Carbon storage in marine vegetated habitats (blue carbon) is increasingly being considered in carbon financing and coastal ecosystem management. Amongst other ecosystem functions, seagrass meadows are reported to be highly efficient at sequestering and storing significant amounts of carbon. However, seagrass blue carbon data remain sparse and regionally biased to tropical regions. In the Pacific Northwest, we lack information on the magnitude and variability of carbon stocks, as well as local drivers of variability. We collected sediment cores from six eelgrass meadows on the central coast of British Columbia, Canada, to quantify sedimentary organic carbon (Corg) stocks and accumulation rates. Carbon stocks exhibited 10-fold variability (335.35 – 3664. 48 g Corg m-2) in the top 20cm of sediment; these values align with other temperate eelgrass meadows, but are lower than reported global seagrass values. On average, Corg stocks within seagrass beds and adjacent unvegetated habitat overlapped, although stocks in the meadow interior (1392.05 g Corg m-2) were greater than those along meadow edges (1129.82 g Corg m-2) and in adjacent unvegetated sediments (977.10 g Corg m-2). Corg accumulation rates ranged from 12.57 to 50.45 g Corg m-2 year-1, lower than the global average reported for seagrasses (138 g Corg m-2 year-1), but again similar to other eelgrass meadows. Further, Corg in sediments beneath eelgrass meadows appears to be largely from non-eelgrass sources (terrestrial, benthic microalgae and macroalgae). Generalized linear mixed effects models suggest that hydrodynamic regime is the strongest driver of carbon stocks in the top 5cm of sediment, more important than the structural complexity of seagrass beds, or the proportion of fine sediments. Lower water velocities may allow greater deposition of particles within meadows, together with reduced erosion and resuspension. These results support physical characteristics over seagrass features as primary determinants of blue carbon storage in nearshore soft sediment habitats
