Related Images
Beach wrack
Beach wrack dynamics
Detached macrophytes (seagrass and macroalgae) are transported from offshore areas and accumulate in substantial volumes on beaches, commonly called wrack. Wrack is an important feature of coastlines as it can play a major role in subsidising terrestrial production and supporting marine food webs. However, with human alteration of beaches such as groynes, the build-up of wrack can create management issues.
This project involves a multidisciplinary team from Edith Cowan University, The University of Western Australia and DHI to investigate seagrass wrack dynamics, especially transport and decomposition on beaches. There are three main phases:
- Building a hydrodynamic model of the study site, Geographe Bay in Australia’s southwest.
- Characterising when and what type of wrack moves on and off beaches.
- Identifying the key drivers of decomposition processes on the beach.
This information will be used to help with the management of wrack build-up on beaches with altered structure. A 2D hydrodynamic numerical model of Geographe Bay using DHI’s MIKE21 will be built and calibrated. Wrack movement onto beaches will be captured using web cams, regular surveys by the research team and also photography by volunteers. Decomposition will be assessed by gas evolution and the biogeochemistry of the wrack.
Researchers
Dr Kathyn McMahon
Professor Paul Lavery
The University of Western Australia, Professor Carolyn Oldham
The University of Western Australia, Winthrop Professor Chari Pattiaratchi
The University of Western Australia, Brett Branco
DHI, Tony Chiffings
DHI, Morten Rugbjerg
The Department of Planning and Infrastructure
The Busselton Shire
Port Geographe