Characteristics and niche analysis of periphyton communities in mainstream of Yalong River

Abstract

[Objective] To investigate the current status of periphyton communities across the entire mainstream of the Yalong River and the community differences among different river sections. [Methods] Based on a sampling survey of periphyton in 29 cross-sections of the Yalong River mainstream in May 2023, combined with habitat evaluation, the variations in periphyton community structure and the ecological niches of dominant species across different river sections were analyzed. Redundancy analysis(RDA) and Pearson correlation analysis were used to examine the responses of dominant species to environmental factors. [Results] The result showed that a total of 96 species of periphyton were collected, with Bacillariophyta accounting for 89.6%. In the upper reaches, 77 species were identified, with an average cell density of 4 296.3 cells/cm². The dominance of dominant species was relatively balanced, with niche width ranging from 1.35 to 2.05 and niche overlap at 0.628, significantly higher than those in both the better and poorer habitat sections of the middle and lower reaches. This indicated that the upper reaches, unaffected by dam construction, exhibited a more stable composition of periphyton communities, lower interspecies competition, and stronger ability to utilize environmental resources. The RDA and Pearson analysis result showed that the dominant species of periphyton were positively correlated with ammonia nitrogen, conductivity, total carbon, dissolved total silicon, and ammonium nitrate, but negatively correlated with dissolved oxygen, water temperature, and dissolved total carbon. [Conclusion] It has been demonstrated that the construction of hydropower stations in the middle and lower reaches of the Yalong River affects certain environmental factors, leading to significant differences in the characteristics of periphyton communities across different river sections. The findings provide a reference for aquatic ecological conservation and restoration in the Yalong River.

Keywords

periphyton / niche width / water environment / environmental factor / climate impact / influence factor / Yalong River