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.