Monensin Is Not Toxic to Aquatic Macrophytes at Environmentally Relevant Concentrations

  • Erin B. McGregor
  • K. R. Solomon
  • M. L. HansonEmail author


Monensin, a common livestock feed additive, has been detected in surface waters around areas of intensive agriculture. The effect of this ionophore antibiotic on floating (Lemna gibba) and submersed (Myriophyllum spicatum, Elodea canadensis, Egeria densa) freshwater macrophytes was investigated under seminatural field conditions using 12,000 l of outdoor microcosms. Exposure concentrations of 0, 12, 25, 50, and 100 μg/l (n = 3) were evaluated over a 35-day period. Submersed plants were grown individually in 115-ml plastic “cone-tainers” and assessed for various growth and pigment end points. E. canadensis and M. spicatum also were grown in assemblages to represent model populations and two-species communities. Few statistically significant differences from control organisms were observed for any of the monitored end points. Overall, monensin is deemed unlikely to cause toxicity in freshwater macrophytes at current environmental concentrations. However, the ability to characterize toxicity in macrophytes is based partially on the relative growth rates (RGRs) of the plants. The greater the RGR, the more sensitive the assay may be to contaminants. The RGRs of E. canadensis and M. spicatum grown in model populations and communities were found to be significantly higher than the RGRs of plants grown individually. This implies that the “cone-tainer” method, although simple and easy to perform, may underestimate toxicity in simulated field studies.


Macrophyte Relative Growth Rate Aquatic Macrophyte Monensin Hazard Quotient 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



We wish to thank Craig DeVito, Jason Miller and Mike Carl for their help in the field and Tamara Reitsma, Amanda Warne, Linda Lissemore, and Richard Brain for experimental assistance. This research was funded by the University of Manitoba.


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Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • Erin B. McGregor
    • 1
  • K. R. Solomon
    • 2
  • M. L. Hanson
    • 1
    Email author
  1. 1.Department of Environment and GeographyUniversity of ManitobaWinnipegCanada
  2. 2.Department of Environmental BiologyUniversity of GuelphGuelphCanada

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