Oral Presentation World Lake Conference 2025

Since the 2007 water crisis, Lake Taihu has experienced severe algal blooms and elevated total phosphorus (TP) levels, with recent improvements showing 35-40% reduction in algal density and altered phytoplankton composition over the past two years. However, emerging challenges include localized 2-methylisoborneol (2-MIB) outbreaks and water quality rebound in eastern regions. Enhanced water exchange through diversion projects has shortened the lake's renewal cycle from >200 to 180 days, intensifying east-west water quality homogenization. Implementation of comprehensive measures including large-scale sediment dredging (over 100 million m³ removed) and decade-long fishing bans has contributed to ecological recovery. Analysis suggests reduced external phosphorus loading (annual input decreased by 28% since 2015) serves as the primary driver of improvement, though internal nutrient cycling maintains TP concentrations at 0.08-0.12 mg/L. The sustainability of these gains remains uncertain due to potential legacy pollution effects and climate-driven hydrological variability. This transitional recovery phase necessitates continued nutrient flux control coupled with adaptive ecosystem management to prevent resurgence of eutrophication symptoms.