Variability in blue carbon storage related to biogeochemical factors in seagrass meadows off the coast of the Korean peninsula

Coastal vegetated habitats such as mangroves, salt marshes, and seagrasses, referred to as blue carbon ecosystems, play an important role in climate change mitigation by an effective CO2 capture from atmosphere and water columns and long-term organic carbon (Corg) storage in sediments. Although seagrass meadows are considered intense carbon sinks, information on regional variability in seagrass blue carbon stock and factors influencing its capacity still remain sparse. In the present study, seagrass blue carbon storage by measuring Corg stocks in sediments and living seagrass biomass, and carbon accumulation rates (CARs) in seagrass meadows were estimated along the Korean coast. Factors affecting variability in Corg stocks were also analyzed using partial least squares (PLS) regression and principal component analysis (PCA). Projected Corg stocks in sediment, extrapolated to a depth 1 m, exhibited substantial variability among sites, ranging from 49.91 to 125.71 Mg C ha-1. The majority of Corg (96-99%) was stored in sediments, whereas the contribution of living biomass was minor. PLS regression and PCA indicated that Corg stocks in seagrass meadows are strongly associated with sediment characteristics such as dry bulk density and water and mud content. Among seagrass traits, above- to below-ground biomass ratio was significantly related to the quantity of Corg stocks in seagrass meadows. Because of the high spatial variability in Corg stocks and CARs, local and regional differences in seagrass blue carbon storage should be considered to accurately assess the climate change mitigation potential of seagrass ecosystems.

Automated summary

This study examined the blue carbon storage of seagrass meadows along the coast of Korea, revealing significant variability in Corg stocks in sediments, which are mainly influenced by sediment characteristics such as dry bulk density and water and mud content. The ratio of above- to below-ground biomass in seagrass meadows also significantly impacts the quantity of Corg stocks.