扰动强度对太湖水华微囊藻群体生长和叶绿素荧光的影响

风浪扰动在湖泊和水库中频繁发生，是影响湖泊生态系统的重要因素之一.为了解太湖风浪扰动对水华微囊藻群体生长的影响，并探究其影响机理，利用室内摇床试验，设置不同的扰动强度（0、50、100、200、400 r/min）来模拟太湖风浪扰动，扰动时间为24 h，并测定不同扰动强度下水华微囊藻群体生长和叶绿素荧光参数.结果表明，所有试验组中，100 r/min组的ρ（Chla）、微囊藻数量、F_v/F_m（潜在最大光合效率）、ETR_max（潜在最大光合速率）、I_k（半饱和光强）和α（光能利用效率）增加最快，试验结束时分别为扰动前的3.29、10.75、1.20、2.30、2.21和1.21倍；并且扰动结束后，100 r/min组中3~10细胞群体细胞数量占比由25.80%降至20.70%，显著低于对照组（P < 0.05），而>10细胞群体细胞数量占比由0增至25.55%，显著高于对照组（P < 0.05）.方差分析表明，试验第7~11天，100 r/min组的ρ（Chla）、水华微囊藻数量、F_v/F_m、ETR_max和α显著高于对照组（P < 0.05）；第1~5天，400 r/min组的ρ（Chla）、ETR_max和I_k显著低于对照组（P < 0.05）.研究显示，适宜的扰动强度（100 r/min）促进水华微囊藻群体生长和光合活性，过高的扰动强度（400 r/min）则抑制水华微囊藻群体生长和光合活性. 

Effect of Disturbance Intensity on the Growth and Chlorophyll Fluorescence of Microcystis flos-aquae Colony in Lake Taihu

Disturbance induced by wind-wave occurs frequently in lakes and reservoirs, and it is one of the important factors affecting the lakes ecosystem. To understand the effect and mechanism of mixing induced by wind-wave on the growth of Microcystis flos-aquae colony in Lake Taihu, an experiment was conducted in lab, using different disturbance intensity (0, 50, 100, 200 and 400 r/min) by agitator to simulate the mixing induced by wind-wave in Lake Taihu. The disturbance time is 24 h. Growth and chlorophyll fluorescence parameters of M. flos-aquae colony were measured in this study. The study results showed that the increasing speeds of ρ(Chla), abundance, potential maximum photosynthetic efficiency (F_v/F_m), the potential maximum photosynthetic rate (ETR_max), half saturation light intensity (I_k) and light use efficiency (α) of M. flos-aquae in the 100 r/min groups were the highest among all treatment groups. In the end of the experiment, the value of ρ(Chla), abundance, F_v/F_m, ETR_max, I_k and α of M. flos-aquae in the 100 r/min groups were 3.29, 10.75, 1.20, 2.30, 2.21 and 1.21 times as more as that before mixing in the experiment. In the end of this experiment, the cell abundance of 3-10 cells colony of M. flos-aquae in the 100 r/min groups decreased from 25.80% to 20.70% to total cell abundance, and which was significantly lower than that in the control groups (P < 0.05). However, the cell abundance of >10 cells colony of M. flos-aquae in the 100 r/min groups increased significantly from 0 to 25.55% to total cell abundance, which was significantly higher than that in the control groups (P < 0.05).The variance analysis showed that the ρ(Chla), abundance, F_v/F_m, ETR_max and α of M. flos-aquae in the 100 r/min groups were significantly higher than those in the control groups (P < 0.05) during the 7th-11th day in the experiment. During the 1st-5th day, the ρ(Chla), ETR_max and I_k in the 400 r/min treatment groups were significantly lower than those in the control groups (P < 0.05) in the experiment. The results showed that the suitable disturbance intensity (100 r/min) promoted the growth and photosynthetic activity of M. flos-aquae, but the high disturbance intensity (400 r/min) inhibited the growth and photosynthetic activity of M. flos-aquae.