Development of a structurally dynamic model for ecosystem health prognosis of Baiyangdian Lake, China

A structurally dynamic model (STDM) based on nutrient cycling within the food web was developed for Baiyangdian Lake in North China. The model was calibrated and validated based on the data of four types of water areas with different ecological conditions. Moreover, the model combined with ecosystem health assessment was applied to predict the state of health of Baiyangdian Lake's water areas. The indicators used for ecosystem health characterization included phytoplankton biomass, ratio of zooplankton to phytoplankton biomass, eco-exergy and structural eco-exergy. The results indicated that the health states of the four types of water areas had relatively intense responses to the changes of the nitrogen loading and meanwhile there were discrepancies found in the health state responses to the changes of nutrient loadings between the four types of water areas. Water area A with relatively good health state showed a certain degree of resistance to the changes of nutrient loadings. For water area B, the health state had further degraded when the nutrient loadings were increased or reduced to some extent and only improved following the great decline in nutrient loadings. The health state of water area C had degraded and improved following the increase and decrease in nutrient loadings, respectively. For water area D, the health state had degraded to some extent when the nutrient loading was increased and improved a little at relatively low loading level. Furthermore, based on the prognosis results under different scenarios, suggestions for improving the health states of impaired water areas in Baiyangdian Lake were presented as guidelines for lake restoration and management in this specific region. The STDM established could reasonably reflect the health state responses of different water areas to the changes of forcing functions and the results from the prognoses laid the quantitative foundation for making the restoration and management plans of Baiyangdian Lake.

► We establish a structurally dynamic model for health prognosis of Baiyangdian Lake. ► Health responses of water areas are various and intense to nitrogen loading changes. ► Decreasing nitrogen loading will improve the health state of water areas B and C. ► Increasing removal rate will improve the health state of water area D. ► Prognosis results can provide quantitative basis for lake restoration and management.