Comparison of the Conventional Algal Growth Inhibition Tests Using Cell Counting and Algal Bioassay Using Delayed Fluorescence: Application to Industrial Effluents

Abstract

We propose that rapid algal bioassay using delayed fluorescence (DF) may be useful to apply to the whole effluent toxicity test. In this report, we compared the conventional algal growth inhibition test and the rapid algal bioassay using DF to detect the toxicity of industrial effluents. We used the industrial effluents from eight factories in Toyama Prefecture. Delayed fluorescence is a special type of luminescence; it detects the growth of only those cells that have photosynthetic capability. Therefore, DF can detect algal growth inhibition in a shorter time than the 72 h conventional test, as cells that have lost photosynthetic capability can be detected. The DF test in 6 h and 24 h exposure found algal inhibition from six out of eight effluent samples, and found chronic toxicity unit over 10 from four out of eight effluent samples, the same as the conventional 72 h growth test. These observations suggest that the rapid bioassay using DF is potentially applicable to the selected industrial effluents.