Abstract:
To investigate the effects of two strains of
Microcystis aeruginosa (microcystin-producing and microcystin-free) at different concentrations on the life table parameters of
Brachionus calyciflorus, we conducted a life-table study at 25℃ and investigated the responses of life table parameters of
B. calyciflorus to microcystin-producing
M. aeruginosa concentrations at five temperature gradients. The results showed that both
M. aeruginosa toxicity and concentration significantly mediated the net reproduction rate (
R0;
F=31.83,
P<0.01;
F=30.36,
P<0.01) and intrinsic growth rate (
rm;
F=34.67,
P<0.01;
F=18.73,
P<0.01) of
B. calyciflorus with a significant interactive effect, and that temperature and microcystin-producing
M. aeruginosa concentration had significant independent and interactive effects on the net reproduction rate (
R0;
F=13.51,
P<0.01) and intrinsic growth rate (
rm;
F=12.99,
P<0.01) of
B. calyciflorus. Microcystin-free
M. aeruginosa promoted the rotifer population and it could be used as a food source for rotifers at low concentration (1×10
4 cells/mL), but its food quality was low due to the lack of fatty acids and other nutrients. High concentration of Microcystin-free
M. aeruginosa (1×10
5 cells/mL and 5×10
5 cells/mL) obviously inhibited the growth of rotifers because rotifers prefer microcystin-free
M. aeruginosa. The net reproductive rate and intrinsic growth rate of
B. calyciflorus increased significantly by increasing concentration of microcystin-producing
M. aeruginosa. Moreover, high temperature (30℃ and 35℃) accelerated their reproduction and growth rate, shorten the generation time, and promoted inhibitory effect of microcystin-free
M. aeruginosa on rotifers.