**Featured Application: Complement monitoring tool.**

**Abstract:** The nonlinearity and complexity of coastal ecosystems often cause di fficulties when analyzing spatial and temporal patterns of ecological traits. Environmental DNA (eDNA) monitoring has provided an alternative to overcoming the aforementioned issues associated with classical monitoring. We determined aquatic community taxonomic composition using eDNA based on a meta-barcoding approach that characterizes the general ecological features in the Gwangyang Bay coastal ecosystem. We selected the V9 region of the 18S rDNA gene (18S V9), primarily because of its broad range among eukaryotes. Our results produced more detailed spatial patterns in the study area previously categorized (inner bay, main channel of the bay and outer bay) by Kim et al. (2019). Specifically, the outer bay zone was clearly identified by CCA using genus-level identification of aquatic organisms based on meta-barcoding data. We also found significant relationships between environmental factors. Therefore, eDNA monitoring based on meta-barcoding approach holds grea<sup>t</sup> potential as a complemental monitoring tool to identify spatial taxonomic distribution patterns in coastal areas.

**Keywords:** coastal ecosystem; eDNA; spatial patterns; complemental monitoring tool
