This project aims to quantify and clarify whether or not hybrid/narrowleaf cattail removal can increase plant diversity and benefit fish communities in nearshore lake ecosystems and how these effects vary regionally in Minnesota.
To accomplish this, researchers will experimentally remove sections of cattail in up to 24 lakes across Minnesota’s major ecoregions and measure environmental, vegetation, and fish responses. In Minnesota, hybrid/narrowleaf cattail (hereafter cattail) have expanded in nearshore lake communities, altering environmental conditions and displacing other plant species. Cattail acts as an “ecosystem engineer” by replacing diverse wetland and aquatic plant communities with a more homogenous environment dominated by tall, dense, difficult-to-penetrate cattail and its litter (dead cattail). As plant diversity is reduced, research suggests that fish diversity may decline, though it is unknown if this occurs in cattail dominated, nearshore lake ecosystems in Minnesota. Despite the negative impacts of dense cattail in many habitats, in some Minnesota lakes (e.g. shallow southern lakes where other species struggle to survive), cattails play crucial roles by providing vegetated habitat and preventing erosion. Thus, the extent to which cattails are detrimental or beneficial to nearshore habitats is likely to vary across the state.
Nearshore aquatic plants are an important source of biodiversity in Minnesota lakes and are critical to fish communities, including important game species (walleye, bass, pike, sunfish, etc.) and forage fishes (minnows, darters, etc.). Fishes using nearshore, vegetated habitat usually prefer a combination of emergent, floating-leaved, and submerged plants for spawning, rearing, refuge, and feeding habitat. In Minnesota, hybrid/narrowleaf cattail (hereafter cattail) have expanded in nearshore lake communities, altering environmental conditions and displacing other plant species.
Progress
The team completed post-cattail removal sampling of water quality, plants, and fish at their nine study lakes in August 2022. With both pre- and post-removal sampling complete, they are now analyzing data and writing their report.
Over the past six months, the team disseminated information about their project by distributing an informational postcard at boat launches and lake association meetings. They also delivered five presentations and workshops on cattails and their project progress, including:
- A virtual presentation to Minnesota DNR invasive species, aquatic plant management, and shallow lakes staff
- An in-person presentation to the Rainy Lake Property Owners Association
- A virtual presentation at the MAISRC showcase
- Two field events for lake property owners and the public at Long Lake in Becker County and Big Marine Lake in Washington County
Additionally, the team produced and disseminated a video about their project through the MAISRC YouTube channel.
Phase I
Researchers quantified and clarified whether or not hybrid/narrowleaf cattail removal increased plant diversity and benefited fish communities in nearshore lake ecosystems and how these effects varied regionally in Minnesota. To accomplish this, they experimentally removed sections of cattail in up to 24 lakes across Minnesota’s major ecoregions and measured environmental, vegetation, and fish responses.
Objectives:
- Understand the little known effects of hybrid/narrowleaf cattail on the ecological dynamics of nearshore lake communities across Minnesota.
- Determine if small-scale cattail removal can increase plant diversity and heterogeneity and positively affect fish abundance and diversity.
- Compare the regional effects of cattail removal on nearshore lake ecosystems.