Exp. 389 Hawaiian Drowned Reefs


船上レポート1(2023年09月21日受領)>>Coral reefs, sunrises, and doughnuts – IODP Expedition 389 (Hawaiian Drowned Reefs)


船上レポート1:Coral reefs, sunrises, and doughnuts – IODP Expedition 389 (Hawaiian Drowned Reefs)

Marc Humblet (Nagoya University)

I arrived in Honolulu a few days before boarding the ship that was to become my home for two months, just enough time to buy a few items that I had overlooked in my travel checklist, and more importantly, to meet other members of the science team, some who I already knew, some who I was meeting for the first time.
We boarded on the 31st of August. Our ship is the MMA Valour, an 84 m long multi-purpose platform supply vessel. IODP Expedition 389 is a mission specific platform expedition, which means that the ship had to be transformed to fulfil the requirements of the mission. For this expedition, a remotely operated seabed coring system was loaded on the ship, and containers were installed at the rear to accommodate lab facilities and the equipment needed for coring.
We departed from Honolulu in the evening of the 31st, and after some testing of the coring equipment offshore Oahu, we transited to our first coring site off the western coast of Hawaii (the Big Island). Since then, we have been staying in the same area and are now stationed about 10 km from the coast. From where we are, we have a stunning view of Mauna Kea, the tallest volcano in Hawaii.
Work on the ship is organized in shifts: a day shift and a night shift. I was assigned to the night shift, which means that I work from midnight to noon. I wake up every day at 11:00 pm, have my breakfast at 11:30 pm, my lunch at 6:00 am, and my dinner at 12:00 am. The first few days are tough, but you ultimately get used to it. There are advantages to the night shift. One is the quietness you experience during the night-time hours. You also get to see a beautiful sunrise every morning (daily contemplation time guaranteed!). You escape most of the afternoon heat, and – in my opinion, a crucial advantage – you get to enjoy the morning doughnuts, a perfect excuse to take a well-deserved pause during your shift!
Our expedition is collecting cores from submerged fossil coral reefs around the island of Hawaii to reconstruct the history of sea-level and climate changes over the past 500,000 years and understand how coral reefs and reef organisms have responded to environmental changes.
It has been extremely rewarding to see the cores that were brought on deck and discover for the first time these amazing sequences of fossil reef framework, preserved for tens or hundreds of thousands of years under the seafloor, and now revealing the beauty of an ecosystem teaming with life in the distant past. I cannot wait to see more of them!

A colorful sunrise and the island of Hawaii – the mountain to the right is Mauna Kea

Panoramic view of the area of the vessel MMA Valour where cores are curated and analyzed

First cores on deck!




Hawaiian Drowned Reefs




Offshore (乗船): 2023年8月31日~10月31日
Onshore Science Party (航海後の陸上分析): 2024年2月(詳細な日程は未定) at MARUM(ドイツのブレーメン大学海洋環境科学センター)



MMA Valour, equipped with the Benthic Portable Remotely Operated Drill (PROD5)(Mission Specific Platform)


Honolulu, Hawaii (TBC)


Hawaiian drowned reefs
ハワイ島近海 沈水サンゴ礁



The overall goal of the drilling campaign is to sample a unique succession of drowned coral reefs around Hawaii now at -134 to -1155 m below sea level. As a direct result of Hawaii’s rapid (2.5-2.6/kyr) but nearly constant subsidence, a thick (100-200 m) expanded sequence of shallow coral reef dominated facies is preserved within the reefs. These reefs span important periods in Earth climate history, either not available or highly condensed on stable (Great Barrier Reef, Tahiti) and uplifted margins (Papua New Guinea, Barbados) due to a lack of accommodation space and/or unfavourable shelf morphology. Specifically, these data show that the reefs grew (for ~90-100 kyrs, albeit episodically) into, during and out of the majority of the last five to six glacial cycles.

Therefore, scientific drilling through these reefs will generate a new record of sea-level and associated climate variability during several controversial and poorly understood periods over the last 500 kyr.

The project has four major objectives:

1) To define the nature of sea level-change in the central Pacific over the last 500 kyr, we will construct a new, more complete sea level curve from the drowned Hawaiian reefs that will allow: a) more detailed testing of Milankovitch climate theory predictions and; b) improved constraints on millennial-scale sea-level changes over the last 500 kyr.

2) To identify critical processes that determine paleoclimate variability of the central Pacific over the last 500 kyr, we will: (a) reconstruct the mean and seasonal/interannual climate variability from massive coral samples; and (b) use these records to investigate how high latitude climate (e.g., ice sheet volume), pCO2, and seasonal solar radiation impact subtropical Pacific climate. This approach can be used to test theoretical predictions of climate response and sensitivity to changes in boundary conditions and climate forcing.

3) To establish the geologic and biologic response of coral reef systems to abrupt sea-level and climate changes, we will: (a) establish the detailed stratigraphic and geomorphic evolution of the reefs in response to these changes; (b) test ecologic theories about coral reef resilience and vulnerability to extreme, repeated environmental stress over interglacial/glacial to millennial time scales; and (c) establish the nature of living and ancient microbial communities in the reefs and their role in reef building.

4) To elucidate the subsidence and volcanic history of Hawaii, we will: (a) refine the variation through space and time of the subsidence of Hawaii, and; (b) improve the understanding of the volcanic evolution of the island.

詳細についてはCall for ApplicationsECORDのページをご参照ください。



Jody Webster and Christina Ravelo

氏名 所属 役職 乗船中の役割
浅海 竜司 東北大学 准教授 Inorganic Geochemist
横山 祐典 東京大学 教授 Inorganic Geochemist
福與 直人 産業技術総合研究所 学振特別研究員 Paleomagnetist
HUMBLET Marc 名古屋大学 准教授 Paleomagnetist _Offshore







      • 日本国内の研究機関に所属する研究者、大学院生(乗船時に修士課程に進学見込みの学部生を含む)
      • 英語でコミュニケーションが取れる方





Offshore (乗船): 2023年8月中旬~10月末 (最大60日間)
Onshore Science Party (航海後の陸上分析): 2024年早々(詳細な日程は未定) at MARUM(ドイツのブレーメン大学海洋環境科学センター)



・英語のcurriculum vitae(CV)を、応募フォームから添付ください。


募集の詳細については、Call for Applicationsをご参照ください。




日時:2022年9月9日(金)1pm UTC(日本時間22時)




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