MHAS Partners with the University of Minnesota to Study the Effects of Invasive Cattails
This article was written by Sam Duerksen, Mississippi Headwaters Audubon Society member and Board Vice President.
A Gem in the North Woods
Spearhead Nature Preserve contains one of Minnesota’s blue jewels, Spearhead Lake. It is approximately 180 acres and 80 feet in the deepest part of the lake. It hosts a wide variety of fish species from crappies to tullibee, which is a form of lake herring. Many different aquatic and terrestrial species call the lake and its shores home.
Change on the Wind
In the 1980s, a new aquatic resident started to make Spearhead home…. Typha x glauca. This is the scientific name for a hybrid cattail that is a combination of the native broad leaf and the invasive European narrow leaf varieties. This plant thrives in perennially wet low areas and shallow lakes and streams and the shorelines of deeper lakes like Spearhead. The plant grows in dense stands, blocking out all other plant life by becoming a monoculture that supports little diversity in species composition and habitat within its grasp. By the late 1990s, Almost all the over 17,000 feet of shoreline had been engulfed in hybrid cattails. The result of this quiet invasion is shoreline and shallow water that is nearly inaccessible to many species that used to call it home. Shorebirds and waterfowl, including loons, cannot navigate the dense stands and are no longer able to use shallow water for feeding, loafing and nesting.
Study of Typha x to Include Spearhead Lake in 2026
Amy Schrank from the University of Minnesota Sea Grant and Daniel Larkin from the University of Minnesota have been conducting a research project funded by the Minnesota Aquatic Invasive Species Research Center and the Minnesota Environmental Trust Fund. The project started in 2021 on several lakes spread across Minnesota and is designed to monitor the effects of hybrid cattail removal on the aquatic ecosystem. Test plots are selected and the cattail is killed by cutting it below the waterline to essentially drown the stem. They measure key indicators to a healthy ecosystem like dissolved oxygen content, plant diversity and fish populations within the zone occupied by the invasive plant. They measure areas with cattail and areas where it has been removed prior to and post removal. Volunteers of MHAS will also be conducting some of the short-term and long-term sampling at the new Spearhead location.
The Potential for Reestablishment of Native Cattails
The results from other lakes indicate that native plants once overtaken by Typha x start to come back from seeds and rhizomes left in the muck from years before the cattail arrived. Results have also shown an increase in available dissolved oxygen and a wider diversity of fish species. Although more data is needed, the current results are very promising.
A Start to Something Bigger?
Currently, the project area will consist of 30 linear feet of shoreline extending out to open water based on requirements by the Minnesota Department of Natural Resources. The hope of MHAS is to increase the amount of treated shoreline over time to increase the benefit of plant and animal diversity around the lake. This partnership with the U of M and coordination with the MNDNR is an important first step in addressing the invasive cattail.
Volunteers are Key to Success and Longevity
Removal of the dead portion of cattail in the study area will occur in late February 2026 with the cutting of the live portion to occur in the fall. In the long term, the treated area will need regular maintenance to keep the invader out. Ultimately, we will have to strike a balance of managing Typha x as it is here to stay. This will be cared for by volunteers that are dedicated to learning, sharing and protecting this beautiful gem in the north woods.
If you would like more information on the research being conducted by the University of Minnesota, check out their YouTube channel: https://www.youtube.com/watch?v=R6o-YifMAJk
For more information on volunteering to help with this project or others, join our mailing list, here.
To contact be in touch sooner please email: outreach@spearheadmhas.org
