Surface water connectivity is unstable in European Ramsar wetlands

Wetland restoration under the EU Nature Restoration Law prioritises the recovery of surface water connectivity, yet our understanding of how water moves and connects in European wetlands remains largely unknown, hindering effective restoration and monitoring. To address this, we analysed ~50 European Ramsar wetlands between 2015 and 2024 using satellite-derived surface water extent data and connectivity metrics. We found that ~80% of wetlands showed highly variable and unpredictable connectivity patterns across years, despite their protected status. Connectivity dynamics also showed a strong latitudinal gradient (r = 0.67, p = <0.05): northern wetlands displayed regular, seasonal connectivity patterns closely linked to precipitation and temperature, whereas continental wetlands showed erratic, highly variable connectivity behaviour decoupled from climate. While Scandinavian wetlands provide a reliable baseline for restoration, many continental wetlands lack predictable connectivity regimes and are weakly related to hydroclimatic inputs, suggesting that connectivity has been altered by human interventions within the wetlands and their catchments. Furthermore, ~10% of wetlands had connectivity dynamics that did not match water extent patterns, demonstrating that extent alone can misrepresent wetland hydrological functioning. Together, our results show that restoration should account for differences in connectivity regimes. By establishing where baselines exist and where they are absent, this study provides guidance for monitoring, prioritising, and designing restoration strategies adapted to the hydroclimatic and surface water connectivity context of individual wetlands.