Background and aims

The intensification of climate change and increases in dam construction have altered the inherent hydrological rhythms of river-connected lakes and led to the formation of a new feature of lake sediment known as sediment hardening. However, changes in sediment characteristics caused by sediment hardening and their potential effects on submerged macrophytes remain unclear.

Methods

A field investigative study and mesocosm experimental study were performed in Dongting Lake to provide evidence on how variations in sediment hardening affect the physical, chemical, and microbial properties of sediments and subsequently impact the health of submerged macrophytes.

Results

Sediment hardening mainly changes the characteristics of the 0–20 cm sediment layer by increasing the proportion of macroaggregates, decreasing the bulk density (BD) and pH, and increasing the contents of sediment total nitrogen (TN), total phosphorus (TP), and organic carbon (SOC). Sediment type (hardened and unhardened) and depth (0–5, 10–15, and 20–25 cm) significantly influenced the richness indices of bacteria and fungi, with sediment type having the greatest effect on the fungal community composition and sediment depth having the greatest effect on the bacterial community composition. The combination of high water depth and sediment hardening resulted in shorter root systems in submerged macrophytes that are not conducive to growth.

Conclusion

Our study is the first to establish a link between sediment hardening and the growth and development of submerged macrophytes. Moreover, it highlights the potential role of sediment hardening and water level interactions in regulating the development and growth of submerged macrophytes in river-connected lakes.

中文翻译：

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沉积物硬化改变了沉积物的物理化学特性和微生物多样性，对沉没的大型植物具有潜在影响

 背景和目标

气候变化的加剧和大坝建设的增加改变了与河流相连的湖泊固有的水文节奏，并导致湖泊沉积物形成一个新的特征，称为沉积物硬化。然而，沉积物硬化引起的沉积物特性的变化及其对淹没大型植物的潜在影响仍不清楚。

 方法

在洞庭湖进行了一项田间调查研究和中宇宙实验研究，为沉积物硬化的变化如何影响沉积物的物理、化学和微生物特性以及随后影响沉没大型植物的健康提供证据。

 结果

沉积物硬化主要通过增加大团聚体比例、降低堆积密度 （BD） 和 pH 值，增加沉积物总氮 （TN） 、总磷 （TP） 和有机碳 （SOC） 含量来改变 0–20 cm 沉积层的特性。沉积物类型（硬化和未硬化）和深度（0-5、10-15 和 20-25 cm）显著影响细菌和真菌的丰富度指数，其中沉积物类型对真菌群落组成的影响最大，沉积物深度对细菌群落组成的影响最大。高水深和沉积物硬化的结合导致淹没的大型植物的根系较短，不利于生长。

 结论

我们的研究首次确定了沉积物硬化与沉没大型植物的生长发育之间的联系。此外，它强调了沉积物硬化和水位相互作用在调节河流相连湖泊中淹没大型植物发育和生长的潜在作用。