2:30 PM - 2:45 PM
[HQR04-09] Reconstruction of paleo-environment using the DNA metabarcoding targeted on the plankton community: a case study in Lake Shinji
Keywords:environmental DNA, sedaDNA, protist, sedimentary core, Anthropocene
As a case study, we will present a sedimentary study targeted on plankton community in Lake Shinji, Japan. Lake Shinji is a low salinity lake (the PSU is ca. 5 in the highest layer), but it was a semi-closed bay filled with sea water before 2000 years ago. Previous studies clarified that the concentration of sulfur, which indicates the inflow of sea water, decreased in a certain period during the past 2000 years. It is therefore hypothesized that in this period, the semi-closed bay became an almost freshwater lake. Yet, this hypothesis was not supposed by enough biological evidences.
Given this situation, a sedimentary core of ca. 4 m was sampled in July 2021 from the center of the lake, and the DNA-MB focused on plankton was conducted for the sedimentary samples taken from every 4 cm. Marine plankton were mainly detected in the samples lower than ca. 2.5 m in depth, and the plankton composition was largely different among the samples upper and lower than ca. 2.5 m. This core depth corresponded to the timing of the sulfur decrease, and the age was estimated at A.D. 1250–90. Judging from these results, the desalinization of the lake and the drastic change of ecosystem stared presumably around A.D. 1250–90.