Seawater, Sea Squirts, and Stories from Onagawa

こんにちは！D3のMiyaです！

I recently visited Onagawa to help Professor Tanaka and her students with fieldwork on hoya (sea squirts). Their research focuses mainly on cellulose analysis and DNA-based investigations, while my role was to help collect seawater for dissolved inorganic carbon (DIC), uranium/thorium (U/Th), and oxygen isotope (δ¹⁸O) analyses. I thought hoya is called sea pineapple, but realized only the commonly-eaten species マボヤ is called sea pineapple.

My first encounter with hoya was a few years ago, when I bought a sea pineapple at a supermarket in Otsuchi. It was my first time eating one, and I dissected it myself to prepare it. Cutting into it felt strangely like cutting into a heart—not that I’ve ever cut into one! This time in Onagawa, I got to see a wider variety of sea squirts as we sorted the different species by hand.

We sampled seawater both inside and outside the aquaculture farm, and the team also collected sediment samples. We even got to enjoy a bite of the fresh ones during sampling! 

Alongside the sampling, we sorted different species of hoya by hand, including マボヤ, エボヤ, and 白ボヤ. Working through the specimens gave me a closer look at the variety of sea squirts living in the area—something quite different from my usual work with abalone shells.

One evening, we had dinner with people working at Tohoku University’s Onagawa Field Center, part of the Graduate School of Agricultural Science. Over dinner, they shared their memories of the 2011 earthquake and tsunami.

One person recalled being on a research cruise with the coastal research center when the earthquake struck. After seeing the tsunami, he decided to sail farther offshore rather than return to land. He and his colleague ended up staying offshore for three days.

Hearing this account directly from someone who experienced it made a strong impression on me. Our visit was centered on collecting samples, but the conversations over dinner also offered a glimpse into the experiences of the people who live and work along this coast.

Thank you to Professor Tanaka, her students, and everyone at the Onagawa Field Center for welcoming me and sharing both their research and their stories. Also thank you Yosuke and Shishi for helping me with preparation and Yusuke for sponsoring the trip!

New Paper Nature and others (25/08/26 -01/09/26)

 

Science Advances

Near-term, geospatial opportunity for biomass carbon storage to address the wildfire and climate crises

Leah K. Clayton, Alexander S. Wyckoff, and Sinéad M. Crotty 

PNAS

Weak prestorm submesoscale sea surface temperature gradients conducive to tropical cyclone intensification

Hanrui Liu, Wenju Cai, Shoude Guan, +4 , and Zhengguang Zhang 

Rethinking the origin of life at seafloor hydrothermal vents

Benjamin M. Tutolo

Recent high-severity wildfires in a dry-conifer landscape are unprecedented over five centuries and foretell future forest loss

Andreas P. Wion, Jens T. Stevens, Jonathan D. Coop, +3, and Ellis Q. Margolis 

Major role for internal variability in tropical Pacific warming pattern over satellite era

Shang-Ping Xie  ,  Ayumu Miyamoto   Qihua Peng , and  Matthew T. Luongo

Nature Geoscience

Fan, CS., Sun, C., Xie, Z.  et al.  Hadley circulation drives material isolation and pole-to-pole teleconnection on Mars.  Nat. Geosci.  (2026). https://doi.org/10.1038/s41561-026-02090-2

Su, Y., Xu, Y., Zhang, X.  et al.  Disturbance characteristics and forest properties regulate surface warming and recovery across Europe.  Nat. Geosci.  (2026). https://doi.org/10.1038/s41561-026-02071-5

Liu, D., Jiang, F., Hu, K.  et al.  Warming potential of atmospheric black carbon modulated by particulate matter.  Nat. Geosci.  (2026). https://doi.org/10.1038/s41561-026-02068-0

Nature Communications

Fan, D., Duarte, CM, Wang, F.  et al.  The global distribution of macroalgal carbon burial in coastal sediments.  Nat Commun  (2026). https://doi.org/10.1038/s41467-026-77215-7

Namur, O., Charlier, B., Cartier, C.  et al.  Carbon distribution in planet Mercury from magma ocean evolution to graphite crust and core composition.  Nat Commun  17 , 9227 (2026). https://doi.org/10.1038/s41467-026-75458-y

Alcott, LJ, Mills, BJW, Bekker, A.  et al.  A nutrient control on oxygenation dynamics during Earth's Great Oxidation Episode.  Nat Commun  (2026). https://doi.org/10.1038/s41467-026-76597-y

Larsen, KMH, Eriksdóttir, G., Hansen, B.  et al.  Iceland-Faroe overflow revealed by in-situ observations.  Nat Commun  (2026). https://doi.org/10.1038/s41467-026-77220-w

Wang, S., Oppo, DW & Ummenhofer, CC Coupling of Pacific and Indian Ocean variability disrupted by 19th century volcanism.  Nat Commun  17 , 8572 (2026). https://doi.org/10.1038/s41467-026-76705-y

Pondom National Centre

Wang, H., Liu, J., Holden, J. et al. Climate warming drives thermal shocks and accelerated freshwater habitat fragmentation. Nat. Clim. Chang. (2026). https://doi.org/10.1038/s41558-026-02731-9

New Papers (Elsevier) 2026/08/25~2026/09/01

Earth and Planetary Science Letters

1. Eastern equatorial Pacific deep water Δ[CO₃^2-] changes during the last glacial maximum and early deglacial

    Matthew W. Schmidt, Brian J. Close, Jennifer E. Hertzberg, Franco Marcantonio

2. Full-waveform tomography of southeastern Tibet: Evidence for dual crustal low-velocity zones and hybrid tectonic processes

