水波对微囊藻群体迁移分布的影响

Effects of waves on migration and distribution of Microcystis colonies

波浪作用下微囊藻群体的迁移分布规律对理解微囊藻水华暴发具有重要意义。本文采用波浪水槽实验,研究了小幅波作用下微囊藻群体的迁移轨迹、浓度分布以及聚集现象。结果表明:与静水环境中近似竖直向上的迁移轨迹不同,微囊藻群体在水波中呈周期性运动,但仍具有向上运动趋势;距水面越近,微囊藻群体受水波影响越大;波高越大,水波引起的水流挟带能力越强,微囊藻群体周期性运动范围越大,水深方向分布越均匀;较大波高条件下,漂浮于表层的微囊藻群体易于出现破碎,并被水波挟带分散至下层水体;大尺寸微囊藻群体具有较强的垂向自主迁移能力,易于聚集在水面,形成较高的表层浓度,而小尺寸微囊藻群体,自主迁移能力弱,易被水波挟带至下层水体,垂向分布相对均匀。

The migration and distribution of Microcystis colonies under waves are of great significance for understanding Microcystis blooms.This work experimentally investigates the trajectory,concentration distribution,and aggregation of Microcystis colonies under small amplitude waves.Results show that unlike the approximately vertical upward migration trajectory in still water,the Microcystis colonies show periodic motion in waves but still take an upward trend.The closer the Microcystis colonies are to the water surface,the greater the influence of water waves on them.The larger the wave height,the stronger the water carrying capacity caused by water waves.This leads to a more extensive range of periodic movement,and a more uniform profile of vertical concentration.When floating on the surface under large wave heights,the Microcystis colonies are prone to fragmentation and dispersion into the lower water layer by water waves.Large-scale Microcystis populations have a strong capability of vertical autonomous migration and tend to aggregate on the water surface,forming higher surface concentrations,while small-scale ones are weak in autonomous migration and are easily carried by water waves to the lower layer of water,with a relatively uniform vertical distribution.