
Young zebra mussels settle on various
surfaces and firmly attach to them with
threads secreted from a gland at the base
of the muscular foot (Miller et al. 1992).
F/GORE .~. P/PE BLOCKED W/TH ZEBRA MUSSELS.
They also can attach to each other, and
thus form mussel clusters with
population densities of 5,000 to 30,000
mussels/mz not being uncommon.
High densities of 342,000 to 700,000
mussels/mZ have been reported (Miller
et al. 1992; Leach 1993), and at high
densities zebra mussels can form dense
mats of 12 inches thick or perhaps
more. Because concrete structures,
steel pipes, and other man-made items
are good attachment substrate for the
After its introduction into Lake St.
Clair, economic damages caused by the
mussel in the Great Lakes was
estimated at $5 billion (Nonindigenous
Aquatic Nuisance Prevention and
Control Act of 1990). Infestations of
zebra mussels ranging from 1,000/mZ
to 750,000/mZ have been recorded
from 10 power plants located from
Lake Huron to Lake Erie (Kovalak et
al. 1993). Costs to the power industry
alone has been estimated at $3.1 billion
mussels, they have become a major
problem for industrial and municipal
water supply facilities. Severe problems
to power plants have been caused by
zebra mussel colonization inside pipes
(Figure 3).
over a 10 year period, which includes
costs for plant shutdown, new design,
and annual maintenance (U.S. Con-
gress, Office of Technology Assessment
1~~3). Some power plants have
expended costs of $250,000 per year