Effects of disturbance modes on the size of <i>Microcystis flos-aquae</i> colonies

Abstract

风浪扰动是影响湖泊生态系统的重要环境因素之一.为了解扰动方式对微囊藻群体大小的影响，在实验室可控条件下，模拟不同扰动方式（持续扰动和间歇扰动）对太湖水华微囊藻（Microcystis flos-aquae）群体大小的影响.结果显示，间歇扰动组水华微囊藻群体从35.09 μm迅速增大至43.73 μm，实验第17天时为59.00 μm；而持续扰动组水华微囊藻群体大小先从35.07 μm增大到43.51 μm，实验第17天时减小至13.95 μm；不扰动组整个实验期间群体大小相对稳定，实验初为35.38 μm，实验第17天时为33.67 μm.方差分析显示，间歇扰动组群体大小显著大于持续扰动组和不扰动组，持续扰动组显著小于不扰动组.实验第17天时间歇扰动组藻细胞密度（1.675×10⁶ cells/ml）显著高于持续扰动组（0.344×10⁶ cells/ml）和不扰动组（1.461×10⁶ cells/ml）.研究结果表明，适当强度下的间歇扰动能促使水华微囊藻群体显著增大和生长，而长时间的持续扰动则会抑制水华微囊藻群体的聚集和生长，该结果有助于人们对太湖微囊藻水华暴发机理的认识.;Disturbance induced by wind-wave is one of the important environmental factors that affect the lake ecosystem. To understand the effect of disturbance modes on the size of Microcystis flos-aquae colonies in lakes, one experiment on the effects of different simulated disturbance modes (continuous disturbance and intermittent disturbance) on the size of Microcystis flos-aquae colonies from Lake Taihu was conducted under controlled conditions in laboratory. The experiment results showed that the size of Microcystis flos-aquae colony increased rapidly from 35.09 μm to 43.73 μm in the intermittent disturbance groups, and to 59.00 μm on the 17th day of the experiment. However, the size of Microcystis flos-aquae colony in the continuous disturbance groups increased from 35.07 μm to 43.51 μm, and decreased to 13.95 μm on the 17th day of the experiment. The size of Microcystis flos-aquae colony in the non-disturbance groups was relatively stable throughout the experiment, which was 35.38 μm, 33.67 μm at the beginning and on the 17th day of the experiment, respectively. Variance analysis showed that the size of Microcystis flos-aquae colony in the intermittent disturbance groups was significantly greater than that in the continuous disturbance groups and the non-disturbance groups. Also, the size of Microcystis flos-aquae colony in the continuous disturbance groups was significantly smaller than that in the non-disturbance group. On the 17th day of the experiment, the algal cell density (1.675×10⁶ cells/ml) was significantly higher in the intermittent disturbance groups than that in the continuous disturbance groups (0.344×10⁶ cells/ml) and the non-disturbance groups (1.461×10⁶ cells/ml). The results showed that intermittent disturbances at appropriate intensities could significantly increase the size and the growth of Microcystis flos-aquae colony, but continuous disturbance could inhibit their aggregation and growth over long time, which is valuable for understanding the breakout mechanism of Microcystis blooms in Lake Taihu.