Metagenomic Sequencing and Image Analysis of Autonomous Reef Monitoring Structures (ARMS) for Identifying Crustose Coralline Algae (CCA) Communities in Coast of Jeju Island, South Korea

Abstract

Crustose coralline algae (CCA) are constantly increasing in their coverage along the coast of Jeju Island. This change can alter the composition of benthic substrates, which may have a major impact on the benthic ecosystem. In this study, we used image analysis and metagenomic sequencing to investigate total coverage of CCA and their species composition on the shallow (15 m) subtidal rocky habitats in Seongsan (SS), Kangjeong (KJ), and Bomok (BM) of Jeju Island. In August 2018, Autonomous Reefs Monitoring Structure (ARMS) units were deployed for 12 months at SS, KJ, BM to monitor CCA community diversity. ARMS units were re-deployed in August 2019 and retrieved in February 2020. The results of image analysis indicated that the percent coverage of CCA at KJ and BM accounted for 96% and 97%, respectively, after three months. However, the percent coverage of CCA at SS showed 68% after three months, reaching 98% after six months. According to the results from metagenomic sequencing, 11 genetically distinct CCA species were identified across three sites. BM showed 1 species, whereas KJ and SS showed 8 and 9 species, respectively. Lithophyllum margaritae was found in all three sites, Mastophoropsis canaliculata, Synarthrophyton chejuense, Synarthrophyton patena were found only in SS, and Lithophyllum corallinae, Harveylithon sp. were found only in KJ. We continue to investigate CCA presence to determine which environmental parameters affect their coverage and species composition among three sites.