Enhancing habitat and diversity in cattail-dominated shorelines

Project background

Invasive hybrid and narrowleaf cattails (hereafter cattails) are expanding along Minnesota lakeshores, creating dense stands that crowd out native plants. This study aimed to understand if mechanically cutting and clearing cattails can restore healthy nearshore lake zones. The research team compared three types of nearshore sites across six Minnesota lakes: 

  1. Cattails left alone (cattail retained)

  2. Cattails mechanically removed below the water (cattail removed)

  3. Nearshore zones without cattails (uninvaded)

At each site, and throughout the project, the researchers measured plant diversity, water temperature, oxygen levels and local fish populations. 

Research findings

MAISRC researchers demonstrated that cattail-infested shorelines had warmer water, lower oxygen levels, fewer fish, and less diverse fish communities than healthy, uninvaded areas. Removing cattails improved conditions by increasing oxygen and allowing native plants (especially submerged and floating-leaf) to return. Fish also showed signs of returning after removal, although native tall emergent plants did not immediately recover.

To put these findings into action, the research team created the Minnesota Cattail Collaborative. Through the Collaborative, researchers are partnering with watershed managers, lake associations, tribal organizations, and others to put standardized removal methods into practice to empower communities to restore Minnesota’s nearshore lake zones. 

Phases

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Phases

Phase I

Project manager: Amy Schrank, Extension Program Leader; Assistant Professor, Fisheries and Aquaculture Extension Educator, Minnesota Sea Grant

Project title: Enhancing Habitat and Diversity in Cattail-Dominated Shorelines

Project team: 

  • Daniel Larkin, project co-manager, assistant professor, Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota.
  • Brendan Nee, project team member, master's student, Department of Fisheries, Wildlife, and Conservation Biology, Diversity Scholar and Dobie Fellow, University of Minnesota.
  • Michael Tuma, project team member, master's student, Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota.
  • Kailyn Schmitt, project team member, undergraduate student, Swenson College of Science and Engineering, University of Minnesota Duluth.
  • Dylan Dahn, project team member, undergraduate student, Swenson College of Science and Engineering, University of Minnesota Duluth.


Funded by: MAISRC and Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources.

Project timeline: 2021-2023

Research findings:

Removing cattails led to increased dissolved oxygen levels and a resurgence of native plants in the nearshore zones. Fish communities also changed, with some removal sites showing higher fish abundance and an increase in minnow species. These results indicate that mechanical cattail removal can help restore nearshore lake ecosystems with minimal negative impacts on other species. By allowing more dissolved oxygen into the nearshore zones and creating space for native plants to regrow, cattail removal enhances high-quality fish habitat. 

The findings from this study can directly inform Minnesota Department of Natural Resources (MNDNR) policies and management strategies regarding cattail removal for lake restoration efforts across the state.

Media

Research topic
Plants
Narrowleaf cattail
Hybrid cattail