Efficacy of the 28S rDNA barcode in differentiating Caribbean octocorals

The ecological landscape of Caribbean reefs is rapidly changing as octocorals fill the void left by declining scleractinian populations. Effective molecular barcodes are necessary to accurately identify these octocorals and monitor this shifting ecosystem. We tested the efficacy of the 28S rDNA as a barcode compared to the most commonly used mtMutS barcode on a collection of octocorals from across the Caribbean. Based on pairwise genetic distance values, 28S appeared to be more effective at differentiating species within the families Plexauridae and Gorgoniidae, while mtMutS was slightly more effective at distinguishing species of Pterogorgiidae. However, the standard 28S rDNA primers did not amplify all species as effectively as mtMutS, especially those belonging to the genus Eunicea. A shorter 28S barcode developed for eDNA applications distinguished species as effectively as the complete 28S barcode.