Effects+of+Zebra+Mussels+on+Lake+Erie

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ECOLOGICAL IMPACTS ** : Zebra mussels have had a dramatic impact on the food web of Lake Erie. As seen on the food web, zebra mussels feed on massive amounts of plankton. Their primary energy source comes from diatoms, green algae, blue-green algae, and miscellaneous flagellates. Plankton is also the major food source for native mollusks, water fleas, gammarus, and mayfly nymphs. The greater effect on Lake Erie, Presque Isle in particular, being a huge sport fishing area, may come from the lack of these organisms for our sport fish. Perch, walleye, trout, and bass are all suffering due to the lack of food. The only aquatic predators of the zebra mussel in Lake Erie are the round goby (invasive species), sunfish, yellow perch, and catfish, which are solely bottom feeders. (5) These fish cannot keep up with the speed at which the mussel reproduces.

FOOD WEB OF LAKE ERIE: []

These filter feeders can clean up to 1 L of water per day, which is significantly higher than Lake Erie's native mollusks filter. The more water that is filtered the clearer Lake Erie has become. It has gone from clarity depths of 3ft in the 1970's to 6-10ft in the late 1980's to 17ft in the 1990's. The idea of eutrophication is now dead in Lake Erie. The greater the visibility the more light can penetrate the lake. The more light means higher temperatures and then deeper thermoclines. The greater the light penetration the more rooted vegetation is starting to grow. This could eventually lead to some of the ponds to start filling in. BIOLOGICAL IMPACTS ** : An important difference between zebra mussels and native mussels is the process of bio-fouling. Adult mussels attach to hard surfaces using sticky threads called byssal threads. Bio-fouling is when zebra mussels attach to the surface of other mussels. The native mussels are then smothered and will eventually die due to the added stress. (5) There is also a human factor that may have us worried. Zebra mussels are filter feeders and in filtering they accumulate organic pollutants in their tissues. (PCB's and PAH's) They collect these pollutants at a rate of 300,000 times the normal amount. Fish and birds are then exposed to these pollutants as well other organisms in the lake that come into contact with their feces. As the food chain continues we may eventually become exposed. ECONOMIC IMPACTS ** : Zebra mussels attach to hard surfaces and because of this have caused tremendous trouble to local industry. They have clogged water intake valves at power plants and wastewater treatment plants, water supply plants, and industrial facilities. They have also had an effect on the tourist industry of Presque Isle State Park. The mussels attach to boats increasing the drag and making their engines work harder. Attaching to their engine cooling systems has also caused some boat engines to overheat. Lastly, the sharp shells have washed up on beaches and caused a problem for people trying to swim there or just take a leisurely walk. The cost of dealing with zebra mussels varies depending on the type of facility, how long and the severity of the infestation, and the actual control method that is selected. (5) The amount of money spent on trying to prevent or stop these zebra mussels as well as cleaning up after their damage is in the millions. "Controlling zebra mussels has cost more than $1 billion since they were first discovered in the Great Lakes in 1988," said DEP Secretary John Hanger. "It will require constant vigilance by fishermen, boaters and others who use our waterways to keep these invasive creatures out of the Susquehanna River and its tributaries." (garry lenton) The U.S .Fish and Wildlife Service estimates the potential economic impact at $5 billion from 2000 to 2010 to U.S. and Canadian water users within the Great Lakes region alone. The United States and Canada may lose 140 billion in economic productivity just this year. (1)

VIDEO CLIP: [|Positive and negative effects of the zebra mussel on Lake Erie]