角突网纹溞在太湖微囊藻群体形成中的作用

Effect of Ceriodaphnia cornuta in colony formation of Microcystis in Lake Taihu

将太湖微囊藻水华中3种优势微囊藻包括水华微囊藻1028、惠氏微囊藻929、铜绿微囊藻469和铜绿微囊藻905培养在改良后的BG-11培养基(TN=10mg/L,TP=0.4mg/L)中,然后加入角突网纹溞,以研究3种优势微囊藻对浮游动物摄食压力的形态反应,整个实验共进行了12d.除了水华微囊藻1028以外,在惠氏微囊藻929、铜绿微囊藻469和铜绿微囊藻905中没有观察到有大群体(大于10个细胞)的出现.在水华微囊藻中,处理组大群体细胞所占总细胞的比例与对照组显著不同,其中对照组占22%,而试验组占53%.水华微囊藻对照组和处理组中单细胞、2细胞、小群体(3-10个细胞)和大群体(大于10个细胞)细胞密度存在显著的不同.实验第6-12d,水华微囊藻对照组和试验组单位大群体细胞数量存在显著差异.研究结果表明,角突网纹溞的摄食压力不能促使惠氏微囊藻929、铜绿微囊藻469和铜绿微囊藻905形成大群体.角突网纹溞的摄食促使水华微囊藻形成更大的群体.

Experiments were carried on by using four dominant species of Microcystis of Lake Taihu, including Microcystis aeruginosa 905 （toxic）, M. aeruginosa 469 （non toxic）, M. flos-aquae 1028 and M. wesenbergii 929, grazing by Ceriodaphnia cornuta cultured in a modified BG-11 medium （TN=10mg/L, TP=0.4mg/L） with over 12 day tests. No large colony （above 10 cells） formations in M. aeruginosa 905, M. aeruginosa 469 and M. wesenbergii 929 were observed in the controls and treatments except for M. flos-aquae 1028. The cells proportion of large colony of M. flos-aquae to total cells was significant different between controls and treatments, contributing 22% in controls and 53% in treatments. There were significant differences between controls and treatments in M. flos-aquae in density of different units of unieell, two-cells, small colony （3-10 cells） and large colony. Significant differences were found between controls and treatments in the number of cells per large colony of M. flos-aquae from day 6 to day 12 in the experiment. Our results showed that large colony of M. aeruginosa 905, M. aeruginosa 469 and M. wesenbergii 929 can not be obtained by grazing in the C. cornuta, but C. cornuta is one of important factors in enlarging colony formation of M.flos-aquae.