Climate Change Impacts on Ecological Connectivity of Marine Protected Areas in the Yangtze River Estuary and Adjacent Waters

Marine protected areas (MPAs) are vital for conserving marine biodiversity and managing fishery resources. Ecological connectivity, defined as the interconnection between populations, communities, ecosystems, or habitats through the exchange of genes, organisms, nutrients, and energy, plays a fundamental role in ecosystem resilience and is a key factor in the design of effective marine protected areas (MPAs). Both MPAs and the connectivity between them are increasingly threatened by climate change, yet the impact on connectivity patterns remains poorly understood. Focusing on the economically and ecologically significant migratory fish species Coilia mystus , Harpadon nehereus , and Larimichthys crocea , we evaluated the impacts of climate change on ecological connectivity (including ecological corridor effective resistance, electric current density, and pinch-point areas) of MPAs in the Yangtze River estuary and adjacent waters. We constructed resistance surfaces based on environmental gradients by predicting potential suitable habitats for the target species and identified the least-cost ecological corridors and key migration pinch points under current and future scenarios. Our key findings include: 1) C. mystus is projected to experience significant reductions in habitat suitability and area, while H. nehereus is expected to see an increase in habitat area but a decrease in habitat suitability and L. crocea is projected to experience habitat expansion overall. 2) Under future climate scenarios, the electric current density between MPAs is expected to decrease for C. mystus , but increase for H. nehereus and L. crocea . 3) For H. nehereus and L. crocea , corridor resistance is expected to decrease, particularly along the northern Yangtze River estuary, while C. mystus will experience a significant increase in corridor resistance, indicating greater migration challenges. 4) The pinch points will decrease for L. crocea , remain stable for H. nehereus , and increase for C. mystus . This study emphasizes the importance of incorporating climate resilience and connectivity into MPA assessment and design, while considering species-specific dispersal and future migration patterns.