Advancing climate change vulnerability assessment of Mediterranean seagrass meadows

Seagrass meadows are pivotal marine ecosystems supporting biodiversity, stabilizing coastlines, and acting as major carbon sinks worldwide. Yet, these habitats are increasingly threatened by climate change. This global pattern is especially evident in the Mediterranean Sea, where rising temperatures and ocean acidification surpass global trends. This study presents a comprehensive vulnerability assessment for key Mediterranean seagrass families (Cymodoceaceae and Posidoniaceae) under different climate scenarios, using the latest Shared Socio-economic Pathways (SSPs) from the IPCC’s 6th Assessment Report. We integrated species distribution models (SDMs) and climate-niche factor analysis (CNFA) to capture sensitivity (encompassing ecological marginality and niche specialization) and exposure (quantifying climate departure from baseline conditions). Our ensemble SDMs, trained on an extensive dataset of seagrass occurrences and multi-decadal environmental data, revealed high predictive performance for both Cymodoceaceae and Posidoniaceae. Results indicate that Posidoniaceae generally exhibit higher risk owing to slower growth rates and reduced adaptive capacity. Under moderate to high emission scenarios (SSP2-4.5 and SSP5-8.5), hotspots of heightened seagrass vulnerability emerge in the northern and eastern Adriatic Sea, the northeastern Aegean-Levantine Seas, and parts of the Western Mediterranean. A marked “tipping point” in exposure-vulnerability relationships suggests that even incremental increases in climate stressors can trigger disproportionate ecological responses. Further, while warming also poses a significant threat, our findings identify ocean acidification as a dominant driver of future seagrass declines in the Mediterranean, with vulnerability trends persisting beyond 2070 under high-emission pathways. These insights emphasize the urgent need for integrated climate mitigation and targeted regional management strategies, including robust greenhouse gas emission reductions and local conservation measures. By elucidating the spatial heterogeneity of seagrass responses, this study offers a critical framework to prioritize interventions, protect essential ecosystem services, and guide policy-making for sustaining Mediterranean marine biodiversity and coastal resilience in an era of rapid environmental change.