MICHIGAN Trout
Be on the Lookout for Invasive European Frog-Bit
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by Paige Filice and Erick Elgin, Michigan State University Extension
Spring 2021
Urgent action is needed to stop the spread of invasive European frog-bit in Michigan. The most effective way to prevent its spread is to clean, drain, and dry all fishing gear, including waders and boating equipment. Frog-bit was recently discovered at multiple state lands, including Waterloo Recreation Area, Pentwater State Game Area, Dansville State Game Area, and the lower Grand River. The swift expansion of European frog-bit from coastal marshes to inland water bodies is alarming. It can quickly form dense floating mats that reduce native plant diversity, cause oxygen depletion in the fall, and is a nuisance for anglers, hunters, boaters, and swimmers. European frog-bit is a free-floating aquatic plant that thrives in slow-moving waters with little to no wave action and in wetland areas with vegetation like cattails and phragmites. It reproduces several ways, including via turions. Turions develop in the fall and sink to the bottom in the winter. In the spring, they rise to the surface to form a new plant. A single European frog-bit plant can produce 100–150 turions a year. First detected in Southeast Michigan in 1996, European frog-bit spread along the coastal areas of Lakes Erie and Huron up to the eastern Upper Peninsula by 2010. In 2016, it was first discovered inland at Reeds and Fisk Lakes in Grand Rapids. Since then it has been found in Oceana, Ottawa, Kent, Ingham, Jackson, Washtenaw, and Oakland counties.
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White flowers with three petals and a yellow center
If European frog-bit is discovered in a waterbody, rapid response is key to its control and potential eradication. If you find European frog-bit, please contact the Michigan Department of Environment, Great Lakes, and Energy Aquatic Invasive Species Program at EGLE-WRDANC@michigan.gov or 517-284-5593. Or report it online at misin.msu.edu. Sightings reported online to the Midwest Invasive Species Information Network are shared with EGLE and the Michigan Department of Natural Resources. Both agencies, along with local conservation partners, will respond to sightings. Photo documentation is appreciated. The invasion of European frog-bit is in a critical stage since it is not widespread across Michigan. Currently, state agencies and conservation partners respond to sightings to contain, control, and eradicate it, if possible. However, if European frog-bit continues to spread into new water bodies, eradication efforts may become ineffective. Therefore, it is extremely important to clean, drain, and dry boats and gear thoroughly after each outing and report sightings.
Although occurrences of European frog-bit are increasing, there is still an opportunity to slow and prevent its spread. After fishing, always remove all plants and mud from your gear. Like many aquatic invasive plants, European frog-bit can spread from one location to another when the plants, plant fragments, winter buds, and seeds get inadvertently transported in watercraft and on gear such as waders. While much of the plant has died back by fall, seeds and winter buds accumulate in mud and can be easily transported to new waterbodies. To identify European frog-bit, look for: •
Round/heart-shaped leaves that resemble small water lilies (0.5 – 2.25 inches)
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Free-floating heart-shaped leaves with roots hanging below that resemble small waterlilies
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Leaves with a dark purple underside and a spongy accumulate in areas with other vegetation such as cattails and area around the center of the leaf
European frog-bit thrives in slow-moving waters and tends to phragmites.
Photo credit: Todd Marsee
Michigan Trout Unlimited
