Spatiotemporal distribution of phytoplankton community structure and its relationship with environmental factors in Hongze Lake, China

Abstract

Hongze Lake, which ranks as the fourth-largest freshwater lake in China, has considerable importance as a water transfer reservoir under the South-to-North Water Transfer Project. The evaluation of the lake's health and nutritional status could be achieved by the analysis of the phytoplankton community. Nevertheless, the understanding of the long-term phytoplankton dynamics in Hongze Lake after the implementation of the South-to-North Water Diversion remains insufficient. In this study, an investigation was conducted to analyze the community structure, distribution patterns, and environmental factors influencing the abundance of phytoplankton in Hongze Lake. The results of the study revealed that Hongze Lake showed seasonal variations in both the structure and biomass of its phytoplankton population. In fall, winter, and spring, Chlorophyta dominates, while Cryptophyta dominates in summer. Algae predominantly inhabit Chengzi Lake and Lihewa during the summer season. According to the redundancy analysis, temperature is positively correlated with algal abundance in summer but negatively correlated in spring and winter. Furthermore, the mantel analysis indicated that the abundance of different algal species was significantly correlated with dissolved oxygen and nutrient levels. The generalized linear model further clarified the contribution of environmental factors to algal abundance: total nitrogen (weights = 30.67%) ranked second in importance after temperature (weights = 34.52%). The results of this study provide insight into the alterations in the phytoplankton community within Hongze Lake following the implementation of the water transfer project. In addition, these findings offer valuable guidance for the regulation of lake water resources and water quality.