Environmental drivers of sediment carbon storage in temperate seagrass meadows

Seagrass meadows are productive ecosystems that contribute to climate change mitigation by accumulating ‘Blue Carbon’ in their plant biomass and sediments. However, there is wide variation in reported sediment carbon stocks (Cstocks) across different global regions and between meadows composed of different seagrass species. Therefore, understanding the drivers for sediment Cstocks variation is crucial to developing effective conservation and restoration projects for seagrass ecosystems. This study analyses the influence of environmental factors on the variation in sediment Cstocks for six intertidal seagrass meadows within the Solent region, in southern England. There were significant differences between sites for all variables, except leaf density, and concentrations of the sediment pore water nutrients. Sediment dry bulk density, mean grain size, sorting coefficient, % mud, elevation above sea level, and pore water salinity showed high levels of association with Cstocks when assessed individually. Multivariate analyses showed that sediment dry bulk density, sorting coefficient, % mud, and pore water pH and concentration of nutrients greatly influenced Cstock. Moreover, sediment characteristics acted in conjunction to explain most of the variation in Cstock among sites. Therefore, sediment characteristics should be considered as important indicators for carbon storage potential in intertidal temperate seagrass meadows.