[A-HW22] Material transportation and cycling at the land-sea interface: from headwaters to the ocean

[AHW22-P10] Coastal fish functional patterns correlated with environmental drivers in an island of Seto Inland Sea, Japan

*Nhat Hong Nguyen^1,5,6, Mitsuyo Saito², Shin-ichi Onodera², Mayuko Hamada³, Fujio Hyodo⁴, Hideaki Nagare⁴ (1.Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan, 2.Graduate School of Advanced Science and Engineering, Hiroshima University, Hiroshima, Japan, 3.Ushimado Marine Institute (UMI), Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, Okayama, Japan, 4.Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Okayama, Japan, 5.Faculty of Technology – Engineering – Environment, An Giang University, An Giang, Viet Nam, 6.Vietnam National University Ho Chi Minh City, Vietnam)

Keywords:environmental DNA, taxonomic diversity, functional diversity, environmental divers, semi-enclosed coastal

Fish communities, integral to ecosystem dynamics and services in coastal zones, are shaped by diverse environmental conditions and habitats. This study used environmental DNA (eDNA) monitoring to explore spatial variations in the composition and functional traits of fish communities. Our research reveals that the fish community on Ikuchijima Island is predominantly comprised of the Sparidae family, with a significant representation of benthic habits (66.10% demersal fish) and carnivorous species (55.93%) in the functional composition. Distinct variations in species occurrence and distribution across different sites led to diverse impacts on functional diversity patterns. Key environmental drivers, including salinity, DIN, DSi, submarine groundwater discharge (SGD), and offshore seawater mixing, were found to significantly influence the composition and functional diversity of fish communities. SGD and DSi had a notable impact on omnivorous demersal fish species. These findings underscore the intricate responses of fish composition and functional diversity to the interplay of physical and biochemical drivers in semi-enclosed coastal environments, thereby enhancing our understanding of ecosystem complexities.

Acknowledgments
This research was supported by JSPS Grant-in-Aid for Scientific Research (B) (No. 21H03650, PI: Mitsuyo Saito) and Fostering Joint International Research (A) (No. 20KK0262, PI: Mitsuyo Saito).