| 研究課題/領域番号 |
18K03824
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| 研究機関 | 名古屋大学 |
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研究代表者 |
HUMBLET Marc 名古屋大学, 環境学研究科, 准教授 (40623616)
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| 研究期間 (年度) |
2018-04-01 – 2022-03-31
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| キーワード | Coral reefs / Mesophotic habitats / Benthic communities / Seafloor topography / AUV / ROV / Fossil coral communities / Sea-level change |
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| 研究実績の概要 |
(1) Data on the taxonomic composition of fossil corals in the late Middle Pleistocene Minatogawa Formation in southern Okinawa Island collected during 5 field surveys in 2017-2019 were analyzed to identify variations in coral assemblages in space and time. The results were used to reconstruct the depositional history of the Minatogawa Formation, and were compiled in a master’s thesis submitted in February 2021 at Nagoya University. (2) Drilled cores of Holocene reef limestones from Kodakara-jima, Kagoshima Prefecture, were described at the Kochi Core Center (KCC) in December 2020. Other cores, also of Holocene reef limestones and from the same location, were CT-scanned and split in March 2021 at the KCC. The objective of this study is to investigate the response of a high-latitude coral reef to Holocene sea-level rise. This study is part of an ongoing master’s thesis at Nagoya University. (3) Two boreholes, M0040A and M0041A, drilled by IODP Expedition 325 along the modern great barrier reef were examined at the KCC in December 2020. The objective of this study is to understand the long-term history of a deep mesophotic reef ecosystem since the last Glacial period. Results were compiled in an article submitted to a specialized scientific journal. (4) The results of a test survey of mesophotic reef habitats conducted in 2018 in the South Ryukyu Islands using a prototype of lightweight autonomous underwater vehicle (AUV) designed and built by Professor Toshihiro Maki’s lab of the University of Tokyo were compiled in an article submitted to a specialized scientific journal.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
3: やや遅れている
理由
A field survey involving the exploration of the seafloor at mesophotic depths in the South Ryukyu Islands using a AUV was postponed due to the current pandemic and the agendas of the collaborators involved. Another field survey targeting the late Middle Pleistocene Minatogawa Formation in southern Okinawa Island expected to take place in the Summer of 2020 was also postponed due to the pandemic.
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| 今後の研究の推進方策 |
Future research activities during FY2021 will focus on the study of the core sections of Holocene reef limestones from Kodakara-jima. The core sections which have not yet been examined will be described in details. In addition, well-preserved coral skeletons will be sampled for radiocarbon dating.
One field survey targeting the Minatogawa Formation in southern Okinawa Island is also expected to take place during FY2021 in order to study the sedimentology and fossil content of sections of late Middle Pleistocene reef limestones which have not yet been examined in detail.
Another objective of this project is to continue the exploration of the modern mesophotic seafloor in the South Ryukyu Islands using robotic submersibles, and in the meantime also further improving the performances of the new lightweight AUV (HATTORI) developed by Assoc. Prof. Toshihiro Maki’s lab.
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| 次年度使用額が生じた理由 |
The budget for FY2021 will be used to travel to Kochi Prefecture to study the core sections of Holocene coral reef limestones from Kodakara-jima stored at the Kochi Core Center. Part of the budget will also be used to travel to Okinawa Island and survey outcrops of late Middle Pleistocene limestones of the Minatogawa Formation. The remaining budget will be used to cover costs related to the survey of modern mesophotic seafloor near Ishigaki-jima, South Ryukyu Islands.
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