[A-CG43] Coastal Ecosystems - 2. Coral reefs, seagrass and macroalgal beds, and mangroves

[ACG43-05] Depositional environment change and the subsequent habitat relocation affect organic carbon accumulation rate in vegetated coastal ecosystems

*Kenta Watanabe¹, Koji Seike², Rumiko Kajihara³, Tatsuki Tokoro¹, Kazufumi Tada¹, Shigeru Montani⁴, Tomohiro Kuwae¹ (1.Port and Airport Research Institute, 2.Geological Survey of Japan, AIST, 3.Civil Engineering Research Institute for Cold Region, 4.Hokkaido University)

Keywords:Seagrass meadows, Saltmarshes, Carbon storage, Isotopic analyses, Age-depth modelling

Vegetated coastal ecosystems store substantial amounts of organic carbon (C_org), and the conservation and restoration of these habitats are considered as important measures for mitigating climate change. Although various geophysical and biogeochemical factors control C_org 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 C_org accumulation rate is uncertain. In this study, we showed that depositional environment changes and the subsequent habitat relocation regulate C_org accumulation rate in boreal contiguous seagrass-saltmarsh habitats by using the historical depositional records. In particular, the C_org 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 C_org accumulation rate in vegetated coastal ecosystems.