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Aquatic Invasive Plant Species in Southeast Wisconsin

Water is the mainstay of life in Wisconsin. Land, history, culture, population, ecosystems, tourism, and economy are primarily based on water resources. The state of Wisconsin is very rich in terms of aquatic resources with 15,000 lakes; nearly 45,000 miles of water streams; 5.3 million acres of wetlands; and 1.2 quadrillion gallons of groundwater. These abundant aquatic resources provide sustainability to the multi-billion dollar tourism and hospitality industry of the state. However, the state’s aquatic treasures are having harmful invaders in the form of Aquatic Invasive Plant Species. 

What are Aquatic Invasive Plant Species?

Project REDInvasive Species are animals and plants that are introduced to a new environment in which they become non-native and negatively effect environmental, economic and social factors. Aquatic Invasive Species (AIS) are harmful and destructive non-native plants growing within or near waters affecting native plants and ecosystems, and have even been know to harm our own health. These AIS may potentially be the greatest threat to the overall health of Wisconsin’s natural landscapes, such as wetlands and riverine systems. When this happens, the diversity of plant species is lowered, thus impairing the natural functions of wetland systems. If not detected and controlled at an early stage, AIS populations can grow out of proportion and create long-term, costly projects.

How do these species get to non-native places?

Invasive species are notoriously known for traveling around the globe, which in part is due to poor management practices and global trade. Most AIS stow away in ship ballasts. Approximately, 45,000 cargo ships transport over 10 billion tons of ballast water around the globe per year. To balance out cargo weight, ships and large boats have water tanks in their hulls which are filled with water. These ships draw in water at their cargo loading ports and when ships arrive at their destination ports, they release water from their ballasts. There are plenty of opportunities for hitchhiking plant species in this ballast water to invade to territories. AIS can also attach to the outside of ship hulls and on millions of tons of waste that freely floats around the world in rivers and seas.

Climate change is also having an impact on spread of AIS, as warmer conditions can alter habitats and soil conditions. When this happens, invaders found further to the south, such as Kudzu (Pueraria montana), will start to follow these ever warming climatic conditions to the north, establishing new populations of invasive species in new ecosystems. 

The remaining culprit for spreading AIS is human activity. Human activities such as urban development, farming, recreation and gardening have resulted in the introduction of many invasive plant and animal species to Wisconsin. For example, equipment used near an infested area has great potential to accumulate seed onto tires when driving over soil. If not cleaned thoroughly, any remaining seed will be dispersed in transit or at the next site where the equipment is used. AIS seed can also be introduced when fill is brought in for landscaping and restoration. For more information on Best Management Practices to reduce the spread of invasive species, visit:

How do these species grow so fast?

AIS have the capability to flourish and multiply belligerently outside their natural habitats, creating an ecologically disadvantage for native plant species.  AIS that take possession of a new place may gain this ecological advantage because their native competitors (i.e. disease, bacteria, and insects) that naturally keep their growth in control are not present. Moreover, natural predators mentioned above will naturally attack and consume native plant species. This creates a situation where not only do AIS have little to no predation, but also lack competition from native plant species that become crowded out.

Joe phragmitesMost AIS have variable characteristics, including different growth rates and effects on ecosystems. There are some aquatic plant species that do not progress to the stage of being invasive for a long time, because different aquatic plant species are not equally invasive in nature. The more a species is invasive in nature, the more urgent attention it requires to be monitored and controlled.

There is also a human factor in the spread of invasive plants.  Unfortunately, a number of invasive plant species are continuing to be accepted and liked for their aesthetics by gardeners irrespective of their harmful nature. Some property owners are responsible in the sense that they are not doing enough to remove AIS from their lands. In addition, road crews unintentionally spread invasive plants when they mow roadsides.  If the plant is mowed at the wrong time of the year, seeds dispersal can actually be increased, therefore worsening the situation.     

Why are native aquatic plant species beneficial for Wildlife?

Native aquatic plants provide natural shelter, forage and refuge to fish, birds, and other native flora and fauna. In addition, native plant species preserve beaches and shorelines from eroding and washing away and keep water pollution in check. Local and native plants have formed symbiotic relationships with landscapes throughout the years, and need to be managed accordingly to enhance the beneficial function of Wisconsin’s natural ecosystems.

On the other hand, AIS in ecosystems such as wetlands can actually change the chemistry of the soil, which alters native flora that would have otherwise served local wildlife species. AIS such as japanese knotweed has been found to completely take over riparian habitat, degrading river frontage and collapsing valuable habitat and cover for fish and threatened wildlife species.

Harmful Impacts of Aquatic Invasive Plant Species

1. Ecological impacts

AIS have the capability to modify and damage ecological systems and wildlife that lives in them. For example, an AIS called Eurasian Watermilfoil forms dense mats over the surface of the water which crowds out native aquatic plant species and lowers oxygen levels due to the decreased air/water exchange. When this happens, additional native aquatic plants struggle to grow while fish species suffer from the degraded water body conditions. This plant has also found to create exceptional habitat for mosquitoes when mats turn stagnant. 

2. Economic impacts

On an average, AIS cost the economy of United States 120-140 billion dollars in damages per annum, and the costs of monitoring and controlling invasive plant species are extremely high. Individual lake organizations have to spend hundreds of thousands of dollars per year to just keep in check – not eliminate or reverse – the spread of these species. These costs are increasing every year because new invaders are being detected and more AIS are intruding new landscapes.

