Acute toxicity tests on three species of the genus Lecane (Rotifera: Monogononta)

Three rotifer species, Lecane hamata L. luna, and L. quadridentata, were submitted to acute toxicity tests to compare their susceptibility to 11 toxicants. In acute tests with 48-h exposure of neonates of less than 24 h old, copper was most toxic with LC₅₀ values in the range of 0.06–0.33 mg l^–1, while acetone was the least toxic with LC₅₀ values in the range of 5000–7000 mg l^–1. Differences in LC₅₀ value of up to 22-fold were found in the susceptibility to lead between the three species. These data indicate large differences in toxicity among members of the same genus, and point out that it is necessary to submit several species to toxicity tests in order to assess the potential effects of toxicants to rotifers. The commonly used Brachionus calyciflorus cannot be considered representative of all freshwater rotifers in this respect.