EFFECTS OF MICROCYSTIS AERUGINOSA ON THE LIFE-TABLE PARAMETERS AND PHENOTYPIC TRAITS OF ROTIFERS

To evaluate the effects of microcystin-producing and microcystin-free Microcystis aeruginosa on the population growth and phenotypic traits of rotifers, we discussed the responses of life history parameters and morphology of Brachionus calyciflorusto differentM. aeruginosa solutions. In order to ensure that rotifers obtained food supply from same carbon content, the total carbon content was maintained at a level of (20.61±0.15) μg C/mL per unit volume in every treatment group. Rotifers were fed onChlorella pyrenoidosa, Scenedesmus obliquus, microcystin-producing and microcystin-free M. aeruginosa, and mixtures of green algae with toxic and nontoxic cyanobacteria, respectively. Compared with the control group, the life-table experimental results showed that net reproduction rate R₀ (F=102.71, df=32, P<0.001), generation timeT (F=17.05, df=32, P<0.001) and intrinsic growth rater_m (F=18.89, df=32, P<0.001) of rotifers decreased 1.36%—210.34% in the groups fed with differentM. aeruginosa mixtures. Posterolateral spine length (F=28.18, df=65, P<0.001) and swimming speed (F=181.69, df=65, P<0.001) ofB. calyciflorusdeclined 2.63%—39.07%, and the rotifer body length (F=690.04, df=65, P<0.001) changed significantly. The life table parameters and phenotypic traits of rotifers changed with concentrations ofMicrocystis solutions compared with those in groups fed with green algae. Under the stress ofM. aeruginosa, the growth and reproduction of B. calyciflorus were inhibited, and its morphology changed to defend adverse living environment.