Using Environmental DNA to Assess Fish Communities Post‐Waterway Regulation in the Yangtze River

Aquatic ecosystems, essential for global biodiversity and human health, are increasingly threatened by hydraulic engineering projects. This study examines the impact of waterway regulation on fish communities in the Jiujiang section of the Yangtze River using environmental DNA (eDNA) technology. Water samples were collected from multiple locations within and outside the construction areas during the low and high water periods (HWPs) of 2022 and 2023. The results reveal differences in fish community composition and diversity between construction and nonconstruction areas, as well as between low and HWPs. Notably, fish diversity was higher during HWPs, with Cyprinidae being the predominant family in the study area. Canonical correspondence analysis (CCA) identified pH and water temperature as key environmental factors affecting fish communities. This study demonstrates the effectiveness of eDNA technology in monitoring aquatic ecosystems and provides valuable insights for the sustainable management and conservation of regulated waterways. The findings highlight the necessity of long‐term ecological monitoring to address the negative impacts of hydraulic engineering projects.