Taylor Jackie, Calderer M Carme, Hondzo Miki, Voller Vaughan R
St. Anthony Falls Laboratory Minneapolis Minnesota USA.
Department of Civil, Environmental and Geo Engineering University of Minnesota, Twin Cities Minneapolis Minnesota USA.
Ecol Evol. 2022 Jul 3;12(7):e9042. doi: 10.1002/ece3.9042. eCollection 2022 Jul.
Climate change is leading to an increase in severity, frequency, and distribution of harmful algal blooms across the globe. For many harmful algae species in eutrophic lakes, the formation of such blooms is controlled by three factors: the lake hydrodynamics, the vertical motility of the algae organisms, and the ability of the organisms to form colonies. Here, using the common cyanobacterium as an example, we develop a model that accounts for both vertical transport and colony dynamics. At the core of this treatment is a model for aggregation. For this, we used Smoluchowski dynamics containing parameters related to Brownian motion, turbulent shear, differential setting, and cell-to-cell adhesion. To arrive at a complete description of bloom formation, we place the Smoluchowski treatment as a reaction term in a set of one-dimensional advection-diffusion equations, which account for the vertical motion of the algal cells through molecular and turbulent diffusion and self-regulating buoyant motion. Results indicate that Smoluchowski aggregation qualitatively describes the colony dynamics of . Further, the model demonstrates wind-induced mixing is the dominant aggregation process, and the rate of aggregation is inversely proportional to algal concentration. Because blooms of typically consist of large colonies, both of these findings have direct consequences to harmful algal bloom formation. While the theoretical framework outlined in this manuscript was derived for , both motility and colony formation are common among bloom-forming algae. As such, this coupling of vertical transport and colony dynamics is a useful step for improving forecasts of surface harmful algal blooms.
气候变化正导致全球有害藻华的严重程度、发生频率和分布范围增加。对于富营养化湖泊中的许多有害藻类物种而言，此类藻华的形成受三个因素控制：湖水动力学、藻类生物的垂直运动性以及生物形成群体的能力。在此，我们以常见的蓝细菌为例，开发了一个既考虑垂直输运又考虑群体动态的模型。这种处理方法的核心是一个聚集模型。为此，我们使用了包含与布朗运动、湍流剪切、差异沉降以及细胞间黏附相关参数的斯莫卢霍夫斯基动力学。为了全面描述藻华的形成，我们将斯莫卢霍夫斯基处理方法作为一个反应项置于一组一维平流 - 扩散方程中，这些方程考虑了藻类细胞通过分子扩散、湍流扩散以及自我调节的浮力运动的垂直运动。结果表明，斯莫卢霍夫斯基聚集定性地描述了[具体藻类名称未给出]的群体动态。此外，该模型表明风致混合是主要的聚集过程，并且聚集速率与藻类浓度成反比。由于[具体藻类名称未给出]的藻华通常由大群体组成，这两个发现都对有害藻华的形成有直接影响。虽然本手稿中概述的理论框架是针对[具体藻类名称未给出]推导出来的，但运动性和群体形成在形成藻华的藻类中都很常见。因此，这种垂直输运与群体动态的耦合是改进对表层有害藻华预测的有益一步。
