Restoration Outplant

We have learned that outplanting whole coral colonies in high densities results in significantly higher survival than outplanting smaller coral fragments.

Ecological Rationale

This is in line with coral ecology:

1. Highest mortality rate of corals in the wild is generally at the youngest, smallest stages. This is when the coral is the most vulnerable to smothering, predation, scouring, etc., because they do not have the resources to recover from damage. Our nurseries protect these smaller corals through this vulnerable stage.
2. Corals that grow branches and create habitat attract and retain fishes and invertebrates that add resilience to the coral via protection, aeration, sediment removal, nutrient delivery, etc.
3. Flipping the system to a coral-dominated system complete with associated fishes and invertebrates kick-starts the ecological function of the reef, bringing with it inherent ecosystem resilience. Associate invertebrates create chemical and audio cues that attract conspecifics and other reef organisms generally, accelerating the creation of a functioning reef ecosystem.

Outplant Steps

1. Ecosystem monitoring (fish/inverts/recruits/benthic cover) at the outplant and control site occurs prior to outplanting.
2. Outplant area is prepared by removing all dead corals that were outplanted the previous year and cleaning macro and turf algae from the area. Outplant corals will replace these dead ones to keep the % coral cover at 50%.
3. A full nursery monitoring occurs right before/prior to outplanting.
4. Corals must be planted onto substrate that fits them; careful consideration must be made to find the right place for each coral.
5. Whole 2–3-year-old (TBC) corals are outplanted onto the reef each outplant cycle (~⅓ of the nursery).
6. Corals are then carefully removed from the nursery and moved to the outplant area. Corals should be kept in water when moved from nursery to outplant to reduce stress and retain associated species.
7. Corals are attached to the reef as appropriate for the substrate. (E.g., French Polynesia has had success using coral clips and cement to outplant on dead coral substrate. Other sites may develop other techniques if this method does not work for the substrate they are working with.)

Targets

We aim for:

• 50%+ live coral coverage (total existing and outplant)
• Mix of species diversity and morphotypes — as determined from Reference sites
• Mix of genotypes in cells/bommies — guideline: no more than 3 corals of the same genotype of one species on each bommie/cell

Spatial Strategy

Plant on all available substrate in restoration areas. Priority for outplanting is in the established area. If there are extra corals once the existing restoration area is filled in, then the restoration site can be expanded into new adjacent areas.

• If the outplant area consists of discrete bommies, they are all outplanted, and a subset monitored as determined by Coral Gardeners Labs statistical analysis. All available bommies/areas should be used for outplant so the restoration area is concentrated — i.e. do not skip bommies in the restoration area.
• If the area is solid substrate suitable for outplanting, aim for blanket coverage across the area and monitor 1×1 m cells within that area. Aim for continuous compact coverage (i.e. outplant on all available substratum in the restoration area).

In control sites, the same number of cells/bommies will be monitored in the same way at the same intervals.