Saint-Lawrence River Action Plan

For both the Saint-Lawrence River Action Plan (Costan et al., 1993) and the Toyama Bay Japanese (Kusui and Blaise, 1999) studies, the two suites of bioassays employed represented three trophic levels (decomposers, primary producers and primary or secondary consumers), and sought to measure both acute and chronic toxicity. Toxicity tests were selected on the basis of practical and scientific criteria including low sample volume requirement, sensitivity, simplicity of undertaking the assay, ease in maintaining laboratory cultures, cost-effectiveness, procedural reliability and/or frequency of use internationally. 

Figure 4. Emplacement of the 50 priority industrial effluents investigated during the first Saint-Lawrence River Action Plan (1988-93).

Requiring low-sample volume micro-scale tests for its cost-effective application, the PEEP index has thus far employed bioassays with bacteria, algae and microinvertebrates. While well-standardized toxicity tests using freshwater fish existed at the time of the PEEP s conception in the early 1990 s (e.g., the Environment Canada fingerling rainbow trout 96-h lethality test to assess industrial wastewaters), they were excluded because of their large sample volume needs (e.g., close to 400 L of effluent sample required to undertake a multiple dilution 96-h LC50 bioassay in the case of the trout test). In addition to effluent sample volume, the cost of carrying out salmonid fish acute lethality bioassays for the 50 priority industrial effluents identified under SLAP I (the first 1988-93 Saint-Lawrence River Action Plan) was prohibitive. 

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