Analysis of aquatic community structure characteristics and water quality assessment of Chishui River during wet season

Abstract

[Objective] To investigate the characteristics of aquatic community structure and water quality in the Chishui River during the wet season, thereby providing important references for establishing water ecological assessment standards in the Yangtze River Basin. [Methods] During the wet season in 2023, field sampling surveys were conducted along the mainstream of the Chishui River. Redundancy analysis(RDA) and Pearson correlation were used to analyze the community structure characteristics of phytoplankton, zooplankton, zoobenthos, and periphytic algae. Water quality was assessed using aquatic biological indicators(dominant species indicator method and biodiversity indices) and physicochemical indices(water quality index, WQI, and comprehensive pollution index, CPI). [Results] The result showed that a total of 69 species of phytoplankton, 45 species of zooplankton, 30 species of zoobenthos, and 34 species of periphytic algae were collected. Dominant species included 7 phytoplankton, 7 zooplankton, 4 zoobenthos, and 3 periphytic algae. Physicochemical assessment indicated that the river was generally lightly polluted. Biological assessments, primarily based on plankton biodiversity indices, indicated light to moderate pollution. RDA and Pearson correlation analyses demonstrated that phytoplankton were affected by total nitrogen, total phosphorus, permanganate index, and conductivity. Zooplankton were affected by conductivity, total nitrogen, and ammonia nitrogen. Zoobenthos were influenced by ammonia nitrogen and dissolved oxygen. Periphytic algae were affected by dissolved oxygen and five-day biochemical oxygen demand. [Conclusion] During the wet season, plankton are significantly affected by environmental factors such as nutrients and pollutants. Both biological and physicochemical assessments indicate the presence of pollution in the Chishui River during the wet season. Continuous monitoring shows that there is a certain degree of recovery after the end of the wet season.

Keywords

Chishui River / aquatic organism / community structure / wet season / water quality assessment