[A-CG40] 沿岸海洋生態系─１．水循環と陸海相互作用

[ACG40-P03] 沿岸潟湖の有機炭素貯留に人工的な湖口開削が与える影響

*渡辺 謙太¹、桑江 朝比呂¹ (1.港湾空港技術研究所)

キーワード：有機炭素貯留、海草藻場、塩性湿地、海岸工事、堆積年代推定

Organic carbon (C_org) storage is one of the important functions of vegetated coastal ecosystems for mitigating the adverse effects of climate change. The artificial alteration of landforms by coastal constructions would impact on habitats, hydrological conditions, and sediment loads. However, how the coastal constructions change C_org accumulation in vegetated coastal ecosystems is poorly understood. In this study, the sediment profiles of geological and biogeochemical characteristics were measured in Komuke Lagoon, Hokkaido. Stable isotope ratios and ²¹⁰Pb profiles were used to investigate the origin of C_org and sediment age. We showed that C_org accumulation rates and the origin of accumulated C_org significantly changed after the construction of an artificial outlet channel. C_org accumulation was enhanced, the contribution of terrestrial-derived C_org decreased, and that of microalgae- and seagrass-derived C_org increased after the coastal construction at the site. These findings indicate that the construction of an artificial outlet channel alters the frequency of seawater exchange and affects habitat types and C_org accumulation.