Results of Interlaboratory Testing of the Standardized Aquatic Microcosm Protocol

    Published: Jan 1988

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    The “standardized aquatic microcosm” (SAM) protocol was performed by four laboratories, including the authors' laboratory, and the results of seven experiments are presented. Each laboratory tested the toxicant copper at three concentrations (500, 1000, and 2000 ppb) plus a control.

    Nitrate depletion and an early algal bloom which was terminated by an increase in grazers (mainly Daphnia) were consistently observed in the control microcosm. In comparison with controls, the copper-treated microcosms were associated with reductions in Daphnia and in sensitive algal populations. In all toxicant treatments, copper eliminated the Daphnia and inhibited primary production; the duration of inhibition was prolonged at the higher copper concentrations. At the lowest concentration, recovery was characterized by an algal bloom of copper-resistant green algae, which was followed by a Daphnia bloom. Recovery occurred in most of the 1000-ppb copper-treated microcosms but was usually absent at the 2000-ppb concentration until late in the experiment.

    All experiments exhibited the same sequence of events, but the timing of these events varied among experiments. Experiments provided similar statistical differences between control and treatment microcosms within the same experiment and gave the same rank order of the day-weighted-by-variable” (DWV) statistic, denned in the text. Comparison of the variable means on a day-by-day analysis of variance did show the experiments to be statistically different because of differences in the timing of events.


    microcosms, copper, interlaboratory testing, standardized aquatic microcosm, toxicity, Daphnia, algae, toxicity testing, aquatic toxicology

    Author Information:

    Taub, FB
    Professor and predoctoral research associate, School of Fisheries, University of Washington, Seattle, WA

    Kindig, AC
    Senior scientist, Beak Consultants, Bellevue, WA

    Conquest, LL
    Associate professor, Center for Quantitative Science, School of Fisheries, University of Washington, Seattle, WA

    Meador, JP
    Professor and predoctoral research associate, School of Fisheries, University of Washington, Seattle, WA

    Committee/Subcommittee: E47.01

    DOI: 10.1520/STP10302S

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