Designing ecologically connected marine protected area networks under global change: the Yellow and Bohai Seas, China

Accelerating climate change and chronic anthropogenic pressures demand connectivity-based design of marine protected area networks (MPANs). Yet integrating dynamic species responses and cumulative human pressures into spatial planning remains a key challenge, particularly in marginal seas at the land–ocean interface. As a biodiversity hotspot under intensive development, the Yellow and Bohai Seas (YBS) exemplify this complexity, yet how global change will reshape connectivity here remains unclear. Using ensemble species distribution models, we projected suitable habitats for 70 representative marine taxa under present-day conditions and two future scenarios (SSP1-2.6 and SSP5-8.5, representing low- and high-emission Shared Socioeconomic Pathways), generating multi-species natural resistance surfaces. These were combined with an entropy-weighted anthropogenic resistance layer—comprising fishing, shipping, mariculture, and pollution—to produce integrated resistance surfaces (IRS) for each scenario. Circuit theory was then applied to quantify ecological corridors, current density, pinch points, and barriers among 61 MPAs. Our results showed that: (1) climate forcing drove pronounced habitat redistribution, with cold-adapted taxa contracting within the Bohai Sea while warm-adapted species shifted poleward, especially under SSP5-8.5; (2) the IRS intensified overall (mean rising from 1.00 to 1.22), especially in the central-northern Bohai, while the southern Yellow Sea—particularly the central trough influenced by the Yellow Sea Cold Water Mass (YSCWM)—retained relatively low resistance, indicating a potential climatological corridor; (3) although total corridor length increased modestly (6,937 to 7,634 km), functional connectivity declined sharply, with Critical Corridors decreasing from 66 to 36 and effective resistance rising by 27%; (4) Grade-1 pinch points expanded by 35% and barrier clusters nearly tripled in area, concentrating where climate-degraded habitats overlap with intense human activities. Together, these drivers create a high-resistance Bohai core and more permeable Yellow Sea margins—a north–south divergence with direct consequences for species persistence and climate-driven range shifts. Embedding global change-adjusted corridor, pinch-point, and barrier metrics into spatial planning is therefore essential for maintaining MPA network resilience in the YBS and other marginal seas.