[Over-compensatory growth of Microcystis aeruginosa after high temperature stress]

Two groups of Microcystis aeruginosa FACHB 905 cultures, 40 degrees C and 25 degrees c cultures were set in present study. Both of them were cultured for 5 and 10 days before transferred to fresh medium in same cell densities and then cultured under the same conditions at 25 degrees C. The algae which were cultured under 25 degrees C for all the time were set as the control. The growth, chlorophyll a concentration, Fv/Fm, net photosynthetic rate and respiration rate were determined after re-inoculation. The result showed that the high temperature treated groups have lower specific growth rate and lower Fv/Fm than those of control groups (p < 0.01). However, in the middle-later stage of recovery growth, the specific growth rate of 40 degrees C for 5 days group was 0.362, and it was significantly higher than that of control groups of 0.301 (p < 0.05), while the specific growth rate of 40 degrees c for 10 days group was 0.358, and there was no significant difference with control. 40 degrees C for 5 days group showed over-compensatory growth while 40 degrees C for 10 days group showed exact-compensatory growth. It implies that the over-compensatory growth characteristics of Microcysis aeruginosa is an endogenous biological factor that contributing the outbreak of blooms.