biostudies-literatureChoi SKorea Environmental Industry and Technology Institute1618https://www.ebi.ac.uk/biostudies/studies/S-EPMC9687118biostudies-literatureUnknown11(11)A chemical analysis of water quality cannot detect some toxicants due to time constraints, high costs, and limited interactions for detection. Bioassays would offer a complementary means to assess pollution levels in water. <i>Euglena</i> is a flagellate green alga and an excellent system for toxicity testing thanks to its ease of culture, rapid growth, and quick response to environmental stresses. Herein, we examined the sensitivity of <i>E. agilis</i> to seven heavy metals by analyzing six end-point parameters: motility, velocity, cell compactness, upward swimming, <i>r</i>-value, and alignment. Notably, the velocity of <i>E. agilis</i> was most sensitive to cadmium (96.28 mg·L^-1), copper (6.51 mg·L^-1), manganese (103.28 mg·L^-1), lead (78.04 mg·L<sup>-1</BiologyA Ten-Minute Bioassay to Test Metal Toxicity with the Freshwater Flagellate <i>Euglena agilis</i>.PMC96871182022003050003Choi SPark JTLee MSPark JAsselman JLee HHeynderickx PMWu DDepuydt SJanssen CHader DPHan TfalseA Ten-Minute Bioassay to Test Metal Toxicity with the Freshwater Flagellate <i>Euglena agilis</i>.A chemical analysis of water quality cannot detect some toxicants due to time constraints, high costs, and limited interactions for detection. Bioassays would offer a complementary means to assess pollution levels in water. <i>Euglena</i> is a flagellate green alga and an excellent system for toxicity testing thanks to its ease of culture, rapid growth, and quick response to environmental stresses. Herein, we examined the sensitivity of <i>E. agilis</i> to seven heavy metals by analyzing six end-point parameters: motility, velocity, cell compactness, upward swimming, <i>r</i>-value, and alignment. Notably, the velocity of <i>E. agilis</i> was most sensitive to cadmium (96.28 mg·L^-1), copper (6.51 mg·L^-1), manganese (103.28 mg·L^-1), lead (78.04 mg·L<sup>-1</2022-01-01T00:00:00Z2022 Nov2025-06-01T02:50:12.98Z2025-06-01T02:50:12.98ZS-EPMC96871183635831910.3390/biology11111618