Zebra mussels found in a Tioga lake
First time invasive species found in Susquehanna
Harrisburg – Officials from the state Department of
Environ-mental Protection, Fish & Boat Commission and
Pennsylvania Sea Grant in early July confirmed the discovery of
zebra mussels in Cowanesque Lake, Tioga County.
This marks the first time zebra mussels have been discovered in
a Pennsylvania waterway in the Susquehanna River watershed.
Invasive species such as zebra mussels pose serious threats
because of their potential to foul industrial facilities and plug
public water supply intakes that draw from infested waters. Zebra
mussels also can interfere with the operation of locks and dams on
rivers, or damage boat hulls and engines.
Zebra mussels threaten aquatic ecosystems because of their
ability to filter about a quart of water per day. While water
clarity is improved during this process, the zebra mussels disrupt
the food chain by removing plankton, which supports the existence
of native mussels and fish.
“Public education is key to preventing the spread of
zebra mussel infestations, as well as for protecting the many
unspoiled Pennsylvania waterways we all enjoy,” said Department of
Environmental Protection Deputy Secretary for Water Management
Cathy Curran Myers.
The Pennsylvania Zebra Mussel Monitoring Network first
discovered the mussels in Cowanesque Reservoir on May 17 as part of
a routine monitoring visit. Verification analyses were conducted by
DEP and Pennsylvania Sea Grant to confirm the species of
Since the discovery, Pennsylvania Sea Grant has worked with the
U.S. Army Corps of Engineers to alert visitors and assess the
degree of the mussels presence in the lake.
Zebra mussels are prolific breeders and, since they are not a
native species, have no natural predators, making control and
clean-up methods difficult, very expensive and generally
unsuccessful. The best control is to limit the spread of zebra
mussels by cleaning boats and equipment before and after use.
“The introduction of invasive species like zebra
mussels can have a substantial and lasting impact on the balance of
aquatic life in a waterway,” said Doug Austen, executive director
of the Fish & Boat Commission. “Anglers and boaters
should exercise great care when moving from one waterway to another
so that they don’t inadvertently move an aquatic nuisance species
Adult zebra mussels can be found in other Pennsylvania waters,
including Lake Erie, the Ohio River and lower portions of the
Allegheny and Monongahela rivers. The mussels also have been
reported in Edinboro and Sandy lakes in northwestern Pennsylvania,
as well as upper French Creek in Crawford County.
The zebra mussel is native to the Black and Caspian seas region
of Eastern Europe. They were introduced to this country around 1986
when ocean-going ships released infested ballast water into the
lower Great Lakes.