講演情報
[5O1-IS-1-05]Mathematical analysis of regime shifts in river surface water microbiota
〇Norinaga Kanemoto1, Hitoshi Hirata1, Tamao Saito1, Ikuko Eguchi Yairi1 (1. Graduate School of Sophia University)
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キーワード：
Mathematical analysis、Regime shift、River surface water、DNA、Metagenome
This study seeks to formalize the dynamics of microbial communities in river surface water by analyzing bacterial data collected from the Tama River during the 2018 and 2024 fiscal years, focusing on regime shifts—discontinuous and irreversible ecosystem changes. Samples were collected at 10 sites near Lake Okutama, resulting in 60 samples for 16S rRNA gene analysis. Site characteristics were evaluated by calculating various diversity indices and assessing similarities between locations using NMDS. A mathematical model based on differential equations derived from the heartbeat cycle formula was developed and validated as representative of regime shift features. Results indicated structural differences in microbiota among the upstream sites (L1–L3), Lake Okutama (L4), and downstream sites (L5–L10), with a notable transition at L4. Additionally, the link between COD and Bdellovibrionota abundance ratios showed irreversible behavior, persisting even after environmental improvements. This supports the concept of regime shifts, suggesting potential transitions from upstream to downstream in the Tama River.