Abstract Summary
Coral reefs naturally protect coasts from erosion and flooding by attenuating wave energy and supplying sediment to the adjacent beaches. Declines in reef condition coupled with increasing rates of global sea level rise are jeopardizing communities and coastal infrastructure. The typical hard engineering solution to this problem is to construct breakwaters or groins to protect high value shorelines, even in places where shallow reef crests occur. Softer solutions such as coral restoration may offer a cost-effective alternative to traditional engineered solutions in some places. It should be feasible to structurally restore degraded reefs using both biological and physical techniques including the use of structural materials. However, few reef restoration projects have been designed with coastal protection as a primary objective and guidelines are lacking. Here we discuss the process of designing a low crested breakwater structure to restore the wave breaking properties of a degraded reef crest in Grenada. Structures were designed to withstand hurricane wave forces, have a minimum 30 year lifespan, and promote coralline algae and coral growth. A total of 30 meters of pilot structures were constructed in 2015 and installed on a high energy back reef environment using local materials, community labour, and a specially built shallow water barge. Monitoring results of the pilot structures suggest they perform similar to traditional submerged breakwaters but have significantly greater ecological benefits including the potential to enhance natural reef accretionary processes.
