Study on Nutrient Release Characteristics During the Decomposition of Potamogeton crispus L. in the Huayang Lakes

The senescence and decomposition of Potamogeton crispus L. are critical drivers of internal nutrient loading and eutrophication in shallow lakes during late spring. Combining field monitoring and laboratory microcosm experiments, we investigated the effects of temperature (20–30 °C) and biomass loading on nutrient release from P. crispus, and the underlying microbial mechanisms. Results showed that total phosphorus (TP) release followed an asymptotic exponential model (R2 = 0.98), with a half-life of only 12.2 d, and 30 °C increased the final TP concentration by 42.1% compared with 20 °C. A biomass loading of 30 g was identified as the critical threshold for water quality deterioration. Nutrient release showed significant asynchrony (TP >> TN ≈ TC), and microbial communities exhibited distinct functional succession under different temperature and biomass conditions. This study provides a scientific basis for targeted management of internal loading in shallow lakes.