Tropical coastlines are facing increasing risks from coastal storms coupled with degradation of their nearshore shallow reefs. Degraded reefs begin to erode when the live coral cover decreases below a threshold level (between 10% and 15% cover). ref As the reefs become lower in the water column the amount of wave energy they block is reduced. Reef degradation, combined with these rising risks combine to cause greater flooding and erosion. Interest is growing in how best to confront these challenges. Decision-makers often turn to built infrastructure such as seawalls that further degrade coastal ecosystems. Consequently there has been a growing interest in the use of structural reef restoration as a means to meet coastal protection (risk reduction) and conservation management objectives.

Coral restoration historically used engineered structures to rebuild or stabilize coral reef framework after major damage caused by ship groundings, mining, or blast fishing. These projects often utilized manmade materials (e.g., limestone blocks, rock piles, molded cement, steel, wood, and tires) that failed to recruit reef-building corals onto structures. Modern structural reef restoration projects today use more natural materials, and seek to enhance both ecological health and ecosystem services to people, like coastal protection. In some areas, restoration of the physical environment may be required before biological restoration of the coral and fish communities can occur.

Structural reef restoration requires working with professional partners such as government agencies and coastal engineers. In many ways, the coral restoration community has a lot to learn from the oyster reef community, which has been addressing structural restoration questions for the past two decades. The following sections provide information on types of structures and methods being used.

Pilot hybrid or 'artificial' reef structures, built with steel cages and filled with stones and cement, were installed in 2015 in Grenville Bay, Grenada to protect a vulnerable coastline from strong wave action and the impacts from climate change, such as severe erosion. The pilot structures are successfully hosting marine life, coral fragments and crusting over with coralline algae. Photo © Tim Calver

In some areas, restoration of the physical environment may be required before biological restoration of the coral and fish communities can occur.

Last updated October 23, 2017

Uses for Restoration

Uses of artificial structures for coral restoration, such as climate change adaptation, and risk reduction. Learn more.

Planning & Methods

Current types of structures and methods being used as well as important characteristics of structures. Learn more.

Monitoring & Evaluation

Considerations for monitoring projects using artificial structures. Learn more.

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