A preliminary exploration of the physical properties of seagrass wrack that affect its offshore transport, deposition, and retention on a beach

Lay Abstract The accumulation of seagrass wrack on beaches provides a link between the marine and terrestrial environments and has been shown to play an important role in beach ecology. However there are parts of the world where accumulations of wrack are so pronounced that the wrack piles affect beach shape, and erosion can block harbors and breakwaters. The production of poisonous gases caused by its decay can become a human health hazard. Ideally, numerical models should allow us to predict wrack accumulation under a variety of management scenarios; however, there are few data to use in such numerical modeling. Indeed our understanding of how wrack is deposited to and removed from beaches is limited. This paper provides an exploratory investigation of a range of physical properties of seagrass wrack and establishes a baseline understanding of how these physical properties might impact on its transport and accumulation onto beaches.