Risk assessment, control, and restoration research on aquatic invasive plant species

Project manager: Dan Larkin

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

Description: Aquatic invasive plants are a major threat to Minnesota’s lakes, rivers, and wetlands. Aquatic invasive plants can form dense mats on the water’s surface, reducing space and light available to other plant species. This can lower native plant diversity, reduce habitat quality for fish and other animals, and change the way lakes function. They can also interfere with boating, recreation, and other human uses.

Using applied research on three high-priority aquatic plant species that are invasive or potentially invasive in Minnesota lakes, this research aims to address the need for more guidance and options for controlling these nuisance plants. Species of research include:

  • Nitellopsis obtusa (Starry stonewort), a new invasive alga in Minnesota. Researchers will assess the risk of spread through modeling and will also test how long starry stonewort can remain viable out of water to better understand how best to prevent its spread. Additionally, researchers will conduct laboratory experiments to test the efficacy and selectivity of different herbicides and algaecides. This information is urgently needed during this window of opportunity to minimize impacts of starry stonewort to Minnesota lakes.

  • Myriophyllum spicatum (Eurasian watermilfoil) and Potamogeton crispus (curly-leaf pondweed), both of which have been in Minnesota for several decades and are now found in hundreds of lakes throughout the state. Although both of these species have been a focus of management and research for several years, there are still limits in our ability to effectively control these species and to support the post-control recovery of native plant species. Researchers will analyze existing datasets, perform new field work, and develop a citizen-science monitoring program to improve understanding of factors that drive invasion of these species and that influence the effectiveness of management efforts.

Collectively, this research will aim to create biologically and economically sound solutions to prevent and control these invasive plants and to disseminate scientific information that assists the DNR, watershed districts, lake associations, and citizen groups around the state with management strategies.

Project start date: 2015

Estimated project end date: 2019

Progress:

As of July 2018, laboratory experiments to test the effectiveness of different algaecides/herbicides on starry stonewort have been initiated. Field sampling is ongoing to evaluate outcomes of starry stonewort control efforts in lakes. Data from statewide treatments of Eurasian watermilfoil and curly-leaf pondweed have been acquired and are currently being synthesized. For both species, researchers have also initiated in-lake removal experiments to determine whether effective control of these AIS is sufficient to support recovery of native aquatic plant communities or whether additional management strategies (e.g., water quality improvement, native plant seed addition) are needed to restore native aquatic vegetation. 

Ecological niche modeling has been completed for starry stonewort, using occurrence data from 8 countries, 19 climate variables, and remotely sensed environmental data to characterize the environmental niches occupied by starry stonewort in its native and invaded ranges. Initial findings indicate that starry stonewort has expanded into regions of the U.S. with climate conditions distinct from those found in its native range. Roughly one-third of Minnesota appears to constitute suitable habitat for starry stonewort, as do large portions of the Intermountain West, Great Plains, and Mid-Atlantic — areas with no known occurrences to date. Next, researchers will scale down risk assessment to individual lakes within Minnesota. Lakes identified as high-risk will be recommended for targeted surveillance by the AIS Detectors program.

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