Algal blooms and sediment diatoms are crucial indicators of lake water ecology, influenced by water quantity and quality. However, the coupled effects of water quality and quantity changes on algal blooms are still unclear, especially for lakes in cold and arid regions. This study assessed the long-term variations in algal blooms in Hulun Lake using a novel approach combining remote sensing and sediment core samples for diatom analysis. Two mutation points from the structural change test were identified in approximately 2000 and 2010 for algal bloom area (MBE) and sediment diatom richness, indicating asynchronous algal blooms. A structural equation model (SEM) demonstrated that water level (WL) changes were the dominant influencing factor, co-driving the variations in algal blooms and sediment diatoms in conjunction with total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD). The results revealed nonlinear relationships between the lake WL, TN, Chla, and COD. The water level of 543 m emerged as a critical threshold affecting the relationship between water quality and quantity. Distinct differences in this relationship were observed when water levels were above or below this threshold. These variations became particularly pronounced during periods of high and low water levels. The results provide novel insights into the dynamics of algal blooms and can further support lake ecosystem conservation and management.

中文翻译：

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遥感与泥沙岩心双重视角下水质和水量对呼伦湖藻华耦合效应的梳理


藻华和沉积物硅藻是湖泊水生态的关键指标，受水量和水质的影响。然而，水质和水量变化对藻类大量繁殖的耦合影响仍不清楚，尤其是对于寒冷和干旱地区的湖泊。本研究使用一种结合遥感和沉积物岩芯样品进行硅藻分析的新方法评估了呼伦湖藻华的长期变化。大约在 2000 年和 2010 年，从结构变化测试中确定了藻华面积 （MBE） 和沉积物硅藻丰富度的两个突变点，表明非同步藻华。结构方程模型 （SEM） 表明，水位 （WL） 变化是主要影响因素，与总氮 （TN）、总磷 （TP） 和化学需氧量 （COD） 共同驱动藻华和沉积物硅藻的变化。结果揭示了 WL 湖、 TN 、 Chla 和 COD 之间的非线性关系。543 m 的水位成为影响水质和水量之间关系的关键阈值。当水位高于或低于此阈值时，观察到这种关系存在明显差异。这些变化在高水位和低水位期间变得尤为明显。这些结果为藻华的动态提供了新的见解，可以进一步支持湖泊生态系统的保护和管理。