Abstract:
Seagrass meadows provide numerous ecosystem services and their rapid global loss may reduce human
welfare as well as ecological integrity. In common with the other ‘blue carbon’ habitats (mangroves
and tidal marshes) seagrasses are thought to provide coastal defence and encourage sediment
stabilisation and surface elevation. A sophisticated understanding of sediment elevation dynamics in
mangroves and tidal marshes has been gained by monitoring a wide range of diferent sites, located
in varying hydrogeomorphological conditions over long periods. In contrast, similar evidence for
seagrasses is sparse; the present study is a contribution towards flling this gap. Surface elevation
change pins were deployed in four locations, Scotland, Kenya, Tanzania and Saudi Arabia, in both
seagrass and unvegetated control plots in the low intertidal and shallow subtidal zone. The presence of
seagrass had a highly signifcant, positive impact on surface elevation at all sites. Combined data from
the current work and the literature show an average diference of 31mm per year in elevation rates
between vegetated and unvegetated areas, which emphasizes the important contribution of seagrass
in facilitating sediment surface elevation and reducing erosion. This paper presents the frst multi-site
study for sediment surface elevation in seagrasses in diferent settings and species.
