Invasive Species



What is an Invasive Species?

Humans move organisms around all the time. Sometimes when a non-native species is brought into a new area, it may spread rapidly and widely throughout the area and cause major harm to the native ecosystem and humans. When non-native plants, animals, or pathogens quickly take over a new location and alter the ecosystem, they are considered to be invasive species.


How do they become a problem?

One of the reasons that invasive species are able to thrive in a new ecosystem is that they often do not have the predators and competitors they had in their native ecosystem. Without these natural checks and balances they are able to reproduce rapidly and out-compete native species.   The net result is a loss of diversity of native plants and animals as invasive species multiply and take over. 


Aquatic Invasive Species (AIS) in Dane County Waters

Photo courtesy of Jim Stewart

Aquatic invasive species (AIS) are a serious ecological and economic threat to Dane County waters.  Several AIS, such as Eurasian water-milfoil, curly-leaf pondweed, purple loosestrife, rusty crayfish, spiny water fleas, Cylindrospermopsis, and common carp, are already present in Dane County waters.  Other AIS, such as silver carp, hydrilla or quagga mussels, are already in Wisconsin or surrounding states and could invade Dane County waters in the future.

To combat the problems caused by existing AIS and potential future threats, the Dane County Office of Lakes and Watersheds developed an Aquatic Invasive Species Prevention and Control Plan (PDF) in June 2009. The plan includes all rivers, lakes and wetlands and guides the county’s work with stakeholder groups, surrounding counties and the state to prevent the introduction and transport of AIS into Dane County waters, and transport of AIS from Dane County to waters in other counties.

Learn about what Dane County is doing and what you can do to help prevent the spread of aquatic invasive species.


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