SEDL / STP / STP971-EB / STP34054S

Interlaboratory Testing of a Standardized Aquatic Microcosm

Taub, FB
Professor, School of Fisheries, WH-10, University of Washington, Seattle, WA

Kindig, AC
Fisheries biologist, School of Fisheries, WH-10, University of Washington, Seattle, WA

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

Pages: 22    Published: Jan 1988

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Abstract

The “Standardized Aquatic Microcosm” (SAM) Protocol is being tested in three laboratories as well as in the laboratory where it was developed (University of Washington). Each laboratory has used a control and three concentrations of copper sulfate and has completed at least one experiment.

The successional sequence in the controls has consistently included nitrate depletion and an early algal bloom terminated by increases in grazer populations, especially Daphnia. In all experiments analyzed to date, low copper sulfate concentrations were associated with temporary reduction in Daphnia and concurrent algal blooms; at higher concentrations, the algae were inhibited to a greater extent and for a longer duration.

The concept of a “days-weighted-by-variable” statistic (DWV) is introduced to assess variation between experiments. The DWV, as a measure of the center of gravity of a microcosm time trace, is useful to detect shifts in timing under increased copper concentrations.