There is considerable spatial variability in the organic carbon stock of seagrass sediments. This variability may be related to both the species of seagrass and the habitat setting in which they occur, particularly water depth. The data set presented here is limited and the errors associated with the estimates are likely to be significant, though no more so than the global estimates of seagrass C capture extrapolated from a much more limited set from the mediterranean Sea, acknowledging that at the time those were the best available data. However, our data serve to emphasise the need for robust data sets on the carbon storage and accumulation rates in different seagrass ecosystems. There is also a pressing need to
better understand the habitat features that drive this variability in C storage and accumulation rates. Assuming a uniform ability to capture and sequester carbon among the 70 species of seagrasses will potentially lead to erroneous estimates of global C storage and improving our understanding of the variability in C stocks and accumulation rates is critical if we are to produce robust estimates of regional and global C capture and storage in seagrass ecosystems.