水体硅碳化学计量趋同的浮游植物驱动机制

doi:10.13745/j.esf.sf.2025.3.22

摘要/Abstract

摘要：

浮游植物元素化学计量比对其生境中营养元素可利用性变化的响应与反馈研究,是理解水生生态系统结构和功能相互关系的关键要素。水体中硅(Si)碳(C)化学计量比的动态变化一定程度上能够反映其中Si-C生物地球化学循环的耦合关系,但目前浮游植物Si∶C计量比与溶解硅(DSi)和CO₂浓度的相互作用模式和潜在机制尚不清楚。在此,我们发现湖泊浮游植物Si∶C摩尔比随年际变化趋向于与其生境中DSi∶CO₂摩尔比一致(即硅碳化学计量趋同),且这种趋同是由浮游植物群落演替来驱动的。不同类型内陆水体(河流、湖泊、水库和湿地)大空间尺度调查结果显示浮游植物Si∶C摩尔比和DSi∶CO₂摩尔比空间差异显著,大都偏离Redfield比例。随机森林分析显示,硅藻门相对丰度、水温和溶解无机氮是浮游植物Si∶C比形成的重要预测因子。宏转录组学证据表明,伴随着浮游植物群落演替,其分子水平上蛋白质周转响应并反馈DSi∶CO₂比变化,进而导致水体硅碳化学计量趋同。这些发现为水体浮游植物化学计量学的认识提供了新的见解。硅碳化学计量趋同在一定程度上可以表征表层地球系统岩石圈、水圈和生物圈之间的相互作用,并为描述水生生态系统结构和功能对环境变化的响应提供了一种定量模式。

关键词: 水生生态系统, 浮游植物, 化学计量比, 群落组成, 宏转录组

Abstract:

The response and feedback of phytoplankton elemental stoichiometry to their ambient available nutrients is a vital approach to understand the relationship between structure and function of aquatic ecosystems. The change of silicon (Si) to carbon (C) stoichiometric ratio in water can reflect the coupling of Si-C biogeochemical cycles to some extent; however, the pattern of phytoplankton Si∶C ratio interacting with the ambient dissolved silicon (DSi) and CO₂ and the underlying mechanisms are still unclear yet. Here, we found that phytoplankton Si∶C molar ratio converged towards the DSi∶CO₂ molar ratio with years (i.e., Si-C stoichiometric convergence), and this convergence was driven by phytoplankton community succession in lakes. The large-scale survey across different inland waters (including rivers, lakes, reservoirs, and wetlands) showed that there was significant spatial difference in phytoplankton Si∶C and DSi∶CO₂ molar ratios, and most of them deviated greatly from the Redfield ratio. Random forest analysis indicated that the relative abundance of diatoms, water temperature, and dissolved inorganic nitrogen were important predictive factors for phytoplankton Si∶C ratio. Metatranscriptomic evidence suggested that phytoplankton community succession and its matched protein turnover in response to the changing DSi∶CO₂ ratio resulted in a Si-C stoichiometric convergence in water. The study will provide some new insights into phytoplankton stoichiometry, and the Si-C stoichiometric convergence could characterize the interaction between the lithosphere, hydrosphere, and biosphere in surface-earth system to some extent and provide a quantitative pattern for describing the structure and function of aquatic ecosystems in response to environmental changes.

Key words: aquatic ecosystems, phytoplankton, stoichiometric ratio, community composition, metatranscriptome

中图分类号:

P593
X171

李婉珠, 王宝利, 刘丛强. 水体硅碳化学计量趋同的浮游植物驱动机制[J]. 地学前缘, 2025, 32(3): 311-319.

LI Wanzhu, WANG Baoli, Liu Cong-Qiang. The mechanism of phytoplankton-driven silicon and carbon stoichiometric convergence in water[J]. Earth Science Frontiers, 2025, 32(3): 311-319.

图/表 6

图1 水体理化因子数据分布概况红线表示中位值。

Fig.1 Distribution of physical and chemical parameters in water

图2 英国湖区湖泊硅碳化学计量比中位值的季节(a)和年际变化(b) 蓝色箭头表示随时间硅碳化学计量比的变化方向,灰色线表示硅碳化学计量平衡线y=x。

Fig.2 Seasonal (a) and interannual (b) variations in silicon and carbon stoichiometric median ratios in the lakes of English Lake District, UK

图3 英国湖区湖泊硅碳化学计量比随时间变化趋势波形图表示硅碳化学计量比的季节变化,直线表示随时间硅碳化学计量比的年际变化趋势。

Fig.3 Trends of silicon and carbon stoichiometric ratios with time in the lakes of English Lake District, UK

图4 硅碳化学计量比的随机森林分析(a-c)及其与环境因子的相关性分析(d) 随机森林分析(a-c)中,**和*分别表示在0.01和0.05水平上的显著预测变量,%IncMSE为预测变量对响应变量的相对重要性;相关性分析(d)中,热图中数值表示显著相关(p < 0.05)的参数间相关性系数值。

Fig.4 Random forest analyses of environmental parameters for silicon and carbon stoichiometric ratios (a-c) and their Pearson correlation analyses (d)

图5 天津水库宏转录组代谢途径(a)和浮游植物群落组成(b)及其与水体硅碳化学计量比的相关性分析(c) 渤龙湖(BLH)、潮白河支流(CBH1)、潮白河(CBH)、海河(HH)、团泊洼支流(TBW1)、团泊洼水库(TBW)、永定河(YDH)、于桥水库(YQ)和东丽湖(DLH)为各采样点,采样点细节引自文献[20];相关性分析中,热图中数值表示显著相关(p < 0.05)的参数间相关性系数值。

Fig.5 Metabolic pathways in metatranscriptomic analysis (a), phytoplankton community composition (b), and their Pearson correlation analyses (c) in the Tianjin’s reservoirs

图6 硅碳化学计量比在内陆水体和海洋中的分布特征海洋中硅碳化学计量比为平均值,引自文献[9]。本文中内陆水体硅碳化学计量比为中位值;箭头表示硅碳化学计量比向平衡线移动的方向;灰色线表示硅碳化学计量平衡线y=x。

Fig.6 Distribution of silicon and carbon stoichiometric ratios in inland waters and ocean

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