Impacts such as ship groundings, coral mining and blast fishing can cause major physical damage to the coral reef framework or create substantial areas of unstable coral rubble and sand that are unlikely to recover unless some physical restoration is performed. Physical restoration focuses on repairing the topographic complexity of the reef using an engineering perspective. Major physical restoration is generally an expensive civil engineering project.
There are two main types of physical restoration:
- Repair of damaged reefs — In cases where acute impacts have cracked coral boulders, overturned massive corals, dislodged and fragmented coral colonies and other sessile organisms, or deposited foreign objects on the reef, emergency restoration in the short term can greatly assist recovery. This may involve applying cement or epoxy to large cracks in the reef framework, or righting and reattaching corals, sponges and other reef organisms.
- Artificial reef creation — Within the scope of physical restoration lies the use of artificial reefs. These may range from limestone boulders, to designed concrete (e.g., Reef Balls) or ceramic (e.g., EcoReefs) modules, to minerals (brucite and aragonite) electrolytically deposited on shaped wire mesh templates (e.g. Biorock™).
Potential roles for artificial reefs in restoration include:
- Stabilizing and restoring topographic complexity to degraded rubble areas such as those produced by blast fishing
- Tourism or marine park education and public awareness
- Reducing diving pressure on natural reefs in areas with large numbers of tourist divers
If well designed and constructed, artificial reefs can provide:
- Instant increase in topographic complexity
- Stable substrate for coral settlement or transplantation
- Fish aggregations
- Coastal defense services
- Hard structures to discourage net-based fishing
- Dive sites to reduce diving impacts on natural reefs
Video: Two year old Biorock® reef