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<p>This study investigates the community composition, ecological niche characteristics of dominant species, and interspecific associations of periphytic algae in the middle reaches of the Yarlung Zangbo River. Field surveys and sample collections were conducted in October 2023 (autumn), February 2024 (winter), and May 2024 (spring) along the river section from Zhanang County to Luxia Bridge. A comprehensive analysis of the periphytic algal communities across the three seasons was performed using co-occurrence network analysis, niche breadth indices, and interspecific association metrics. The results revealed that the communities were predominantly composed of Bacillariophyta, Chlorophyta, and Cyanophyta, which accounted for 88.67% of the total algal density. Notable seasonal variations in community composition were observed, although diatoms consistently remained the dominant group throughout all seasons. Co-occurrence network analyses demonstrated well-defined modular structures in each season (modularity coefficient <i>Q</i> &gt; 0.3), with the winter assemblages showing the highest levels of synergy and network stability. Niche analysis indicated that all dominant species, except <i>Eunotia</i> spp. (a specialist species with niche breadth <i>B</i><sub><i>i</i></sub> &lt; 1.5), exhibited generalist strategies (1.5 ⩽ <i>B</i><sub><i>i</i></sub> ⩽ 8.7). The highest niche overlap was recorded in spring, suggesting elevated levels of interspecific competition during this season. Interspecific association analysis showed significant positive correlations among dominant taxa across all seasons (<i>W</i> &gt; χ<Stack> <sub>0.05<i>N</i></sub> <sup>2</sup> </Stack>), with both the association coefficient (<i>AC</i>) and Jaccard index (JD) predominantly indicating positive associations. This pattern reflects a stable community structure characteristic of a positively progressing successional stage. Importantly, a strong positive association was detected between <i>Eunotia</i> spp. and <i>Nitzschia longissima</i> in spring (<i>AC</i> &gt; 0.6; 0.4 ⩽ <i>JD</i> &lt; 0.6), indicating their potential for stable coexistence. These taxa may serve as reliable bioindicators for evaluating aquatic ecosystem health during the spring season and are suitable for long-term ecological monitoring and assessment efforts. Overall, the findings offer key insights into the ecological dynamics of periphytic algal communities in plateau river systems and provide valuable baseline data to support the ecological evaluation of future hydropower development in the lower reaches of the Yarlung Zangbo River.</p>

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Analysis of ecological network and interspecific association characteristics of periphytic algae in the middle reaches of Yarlung Zangbo River

  • 期刊论文

  • 发表日期：

    2025年7月18日

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  • Kang Zhao,
  • Qinghui Zeng,
  • Wei Liu,
  • Yufei Bao,
  • Fengbo Zhang,
  • Jiaxuan Tang,
  • Pingfeng Li,
  • Yicheng Wang,
  • Peng Hu

摘要

This study investigates the community composition, ecological niche characteristics of dominant species, and interspecific associations of periphytic algae in the middle reaches of the Yarlung Zangbo River. Field surveys and sample collections were conducted in October 2023 (autumn), February 2024 (winter), and May 2024 (spring) along the river section from Zhanang County to Luxia Bridge. A comprehensive analysis of the periphytic algal communities across the three seasons was performed using co-occurrence network analysis, niche breadth indices, and interspecific association metrics. The results revealed that the communities were predominantly composed of Bacillariophyta, Chlorophyta, and Cyanophyta, which accounted for 88.67% of the total algal density. Notable seasonal variations in community composition were observed, although diatoms consistently remained the dominant group throughout all seasons. Co-occurrence network analyses demonstrated well-defined modular structures in each season (modularity coefficient Q > 0.3), with the winter assemblages showing the highest levels of synergy and network stability. Niche analysis indicated that all dominant species, except Eunotia spp. (a specialist species with niche breadth Bi < 1.5), exhibited generalist strategies (1.5 ⩽ Bi ⩽ 8.7). The highest niche overlap was recorded in spring, suggesting elevated levels of interspecific competition during this season. Interspecific association analysis showed significant positive correlations among dominant taxa across all seasons (W > χ 0.05N 2 ), with both the association coefficient (AC) and Jaccard index (JD) predominantly indicating positive associations. This pattern reflects a stable community structure characteristic of a positively progressing successional stage. Importantly, a strong positive association was detected between Eunotia spp. and Nitzschia longissima in spring (AC > 0.6; 0.4 ⩽ JD < 0.6), indicating their potential for stable coexistence. These taxa may serve as reliable bioindicators for evaluating aquatic ecosystem health during the spring season and are suitable for long-term ecological monitoring and assessment efforts. Overall, the findings offer key insights into the ecological dynamics of periphytic algal communities in plateau river systems and provide valuable baseline data to support the ecological evaluation of future hydropower development in the lower reaches of the Yarlung Zangbo River.