摘要：This study seeks to determine whether microcystins of unicellular Microcystis are the sole explanation for its adverse effects on rotifer growth. Brachionus calyciflorus were exposed to toxic and non-toxic strains of Microcystis aeruginosa separately and together with an edible alga ( Scenedesmus obliquus ) at different algal ratios and carbon compositions. Complete mortality was observed on B. calyciflorus cultured on toxic M. aeruginosa at all food concentrations (50, 100, and 400 μg C·L −1 ) and non-toxic M. aeruginosa at 400 μg C·L −1 . Rotifers fed the pure non-toxic strain exhibited reduced viability at lower food concentrations. Overall, growth rate decreased with increased proportions of M. aeruginosa . In mixed-diet experiments, rotifers showed greater tolerance to the non-toxic M. aeruginosa . Diets composed of both toxic and non-toxic Microcystis combined with Scenedesmus slightly supported rotifer growth at 100 μg C·L −1 . Due to the mixtures with sufficient S. obliquus at 400 μg C·L −1 , nutritional deficiency could be excluded. Results are in agreement with the fact that unicellular M. aeruginosa cultured in the laboratory is a poor food for aquatic herbivores and might contain other toxic inhibiting substances to B. calyciflorus .
