Paleoenvironmental proxy development focusing on the morphology of the Southern Ocean diatom F. kerguelensis.

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K14030
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 17050:Biogeosciences-related
• Research Institution: Kochi University (2023); University of Tsukuba (2021-2022)
• Principal Investigator: Kato Yuji 高知大学, 教育研究部自然科学系理工学部門, 講師 (80863406)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 珪藻 / 南大洋 / 形態 / 古環境復元

Outline of Final Research Achievements

Seawater plankton samples and surface sediment samples collected during a series of scientific cruises in the Indian Ocean sector of the Southern Ocean (e.g., R/V Hakuho-Maru KH-19-1 and KH-20-1) were analyzed. In addition, we successfully acquired a large number of specimen images by utilizing a slide scanner during the analysis in FY2023. As a result, it was found that the valve area of F. kerguelensis was the largest near the Antarctic Polar Front in the seawater plankton samples, and a similar trend was observed in the surface sediment (fossils) samples. This suggests that the valve morphology of F. kerguelensis fossils may be useful for reconstructing the variability of the oceanic front in the geological past.

Free Research Field

微古生物学

Academic Significance and Societal Importance of the Research Achievements

南大洋は，南極大陸を周回する世界最大の海流である南極周極流（ACC）の成立などを通じて地球規模の気候変動を駆動してきた。そのため，南大洋の古環境復元とりわけ「過去のACCがどのように振る舞ったか」を知ることは気候システムの理解さらには気候将来予測のためにも必須の課題である。従来手法では長期・連続的にACCの挙動を復元することは難しかったが，本研究を通じて，南大洋堆積物中に連続的に多産する珪藻であるF. kerguelensisの形態変化から過去のACC南限位置の情報を取り出すことができる可能性が示されたため，長期的かつ連続的なACC全体の変動史にアプローチ可能となった。