The duckweed Lemna minor recovers following 7, 14, 21, and 28 day exposures to atrazine at environmental concentrations

  • Carlie Lau University of Manitoba
  • Dana Moore University of Manitoba
  • Mark L. Hanson University of Manitoba


We characterized the ability of the duckweed Lemna minor to recover from 7, 14, 21, and 28-day exposures to the herbicide atrazine. Static renewal assays were performed for each duration (with an exposure series of 0, 10, 20, 40, 80, 160 and 320 µg/L atrazine) followed by a 7-day recovery period in clean media. We observed full recovery (no statistical difference from control) in dry mass, frond number, and plant number growth rates at concentrations typically found in the environment ( ≥80 µg/L atrazine), regardless of the exposure duration. The USEPA currently regulates atrazine on an aquatic plant Concentration Equivalent Level of Concern of 10 µg/L (60-day average concentration) and our data support this decision.