Insights from spatial Markov chain and dynamic QCA into the spatiotemporal evolution and configurational pathways of eco-efficiency in China’s coastal megaregions

As critical zones subject to intensive human activities and significant environmental pressures, coastal megaregions require differentiated improvements in ecological efficiency (EE) to advance sustainable development. Adopting an institutional logics perspective, this study examines China’s five major national coastal city clusters and develops a triple-dimensional framework integrating “government–market–technology” forces to enhance EE. By innovatively combining a spatial Markov chain model with dynamic qualitative comparative analysis (QCA), we investigate the dynamic evolution of EE and the spatiotemporal heterogeneity of its configuration pathways. The results indicate that: (1) EE in coastal megaregions exhibited fluctuating growth, with the Pearl River Delta and the West Coast Straits regions consistently leading. The number of high-efficiency cities increased annually, showing a clear pattern of spatial agglomeration. (2) Latitudinally, EE displayed a south-high-north-low gradient with a central trough; longitudinally, it followed a persistent U-shaped distribution. (3) EE demonstrated significant path dependency and club convergence, which constrain short-term rapid improvement. However, spatial spillover effects from adjacent areas facilitated dynamic transitions and gradient leaps. (4) High EE is not determined by any single factor but arises from the synergistic interaction of multiple conditions, manifested through three dominant configuration paths: market-dominated, government–market dual-driven, and market–technology dual-driven. The explanatory power of these pathways strengthens over time, exhibiting pronounced spatial imbalance and geographic dependence within city clusters. This study extends the theoretical framework for promoting EE and offers practical insights for optimizing ecological governance in coastal megaregions, thereby supporting the acceleration of sustainable development goals.