Hybrid artificial reef structures can be designed to promote the development of a self-sustaining habitat for reef organisms while simultaneously enhancing the extent to which they provide coastal protection. In this study we investigate the wave attenuation capacity of engineered porous oyster reef modules that have been designed through the DARPA initiative Reefense: A Mosaic Oyster Habitat for Coastal Defense. Reduced scale (1:2) physical model testing of numerous modular reef layouts was conducted in the wave flume at the University of Western Australia's Coastal and Offshore Research Laboratory. The attenuation of wave energy was dominated by dissipative processes, due to both drag forces associated with the porous modules and wave breaking. Wave transmission was strongly governed by the dimensionless relative freeboard, the mean water depth above the top of the reef relative to the offshore incident wave height.
