Wu Huaming, Wu Xingqiang, Rovelli Lorenzo, Lorke Andreas
Institute for Environmental Sciences, University of Kaiserslautern-Landau (RPTU), Landau, Germany.
Key Laboratory of Algal Biology of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.
Front Plant Sci. 2024 Mar 11;15:1370874. doi: 10.3389/fpls.2024.1370874. eCollection 2024.
Due to climate change, blooms occur at increasing frequencies in aquatic ecosystems worldwide. Wind-generated turbulence is a crucial environmental stressor that can vertically disperse the surface scum, reducing its light availability. Yet, the interactions of scum with the wind-generated hydrodynamic processes, particularly those at the air-water interface, remain poorly understood. Here, we explore the response of (including colony size and migration dynamics) to varying magnitudes and durations of intermittent wind disturbances in a mesocosm system. The flow velocities, size of colonies, and the areal coverage of the water surface by scum were measured through video observations. Our results demonstrate that low wind speeds increase colony size by providing a stable condition where forms a scum layer and aggregates into large colonies at the air-water interface. In contrast, wind disturbances disperse scum and generate turbulence, resulting in smaller colonies with higher magnitudes of wind disturbance. We observed that surface scum can form rapidly following a long period (6 h) of high-magnitude (4.5 m s) wind disturbance. Furthermore, our results indicate reduced water surface tension caused by the presence of , which can decrease surface flow velocity and counteract wind-driven mixing. The reduced surface tension may also drive lateral convection at the water surface. These findings suggest that reduces surface tension, likely by releasing surface-active materials, as an adaptive response to various wind conditions. This could result in an increased rate of surface scum re-formation under wind conditions and potentially facilitate the lateral expansion of scum patches during weak wind periods. This study reveals new insights into how copes with different wind conditions and highlights the importance of the air-water interface for scum dynamics.
由于气候变化，全球水生生态系统中藻华出现的频率越来越高。风力产生的湍流是一种关键的环境压力源，它能使表层浮沫垂直扩散，减少其光照。然而，浮沫与风力产生的水动力过程之间的相互作用，尤其是气 - 水界面处的相互作用，仍知之甚少。在这里，我们在中宇宙系统中探究了（包括群体大小和迁移动态）对不同强度和持续时间的间歇性风扰动的响应。通过视频观测测量了流速、群体大小以及浮沫覆盖水面的面积。我们的结果表明，低风速通过提供一个稳定条件来增加群体大小，在这个条件下，在气 - 水界面形成浮沫层并聚集成大群体。相反，风扰动会驱散浮沫并产生湍流，导致在更强的风扰动下群体更小。我们观察到，在长时间（6小时）高强度（4.5米/秒）的风扰动之后，表层浮沫能够迅速形成。此外，我们的结果表明，的存在会导致水表面张力降低，这会降低表面流速并抵消风驱动的混合作用。表面张力的降低也可能驱动水面的横向对流。这些发现表明，可能通过释放表面活性物质来降低表面张力，作为对各种风况的适应性反应。这可能导致在有风条件下表面浮沫重新形成的速率增加，并有可能在微风期促进浮沫斑块的横向扩展。这项研究揭示了有关如何应对不同风况的新见解，并突出了气 - 水界面对于浮沫动态的重要性。
