Effect of Microcystis aeruginosa on the rotifer Brachionus calyciflorus at different temperatures.

Rotifers are one of the smallest metazoans. They serve as a model organism for ecotoxicological studies. More than 60% of the lakes in China are increasingly eutrophic and they are susceptible to blooms of Microcystis aeruginosa. We investigated the effects of M. aeruginosa on the survival and reproduction of Brachionus calyciflorus using the life table method at different temperatures. The findings showed that concentration of M. aeruginosa significantly affected the intrinsic rate of increase (r(m)), net reproductive rate (R(0)), average lifespan (L) and offspring number (p < 0.05). Temperature also significantly affected the generation time (T), average lifespan (L) and offspring number (p < 0.05). Moreover, the interaction between temperature and concentration had statistically significant effects on offspring number (p < 0.05). M. aeruginosa suppressed the survival and reproduction of B. calyciflorus, particularly at a concentration of 10(6) cells/mL. The r(m) values of the rotifers exposed at 10(6) cells/mL decreased more than 200% compared with those of the control group. However, at a lower concentration, 10(4) cells/mL, M. aeruginosa may supply appropriate nourishment to rotifers. In addition, at concentrations of 10(5) and 10(6) cells/mL, the inhibition of rotifers by M. aeruginosa heightened with increasing temperature.