3/5/2007
Marina worker finds zebra mussels at Lake of the Ozarks
The discovery points up citizens' critical role in preventing the pest
from becoming established in Missouri.
CAMDENTON-Officials with the Missouri Department of Conservation have
confirmed another case of zebra mussel infestation at Lake of the Ozarks.
They credit citizens with finding the infestation and say pleasure boaters
and anglers will continue to play a key role in preventing further
outbreaks.
Fisheries Management Biologist Greg Stoner said a marina worker noticed
adult zebra mussels on a boat in the Osage Arm of the lake. He said the boat
was brought to the lake from out of state last September and has been in the
water ever since. It had approximately 40 adult zebra mussels attached to
its hull.
Stoner credited the marina worker for spotting the mussels in an
out-of-the-way location.
"The mussels were not attached to the hull, where they would have been
obvious to a casual observer," said Stoner. "All of them were either tucked
up into the nooks and crannies by the motor's lower unit housing or actually
inside the lower unit itself. This is very significant. Boat owners need to
know that inspecting the hulls of their boats for zebra mussels isn't
enough. Many boat hulls have anti-fouling coatings that prevent zebra
mussels from attaching. You have to look around motor housings and up in
recessed spaces, too."
Because the boat had been in the water for five months, Stoner said, it is
possible the mussels released eggs into Lake of the Ozarks. "The possibility
that there are larvae in the lake make it more important than ever for
boaters and anglers to be aware of the danger of spreading zebra mussels and
take preventive measures."
The zebra mussel (Dreissena polymorpha) is native to the Caspian Sea region.
Adults are dime- to quarter-sized. They attach to solid objects and gather
food by filtering tiny plants and animals from the surrounding water.
Females produce up to a million offspring a year. They can form dense
colonies several layers thick, encrusting objects with their shells.
In some waters, zebra mussels thrive and produce heavy infestations. They
can clog the water intakes of boat motors and power plants. They compete
with native animals for food, and they can smother native mussels, many of
which already are endangered.
The discovery at Lake of the Ozarks is just the latest step in the zebra
mussel's two-decade march across the nation's midsection. Zebra mussels are
believed to have entered North America in 1985 or 1986 when ocean-going
ships discharged ballast water laden with zebra mussel larvae into the St.
Lawrence Seaway. In 1988 they were found in Lake St. Clair. The next year
live zebra mussels were found in Lake Michigan, and in 1991 the first zebra
mussels turned up in the upper Mississippi River.
A year later they were in the Arkansas River between the Mississippi River
and Oklahoma, and the next year they had made it down the Mississippi as far
as southern Louisiana.
Missouri's zebra mussel saga began in 1999, with the discovery of a single
adult mussel attached to a native mussel shell in the Meramec River near the
I-55 Bridge. In 2000 a marina employee at Lake of the Ozarks spotted
thousands of zebra mussels on a 32-foot cabin cruiser brought to Missouri
from out of state. The worker's quick action in reporting his discovery
prevented the boat from being launched into the lake with a load of zebra
mussels.
In 2001, a small number of zebra mussel shells turned up in a filter screen
at a power plant on the Missouri River in the Kansas City area. No live
mussels were found, however. Zebra mussels were found in a Kansas lake in
2003 and in an Oklahoma lake in 2005.
The first report of zebra mussels in Lake of the Ozarks came last June when
a dock owner found the invasive mollusks on submerged objects beneath a
private boat dock. An inspection of nearby docks turned up approximately 50
of the mussels.
-Jim Low-
