[M-IS19] Paleoclimatology and paleoceanography

[MIS19-P23] Utility of sedimentary environmental DNA for indices of past pelagic fish species populations

*Hiromichi Tamai¹, Michinobu Kuwae², Hideyuki Doi³, Toshihumi Minamoto⁴ (1.Graduate School of Science and Engineering, Ehime university, 2.Center for Marine Environmental Studies, Ehime university, 3.Graduate School of Simulation Studies, University of Hyogo, 4.Graduate School of Human Development and Environment, Kobe University)

Keywords:eDNA, sediment core, Quantitative polymerase chain reaction, pelagic fish

Far little is known about long-term dynamics of almost all of fish species populations in the ocean during pre-instrumental era. Here we focused on environmental DNA in marine sediments as a potential tool to elucidate past fish population dynamics and tested its utility to reconstruct fish abundance in Japanese coastal waters. Based on quantitative PCR method applied to the sediment samples collected from anoxic bottom sediments in Beppu Bay, Japan, we found environmental DNA of Japanese anchovy, Japanese sardine, and Jack mackerel in the 1-meter sediment sequences spanning over the last 250 years, which is the first detection of sedimentary marine fish DNA. The observed temporal changes in sedimentary DNA abundances are consistent with those in fish scale abundances and catch in Japan, suggesting the utility of the sedimentary fish environmental DNA to track past changes in fish abundance in waters from the bottom sediment sequences. DNA analyses of five fractions of sediment samples including coarse and fine particle fractions, pore water, fish scales, and bones suggested that a main source of fish DNA in the sediments is derived from fine the particle fraction.