In the summer of 2021, two typhoons, Typhoon Cempaka and Typhoon Lupit, passed through the Pearl River Estuary (PRE), resulting in a noticeable chlorophyll-a (Chla) bloom event on the west side of the PRE. Utilizing a coupled hydrodynamic-ecological model (ROMS-CoSiNE), we investigated the changes in the marine environment during the two-typhoon period and explored the underlying mechanisms involved. Our model effectively reproduces the spatial characteristics of the typhoon-induced algal blooms. The results suggest that the westward invasion of the Pearl River plume has a predominant impact on the alterations in biochemical elements. For further quantitative analyses, we utilized the model to determine the Chla concentration budget in algal bloom region to assess the dominant mechanism, particularly focusing on horizontal advection. Our findings indicated that algal bloom events are mainly attributed to a straightforward physical mechanism, namely, phytoplankton transportation, rather than to nutrient-induced phytoplankton growth. The study also revealed that the different growth processes of the two simulated phytoplankton species did not contribute positively to the increased Chla concentrations. However, further research is needed to investigate the impacts of different phytoplankton functional groups on the marine ecological environment under the influence of typhoons. This study enhances the understanding of the response of ecological environments in coastal areas to typhoons.

中文翻译：

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2021年夏季台风对珠江口生态环境的影响——一次藻华事件研究


2021年夏季，两场台风“千百卡”和“卢皮”穿过珠江口（PRE），导致珠江口西侧出现明显的叶绿素a（Chla）水华事件。利用水动力生态耦合模型（ROMS-CoSiNE），我们研究了两次台风期间海洋环境的变化，并探讨了其中的潜在机制。我们的模型有效地再现了台风引起的藻华的空间特征。结果表明，珠江羽流的西侵对生化元素的变化具有显着影响。为了进一步定量分析，我们利用该模型确定藻华区域的 Chla 浓度预算，以评估主导机制，特别是水平平流。我们的研究结果表明，藻华事件主要归因于一种简单的物理机制，即浮游植物运输，而不是营养诱导的浮游植物生长。研究还表明，两种模拟浮游植物物种的不同生长过程并未对叶绿素浓度的增加产生积极影响。但台风影响下不同浮游植物功能类群对海洋生态环境的影响还需要进一步研究。这项研究增强了人们对沿海地区生态环境对台风响应的认识。