Testing Transplantation Techniques for the Red Coral Corallium rubrum

Corallium rubrum has been exploited by humankind for centuries. The long-term exploitation dynamics of this species make it even more important today to increase protection and restoration efforts as it provides a significant range of ecosystem services. This becomes even more important in areas where natural recovery is hindered or unlikely. So far, only very few experiments have been carried out in the past, investigating suitable techniques for the successful transplantation of this species. For this reason, a review was conducted in order to synthesize previous results and identify the most promising methodologies. Additionally, six different transplantation techniques were tested and discussed in the context of the review. Five techniques used fragments for transplantation, while one used newly settled larvae on PVC-tiles. Shallow C. rubrum colonies often grow upside down under crevices and rims as well as in caves, making the transplantation of fragments comparatively challenging. Here, C. rubrum was transplanted upside down under crevices using a PVC-grid in combination with epoxy putty to hold fragments in place, and the results indicated the potential benefits of this technique. In a novel approach, shallow colonies, and larvae on settling plates were also transferred to deeper areas, suggesting that mesophotic populations can be restored to reconstruct pre-exploitation conditions. Attaching the colonies to the roof of crevices provided a level of survivorship consistent with conventional erect transplantations of colonies on rock bottom but had the advantage of being more removed from sedimentation and anthropogenic disturbance. Future work must develop permanent grid-mounting methods for use in the crevices before this approach can be further explored for large-scale restoration efforts.