Manmade structures are gaining more interest and application in coral reef restoration. Some of the potential positive impacts of artificial structures for coral reefs include:

  1. Stabilize damaged reefs: Structures can stabilize coral reef framework in areas where coral reefs have been damaged or flattened by disturbances (blast fishing, mining, ship groundings). Under natural circumstances, coral reefs can take decades to grow back or may never naturally recover; thus, creating structures to replicate the foundational structure of a reef can help speed up this recovery process.
  1. Replace ecological structure: Adding structures with complex topography or interstitial spaces mimics natural coral reef framework that provides habitat for fish and invertebrates and promotes overall healthy reef functioning.
  1. Increase public awareness: Like coral nurseries and gardening methods, artificial structures (especially those with corals planted with them in a mixed approach) can lead to public understanding and education about the state of local coral reef habitats and current conservation practices.
  1. Reduce tourism pressure: Some resorts have constructed structures that are used by divers for recreation as well as to train divers in safe buoyancy practices. These areas, if attractive to tourists, can help reduce pressure on natural coral reefs that are recovering or under stress.
  1. Boost fisheries: Structures are known to attract fish and have been used around the world to promote recreational and commercial fisheries.
  1. Enhance coastal defense: Structures that enhance reef height and rugosity can increase the ability of coral reefs to buffer wave energy and protect coastlines from storms and erosion. Those benefits are relevant to people that are more vulnerable to flooding and erosion. They are also relevant to the natural ecosystem as they protect leeward reefs from the damaging effects of storms (the greatest source of loss on the GBR). ref By reducing wave energy, structures increase the likelihood of success of other coral reef and mangrove restoration projects (i.e., mangrove restoration projects often fail because wave energy is too high).

Coral Reefs for Protection and Climate Adaptation

Artificial reef structures can successfully host marine life, coral fragments, and coralline algae. Photo © Tim Calver

Artificial reef structures can reduce strong wave action and successfully host marine life, coral fragments, and coralline algae. Photo © Tim Calver

Coral reefs are effective natural breakwaters that dissipate wave energy and subsequent erosion on the coast. Recent studies have found that coral reefs reduce wave energy by 97% and wave height by 84% on average. Reef crests appear to be the most effective area of the reef for reducing wave energy. Human disturbances and climate change that degrade coral reefs have reduced their rugosity and complexity, causing a general flattening of many coral reefs. Thus, coral restoration using structurals may be one effective strategy for boosting reef structure and reducing coastal hazard risk to human populations.

Increased funding opportunities may be available to coral restoration projects that specifically address coastal protection, climate adaptation, and risk reduction. Coral restoration is less expensive than defense structures, and when healthy, a coral reef will naturally grow and sustain these coastal protection benefits. ref Coral restoration with structures must be done alongside effective management that reduces local and chronic stressors to coral reefs. Below  some facts on the benefits people receive from coral reefs through coastline protection that can be used to support restoration funding are highlighted:

  • Coral reefs provide the first line of defense for 63 million people across the globe who live in coastal and low-lying areas ref
  • Coral reefs are living breakwaters that provide protection from waves and storms to over 150,000 kilometers of tropical coastline in over 100 countries ref
  • In countries such as the Bahamas, Maldives, Solomon Islands, and Fiji, scientific models suggest that over half the population directly benefits from coastal protection provided by coral reefs ref
  • Up to 200 million people who receive coastal protection from coral reefs may bear significant adaptation costs if reefs are degraded ref
  • Currently, nearly 40% of the world’s population lives within 100 km of the coast, with this percentage on the rise ref
The Atlas of Ocean Wealth provides a powerful mapping tool that can be used by managers to illustrate how many people, money in property, and area is protected by coral reefs, and how artificial structures can help promote coastal protection.

The Atlas of Ocean Wealth provides a powerful mapping tool that can be used by managers to illustrate how many people, money in property, and area is protected by coral reefs, and how artificial structures can help promote coastal protection.

Resources

The 27-Year Decline of Coral Cover on the Great Barrier Reef and its Causes (pdf, 935k)

The Benefits, Costs and Effectiveness of Natural and Nature-Based Coastal Defenses (pdf, 1.1M)

The Effectiveness of Coral Reefs for Coastal Hazard Risk Reduction (pdf, 632k)

Managing Coasts with Natural Solutions: Guidelines for Measuring and Valuing the Coastal Protection Services of Mangroves and Coral Reefs (pdf, 6.1M)

Atlas of Ocean Wealth: Maps of Ecosystem Services

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Last updated October 23, 2017

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