How residents’ equity perceptions influence MPAs effectiveness: Evidence from Sousa chinensis conservation in the Pearl River Estuary, China

Marine Protected Areas (MPAs) are pivotal governance tools for ecological conservation, yet their effectiveness often hinges on social acceptance and community responses. This study investigates how residents’ perceptions of equity influence conservation effectiveness in the context of the Pearl River Estuary Indo-Pacific humpback dolphin MPAs in China. Drawing on 451 household surveys and semi-structured interviews, we constructed an integrated framework that links three dimensions of perceived equity—distributional, procedural, and recognitional—to conservation behavior and effectiveness outcomes. Using structural equation modeling, we find that distributive equity exerts the most substantial direct and indirect effects on both ecological and managerial effectiveness. Conservation behavior plays a significant mediating role in translating perceived equity into effective outcomes. We further employed agent-based modeling to simulate dynamic system evolution under policy stability. Results reveal a critical threshold in social learning networks that triggers rapid behavioral diffusion and group-level convergence. Notably, managerial effectiveness rises quickly during the early phase due to policy enforcement, while ecological effectiveness lags and improves through sustained behavioral compliance, forming a nonlinear and asynchronous co-evolution pattern. This research advances theoretical understanding by shifting emphasis from procedural to distributive equity in MPAs and proposes a cross-scale methodological framework combining causal modeling and simulation. Practically, we propose a phased governance strategy: initial enforcement followed by long-term behavioral reinforcement. The findings contribute actionable insights for designing adaptive and socially grounded MPAs governance models that enhance compliance, legitimacy, and conservation performance.