基于环境DNA的洞庭湖丰水期浮游植物生物完整性指数健康评价

Abstract

In recent years, anthropogenic activities have exacerbated lake eutrophication and reduced biodiversity. As China's second-largest freshwater lake, Dongting Lake has attracted widespread attention regarding its ecological health. To evaluate the lake's health status during the wet season, 25 environmental DNA (eDNA) samples were collected from Dongting Lake and eDNA metabarcoding was employed to identify phytoplankton taxa, and establish a phytoplankton index of biotic integrity (P-IBI) based on eDNA technology. The comprehensive trophic level index (∑TLI), based on Chlorophyll- a (Chl a ), total nitrogen (TN), and total phosphorus (TP), derived from physicochemical water quality parameters, was used to validate the P-IBI results. A total of 456 phytoplankton taxa were identified, belonging to 7 phyla, 15 classes, 35 orders, 70 families, and 155 genera. The phytoplankton community was characterized by a Chlorophyta–Bacillariophyta structure, with Chlorophyta and Bacillariophyta being absolutely dominant. The overall health status of Dongting Lake was categorized as "Fair". Correlation analysis revealed a significant negative relationship between P-IBI and ∑TLI. The eDNA-based P-IBI demonstrated reasonable reliability for assessing the wet season ecological health of Dongting Lake, confirming its applicability for river-connected lakes in the middle–lower Yangtze River basin. This study provides valuable insights for ecological health assessments of lakes in this region.