After the corals have been allowed to grow in the coral nurseries, the final step is to transplant them back to the natural reef or artificial reef structures.
Generally, the corals are transplanted after reaching a size greater than about 15 cm in diameter or when they are too large to remain in the nurseries without falling off or interfering with the growth of other colonies. The mature colonies can be moved together with the growing substrate (as in the case of concrete plugs or ropes) or can be removed from the growing substrates, as is often the case with the vinyl tubes or coral trees.
Various attachment methods are available depending upon the resources available and the level of expertise of the divers/snorkelers assisting (see examples in Table 3.4). Each method employed will be found to be more or less effective depending upon the unique conditions and considerations for each reef.
There is generally no right or wrong way to do this, as long as the following basic criteria are met:
Attaching corals onto the natural reef often requires skilled assistants as each colony will require a degree of problem-solving regarding site location and layout, transplant spots, attachment methods, etc. Corals moved to natural areas should be tagged or mapped to monitor growth and mortality over time. Depending on the amount of natural structure available and the level of expertise of the volunteers or assistants, it may be preferable to use artificial structures for transplanting the corals.
When constructing artificial substrates to transplant the reared corals onto, it is important to design the structures for the needs of each location or reef.
Techniques such as rope nurseries are easily transplanted to metal structures but work less well for concrete or natural reef features.
If using Reef Balls® or other concrete designs, then holes can be included in the molding process to facilitate the attachment of the vinyl tubes or concrete plugs. This is also very useful when using large groups of volunteers or unskilled labor, as the process is the same for each transplant.
Monitoring of the corals moved to artificial structures is easier than the natural reefs, but some corals should still be tagged so that their health and growth can be tracked over time. We will go into more detail about monitoring in the next lesson. However, over the next few topics, we will dive deeper into the nuances of the 3-Step Coral Restoration System and the pitfalls to be mindful of.