Keywords:Seagrass meadows, Saltmarshes, Carbon storage, Isotopic analyses, Age-depth modelling
Vegetated coastal ecosystems store substantial amounts of organic carbon (Corg), and the conservation and restoration of these habitats are considered as important measures for mitigating climate change. Although various geophysical and biogeochemical factors control Corg storage in the sediment of these habitats, how spatiotemporal variations in the depositional environment (e.g., relative sea-level change, geological settings, habitat type) affect Corg accumulation rate is uncertain. In this study, we showed that depositional environment changes and the subsequent habitat relocation regulate Corg accumulation rate in boreal contiguous seagrass-saltmarsh habitats by using the historical depositional records. In particular, the Corg accumulation rate was accelerated with relative sea-level rise which would be driven by post-seismic land subsidence in this region. Our findings provide historical analogues for the future impact of sea-level change on Corg accumulation rate in vegetated coastal ecosystems.