    Xinyu Jiang, Xiaodong Song, Xuezhen Zhang, Haoyu Xu, Xingchen Wang, Bin He, Hejun Zhu

Quaternary International

3. Sedimentary characteristics of the Ganges Submarine Delta and its response to chemical weathering during the Mid-Holocene

    Hongmin Wang, Lina Ai, Ashraf Ali Seddique, Bingjie Sun, Hui Zhang, Xiaoyan Li, Peng Cao, Kaikai Wu, Kunshan Wang, Shengfa Liu

4. Thermocline and paleo productivity changes off West Simeulue Island in relation to monsoonal hydroclimate since the Last Glacial Maximum

    Ryan Dwi Wahyu Ardi, Purna Sulastya Putra, Septriono Hari Nugroho, Winda Eka Mandiri Puteri, Khoiril Anwar Maryunani

5. Late Quaternary faunal remains as proxies for the human-environment relationships at San Esteban rockshelter in the northern Chihuahuan Desert, southwest Texas, USA

    Erika S. Blecha, Rolfe D. Mandel

6. Geomorphological dynamics at the coast: A sedimentary stratigraphy for Atlit-Yam, the earliest coastal village at the Eastern Mediterranean and its submerged landscape

    Vishal Kataria, Gilad Shtienberg, Isaac Ogloblin Ramirez, Roni Zuckerman-Cooper, Nimer Taha, Elle Grono, Marko Runjajić, Ehud Galili, Nicolas Waldmann, David E. Friesem

 

New Paper Elsiever (08/18/26 - 08/25/26)

Chemical Geology

1. Influence of partial melting and ancient depletion on helium isotopes of mantle-derived magmas - Andrea Giuliani, Senan Oesch, Federico Munch, Ronghua Cai, Jingao Liu, Mark D. Kurz, Peter H. Barry, Luc S. Doucet, Michael J. Walter 

Earth and Planetary Science Letters

2. Nonlocal elastic unloading as a mechanism for breakdown work scaling in laboratory earthquakes - Chun-Yu Ke, Gauss T. Chang, Gregory C. McLaskey, David S. Kammer, Chris Marone

3. Replacing the elastic model with a simple viscoelastic model for more reliable estimation of geodetic locking depths of strike-slip faults - Yijie Zhu, Kelin Wang, Lin Shen, Edwin Nissen

Global and Planetary Change

4. Characterising the changes and regional drivers of tropical cyclone intensification over the western North Pacific - Yuanke Wu, Tao Gao, Xi Xiao, Wei Zhang, Fuqiang Cao, Yang Yu, Yuzhi Liu, Yumin Zhang

5. Future climate change will intensify snow drought in the high-latitude water tower, Changbai Mountain - Moran Xu, Haiqing Wang, Shilin Zhang, Yingyi Chen, Yu An, Guangxin Zhang, Peng Qi

Marine Geology

6. Deepwater sediment waves in mixed contouritic-turbiditic setting: The Bounty Fan, New Zealand - Séverine Russo, Julien Bourget, Thierry Mulder, Gabriele Uenzelmann-Neben

7. Reassessing continental sediment fluxes at a marginal sea gateway: Quantitative provenance of the Korea Strait Shelf Mud (KSSM) - Minji Seo, Hoi-Soo Jung, Jeongwon Kang, Byung-Cheol Kum, Seok Jang, Moonsoo Lim, Bo-Yeon Yi, Jiyoung Choi

Palaeogeography, Paleoclimatology, Paleoecology

8. Integrating pollen and sedimentary DNA refines reconstructions of vegetation change through human settlement: a case study from Lake Waihau, Aoteroa New Zealand - Xun Li, Georgia Thomson-Laing, Marcus J. Vandergoes, Jamie D. Howarth, Susanna A. Wood

9. Palaeoflood records and environmental impacts on the ancient Shu civilisation on the Chengdu Plain, Southwest China - Ming Huang, Chunmei Ma, Tieyong Bai, Dao Xiang, Cheng Zhu

Quaternary Geochronology

10. Optimising bioapatite 14C dating: Chemical pretreatment efficacy across preservation states in archaeological bone - Huihui Cao, Sizhe Ai, Zongli Wang, Jiale Guo

11. Single-grain luminescence dating of lake-core sediment Kusai Lake on the northern Qinghai-Tibet Plateau - Xiaoling Huang, Jingran Zhang, Hao Long, Aimin Zhang, Yandong Hou, Ji Shen

My week in Fukuoka for AOGS

Last week, I traveled to Fukuoka for the Asia Oceania Geosciences Society (AOGS) conference to present my research on dissolved inorganic radiocarbon within North Pacific Subtropical Mode Water. For one week, I listened to many great talks from scientists around the world.

Fukuoka International Congress Center

My presentation was on the 5th of August in the evening. I was excited to share what I have been researching for the past year of my PhD.

Presenting My Research

I had a lot of fun taking photos on my new (old) digital camera from 2008. I had the chance to explore the city on a road trip with a few old and new friends I met at the conference! The weather was very hot everyday, ranging from 35° to 37°C. 

Sakurai Futamigaura in Itoshima City

Aburayama Katae Observation Deck

Reclining Buddha (Nanzoin)

I hope I will be able to attend AOGS again next year!