Spore release by the green alga Ulva: A quantitative assay to evaluate aquatic toxicants

A toxicity test using spore release of the aquatic green alga, Ulva, was developed and evaluated by assessing the toxicity of different organic and inorganic chemicals and elutriates of sewage or waste sludge. The toxic ranking of four metals was: Cu (EC50 of 0.040 mg L−1) > Cd (0.095 mg L−1) > Pb (0.489 mg L−1) > Zn (0.572 mg L−1). The EC50 for TBTO ranged from 24 to 63 μg L−1. The most toxic VOC was formalin (EC50 of 0.788 μl L−1) and the least toxic was acetone. Spore release was significantly inhibited in all elutriates; the greatest and least toxic effects were for industrial sewage (3.29%) and filtration bed (10.08%), respectively. The bioassay is simple, inexpensive and sensitive. The cosmopolitan distribution of Ulva means that the test would have a potential application worldwide.