The Zebra Mussel
Where did the zebra
mussel come from?
Zebra mussels (Dreissona polymorpha) are small mollusks approximately one inch in size and native to the Caspian Sea. They were first discovered in the U.S. in Lake St. Clair, between Lakes Huron and Erie. It is thought that they were introduced from the ballast of water of an oceangoing ship. Today they are likewise believed to travel on the hulls of unsuspecting fishing and recreational boats.
In Lake Erie the density level of zebra mussels can be 560 or more per square foot. At this population density, zebra mussels can clog water pipes, underwater machinery, and even boat motors.
mussels disrupt the aquatic food chain by removing most phytoplankton
(tiny, free-floating plants) and zooplankton (plankton composed of animals)
from water. This causes a dangerous disruption in the aquatic food chain.
Their dense population often overtakes native mussels and other species.
Native clams have disappeared from Western Lake Erie due to these mussels.
Due to their filtering efficiency, zebra mussels can have high concentrations
of toxins, which can pass to many waterfowl that feed on them.
zebra mussels were found in Edinboro Lake, the first inland lake in
northwestern PA to be inhabited by these organisms. Because Edinboro
Lake is a much smaller than Lake Erie, the effects of zebra mussel are
expected to be profound. The current plan is to try to contain the mussels
in Edinboro Lake. If they are not contained, then they may pass into
Conneautee Creek, then French Creek and then into the Allegheny, Ohio
and Mississippi Rivers to further their damage to Pennsylvania's waterways
and aquatic industry and recreation.
is considerable concern over zebra mussel contamination in French Creek
because it represents one of the last refuges for many rare and endangered
species. The Western Pennsylvania Conservancy lists the stream as having
global significance in its near-intact pre-Colonization stream ecosystem.
Almost thirty species of mussels inhabit French Creek and two, the Northern
Riffleshell and the Clubshell mussel, are endangered species
and visitors of Pennsylvania can help prevent the spread of this invasive
species by taking extreme care when transporting boats from one lake
to another inland lake. For a complete list of tips and precautions
and more information on zebra mussels, please visit http://www.great-lakes.net/envt/flora-fauna/invasive/zebra.html.