Species-specific eDNA monitoring and multivariate analysis for early warning of marine harmful organisms in a semi-enclosed Coastal Bay

초록

This study developed and applied a species-specific environmental DNA (eDNA) monitoring approach for detecting 12 harmful marine taxa, including algal bloom species and jellyfish, in Masan Bay, a semi-enclosed coastal ecosystem in the Republic of Korea. Custom primers were designed and validated through in silico BLAST analysis and PCR amplification, providing a cost-effective and non-invasive alternative to traditional metabarcoding and next-generation sequencing approaches. The species-specific eDNA method detected a broader range of harmful taxa than microscopy-based surveys, while sediment eDNA provided complementary information to water-column monitoring. Seasonal patterns in species detection were explored using correlation and multivariate analyses. Multivariate ordination suggested that certain environmental gradients, including pH and temperature, were associated with seasonal variation in eDNA detection; however, these relationships were exploratory rather than predictive. Overall, this case study demonstrates that species-specific eDNA monitoring can enhance detection sensitivity and support qualitative assessment of the seasonal and spatial occurrence of marine harmful organisms in semi-enclosed coastal systems. The proposed approach offers a scalable and accessible framework for regional coastal monitoring and may serve as a complementary tool to traditional surveys in areas vulnerable to harmful algal blooms and jellyfish outbreaks.

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