The predator-prey interaction in freshwater ecosystems is a crucial area in the ecological study field and one of example to find such interaction is to investigate stomach contents. However, traditional method through visual inspection often induce misidentification, as it depends critically on intactness of physically visible data. In this study, we utilized Next-Generations Sequencing (NGS) technology to test the applicability stomach content analysis and overcome such limitation. NGS was applied to analyze the stomach contents of the Hemibarbus labeo, Tachysurus fulvidraco, and Plecoglossus altivelis collected in the lower part of Nakdong River. As a result, T. fulvidraco had a higher number of Animalia operational taxonomic units (OTUs) intake rate than H. labeo. At the same time, P. altivelis had higher number of Plantae OTUs intake rate than T. fulvidraco and higher Protozoa OTUs intake rate than H. labeo respectively. Therefore, NGS technology application enable to overcome traditional method’s limitation and discover hidden interspecific interaction which can further be used in appropriate habitat assessment.

Gut contents analysis is essential to predict the impact of organisms on food source changes due to variations of the habitat environment. Previous studies of gut content analysis have been conducted using traditional methods, such as visual observation. However, these studies are limited in analyzing food sources because of the digestive process in gut organ. DNA metabarcoding analysis is a useful method to analyze food sources by supplementing these limitations. We sampled marine fish of Pennahia argentata, Larimichthys polyactis, Crangon affinis, Loligo beka and Sepia officinalis from Gwangyang Bay and Yeosu fisheries market for analyzing gut contents by applying DNA metabarcoding analysis. 18S rRNA v9 primer was used for analyzing food source by DNA metabarcoding. Network and two-way clustering analyses characterized the relationship between organisms and food sources. As a result of comparing metabarcoding of gut contents for P. argentata between sampled from Gwangyang Bay and the fisheries market, fish and Copepoda were analyzed as common food sources. In addition, Decapoda and Copepoda were analyzed as common food sources for L. polyactis and C. affinis, respectively. Copepoda was analyzed as the primary food source for L. beka and S. officinalis. These study results demonstrated that gut contents analysis using DNA metabarcoding reflects diverse and detailed information of biological food sources in the aquatic environment. In addition, it will be possible to provide biological information in the gut to identify key food sources by applying it to the research on the food web in the ecosystem.