Recent developments in microbiotesting and early millennium prospects

Small-scale toxicity testing with microbiotests is a rapidly-expanding component of the field of aquatic toxicology which contributes diverse contamination assessment tools and approaches for a variety of environmental (liquid and solid) media. In this short review on microbiotesting, some of the recent 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 determine the genotoxic status of major industrial effluents discharging to the St. Lawrence River and their potential impact on downstream biota, 2) developing an algal solid phase assay to predict the toxic potential of freshwater sediments, 3) developing a microplate-based cnidarian assay to screen for toxicity of chemicals and environmental samples, 4) developing an alternative assay to whole fish acute (sub)lethal toxicity testing with the help of rainbow trout primary hepatocytes, 5) developing a microplate-based phagocytosis assay to check for immunocompetence of feral bivalve shellfish and 6) conducting a major investigation to develop a cost-effective multitrophic bioanalytical battery to assess the (geno)toxicity of freshwater sediments. In addition, integrative tools with specific microbiotests were respectively constructed to determine the toxic potential of industrial effluents (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 by recent books entirely dedicated to the subject. It is undeniable that many important challenges still lie ahead for this field early into the third millennium and likely well beyond.