Aslan Hwanhwi Leea,1, Junghyun Leea,1, Junsung Noha, Changkeun Leea, Seongjin Hongb, Bong-Oh Kwonc, Jae-Jin Kimd, Jong Seong Khima,*
aSchool of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea
bDepartment of Ocean Environmental Sciences, Chungnam National University, Daejeon 34134, Republic of Korea
cDepartment of Marine Biotechnology, Kunsan National University, Kunsan 54150, Republic of Korea
dDivision of Environmental Science & Ecological Engineering, College of Life Science & Biotechnology, Korea University, Seoul 02841, Republic of Korea
1These authors contributed equally to this work.
The environmental DNA (eDNA) metabarcoding was applied to assess benthic ecological health in the west coast of South Korea by investigating a long-term microbial community change (2015–17). The ecological interaction among microorganisms, from phylum to family level, and their associations to environmental variables across the five regions were highlighted. As part of the study, the available chemistry and toxicological data in the regions during the monitoring periods were incorporated into an integrated sediment triad assessment. The bacterial communities were dominated by Proteobacteria (34.2%), Bacteroidetes (13.8%), and Firmicutes (10.8%). Proteobacteria and Bacteroidetes dominated consistently across regions and years, while Firmicutes and Cyanobacteria significantly varied by region and years (p < 0.05). The abundance of this phylum declined over time with the increasing abundance of Cyanobacteria, indicating their independent interactions to certain environmental changes. Planctomycetes and Gemmatimonadetes linked to some contaminants (ΣPAHs and Cu), implying indicator taxa. Overall, eDNA-based microbial community analysis combined with exposures of contaminants and responses of microorganisms is a promising strategy for the assessment of benthic ecological health in contaminated sediments from coastal waters.