Abstract
Novel bioassay method that test micioalgae can show the maximum specific growth rate μmax regardless of nutrient conditions in test at was constructed. The method and a previous bioassay method was compared based on the evaluation of growthinhibiting effect by the extracts and culture solution of a brown alga Sargassum homeri using diatom Skeletonema costatum. As a result, the growth-inhibiting effect of the odract in a pevious bioassay method was underestimated compared to that in the novel bioassay method, which would be because of the long-term bioassay period and the de ease of the growth-inhibiting effect by the addition of nuirients to test water in a previous method. Since a previous bioassay method is indispensable to add nutrients to test water to avoid the nutrient limitation for the growth, it was revealed that a previous method cannot make the appropriate evaluation of chemical toxicity. Therefore It was considered that the novel bioassay method is useful to apply for the ecological impact assessment of cheinicals because the method is possible to evaluate a growth-inhibiting effect without the addition ofnutriets to test water.
