Taiki Adachi

Quantitative evaluation of animal upwelling and its implementation into biogeochemical models

Grant No.：JPMJPR25G1

Researcher

Taiki Adachi

Outline

This study focuses on animal upwelling, a natural process in which deep-diving marine top predators transport nutrients to surface waters through excretion. The project aims to: (1) collect excretion data from seal species to quantitatively evaluate the mechanisms of animal upwelling, and (2) implement an animal upwelling module into biogeochemical models to assess the impact of the animal-derived nutrient supply on primary production and CO₂ uptake.

Tomonori Isada

Validation of Ocean Alkalinity Enhancement in the Coastal Oyashio region

Grant No.：JPMJPR25G2

Researcher

Tomonori Isada

Outline

I will conduct a microcosm experiment to investigate the potential effects of Ocean Alkalinity Enhancement (OAE), one of the marine carbon dioxide removal (mCDR) approaches, on seawater chemistry, specifically alkalinity and pH, and on the community structure and physiology of phytoplankton in Akkeshi Bay, which is influenced by the cold coastal Oyashio current. By conducting this research, I aim to contribute to climate change mitigation efforts by harnessing the beneficial functions of marine ecosystems.

Yuko Omori

Investigating the effects of ocean acidification on volatile organic compound dynamics

Grant No.：JPMJPR25G3

Researcher

Yuko Omori

Outline

Volatile organic compounds (VOCs) originating from marine ecosystems are important components of the atmospheric environment and the climate system. Ocean acidification may alter the rates of VOC production and degradation, potentially influencing climate processes. In this study, incubation experiments are conducted using natural CO₂ seep sites to elucidate the effects of ocean acidification on VOC dynamics and the factors controlling them. The findings will provide essential datasets to evaluate the impacts of ocean acidification on climate through VOC pathways.

Takako Saito

Molecular Insights into Tunicate Cellulose and the Development of Carbon Fixation Applications

Grant No.：JPMJPR25G4

Researcher

Takako Saito

Outline

Ascidians are marine invertebrates that filter-feed on phytoplankton and are unique among animals in their ability to synthesize cellulose. In this study, we aim to elucidate the cellulose biosynthetic mechanism of ascidians and quantify carbon fixation during their growth, highlighting their potential as novel contributors to carbon sequestration. Furthermore, by establishing a foundation for the utilization of cellulose accumulated in the tunic as a resource, we seek to develop a circular resource model that leverages ascidian traits for a sustainable, decarbonized society.

Yoshihiro Nakayama

Carbon cycle and steering potential of the Antarctic coastal ocean: an observational model fusion study

Grant No.：JPMJPR25G5

Researcher

Yoshihiro Nakayama

Outline

The importance of the carbon cycle in the Antarctic coastal ocean is widely recognized, yet it remains poorly understood. To address this gap, models that can reproduce Antarctic-specific ocean circulation, ecosystems, and carbon dynamics in agreement with observations are essential. I integrate an ocean biogeochemistry/ecosystem model into a high-fidelity physical ocean model that accurately reproduces regional ocean physics. Building on the hypothesis that the unique Antarctic coastal circulation plays a critical role in transporting anthropogenic carbon dioxide into the deep ocean, I aim to develop a regional ocean-carbon cycle coupled model and use it to elucidate the Antarctic coastal carbon cycle. In addition, sensitivity experiments will be conducted to assess future changes and the mechanisms steering the carbon cycle.

Kohei Hamamoto

Tropicalization of Coastal Waters: The Role of Kuroshio-Induced Kyucho

Grant No.：JPMJPR25G6

Researcher

Kohei Hamamoto

Outline

Tropicalization, a phenomenon in which ecosystems dominated by temperate species are being replaced by tropical species, has been increasingly reported across the globe in recent years due to ocean warming. One possible driver of this shift is the impact of rapid sea temperature fluctuations—such as those caused by marine heatwaves—on local biological communities. This research project focuses on Kyucho, a rapid current phenomenon occurring in the Bungo Channel between Shikoku and Kyushu, to investigate how extreme temperature changes affect marine communities. The study combines instrument-based oceanographic observations with large-scale genetic analyses to elucidate these effects.

Yasuhito Hayashi

Quantifying Marine Snow Fragmentation via Daughter Particle Visualization

Grant No.：JPMJPR25G7

Researcher

Yasuhito Hayashi

Outline

The ocean’s capacity to store CO₂ over long timescales depends on how much organic carbon is transported from the ocean surface into deeper layers by sinking particles known as marine snow. Since the organic content of marine snow decreases with depth, predicting future carbon storage requires understanding its settling behavior. This study quantifies the physical fragmentation of marine snow while settling, addressing unresolved mechanisms of vertical attenuation and improving predictions of the biological carbon pump’s efficiency.

Shoko Hososhima

The physiological roles of rhodopsins in climate change

Grant No.：JPMJPR25G8

Researcher

Shoko Hososhima

Outline

Algae perform photosynthesis and play a key role in the marine carbon cycle. In addition, they utilize light energy through light-activated proteins called rhodopsins, although the physiological functions of rhodopsins remain unknown. This project aims to elucidate algal rhodopsins at the molecular level by analyzing their expression, localization, and function under physiological conditions. By clarifying physiological roles of rhodopsins, this project will provide new insights into algal responses to climate change and their impact on marine biogeochemical cycles.

Makiko Yorifuji

Investigation on biological effect of deadly trio in the ocean and countermeasure by precisely controlled environment

Grant No.：JPMJPR25G9

Researcher

Makiko Yorifuji

Outline

Impacts of anticipated future environmental changes in the ocean—such as ocean warming, acidification, and deoxygenation—as well as the effects of ocean alkalization, currently under consideration as a countermeasure, on marine organisms will be investigated. This will be achieved through precisely controlled biological cultivation experiments and genetical/histological analysis. During the process, differences in experimental species and even their regional strains will be focused, and demonstration experiments to propose mitigation strategies will also be conducted. This study aims to verify physiological response mechanisms and also anticipates to develop conservation-oriented technologies.