Construction and application of coastal ecosystem model coupling multiple human activities.

The combined impact of multiple human activities is the primary driver of coastal ecosystem degradation, and comprehending its mechanisms is essential for developing adaptive management strategies. A coastal ecosystem model coupling multiple human activities, including runoff discharge, reclamation, mariculture, and atmospheric deposition, was developed using the Regional Ocean Modeling System (ROMS) coupled with the Carbon, Silicate, and Nitrogen Ecosystem (CoSiNE) model. The model performance was rigorously evaluated in the Bohai Sea as the study area. Through orthogonal experiment, multiple human activity scenarios were designed, and the contribution rates of these activities to marine ecological factors were quantified using variance analysis. The results showed that (1) the simulated results of dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and Chlorophyll-a (Chl-a) in 2020 were compared with observational data, whose average R values were 0.839, 0.820, 0.814, respectively, which indicated the simulated results were generally in accordance with observational data. (2) Orthogonal experiment results revealed that the contribution rates of runoff discharge to DIN, DIP, the nitrogen content of phytoplankton and zooplankton all ranked first, reaching 59.73 %, 65.05 %, 66.92 %, and 68.23 % respectively, indicating that runoff discharge is a key factor affecting the Bohai Sea ecosystem. (3) The response of ecological factors to human activities exhibited significant spatial heterogeneity, with the impacts of runoff discharge, reclamation, and mariculture diminishing with increasing distance from the coastline. The proposed model not only facilitates efficient scenario simulation but also demonstrates high accuracy, making it a valuable tool for quantifying the combined impact of multiple human activities and simulating coastal ecosystems under intense anthropogenic pressure.