Toxicity testing using esterase inhibition as a biomarker in three species of the genus Lecane (Rotifera)

We have developed an esterase inhibition test to investigate the effects of 10 toxicants, including six metals (cadmium, chromium, copper, lead, mercuric chloride, and titanium) and four organics (benzene, ethyl acetate, toluene, and vinyl acetate) in three species of the benthic rotifer genus Lecane (L. hamata, L. luna, and L. quadridentata). Metals affect esterase inhibition by an average value of 4,957-fold greater than the four organics tested for the three rotifer species. Most of the EC50 (effect concentration where a 50% reduction in esterase activity is observed) values correspond to environmentally realistic concentrations. Comparisons of acute-to-chronic ratios among these three species showed that in two species, L. luna and L. quadridentata, esterase inhibition is an outstanding biomarker for most of the toxicants tested.