STP737

    Development and Evaluation of a Flow-Through Growth Inhibition Test with Duckweed (Lemna minor)

    Published: Jan 1981


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    Abstract

    Duckweed, Lemna minor, has been proposed as a “typical” aquatic macrophyte suitable for laboratory toxicity testing and useful in the environmental hazard assessment of chemicals. The development of a standard, reproducible, flow-through growth inhibition test with duckweed that employs a precisely controlled flow rate, automatic nutrient and test material delivery system, and constant light intensity is described. The test materials included a heavy metal; anionic, nonionic, and cationic surfactants; and an aquatic herbicide. Growth inhibition was measured as a reduction in frond count, dry weight, and root length. Results based on frond count were found to provide the most useful information per unit of laboratory time. The 7-day median effective concentration (EC50) based on frond count ranged from 0.0031 mg/litre for the herbicide to 43 mg/litre for an anionic surfactant. The ecological relevance of EC50 measurements for duckweed growth is unknown.

    Results obtained with duckweed were compared with acute toxicity data for fish and aquatic invertebrates. For all materials except the herbicide, duckweed was the least sensitive species. The data developed indicate that for many materials, criteria developed for fish and invertebrates may be extended to include the macrophyte community.

    Keywords:

    toxicity test, phytotoxicity, aquatic macrophyte, growth inhibition, duckweed, bluegill, daphnid, copper, surfactant, herbicide, hazard assessment, aquatic toxicology


    Author Information:

    Bishop, WE
    Aquatic biologist and bio-statistician, Environmental Safety Department, Procter and Gamble Co., Cincinnati, Ohio

    Perry, RL
    Aquatic biologist and bio-statistician, Environmental Safety Department, Procter and Gamble Co., Cincinnati, Ohio


    Paper ID: STP34172S

    Committee/Subcommittee: D19.24

    DOI: 10.1520/STP34172S


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