Zebra Mussel Infestation Wisconsin

Zebra Mussels In The Great Lakes

Zebra mussels (Dreissena polymorpha) are native to the Caspian Sea region of Asia.  These small, fingernail sized invertebrates are considered one of the most damaging invasive species to make their way into US waterways.   They were introduced to the Great Lakes through ballast water from transoceanic  ships.    Since their introduction in the early 1980’s, they quickly spread throughout the Great Lakes and into many of the inland waterways in the Great Lakes states, and into Ontario and Quebec.  They continue their spread into the western and southeastern portions of the United States.  One of the zebra mussels defining characteristics is their ability to colonize on hard surfaces, such as rocks, dams, and water intake structures, in very high densities; as many as tens of thousands per square yard of water.

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Zebra Mussel Impact

Zebra mussels have negative effects on local ecosystems.    They reduce the number of phytoplankton available for other organisms, and the resulting increase in water clarity causes changes to the ecological structure of the lake or water way.  This can promote the growth of other organic invasive species, such as Asian Milfoil, as well as eliminate food sources for desirable native species and game fish.  In addition, zebra mussels can accumulate contaminant levels in their tissues far greater than the surrounding  waters, increasing the exposure of those contaminants to other organisms.   Zebra and Quagga mussels destroy native mussel and shellfish populations by attaching to them, and in effect, smothering them.

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Zebra Mussel Effects of Invasion & Zebra Mussel Control

Besides promoting the growth of non-native vegetation in the water, and eliminating food sources for desirable species, Zebra mussels  cause a great deal of economic damage to water treatment and power plants by clogging intake pipes, as well as fouling the cooling systems of boat engines.  Unfortunately, solutions to controlling the Zebra Mussel population are few and not yet effective, which results in continued high costs for cleaning and control of shell debris.

A more recent invasive species is the Quaaga Mussel (Dreissena Rostriformis bugensis), which was first identified in Lake Erie in 1989.  This larger mollusk has the ability to colonize soft substrates as well as hard substrates, which has a greater potential to harm native species.

Zebra Mussel control has been a daunting problem and task for governmental agencies.  The species reproduces rapidly and as it can attach to water vessels as well as wildlife such as birds, the shells have made their way into inland waters outside of the Great Lakes region and pose a constant problem in controlling the spread of the species.  Legislation has gone into effect that requires all boaters to be sure to thoroughly clean their boats to prevent the potential spread of the invasion.  Despite these efforts, zebra mussel control has been difficult to say the least and for now, those affected will have to do what they can to clean up and remove the shells as they come ashore.

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