Urban-rural interface watersheds exhibit distinct ecological characteristics due to the reciprocal influence of human activities and natural processes. The Qian Lake water system, a typical water body at the urban-rural interface, exhibits phytoplankton community characteristics that serve as critical indicators of the region’s ecological health. To examine the community structure of phytoplankton and its environmental drivers in the Qian Lake water system, a systematic survey of phytoplankton and water physicochemical parameters was conducted. Algal biological indicators were used to evaluate the nutrient status of the water body. Redundancy analysis (RDA) was employed to explore the correlations between phytoplankton and environmental factors. The findings revealed a total of 112 phytoplankton species across seven phyla, with Chlorophyta being the most abundant (35.7% of total species), followed by Bacillariophyta, which accounted for 27.7%. Diatoms were the dominant species group (Y = 0.20), likely due to soil erosion caused by suburban expansion and their high efficiency in utilizing dissolved silicon (DSi) in the water. The phytoplankton density ranged from 19.59 × 104 to 61.22 × 104 cells/L, with a mean density of 34.04 × 104 cells/L. The biomass ranged from 0.27 to 0.54 mg/L, with an average of 0.38 mg/L. Furthermore, the community structure of the phytoplankton was of the Bacillariophyta-Chlorophyta type. According to algal biological evaluation criteria, the Qian Lake water system was classified as mildly polluted, and the Pielou uniformity index (J) was less than 0.8, indicating weak stability; RDA and environmental coupling analysis showed that pH, and suspended solids (SS) were the main factors influencing the community structure of phytoplankton in the Qian Lake water system, and the spatial distribution of phytoplankton was co-regulated by nutrient availability, DO availability, and hydraulic conditions (flow velocity, depth of water). These findings provide essential data and theoretical insights for water ecological management and health assessment in urban-rural interface watersheds.
Wang et al. (Thu,) studied this question.