starry stonewort

Starry stonewort can grow tall and dense, forming mats on the surface which can interfere with recreation and potentially displace native plant species. When it was first found in Minnesota in 2015, MAISRC researchers had to act quickly to learn the basics of invasive alga. Click here to learn more about starry stonewort and its impacts.

Key findings and accomplishments

  • Found that mechanical and algaecide treatments greatly reduced starry stonewort biomass, but that their star-shaped bulbils, which can regenerate into new plants, remained viable after treatment. This reinforces the importance of a multi-pronged approach to starry stonewort control
  • Launched laboratory experiments to test the effectiveness of different algaecides and herbicides on starry stonewort
  • Conducted field work to better understand the phenology of starry stonewort to guide the timing of management
  • Tested how long fragments and bulbils remain viable out of water to assess risk of overland spread
  • Engaged hundreds of volunteers during Starry Trek, a statewide search for starry stonewort
  • Completed a predictive risk model for zebra mussels and starry stonewort to inform decision-making and prioritize prevention activities for all Minnesota lakes
  • Provided technical assistance to lake associations and agencies on starry stonewort management
  • Used locational and environmental data to predict which lakes and types of lakes in Minnesota are most vulnerable to invasion
    • Used data on where starry stonewort occurs in its native and invaded ranges — and climate and environmental data associated with those occurrences — to predict areas of suitable habitat where it could potentially invade and persist if introduced
    • Found that starry stonewort is occupying a climate niche in its invaded range distinct from the climatic conditions under which it occurs in its native range
    • Substantial portions of the U.S. with no known occurrences of starry stonewort may be at risk of future invasion
  • In June 2016, MAISRC brought together a group of international experts to synthesize what is currently known about the ecology, impacts, and management of starry stonewort and identify key gaps in the science needed to better support management

Starry stonewort research at the Minnesota Aquatic Invasive Species Research Center


Ongoing research

• Conducting laboratory experiments to test the efficacy and selectivity of different algaecides
• Creating a decision-making tool to prioritize resources for optimal prevention and intervention of starry stonewort, taking into account boater movement and environmental factors such as pH and temperature
• Evaluating plant community impacts and environmental factors associated with nuisance growth of starry stonewort
• Characterizing starry stonewort phenology to guide timing of management