Temporal Dynamics of Ecosystem Service Values in Aquaculture Ponds: A Case Study of Grass Carp Pond Systems in Songjiang District, Shanghai, China

To systematically quantify the ecosystem service values in aquaculture ponds and reveal their temporal dynamics, this study provides a scientific basis for promoting sustainable green aquaculture and enhancing ecological and economic benefits. Using a 0.4 hm2 grass carp pond in Songjiang District, Shanghai as the study site, we developed an evaluation framework of “base equivalent—dynamic equivalent—value quantification” and incorporated temperature spatiotemporal adjustment factors and social development coefficients to refine traditional models. The results indicate significant seasonal fluctuations in ecosystem service values for grass carp ponds. The highest value occurs in July at 21,868.21 CNY, and the lowest occurs in February at 4110.22 CNY, with a peak-to-trough ratio of 5.3. Among the five service functions, hydrological regulation accounts for the largest share (approximately 55%), followed by gas regulation (20%) and climate regulation (10%), while environmental purification and aesthetic landscapes, though contributing smaller proportions, remain indispensable. Temperature adjustment factors significantly enhance aquatic plant photosynthesis and microbial metabolism during high-temperature periods (>25 °C), whereas low temperatures suppress these ecological processes. The integration of social development coefficients effectively corrects underestimations of willingness to pay for cultural services. Compared to traditional seasonal-scale assessments, the monthly-scale approach substantially improves the explanatory power for pond ecological processes, offering quantitative support for differentiated ecological compensation mechanisms and optimized aquaculture management practices.