By Emma Costantino
North Country Cooperative Invasive Species Management Area
Aquatic invasive plants are already a problem for many lakes in Michigan as they can cause numerous issues for lakes and are difficult to remove. Now, there is another aquatic invasive plant to watch out for: European frog-bit.
European frog-bit is a small, free-floating aquatic plant. It has tiny leaves, about the size of a half dollar, with reddish-purple undersides. In the summer it produces flowers with three white petals and a yellow center. European frog-bit can sometimes be confused for American waterlilies, which are native to Michigan. While both plants float on the surface of the water, waterlily leaves are much larger and have pointed lobes, while frog-bit’s leaves have rounded lobes.
Frog-bit is often found in areas with slow moving water, such as marshy shorelines, protected coves, and bayous. So far, its spread in Michigan has been limited, but it could pose a serious threat if it becomes established in the state. The problem with European frog-bit is that it spreads quickly and forms dense mats on the surface of the water. These dense mats disrupt fish and wildlife habitat, and make it difficult to recreate in the water. Once European frog-bit becomes established in a lake, there is no known way of eradicating it.
In 2021, European frog-bit was first detected in Mason County. This is the first and only known occurrence of frog-bit in the North Country Cooperative Invasive Species Management Area’s (NCCISMA) coverage area. Since early detection of the plant is key to stopping its spread, NCCISMA has been surveying local lakes for European frog-bit. Several of these lakes are in the Muskegon River Watershed including Haymarsh Lakes, Martiny Lakes, and Dead Stream Flooding. Luckily no European frog-bit has been detected so far! These surveys are funded by the Department of Environment, Great Lakes, and Energy (EGLE), made possible through a Great Lakes Restoration Initiative (GLRI) grant through the US Environmental Protection Agency (EPA).
Boaters can unintentionally spread European frog-bit to new water bodies by helping the plant move between lakes. This happens when frog-bit or its seeds get stuck to a boat, trailer, or other equipment and are transported to a new lake. These plant parts can then start a new population. To prevent frog-bit and other invasive plants from spreading, boaters should clean, drain, and dry their boats, trailers, and other equipment after every trip, even if they plan to go back into the same lake again.
NCCISMA is currently creating an educational video about European frog-bit and how to prevent it from spreading. Be sure to subscribe to NCCISMA’s YouTube channel, if you have not already, so you don’t miss when it is published, together we can help prevent the spread of this highly invasive plant. This project was funded by the Michigan Invasive Species Grant Program (www.Michigan.gov/Invasives).
For more information about NCCISMA, visit www.NorthCountryInvasives.org. To learn more about this grant and the other work NCCISMA does in the region, contact the Program Coordinator by calling 231-429-5072, or email vicki.sawicki@macd.org.
Close up of European frog-bit
Dense mat of European frog-bit. Photo Credit: Huron Pines
European frog-bit with pencil for scale