Surveying Reef Biodiversity with DNA Metabarcoding

DNA metabarcoding is redefining coral biodiversity surveys as a molecular method to identify organisms through DNA extraction from a homogenized community using barcode reference libraries. The paucity of marine invertebrate barcodes within these libraries raises questions on the accuracy of species identifications using this technique for complex marine invertebrate communities. CIMAR Marine Ecosystems Research Project Specialist, Dr. Molly Timmers, and others evaluated the performance of DNA metabarcoding in detecting sponges from a complex community established on Autonomous Reef Monitoring Structures (ARMS). After two years, the number of sponges identified on the ARMS by a taxonomist using morphology and DNA barcodes were compared with the number of species detected from metabarcoding a homogenized subsample of the multi-phyla community on the ARMS. While the study found DNA metabarcoding adequately captures richness overall and at the sponge class level, it uncovered technical and biological constraints associated with order-level identifications. With over 75% of the sponges in the study found to be new species to the DNA reference database, and with the growing movement to use genetics to characterize biodiversity, there is a need for empirical performance tests to improve the utility of metabarcoding.