A simple, miniaturized algal assay procedure using microplates has been developed to assess aquatic toxicity with the green alga, Selenastrum capricornutum. Cell count‐generated EC50 data comparisons with the classic assay using flasks have indicated good agreement between the two methods following toxic assessment of various wastewater samples and metal solutions. Parametric comparisons (ATP us cell counts) with the microplate method show equally good correlation. The technique is highly versatile in conducting basic algal bioassays for varying times (4‐hour, 4‐day, 8‐day EC50's) and with differing parameters, depending on set objectives. Other interesting features of the microplate technique include handling rapidity, economy, space‐saving convenience, and automation potential.

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Past and present Canadian experiences with biological testa for controlling the quality of wastewaters are discussed. Test use has evolved from data acquisition on acute toxicities, to physicochemical and biological parameters being regulated and monitored by industrial sector in the 197013, and hazard assessments conducted by the 1980s. At a time when Environment Canada is reviewing its ecotoxicological procedures, new opportunities for waste assessment with "second generation" biotests are emerging. Recent experiences suggest that small-scale, sensitive, biological testa can be employed for environmentally and economically effective control of effluents entering aquatic environments.It is also expected that biotesting activities will increase because of new environmental strategies and regulations. These will stimulate biological research and development, and promote a partnership between ecotoxicology, environmental chemistry, and biotechnology.

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Despite the considerable amount of effort and resources involved in monitoring water quality, water quality assessment and environmental follow-up are sometimes carried out with simple statistics, the main reason being the lack of appropriate statistical methods adapted to the nature of sampled water quality data.A survey of the classical methods used for trend detection and of their limitations is first presented, including the most recent non-parametric techniques adapted to the structure of the sampled data and to the possible types of trends occuring. This paper then presents an interactive user-friendly software package developed for microcomputers making use of these latest adapted techniques. Afterwards, some applications of the software are described pertaining to the concentrations measured at long-term stations on the St. Lawrence River and to the mass loadings discharged by regulated industries. Finally, conclusions are drawn about the assumptions, performance and limitations of the package as well as about the research needs to improve the usefulness and applicability of the software.