Results of Interlaboratory Testing of the Standardized Aquatic Microcosm Protocol

Abstract

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.

Effect of zinc on four populations and two generations of Gammarus pulex (L.)

“…Variability in the results of toxicity assessment has been found at every level of biological organization, from subcellular (Rattner & Fairbrother, 1991) to community (Taub et al, 1989). Differences between individuals in the response to pollutants can be partitioned into those due to environmental variafion, those due to genefic variation, and those due to a combination of the two (Hoffmann & Parsons, 1991).…”

Unique Information Contributed by Multispecies Systems: Examples From the Standardized Aquatic Microcosm

“…Interlaboratory tests were conducted by three laboratories, for a total of seven experiments that met quality‐control standards (Taub et al 1988, Taub 1989 a , 1993, Conquest and Taub 1989, Taub et al 1989). Each laboratory tested six replicates of the treatments control, 500, 1000, and 2000 μg/L Cu as CuSO 4 ; more details are provided in the papers cited.…”

Toxicity analysis of freshwater and marine sediments with meio- and macrobenthic organisms: a review

“…abundance, can be more sensitive to toxicity than mono-species tests (Lampert et al ., 1989) . Standardized multi-species aquatic toxicity tests have been meanwhile developed which exploit this sensitivity (Taub, 1989 ;Taub et al ., 1989) . An overview of multi-species tests for aquatic toxicity, but which involve sediments, is found in Ahlf (1994, Table 3 .12 therein) .…”