Response of the invasive alga starry stonewort (Nitellopsis obtusa) to control efforts in a Minnesota lake

Wesley J. Glisson, Carli K. Wagner, Steven R. McComas, Kevin Farnum, Michael R. Verhoeven, Ranjan Muthukrishnan, Daniel J. Larkin

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Glisson WJ, Wagner CK, McComas SR, Farnum K, Verhoeven MR, Muthukrishnan R, Larkin DJ. 2018. Response of the invasive alga starry stonewort (Nitellopsis obtusa) to control efforts in a Minnesota lake. Lake Reserv Manage. 00:00–00. Starry stonewort (Nitellopsis obtusa), an invasive green macroalga in the family Characeae, has recently been found for the first time in several Midwestern states. This aquatic invasive species is of increasing concern to management agencies, lakeshore property owners, and other stakeholders. Starry stonewort has proven difficult to control, partly due to its ability to reproduce via bulbils (asexual reproductive structures). There has also been a lack of applied research addressing the efficacy of current management practices for controlling starry stonewort. We examined the effects of mechanical and algaecide treatments on starry stonewort biomass, bulbil density, and bulbil viability by monitoring treated areas and untreated reference locations concurrent with management implemented on Lake Koronis in Minnesota. Chelated copper algaecide applications alone and in combination with mechanical harvesting significantly reduced starry stonewort biomass, but algaecide treatment alone failed to reduce the capacity of starry stonewort to regenerate via bulbils. A second, granular algaecide application following an initial treatment with liquid algaecide did not further reduce biomass in any treated area and was associated with a substantial increase in bulbil density in an area treated with algaecide alone. Bulbil viability was greatest in the area treated only with algaecide (86%) and an untreated reference area (84%) and was lowest in an area treated with both mechanical harvest and algaecide (70%). The ability of starry stonewort to regenerate and persist following algaecide treatment is concerning. Multi-pronged management incorporating both chemical and mechanical approaches may improve outcomes of starry stonewort control efforts.

Original languageEnglish (US)
Pages (from-to)283-295
Number of pages13
JournalLake and Reservoir Management
Issue number3
StatePublished - Jul 3 2018

Bibliographical note

Funding Information:
Funding for this research was provided through the Minnesota Aquatic Invasive Species Research Center from the Minnesota Environment and Natural Resources Trust Fund. Funding for starry stonewort treatment on Lake Koronis was provided by the Outdoor Heritage Fund. We thank the Associate Editor and 3 anonymous reviewers for comments that greatly improved the manuscript.

Publisher Copyright:
© 2018, © Copyright by the North American Lake Management Society 2018.


  • Algaecide
  • Characeae
  • aquatic plant management
  • bulbil
  • chelated copper
  • invasive species
  • macroalgae
  • mechanical removal


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