Thursday, October 22, 2009

Effects of Invasive Species (Zebra mussels) on the Muskegon River

By Brent Vanderstelt

There are 185 invasive species in the Great Lakes, one-third of which were imported in the ballast water of transoceanic freighters, according to government data.

Zebra mussels discovered in the Great Lakes in 1988 have spread to thousands of lakes and rivers across the United States. A related mollusk, the quagga mussel, spread from the Great Lakes to the West Coast on boat hulls and trailers.

Zebra mussels upset ecosystems, threaten native wildlife, damage structures, and cause other serious problems. Millions of dollars are spent each year in attempting to control these small but numerous mollusks.
The Muskegon River below Croton Dam was colonized by zebra mussels in 2000 following their introduction into Croton impoundment in the late 1990's.

There are 93 dams and lake level control structures in the Muskegon River and its tributaries. Four of those dams, including the Croton, Hardy and Rogers hydroelectric facilities, are in the river's main branch.

The reservoirs behind Croton and Hardy dams are popular among boaters and anglers. A spokesman for Consumers Energy, which owns the hydroelectric dams on the Muskegon River, said the dams also prevent some Great Lakes invasive species, such as sea lamprey, from colonizing the entire river.

Researchers said boats used on dam impoundments, and then trailered to natural lakes, are one of the most common ways for zebra mussels and other invaders to spread from reservoirs to lakes.

Scientists have long known that dams disrupt river ecosystems by blocking fish passage, disrupting the natural movement of sediment and causing abnormal fluctuations in water temperatures and in oxygen concentrations downstream of the structures.

Zebra mussels are filter feeders. An adult zebra mussel filters up to a quart of water per day, which multiplied by millions of mussels means that the mussels may be filtering all the water in a lake or stream in a day. The animals and algae that are the food of zebra mussels are also the food for larval fish and other native species, so a large zebra mussel population may cause a decline in other animals, including native fish, mollusks, and birds. The filter-feeding activity of zebra mussels causes a related and frequently dramatic increase in water clarity in infested lakes and rivers.

As Americans, we love to spend time on the water. Protecting these resources is an important part of our overall enjoyment. A concern we must all address is the spreading of harmful plants, animals and other organisms. These aquatic nuisance species can hitch a ride on our clothing, boats, and items used in the water. When we go to another lake or stream, the nuisance species can be released. And, if the conditions are right, these introduced species can become established and create drastic results.

So what can we do? By following a simple procedure each time we leave the water, we can stop aquatic hitchhikers. Knowing which waters contain nuisance hitchhikers is not as important ---- as doing the procedure every time we leave any lake, stream or coastal area. (Click on the links for details on what to do.)

Simple Procedure


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