Maximising genetic diversity during coral transplantation from a highly impacted source reef

Selection of coral materials for restoration initiatives usually does not account for the genetic composition of species. This may result in inadvertent loss of genetic diversity, reduced species resilience towards disturbances, and lowered fitness in the restored populations. Here, we assessed the levels of genetic diversity among four coral species at a severely impacted reef in Singapore using high-throughput sequencing to determine the number of colonies needed to preserve particular levels of genetic diversity. Ten–twelve colonies (33–40% of total) were needed to represent 80% genetic diversity and more than fifteen colonies (> 50% of total) were needed to represent > 90% genetic diversity. We also found that collection of hermaphroditic species from a single reef can be done haphazardly within a small area, but collection of gonochores may need to be carried out over a larger reef area as there was a significant positive relationship between genetic and geographic distances in gonochoric species. Our results are expected to improve reef restoration techniques, especially when decisions have to be made to preserve genetic diversity amidst ongoing impacts against a single reef site.