Microcystis blooms are a global problem adversely affecting the quality of freshwater in lakes and reservoirs. Surface scum (0–1 m) forms as a result of vertical migration by buoyant Microcystis colonies. Accurate forecasting of bloom and scum development is essential for establishing a reliable alert system and requires understanding the role that physicobiological factors play in the vertical distribution of Microcystis in natural ecosystems. We researched the role of limnological processes on the vertical distribution of Microcystis colonies in Lake Kinneret (max depth = 38 m) during a winter–spring bloom. We used measurements from a Laser In situ Scattering and Transmissometry profiler and a plankton image analyser, FlowCAM. Various hydrometeorological conditions were captured during 6 outings from 9 February to 21 March 2017. Thermal stratification and turbulence levels influenced the vertical distribution of Microcystis colonies and scum formation. During periods of weak turbulence (e.g., vertical turbulent eddy diffusivity [K_z] <1 cm² s⁻¹), the volume concentration of Microcystis colonies near the surface abruptly increased. High turbulence levels (e.g., windy conditions) dispersed colonies concentrated near the surface. Simulations of the vertical distribution of Microcystis colonies under different turbulence levels showed that the thickness of the surface scum layer increased and colony concentration of scum decreased as turbulence level increased. We demonstrated that K_z >3 cm² s⁻¹, driven by the wind and surface heating/cooling, dispersed the surface layer of concentrated Microcystis colonies. Our results revealed an underlying interdependency between environmental factors and Microcystis colony distribution that can be utilized to accurately forecast scum formation.

微囊藻水华是一个全球性问题，对湖泊和水库的淡水质量产生不利影响。由于浮游性微囊藻菌落的垂直迁移，表面浮渣（0-1m）形成。准确预测水华和浮渣的形成对于建立可靠的警报系统至关重要，并且需要了解物理生物学因素在自然生态系统中微囊藻的垂直分布中所起的作用。我们研究了微生物学过程在微囊藻垂直分布中的作用冬春季开花期间，金奈雷特湖（最大深度= 38 m）上的菌落。我们使用了激光原位散射和透射测量轮廓仪以及浮游生物图像分析仪FlowCAM的测量结果。2017年2月9日至3月21日的6次郊游中捕获了各种水文气象条件。热分层和湍流水平影响了微囊藻菌落的垂直分布和浮渣的形成。在微弱湍流期间（例如，垂直湍流涡流扩散率[ K _z ] <1 cm ²  s ^-1），微囊藻的体积浓度表面附近的菌落突然增加。高湍流水平（例如，大风天气）分散的菌落集中在地表附近。不同湍流水平下微囊藻菌落的垂直分布模拟表明，随着湍流度的增加，表面浮渣层的厚度增加，浮渣菌落浓度降低。我们证明，在风和表面加热/冷却的驱动下，K _z  > 3 cm ²  s ^-1分散了浓缩的微囊藻菌落的表面层。我们的结果表明环境因素与微囊藻之间存在潜在的相互依赖性。 可用于准确预测浮渣形成的菌落分布。