Zou Songbao, Lian Qingping, Ni Meng, Zhou Dan, Liu Mei, Zhang Xin, Chen Guangmei, Yuan Julin
Key Laboratory of Healthy Freshwater Aquaculture, Ministry of Agriculture and Rural Affairs, Huzhou, Zhejiang, China.
Key Laboratory of Fish Health and Nutrition of Zhejiang Province, Huzhou, Zhejiang, China.
Front Microbiol. 2024 Feb 19;15:1351772. doi: 10.3389/fmicb.2024.1351772. eCollection 2024.
Microeukaryotes play crucial roles in the microbial loop of freshwater ecosystems, functioning both as primary producers and bacterivorous consumers. However, understanding the assembly of microeukaryotic communities and their functional composition in freshwater lake ecosystems across diverse environmental gradients remains limited. Here, we utilized amplicon sequencing of 18S rRNA gene and multivariate statistical analyses to examine the spatiotemporal and biogeographical patterns of microeukaryotes in water columns (at depths of 0.5, 5, and 10 m) within a subtropical lake in eastern China, covering a 40 km distance during spring and autumn of 2022. Our results revealed that complex and diverse microeukaryotic communities were dominated by Chlorophyta (mainly Chlorophyceae), Fungi, Alveolata, Stramenopiles, and Cryptophyta lineages. Species richness was higher in autumn than in spring, forming significant hump-shaped relationships with chlorophyll concentration (Chl-, an indicator of phytoplankton biomass). Microeukaryotic communities exhibited significant seasonality and distance-decay patterns. By contrast, the effect of vertical depth was negligible. Stochastic processes mainly influenced the assembly of microeukaryotic communities, explaining 63, 67, and 55% of community variation for spring, autumn, and both seasons combined, respectively. Trait-based functional analysis revealed the prevalence of heterotrophic and phototrophic microeukaryotic plankton with a trade-off along N:P ratio, Chl-, and dissolved oxygen (DO) gradients. Similarly, the mixotrophic proportions were significantly and positively correlated with Chl- and DO concentrations. Overall, our findings may provide useful insights into the assembly patterns of microeukaryotes in lake ecosystem and how their functions respond to environmental changes.
微型真核生物在淡水生态系统的微生物环中发挥着关键作用，既是初级生产者，也是食细菌消费者。然而，对于不同环境梯度下淡水湖泊生态系统中微型真核生物群落的组装及其功能组成的了解仍然有限。在此，我们利用18S rRNA基因的扩增子测序和多变量统计分析，研究了中国东部一个亚热带湖泊水柱（0.5米、5米和10米深度）中微型真核生物的时空和生物地理模式，该研究覆盖了2022年春秋两季40公里的距离。我们的结果表明，复杂多样的微型真核生物群落以绿藻门（主要是绿藻纲）、真菌、囊泡虫、不等鞭毛类和隐藻门谱系为主。秋季的物种丰富度高于春季，与叶绿素浓度（Chl-，浮游植物生物量的指标）形成显著的驼峰状关系。微型真核生物群落表现出显著的季节性和距离衰减模式。相比之下，垂直深度的影响可以忽略不计。随机过程主要影响微型真核生物群落的组装，分别解释了春季、秋季以及两个季节合并时群落变异的63%、67%和55%。基于特征的功能分析揭示了异养和光养微型真核浮游生物的普遍存在，它们在氮磷比、叶绿素浓度和溶解氧（DO）梯度上存在权衡。同样，混合营养比例与叶绿素浓度和溶解氧浓度显著正相关。总体而言，我们的研究结果可能为湖泊生态系统中微型真核生物的组装模式以及它们的功能如何响应环境变化提供有用的见解。
