Governance pathways shape trophic recovery under climate change in the western Mediterranean Sea

Abstract Marine ecosystems are increasingly shaped by the interacting effects of climate change and human activities, yet the extent to which alternative socio-economic pathways can modify future ecological trajectories remains poorly understood. Here, we integrate climate projections with coherent socioecological scenarios to evaluate long-term ecosystem responses in the western Mediterranean Sea. Using a spatially explicit marine ecosystem model (Ecopath with Ecosim) representing 92 functional groups and five fishing fleets, we simulated ecosystem dynamics from 1995 to 2020 and projected changes to 2100 under contrasting pathways combining climate forcing, fisheries management, marine protection, and habitat restoration. Scenarios included a sustainability-oriented pathway (SSP1–RCP2.6; Global Sustainability), two high-emission pathways with contrasting governance (SSP3–RCP8.5; National Enterprise and SSP5–RCP8.5; World Markets), and associated status quo baselines. Socio-economic pathways substantially modified the ecological outcomes of climate change. Under Global Sustainability, reduced fishing pressure, expanded marine protection, discard mitigation, and habitat restoration promoted rapid rebuilding of commercial and predatory biomass, recovery of conservation-relevant species, and improved trophic structure within two decades, although fisheries catches declined. In contrast, high-emission pathways produced slower and more uneven responses. Despite sharing the same climate trajectory, National Enterprise and World Markets generated markedly different outcomes, highlighting the importance of governance priorities, technological development, and spatial management in shaping ecosystem futures within the same climate constraints. Responses were spatially heterogeneous across the basin, revealing uneven ecological benefits, vulnerabilities, and trade-offs among regions and functional groups. Our findings demonstrate that marine ecosystem trajectories are shaped by interactions between climate forcing and human activities and highlight the potential for management, conservation, and restoration to enhance ecosystem resilience under future climate change.