Additionally, the proliferation of AIS impairs the entire water experience and recreational activities around them. AIS can reduce local, state and national governments income by interfering with recreational activities, such as fishing, boating and swimming. AIS also invade and degrade homeowner lots, therefore lowering property values. For example, phragmites can encroach into properties and block the view of lakes.

3. Human Health Impacts

Joe PospichalSome AIS may create significant health hazards and diseases. For example, very harmful human cholera bacteria strains are found in plant species carried in ballast water during laboratory tests. Invasive species such as japanese barbarry have found to host high populations of ticks, acting as a host and potential vector when humans hike or work near the barbarry plants.

AIS also have the ability to alter soil nutrient dynamics by differing from native plants in overall biomass and productivity, phenology, structure and tissue chemistry; these differences have great potential to degrade the soil that serves such important roles in the function of natural ecosystems.

The harmful effects of AIS expand beyond the direct effects of viruses, bacteria, and parasites as chemicals are often used to control these plant species, which can potentially pollute soil and water which humans come in contact with on regular basis. Unfortunately, chemical control is sometimes the only way to effectively control some species. 

AIS such as japanese knotweed and phragmites host an underground, hardy network of roots called rhizomes. These rhizomes can dominant stream banks and leave soil susceptible to erosion when the above ground biomass dies. The riparian corridor is then susceptible to increased sedimentation into our streams and rivers. The hydrologic regime of our wetlands can even be altered, as AIS such as phragmites is found to increase evaporation rates and trap more sediment.

So what can be done?

In order to successfully control invasive species, an integrated network of education, long-term commitment and prevention are essential in making any progress. Understanding the general ecology of these pest species allows for one to understand why it is important for proper management and control, and can help in creating a sense of pride when taking part of invasive species projects. Through educational workshops, collaborations with dedicated organizations and a willingness to promote educational material, we can protect our natural areas and make progress on a large scale.

The most economically viable approach to treating invasive species is to prevent them from establishing populations in the first place; in other words, keep the natural places natural. This can be reached by knowing your invasive species, the effects they can have and monitoring and reporting infestations to agencies such as the Wisconsin Department of Natural Resources. Once these invasive species are better understood and identified, poor practices such as improper mowing and gardening can be addressed.

purple loosestrife beetle digging-aprilInfestations that are young and small in size are known as “Pioneer Colonies”, and require less amounts of management, such as labor, equipment and monitoring. If our natural places are introduced to invasive species, however, focusing on reporting and treating these pioneer colonies before they become an overwhelming problem will be ideal.

Once a brief background is understood on invasive species, obtaining and reading BMP’s to understand what and what not to do is a great place to start if one would like take their own management path. Sharing this knowledge with local communities and residents is essential, as successful management practices will not be as effective unless it’s from a “ground-up” type approach. Land managers, volunteers or interested public citizens should follow treatment guidelines laid forth by the U.S. Department of Agriculture, Trade and Consumer Protection.

What Aquatic Invasive Plant Species are found in Southeast Wisconsin?

Scientists and researchers have compiled a list of thousands of AIS, most of which are found in United States. A list of the more commonly invasive species found in Southeast Wisconsin, as well as the rest of the state can be found by visiting our partners websites below. These sources will also cover information on the general ecology of each species, management approaches, treatment and control methods and how to report infestations.

  1.  Southeast Wisconsin Invasive Plant Consortium, Inc. (SEWISC)
  2.  Invasive Plants Association of Wisconsin
  3.  Wisconsin Department of Natural Resources
  4.  Great Lakes Phragmites Collaborative

Great Lakes Restoration Initiative 

The Ozaukee Washington Land Trust, Inc. (OWLT) received a major grant from the Environmental Protection Agency to control and eradicate aquatic invasive species in southeastern Wisconsin.

Last year of 2013, OWLT and our partners treated and protected 500 acres of wetland and riparian ecosystems. Planned for this coming 2014 field season, thanks to over 30 involved partnering organizations, OWLT plans to treat and protect over 1,000 acres of wetland and riparian ecosystems in southeastern Wisconsin. 

OWLT Can Help You Remove Aquatic Invasive Species

OWLT is looking for partners who have aquatic invasive plants that need to be controlled. We can help with funding, equipment, training and assistance. We just need to hear from you!

The Partners in Preservation for Aquatic Invasive Species Removal project is funded through the Great Lakes Restoration Initiative. The project focuses on removing targeted noxious and invasive weed species within a six County area abutting Lake Michigan that includes, Ozaukee, Washington, Sheboygan, Milwaukee, Racine and Kenosha Counties.

Target plant species include, but are not limited to, Japanese Knotweed, Lyme Grass, Phragmites, and Purple Loosestrife. The Ozaukee Washington Land Trust will lead this project with help from partner organizations and volunteers. The goal of the project is to organize effective and efficient processes, procedures and groups of people that will endure beyond the project’s scheduled completion date and encourage invasive plant control well into the future.

japanese knotweed-3-lg thumblyme grass-thumbpurple loosestrife thumbreedgrass common thumb

The goals of the project include:

  • Treat and protect 1500 acres
  • Create a data base inventory of sites
  • Follow-up monitoring of treated sites
  • Provide on-going education

The Partners in Preservation for Invasive Species Control is offering funding, equipment, training and assistance to local government units, non-government organizations, non-profit organizations and other environmental groups through a competitive application process.

To learn more or obtain an application form:

        Ozaukee Washington Land Trust: 262-338-1794
        Cody MacDonald:  

  pdf Download an application form here (112 KB) .

  pdf Download an information flyer here (162 KB) .