| 摘要: |
| 盐度是影响湖泊细菌群落最重要的环境因子之一，揭示盐度对细菌群落变化的影响对于深入理解水生生态系统细菌群落具有重要意义。本研究以青藏高原西南部的22个湖泊为对象，探讨33个沉积物样本的细菌丰富度、均匀度和群落组成，分析其随盐度梯度的变化规律，阐明其潜在的环境驱动因素。结果表明，变形菌门（Proteobacteria）、拟杆菌门（Bacteroidetes）和放线菌门（Actinobacteria）是青藏高原湖泊沉积物中的优势细菌门类，相对丰度分别为46.54%、12.41%和7.23%，总和达到整个细菌门类的66.18%。对于细菌α多样性，物种丰富度（R2=0.52, P < 0.001）和均匀度（R2=0.81, P < 0.001）均随盐度增加呈显著下降趋势；对于细菌β多样性， 基于非度量多维排列（NMDS）分析，细菌群落分布根据盐度可以分为三个显著的独立簇（Stress = 0.084），分别对应淡水、咸水和高盐环境。Mantel检验结果表明，相较于地理距离（R2=0.12，P < 0.05），湖泊沉积物细菌群落Bray-Curtis不相似性随盐度（R2=0.42，P < 0.001）的变化更为显著。方差分解分析和随机森林分析结果表明，细菌物种丰富度、均匀度和群落组成变化的最佳预测因子为盐度和PO43-等化学因素，整体贡献率分别为72.98%、59.82%和60.83%，其中盐度是丰富度、均匀度和群落组成变化的主要驱动因素，其相对贡献率分别为45.47%、79.18%和79.50%。进一步地，基于结构方程模型，湖泊沉积物细菌丰富度、均匀度和群落组成变化均受到盐度直接或间接的影响。本研究结果充分探讨了盐度对细菌群落变化的影响，揭示了青藏高原湖泊沉积物细菌组成及其环境驱动因素，为理解湖泊生态系统细菌群落对环境变化的响应提供科学支撑。 |
| 关键词: 湖泊 细菌群落 物种丰富度 物种均匀度 群落组成变化 环境驱动因素 |
| DOI： |
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| 基金项目:国家自然科学基金项目（面上项目，重点项目，重大项目） |
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| The salinity gradient distribution pattern and driving factors of bacterial communities in sediment of lakes on the Qinghai Tibet Plateau |
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CHEN Xingting1, DU Chenliang1, Wang Jianjun2, SHEN Ji1
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1.College of Geography and Ocean Science,Nanjing University;2.Key Laboratory of Lake and Watershed Science for Water Security,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences
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| Abstract: |
| Salinity is one of the most important environmental factors affecting bacterial communities in lake sediments. Revealing the impact of salinity on bacterial community changes is of great significance for a deeper understanding of bacterial communities in aquatic ecosystems. This study focuses on 22 lakes in the southwest of the Qinghai Tibet Plateau, explores the bacterial richness, evenness and community composition of 33 sediment samples, analyzes their changes with salinity, and elucidates their potential environmental driving factors. The results showed that Proteobacteria, Bacteroidetes and Actinobacteria were the dominant bacterial phyla in the sediment of lakes, with relative abundances of 46.54%, 12.41%, and 7.23%, respectively, totaling 66.18% of the entire bacterial phyla. For bacterial α Diversity, species richness (R2=0.52, P < 0.001), and evenness (R2=0.81, P < 0.001) show a significant downward trend with increasing salinity; For bacterial β Diversity, based on non-metric multidimensional permutation (NMDS) analysis, bacterial community distribution could be divided into three significant independent clusters (Stress=0.084) by salinity, corresponding to freshwater, saline and high salinity environments, respectively. The Mantel test results indicated that compared to geographical distance (R2=0.12, P < 0.05), the Bray Curtis dissimilarity of lake sediment bacterial communities varied more significantly with salinity (R2=0.42, P < 0.001). The results of variance decomposition analysis and random forest analysis indicated that the best predictive factors for changes in bacterial species richness, evenness and community composition were chemical factors such as salinity and PO43-, with overall contribution rates of 72.98%, 59.82%, and 60.83%, respectively. Among them, salinity is the main driving factor for changes in richness, evenness and community composition, with relative contribution rates of 45.47%, 79.18%, and 79.50%, respectively. Furthermore, relying on structural equation modeling, changes in bacterial richness, evenness and community composition in lake sediment were directly or indirectly affected by salinity. The results of this study fully explored the impact of salinity on bacterial community changes and revealed the bacterial composition and environmental driving factors of sediment in lakes on the Qinghai Tibet Plateau. This provides scientific support for understanding the response of bacterial communities in lake ecosystems to environmental changes. |
| Key words: lake bacterial community species richness species evenness community composition environmental driving factors |
