Mr Incheol Yeo1, Ms Harim Jeong1, Mr Kyu-Young Shim1, A/Prof. Chang-Bum Jeong1
1Incheon National University, , South Korea
Biography:
In-Cheol Yeo is a Ph.D. student whose research focuses on marine biodiversity and ecosystem dynamics using environmental DNA (eDNA) metabarcoding. His work integrates multi-marker eDNA data with ecological and bioinformatic approaches to investigate community structure, species interactions, and ecological responses to environmental gradients.
Abstract:
Coastal ecosystems are highly productive interfaces between terrestrial and marine environments, yet they are increasingly threatened by climate change and anthropogenic stressors. Here, we reconstructed approximately a century of environmental and ecological change in Jinhae Bay, South Korea, using a sediment core-based multiproxy framework. Radiometric dating, heavy metal profiles, stable isotope signatures, and organic matter analyses identified three distinct historical phases: natural conditions (Phase I), post industrialization (Phase II), and the period following implementation of the Total Maximum Daily Load (TMDL) system (Phase III). To resolve long-term biological responses, we implemented a multi-marker eDNA metabarcoding framework targeting the V4, V7, and V9 hypervariable regions of the 18S rRNA gene. The eDNA record revealed a profound ecological regime shift, characterized by a marked expansion of protists and a substantial decline in metazoans. These transitions indicate that eutrophication and pollutant loading favored opportunistic microeukaryotes, while progressive hypoxia increasingly constrained habitats for multicellular taxa. Notably, although pollutant inputs declined following TMDL implementation, the ecosystem did not recover its pre-industrial community structure. Instead, the biological archive reveals persistent ecological reorganization and strong legacy effects, demonstrating that industrialization-driven eutrophication and hypoxia can push coastal ecosystems beyond recovery thresholds, resulting in long-lasting biodiversity loss and incomplete ecosystem resilience. Together, our findings highlight the long-term ecological consequences of coastal eutrophication and demonstrate the value of sedimentary eDNA archives as powerful tools for reconstructing historical ecosystem trajectories and informing future coastal management strategies.