China has recently launched extensive marine ranching projects, highlighting the need for scientific evaluation of ecosystem structure and function to guide their development. This study established two energy flow models and an evaluation index system to assess the structure, function, carrying capacity, and ecological status of both a marine ranching ecosystem and a nearby control site in the Beibu Gulf. The results show that the ranching ecosystem outperformed the control ecosystem in terms of food chain length, system size, and ecological carrying capacity of economically important species. The ranching ecosystem was classified as “relatively good”, while the control ecosystem was deemed “relatively poor”, which may confirm the success of the ranching efforts. Mussels, large crabs, and scorpaenidae were identified as key species for stock enhancement based on their biomass potential. Scenario simulations using Ecosim, driven by biomass and fishing factors, indicate that stock enhancement strategies targeting MOB (mussels, oysters, and barnacles) significantly improved the ranching ecosystem, raising its status to “good”. However, the simulations also revealed that stock enhancement had limited effects on optimizing food web structure, system organization, and energy transfer efficiency, suggesting that a combination of strategies is necessary for further improvement.

Macrobenthic fauna are vital to the ecological health of the Yellow River Estuary, yet their long-term population drivers are poorly understood. This study used Boosted Regression Tree models to analyze the spatio-temporal distribution of five dominant species: Glycinde gurjanovae, Sternaspis scutata, Moerella jedoensis, Theora fragilis, and Raphidopus ciliatus. Key environmental drivers included ammonia nitrogen, water depth, sand content of sediment, and water temperature. Specifically, S. scutata and R. ciliatus preferred deeper waters, M. jedoensis favored habitats with moderate sand content of sediment, T. fragilis primarily occurred at water temperatures lower than 25 °C, and G. gurjanovae distribution was most influenced by ammonia nitrogen. All species exhibited a preference for lower ammonia nitrogen concentrations. Inorganic nitrogen and freshwater discharge from the Yellow River significantly influenced the distribution of G. gurjanovae, whereas river discharge alone was positively correlated with areas exhibiting a high occurrence probability (>0.5) for M. jedoensis. Future studies that integrate comprehensive seasonal monitoring data, hydrodynamic conditions, and food availability could further enhance predictive accuracy, providing stronger theoretical and technical support for ecological conservation and management in the Yellow River Estuary.

China has recently launched extensive marine ranching projects, highlighting the need for scien-tific evaluation of ecosystem structure and function to guide their development. This study estab-lished two energy flow models and an evaluation index system to assess the structure, function, carrying capacity, and ecological status of both a marine ranching ecosystem and a nearby control site in the Beibu Gulf. The results showed that the ranching ecosystem outperformed the control ecosystem in terms of food chain length, system size, and the ecological carrying capacity of eco-nomically important species. The ranching ecosystem was classified as "relatively good," while the control ecosystem was deemed "relatively poor," confirming the success of the ranching efforts. Mussels, large crabs, and Scorpaenidae were identified as key species for stock enhancement based on their biomass potential. Scenario simulations using Ecosim, driven by biomass and fishing factors, indicated that stock enhancement strategies targeting MOB (mussels, oysters, and barna-cles) significantly improved the ranching ecosystem, raising its status to "good." However, the simulations also revealed that stock enhancement had limited effects on optimizing food web structure, system organization, and energy transfer efficiency, suggesting that a combination of strategies is necessary for further improvement.