Overview
Estimating lake net primary production (NPP) is essential for sustainable lake management, yet it remains difficult to quantify directly. This study applied a comprehensive three-dimensional hydrodynamic and eutrophication model — with three functional phytoplankton groups — to simulate algal dynamics in Lake Erhai, a mesotrophic, phosphorus-limited subtropical plateau lake in southwestern China.
Model Setup
Field investigations characterized the seasonal patterns of external total phosphorus (TP) input, TP concentration, and phytoplankton community composition. The model was calibrated to reproduce the qualitative features and succession of phytoplankton communities, and NPP was calculated from the calibrated output. Four nutrient loading reduction scenarios were simulated to test the lake’s sensitivity to external TP reduction.
Key Findings
Modeled daily NPP ranged between −16.89 and 15.12 mg C/m²/d and exhibited significant seasonal variation. Parameter sensitivity and limitation factor analysis identified competition for phosphorus and temperature as the primary governing factors of NPP. The nutrient loading scenarios showed high phytoplankton biomass and NPP sensitivity to external TP reduction, and a significant positive correlation was found among NPP, total phytoplankton biomass, and TP concentration. The work offers an alternative approach to estimating lake NPP with potential to improve sustainable lake management.