Characteristics and mechanisms of aquatic ecological evolution in water-carrying lakes under the influence of retreating polder
退圩还湖影响下过水型湖泊水生态演变特征及影响机制

摘要

圩垸养殖等人类活动对湖泊水生态健康造成巨大挑战，影响南水北调东线湖泊群水质稳定，而退圩还湖等生态工程的实施有望实现湖泊水生态系统的重构与修复。为系统探究退圩还湖对南水北调东线过水型湖泊水生态系统的影响，选取了典型过水型湖泊骆马湖作为研究区域，系统揭示了退圩还湖下过水型湖泊水生态要素时空分布特征，采用典型对应分析（CCA）与层次分割分析（HP）等方法解析湖泊水生态系统的响应机制及关键影响因子，构建基于关键影响因子的水污染指数（WPI）评价方法，量化退圩还湖影响下湖泊水生态健康状况变化。结果表明，退圩还湖后，退圩区水体透明度有所提升，但高锰酸盐指数和氨氮浓度均有所升高，且叶绿素a浓度显著高于其他区域（27.43 µg/L），蓝藻浓度整体较高，部分监测点位出现严重水华现象。此外，该区域水生生物水生生态系统呈现一定的恢复趋势，多样性指数（1.78–2.66）与均匀度（0.60–0.67）均处于较高水平。进一步分析表明，不同环境因子对水生生物群落的调控作用存在显著差异。总体而言，总氮、氨氮、高锰酸盐指数和溶解氧被识别为影响骆马湖水生态健康的关键环境因子。本研究系统揭示了退圩还湖影响下的水生态演变特征及机制，为保障南水北调东线湖泊水质提供了理论依据及技术支撑。

Abstract

Human activities such as polder aquaculture have posed significant challenges to the ecological health of lakes, affecting the water quality stability of the water-carrying lake system along the Eastern Route of the South-to-North Water Diversion Project. The implementation of ecological restoration projects such as retreating polder holds promise for reconstructing and rehabilitating lake ecosystems. To systematically explore the impact of retreating polder on the aquatic ecosystem of water-carrying lakes along the Eastern Route, Lake Luoma—a typical water-carrying lake—was selected as the study area. This study comprehensively examined the spatial and temporal distribution characteristics of aquatic ecological elements under the influence of retreating polder and applied Canonical Correspondence Analysis (CCA) and Hierarchical Partitioning (HP) analysis to elucidate the response mechanisms and key influencing factors of the lake ecosystem. Based on these key factors, a Water Pollution Index (WPI) evaluation method was developed to quantify changes in aquatic ecological health under the influence of retreating polder. The results showed that following the retreating polder, water transparency in the polder-retreated area improved, but the permanganate index and ammonia nitrogen concentration increased. Meanwhile, chlorophyll-a concentration was significantly higher than in other regions (27.43 µg/L), with an overall high abundance of cyanobacteria, and severe algal blooms were observed at certain monitoring sites. Additionally, the aquatic biological community in this region exhibited signs of recovery, with relatively high diversity indices (1.78–2.66) and evenness values (0.60–0.67). Further analysis revealed significant differences in the regulatory effects of various environmental factors on aquatic biological communities. Overall, total nitrogen, ammonia nitrogen, the permanganate index, and dissolved oxygen were identified as key environmental factors influencing the ecological health of Lake Luoma. This study systematically elucidates the ecological evolution characteristics and mechanisms of water-carrying lakes under the influence of retreating polder, providing theoretical foundations and technical support for safeguarding water quality in lakes along the Eastern Route of the South-to-North Water Diversion Project.