铜绿微囊藻、斜生栅藻对氮磷饥饿的耐受能力研究

Tolerance of Microcystis aeruginosa and Scendesmus obliquus to nitrogen and phosphorus deficiency

在太湖微囊藻水华暴发期间,监测了梅梁湾水体中叶绿素a和氮磷营养盐的动态变化,并通过批量培养实验研究了氮磷缺乏对铜绿微囊藻和斜生栅藻生长的影响,以探讨两种藻对氮磷饥饿的耐受能力对微囊藻水华形成的影响。结果表明,在水华期间,水体的氮磷营养盐浓度并不高,并处于波动状态;铜绿微囊藻和斜生栅藻对氮磷饥饿的耐受能力存在很大差异:在无磷培养基中,铜绿微囊藻能保持8天的指数生长,而斜生栅藻在无氮或无磷培养基中生长都非常缓慢。两种藻对磷饥饿的耐受能力均高于氮。通过生长速率的比较,发现铜绿微囊藻对磷饥饿的耐受能力明显高于斜生栅藻,因此更能够适应波动的营养供给条件。对营养盐饥饿耐受能力的不同导致两种藻在营养盐波动的情况下微囊藻更易取得优势,成为水华期间浮游植物的优势种。

The chlorophyll a, nitrogen and phosphorus concentrations were monitored in Meiliang Bay of Taihu Lake during cyanobacterial bloom. The growth response of Microcystis aeruginosa and Scendesmus obliquus to nitrogen and phosphorus deficiency was investigated using bulk culture experiment. The results showed that nitrogen and phosphorus concentrations remained relatively low and fluctuant during the cyanobacterial bloom. The tolerances of M. aeruginosa and S. obliquus to nitrogen and phosphorus deficiencies were different. M. aeruginosa could maintain exponential growth for about eight days under phosphorus deficiency condition. S. obliquus grew slowly when nitrogen or phosphorus was deficient. The tolerance ability of algae to phosphorus starvation was higher than that to nitrogen starvation. By comparing growth rate, it was found that the tolerance ability of M. aeruginosa to phosphorus deficiency was significantly higher than S. obliquus. So cyanobacteria are more able to adapt to fluctuations of nutrients concentration. This makes cyanobacteria more likely to obtain competitive advantages on nutrients utilization, thereby ensuring its dominance in the phytoplankton community during bloom.