Unlocking seagrass recovery: a global review for scalable and successful Zostera restoration

The global decline of seagrass meadows is diminishing their critical role in coastal resilience, supporting biodiversity, stabilizing sediments, and sequestering carbon. However, despite decades of effort, success remains inconsistent and limited in scale. This global analysis of 119 published studies on Zostera sensu lato reveals major taxonomic and methodological biases that constrain restoration outcomes, as 75% of studies focused solely on Z. marina, and only 7 of 16 Zostera species have been targeted to date. Many interventions took place within or near existing meadows, potentially inflating success rates and overlooking the challenges of true revegetation. Our standardised criteria show that only 36% of trials achieved high success, with limited implementation of long-term monitoring or cost-effectiveness assessments. Moreover, only 12% of trials addressed large-scale interventions (>1,000 m²), mainly seed-based, and limited to Z. marina in sheltered environments. This study provides the first global synthesis of Zostera restoration and identifies knowledge gaps, key factors for improving restoration success and provides a practical decision-support tool for Zostera restoration, integrating genetic, ecological, and socioeconomic considerations. By addressing these gaps and following a comprehensive approach, restoration can become a robust and scalable solution to reverse seagrass decline. This work supports global initiatives such as the UN Decade on Ecosystem Restoration, emphasizing that advancing seagrass recovery is ecological imperative for securing the future of coastal ecosystems and the services they provide.