Table 5 Preliminary eligibility criteria for literature on built structures used for coral restoration

Population of subjects

Shallow, tropical coral reefs

Coral reefs in nearshore, shallow water depths (≤ 30 m) in tropical latitudes (35° N to 35° S) where built structure interventions occur

Coral reefs created by or facilitated by a built structure intervention in a location devoid of reefs (e.g., intervention on soft sediment that creates or is intended to create reef) can also be included

Coral reefs in cold, deep (> 30 m), or mesophotic waters are excluded. Coral reefs > 35° N or > 35° S are excluded. Other types of reefs, like rocky reefs, are excluded. All other coastal, marine, terrestrial, freshwater, or subterranean systems are excluded

Intervention

Built structure established in coral reef systems

Interventions must use a built structure. Built structures may include those of:

    1. Artificial or human-made origin, including structures engineered or designed for reef contexts with or without electricity, structures repurposed from their primary use, and those structures created as artwork

    2. Hybrid origin that are created from a combination of artificial and natural material, such as cement plus natural rock

    3. Natural origin from geologic sources, such as mined rock, limestone, or boulders

These interventions can be related to coral reef-related applications, including restoration, remediation, mitigation, enhancement, rehabilitation, rebuilding, stabilization, providing coastal protection or defense, tourism and recreation, research, etc. These interventions can be established in response to general habitat degradation and chronic disturbances or in response to pulse disturbances, like storms, blast fishing, dredging, mining, and ship groundings

Interventions using electrification and a built structure will be included

Interventions without built structures

Comparator

Comparator

No comparator is required because the only requirement is the presence of built structure

Studies that include a comparator, however, will also be included. Comparators may include: presence vs. absence of built structure intervention, before vs. after built structure intervention, different types of built structure interventions, different projects or sites with the same built structure intervention type, different reef types (e.g., built structure on fore- vs. back-reef), built structure vs. natural coral reef

N/A—no comparator required

Outcome

Ecological and physical performance outcomes

Ecological and physical performance outcomes of built structure interventions that are measured, observed, or modeled

Ecological outcomes must relate to coral and coral reef metrics, such as recruitment, growth, morality, condition, rugosity, and cover (Table 7). Ecological metrics related to biological interactions with coral will be included

Physical outcomes must relate to waves, currents, erosion, flooding, and other coastal processes (Table 8)

Performance outcomes may be related to the built structure or adjacent areas. For example, ecological outcomes like coral growing on the built structure or coral growing adjacent to the built structure would both be included

Ecological outcomes solely related to other trophic groups, such as non-coral invertebrates, macroalgae, and fish. Broader ecosystem-level metrics or processes, such as productivity, pollution, and nutrient cycling. Chemical, economic, and social outcomes

Study type

Experimental, observational, or modeling studies

Experimental, quasi-experimental, modeling (statistical, theoretical), or observational studies with quantitative data. Field and lab studies are included

Reviews, meta-analyses, theoretical studies, commentaries, editorials, opinions, or perspectives