[A-OS13] Marine ecosystems and biogeochemical cycles: theory, observation and modeling

[AOS13-P07] Assessing the influence of different environmental DNA (eDNA) sampling methods on small pelagic fish community structures

*Xueding Wang¹, Zeshu Yu¹, SK ISTIAQUE AHMED^1,2, Sachihiko Itoh¹, Eisuke Tsutsumi³, Shu-Kuan Wong¹, Jun Inoue¹, Susumu Hyodo¹, Tomihiko Higuchi¹, Shin-ichi Ito¹ (1.Atmosphere and Ocean Research Institute, The University of Tokyo, 2.Graduate School of Agricultural and Life Sciences, The University of Tokyo, 3.Kagoshima Univercity)

Keywords:eDNA, Small pelagic fish, Comparison of Methods

Environmental DNA (eDNA) approach, as an innovative monitoring technology, offers a cost-effective, relatively fast, and environmentally friendly approach to explore species communities in multiple ecosystems. As more and more scientists use environmental DNA (eDNA) samples to analyze fish community compositions in the open ocean, it is crucial to understand the influence of sampling methods on eDNA detection results. Chub mackerel (Scomber japonicus), blue mackerel (Scomber australasicus), Japanese anchovy (Engraulis japonicus), Japanese sardine (Sardinops melanostictus), Japanese jack mackerel (Trachurus japonicus) and Pacific saury (Cololabis saira) are small pelagic fishes that are inhabiting the upper 200 m of coastal zones and open oceans and are known as an important fishery resource worldwide. In this study, three eDNA sampling methods including clean-bucket sampling, Niskin bottle sampling and intake pumped sampling were chosen to assess the influence of different eDNA sampling methods on small pelagic fish community. A multiplex real-time PCR method with species specific primers was used to efficiently perform quantitative analysis of eDNA. Totally 90 samples from 30 stations were collected during four cruises throughout the western North Pacific in 2021. Our results showed all three methods enabled small pelagic fish species detection. Nevertheless, in several stations where significant high Blue Mackerel and Japanese Anchovy eDNA concentrations have investigated form the clean-bucket samples, bucket sampling has a crucial potential for spawning ground research. Besides, we detected the differences between samples from the various methods for each species, separately and found a significant difference of Jack Mackerel eDNA concentrations (Kruskal–Wallis test, p < .01) but not for the other four species (Kruskal–Wallis test, p > .05). Shannon index was used to evaluate the community structures and we found that there was significant difference between clean-bucket sampling method and other two sampling method (Wilcoxon signed-rank test, p < .01) and there was no significant difference between Niskin bottle samples and ship bottom intake (Wilcoxon signed-rank test, p > .05), indicating intake sampling should be prioritized in eDNA approaches.