Diver reattaching small colonies of mustard hill coral to stable reef substrate using epoxy. Photo courtesy of NOAA.

Large elkhorn coral fragment reattached to hard reef substrate with Portland Type II cement. Photo courtesy of NOAA.

Once the injury assessment has been completed, if damages have been recovered from the responsible party, scientists and other staff from The National Oceanic and Atmospheric Administration (NOAA) and the state of Florida begin restoration activities. Responsible parties may also have a private contractor to undertake restoration. The primary purposes of restoration are to prevent the injury from getting larger and to rehabilitate coral reef structure and function at the injury site.

The Coral 312 Program uses various techniques to address coral injuries. The technique(s) chosen for each injury site depends on several factors:

• Technical feasibility. Will a particular restoration technique work at this site? Are appropriate technology and management skills available?
• Recovery time. Will implementing a specific restoration action reduce the time needed for the site to recover?
• Risk of additional injury. Will implementing a specific action minimize the potential for additional injury?
• Aesthetic acceptability. Does this alternative create substrate and topography that closely resemble the surrounding habitat, thus minimizing visual degradation?
• Site-specific context. Do environmental conditions at the site (including, but not limited to, location, injury extent and severity, hydrological characteristics, coral species composition, and other social and resource management concerns) support the use of this alternative?

The restoration techniques most commonly used by the Coral 312 Program are described below. However, others have been used in unique situations. Several techniques may be used at the same injury site.

Debris, Sediment, and Rubble Removal

The presence of coral rubble and other reef debris in an injury area may hinder coral recruitment because particles can be resuspended by water movement and subsequently bury or damage coral colonies. Removing this material prevents collateral injury and facilitates the discovery of larger, salvageable fragmented pieces of live coral. This technique involves clearing rubble from the site as soon after the injury as possible. Small quantities of rubble can be removed by divers using baskets, lift bags, and so on, while larger amounts require using diver-guided suction pipes. Some reefs have natural rubble zones behind the fore reef; if the vessel-generated rubble is similar in size and composition, it can be deposited in these natural rubble areas.

Relict Coral and Framework Stabilization

Vessel groundings also affect reef zones composed of relict coral and/or exposed framework. The resulting framework pieces, or boulders, may be stabilized in place to preserve the local environment's three-dimensional structure. To stabilize these pieces, workers place a mixture of concrete and plaster between the boulders like mortar. Plastic composite rebar can also be placed in the concrete to improve adhesion among the boulders, concrete layers, and reef bed. Framework cracks can be stabilized with the same cement/plaster mix, which can be camouflaged by adding living coral fragments on the exposed mortar surface.

Reattachment and Transplantation

Coral fragments that are reattached within or transplanted to vessel grounding injury areas may facilitate the redevelopment of those affected coral communities. In addition to coral fragments found at the injury site, other potential sources exist for donor corals (including coral pieces collected at small-scale orphan sites and held until restoration is implemented), and other corals at risk of human disturbance. When transplanting or translocating corals, every effort is made to maintain the occurrence and diversity of species found within the original injury area.

All fragments are attached using either underwater epoxy (for fragments smaller than 10 centimeters in size) or Portland cement (and, when appropriate, molding plaster to act as a hardening catalyst) and affixed directly to solid substrate. Branching corals may also be attached to appropriate substrate with wire and/or cable ties or by wedging fragments into small crevices and voids.

Specific restoration alternatives appropriate for certain types of injuries can be found in the restoration matrix.

Reef Module Placement

Reef modules recreate the three-dimensional structure lost by injured coral communities. This 3-D relief allows the modules to serve as replacement habitat for affected reef species, which can use nooks and crannies for protection from predators, foraging locations, and shelter from strong wave activity. These modules also provide the settlement habitat needed for larval recruitment of corals that were lost as a result of the injury.

This restoration technique is a long-term solution to coral framework injury and can facilitate the regrowth of the reef community and prevent further degradation of the injured reef foundation. These modules are preformed (on land) from limestone or coral rubble and composite rebar and concrete before they are placed in the injury area. They can be designed in various sizes and patterns to meet site-specific needs. However, they are usually large and heavy and require construction-grade resources (such as a barge and crane) to transport and position safely. Once positioned, reef modules are secured to the underlying substrate using cement rebar and/or other appropriate methods for lasting stability.