Recent developments in microbiotesting and early millennium prospects

Small-scale toxicity testing with microbiotests is a rapidly-expanding comp onent of the field of aquatic toxicology which contributes diverse contamin ation assessment tools and approaches for a variety of environmental (liqui d and solid) media. In this short review on microbiotesting, some of the re cent developments conducted under the second St. Lawrence River Action Plan (1993-1998) at the St. Lawrence Centre (Environment Canada, Quebec Region, Montreal) are recalled. These include 1) employing the SOS Chromotest to d etermine the genotoxic status of major industrial effluents discharging to the St. Lawrence River and their potential impact on downstream biota, 2) d eveloping an algal solid phase assay to predict the toxic potential of fres hwater sediments, 3) developing a microplate-based cnidarian assay to scree n for toxicity of chemicals and environmental samples, 4) developing an alt ernative assay to whole fish acute (sub)lethal toxicity testing with the he lp of rainbow trout primary hepatocytes, 5) developing a microplate-based p hagocytosis assay to check for immunocompetence of feral bivalve shellfish and 6) conducting a major investigation to develop a cost-effective multitr ophic bioanalytical battery to assess the (geno)toxicity of freshwater sedi ments. In addition, integrative tools with specific microbiotests were resp ectively constructed to determine the toxic potential of industrial effluen ts (PEEP: Potential Ecotoxic Effects Probe) and that of sediments (SED-TOX) . Such examples illustrate the diversity of on-going endeavors in the field of small-scale toxicity testing internationally, as further corroborated b y recent books entirely dedicated to the subject. It is undeniable that man y important challenges still lie ahead for this field early into the third millennium and likely well beyond.