Sandy beaches make up approximately three-quarters of the world’s shorelines. They are important ecosystems, hosting abundant invertebrate macrofaunal communities that provide food resource for vertebrate predators such as shorebirds, seabirds, marine mammals and fish. Although possessing a terrestrial appearance, food input on sandy beaches is derived predominantly from the sea. Such food input includes detrital matter, mostly in the form of wrack, and has the potential to support a great diversity of species, as well as stabilising energy fluxes and dynamics of consumer populations. The movement of detritus, along with other vectors such as organisms and nutrients, across ecosystem boundaries can alter productivity and change consumers’ distribution, abundance, and growth rates at multiple trophic levels in recipient systems. Ultimately, the input of nutrients and detritus can increase primary and secondary production and alter food web structures and community dynamics in recipient ecosystems, a process termed “spatial subsidy”.

Ghost crabs (Ocypode spp.) form an important component within beach communities in several places around the world and are part of this trophic complexity. However, little is known of their densities, trophic structure and the role they play as vectors for spatial subsidies through movement of marine derived nutrients inland.