生物多样性 ›› 2023, Vol. 31 ›› Issue (7): 23092.  DOI: 10.17520/biods.2023092

• 研究报告: 植物多样性 • 上一篇    下一篇

确定性过程主导高原典型河流浮游植物地理分布格局和群落构建

杨胜娴1,2,3, 杨清1,2,3, 李晓东1,2,3, 巢欣1,2,3, 刘惠秋1,2,3, 魏蓝若雪1,2,3, 巴桑1,2,3,*()   

  1. 1.西藏大学麦地卡自治区级湿地生态系统定位观测研究站, 西藏那曲 852000
    2.西藏大学生态环境学院青藏高原湿地与流域生态系统实验室, 拉萨 850000
    3.西藏大学地球第三极碳中和研究中心, 拉萨 850000
  • 收稿日期:2023-03-30 接受日期:2023-06-14 出版日期:2023-07-20 发布日期:2023-07-31
  • 通讯作者: *E-mail: basang2003@utibet.edu.cn
  • 作者简介:*E-mail: basang2003@utibet.edu.cn
  • 基金资助:
    国家自然科学基金(32070418);2022年中央支持地方高校发展专项资金项目(藏财预指[2022] 1号)

Deterministic processes dominate the geographic distribution pattern and community assembly of phytoplankton in typical plateau rivers

Shengxian Yang1,2,3, Qing Yang1,2,3, Xiaodong Li1,2,3, Xin Chao1,2,3, Huiqiu Liu1,2,3, Lanruoxue Wei1,2,3, Sang Ba1,2,3,*()   

  1. 1. Provincial Level of Mitika Wetland Ecosystem Observation and Research Station in Tibet Autonomous Region, Naqu, Xizang 852000
    2. Laboratory of Tibetan Plateau Wetland and Watershed Ecosystem, School of Ecology and Environment, Tibet University, Lhasa 850000
    3. Center for Carbon Neutrality in the Earth's Third Pole, Tibet University, Lhasa 850000
  • Received:2023-03-30 Accepted:2023-06-14 Online:2023-07-20 Published:2023-07-31
  • Contact: *E-mail: basang2003@utibet.edu.cn

摘要:

浮游植物在河流生态系统的生物地球化学循环中起着重要作用, 然而, 雅鲁藏布江作为我国典型的高寒河流, 关于调控其浮游植物群落结构的机制尚不清楚。为探究雅鲁藏布江中上游浮游植物群落分布格局及其构建机制, 我们于2019年8月(夏季)、11月(秋季)和2020年5月(春季)对该水域进行了浮游植物样品采集、鉴定及水体理化因子测定。通过固定染色法鉴定浮游植物物种、统计物种丰度。结果表明: 雅鲁藏布江中上游共鉴定浮游植物452种, 隶属8门11纲24目44科121属。浮游植物群落的构建由环境异质性、扩散限制和物种互作关系共同影响。研究区域浮游植物群落在时空上存在显著的地理距离衰减趋势和环境距离衰减趋势; 物种互作关系以协作关系为主; 地理因素中的海拔(ALT)与水环境因子中的酸碱度(pH)、总溶解性固体(TDS)、盐度(Salt)、溶解氧(DO)、浊度(TUR)和水流速度(V)是驱动雅鲁藏布江中上游浮游植物群落构建的重要影响因子, 可通过驱动浮游植物自身的代谢速率及其生态适应性影响群落的地理分布和时空分布格局, 间接介导浮游植物群落的构建过程。距离衰减和中性模型结果表明: 确定性(环境选择)主导了雅鲁藏布江中上游的浮游植物群落构建。

关键词: 雅鲁藏布江中上游, 浮游植物, 群落构建, 地理分布格局

Abstract

Aims: Phytoplankton play a crucial role in biogeochemical cycling of river ecosystems. The ecological environment of the Yarlung Zangbo River, a major representative of high-altitude plateau rivers, is highly complex and more fragile than typical rivers of a lower altitude. Therefore, it features unique geographical characteristics which define the regions biology and ecology. This study aims to elucidate the spatial and temporal distribution patterns and the assembly mechanisms of the phytoplankton community in the middle and upper reaches of the Yarlung Zangbo River and to provide important data reference for the follow-up study of phytoplankton and water environment protection in the Yarlung Zangbo River in Tibetan Plateau.

Methods: In this study, phytoplankton in the middle and upper reaches of the Yarlung Zangbo River were investigated in summer (August 2019), autumn (November 2019) and spring (May 2020). Phytoplankton samples were collected and identified with strict qualitative and quantitative measures, while the physicochemical water features were measured on site. Simpson diversity index, Pielou evenness index and richness index were used to analyze α-diversity. The spatial and temporal differences of the phytoplankton community structure were analyzed by principal coordinate analysis (PCoA) and analysis of similarities (ANOSIM). Neutral models and standardized random rates were used to determine the relative proportions of deterministic and stochastic processes in phytoplankton community assembly. The effects of environmental heterogeneity (environmental distance) and diffusion limitation (geographical distance) on the process of phytoplankton community assembly were investigated through distance-decay patterns. Mantel test (Spearman correlation coefficient) was used to calculate the correlation between phytoplankton abundance and environmental factor distance in each season. Furthermore, network co-occurrence was used to analyze phytoplankton community interactions.

Results: We identified a total of 452 distinct phytoplankton species in the middle and upper reaches of the Yarlung Zangbo River, encompassing 8 phyla, 11 classes, 24 orders, 44 families, and 121 genera. The assembly of phytoplankton communities was found to be influenced by the combined effects of environmental heterogeneity, dispersal limitation, and species interactions. Interestingly, in season (from spring to autumn), we observed a transformation from stochastic to deterministic process, whereas at altitudes (from YJA gradient to YJC gradient), we observed a transition from deterministic to stochastic and then to deterministic. Geographical features along with water quality parameters were identified as pivotal drivers shaping the assembly of phytoplankton communities in the upper reaches of the Yarlung Zangbo River and exhibited pronounced distance-decay patterns, both spatially and temporally.

Conclusion: The middle and upper reaches of the Yarlung Zangbo River were vastly different in both spatial and temporal features, leading to a significant change in phytoplankton ecology between the two regions. Species interactions, environmental heterogeneity and dispersal limitation all play a role in the assembly of phytoplankton communities. Among them, deterministic process (environmental heterogeneity) dominates its assembly process.

Key words: middle and upper reaches of the Yarlung Zangbo River, phytoplankton, community assembly, geographical distribution pattern