In order to sustainably provide safe food, we are conducting research to protect and restore the environments in which coastal organisms live. Specifically, our activities center on two main topics.
At the Laboratory of Aquatic Plant Ecology Laboratory (Nagasaki University), we work on the restoration and protection of coastal ecosystems so that safe food resources can continue to be supplied in a sustainable manner. To that end, we focus on two primary research areas concerning vegetated marine ecosystems beds (seaweeds and seagrasses) that are affected by environmental pollution. First, we develop and refine techniques for assessing the health of these underwater forests. By quantifying ecosystem area, density, and biodiversity, we can detect early signs of stress and degradation. In particular, we investigate how marine debris, especially plastic waste, alters the structure and function of these beds.
Second, we promote fundamental research aimed at restoring and protecting these ecosystems. We are elucidating the mechanisms by which algal beds take up atmospheric carbon dioxide and store it as “blue carbon,” with the goal of improving the precision and accuracy of carbon stock estimates. Accurately assessing the carbon-sequestration capacity of algal beds and clarifying their role in climate‐change mitigation is the ultimate aim of this research.
More than half of our laboratory’s efforts are devoted to fieldwork in support of these studies. We regularly measure the extent and density of algal beds and collect samples of marine debris and sediments deposited there. However, in the laboratory, we analyze organic‐carbon content in sediments and seawater using equipment from Elementar and Shimadzu Corporation. By combining field observations, lab analyses, and data processing, we strive to achieve a comprehensive understanding of the processes of algal‐bed decline and recovery.
As one aspect of our blue‐carbon research, we are evaluating the carbon‐sequestration potential of seaweed aquaculture farms. Cultivated seaweeds absorb CO2 from the atmosphere during their growth and may sequester carbon in biomass or sediments, making them a promising climate‐change mitigation strategy.
One of our major achievements, Sato et al. (2022) in Frontiers in Marine Science (https://doi.org/10.3389/fmars.2022.861932), quantitatively evaluated carbon fixation in Japanese seaweed farms. That study demonstrated that, depending on how harvested seaweed biomass is used, aquaculture sites can function as net carbon sinks. These findings pave the way for formally incorporating seaweed aquaculture into international greenhouse‐gas accounting and policy frameworks.
Furthermore, in a press release from Nagasaki University dated September 18, 2024, it was announced that our laboratory is leading a CREST Strategic Basic Research Program project titled “High‐Precision Quantification and Assessment of Blue‐Carbon Fixation Potential in Seaweed Aquaculture Sites.” This project, the first CREST award for Nagasaki University, is being carried out jointly by Professor Gregory Nishihara of Nagasaki University, Professor Teruko Konishi of the University of the Ryukyus, and with the cooperation of RIKEN Foods Co., Ltd.
Under this project, we focus on net ecosystem production (NEP) and conduct detailed CO2 monitoring in wakame (Undaria pinnatifida) farms in Miyagi Prefecture and okinawa-mozuku (Cladosiphon okamuranus) farms in Okinawa Prefecture. By tracking the dynamics of CO2 uptake and release by seaweeds, as well as the fate of organic substances such as polysaccharides they exude, we aim to comprehensively assess their carbon‐dioxide removal (CDR) capacity. The results are expected to inform carbon‐credit scheme design and contribute to the decarbonization of the seaweed industry.
Japan is overcome with an abundance of herbivores, which has damaged coastal ecosystems to the point where almost no seaweeds or seagrasses remain. We are focused on understanding the process of isoyake ecosystem recovery.
Blue carbon is a relatively new term that generally describes the carbon that is captured by marine ecosystems. We are attempting to understand how this concept applies to a fisheries persepective and how to estimate the ability of coastal ecosystems to sequester carbon.
What will become of Japan’s marine debris problem in the years ahead? Collection and treatment technologies have scarcely evolved over the past fifty years, and research has focused primarily on quantitative surveys and assessments of biological impacts. Because the effects of debris on algal‑bed ecosystems remain unclear, we are developing new monitoring methods and conducting impact evaluations with the aim of conserving and sustainably utilizing these underwater “forests.”
Professor
Kagoshima University (2004 PhD), University of Hawaii at Manoa (1996 BSc)。 2018 Marine Pew Fellow, See researchmap for more https://researchmap.jp/nagaremo
Post-doctoral scientist
I specialize in marine microbiology and ecology, molecular biology, genomics, and metagenomics, with a specific focus on marine macrophytes. My research also focuses on carbon sequestration by marine macrophytes, particularly in the context of blue carbon storage. Currently, I am working on the evaluation and measurement of CO₂ levels using loggers in seagrass and seaweed beds. Additionally, I am interested in exploring the impacts of plastic debris on marine macrophytes, especially how such debris influences biogeochemical processes in coastal ecosystems.
PhD student
Marine litter may affect seagrass growth and productivity. Thus it is vital to understand how marine litter will affect the primary production of seagrass meadows, and to elucdiate which variables affect the carbon capture capability of seagrass ecosystems.
PhD Student
I am evaluating the impact of a specialized ceramic, primarily composed of calcium carbonate, on coastal ecosystems. Since this ceramic acts directly on the seabed, it is expected to particularly affect rooted seagrasses such as eelgrass. By enhancing net primary production, this technology is also expected to contribute to blue carbon.
MS student
Marine macrophyte communities provide habitat for a variety of marine lifes including fish. The structure of macrophyte communities is an important factor contributing to habitat formation in coastal ecosystems. Currently, I am interested in the associations of the structure of macrophyte communities and the diversity of fish communities in Arikawa Bay, Goto islands.
MS student
I am conducting research on the blue carbon function of seaweed aquaculture farms in Matsushima Bay, Miyagi Prefecture. Focusing on the possibility that carbon absorbed by seaweed may be stored in the mud and sand of the aquaculture site, I collect sediment samples from wakame farms to analyze organic carbon content and the presence of wakame-derived DNA. Through this research, I aim to evaluate the carbon storage capacity of seaweed aquaculture sites and clarify their potential as blue carbon resources.
MS student
Seagrass and seaweed beds (algal beds) absorb large amounts of carbon dioxide and release part of it as dissolved organic carbon (DOC). Understanding the dynamics of DOC in these habitats is extremely important for understanding blue carbon. This study aims to investigate the amount and composition of DOC in algal beds with various types of vegetation, and to determine whether differences in vegetation lead to differences in DOC quantity and composition.
MS student
Conducting research on how marine debris buried in the subsurface environment affects the life cycle of eelgrass and the expansion of seagrass beds.
MS student
Investigating the potential of seaweed (*Cladosiphon okaramanus*) farms as a blue carbon ecosystem remains largely unexplored. Hence, the focus of my research is understanding their carbon sequestration dynamics and contribution to climate mitigation.
Undergraduate student
Studying how plastic debris in sediments affects the total organic carbon (TOC) content of the sediments.
Undergraduate student
Investigating the accumulation sites of marine debris and the environmental factors influencing them.
Undergraduate student
Researching whether the amount of seaweed biomass in sediments is proportional to TOC and eDNA content.
Research student(March to May 2025)
Evaluating the C content of seaweeds.
2025 (MS)
2025 (BS)
2025 (BS)
2024 (BS)
2024 (BS)
2024 (BS)
2022 (BS), 2024 (MS)
2022 (BS), 2024 (MS)
2022 (BS), 2024 (MS)
2023 (MS), 2021 (BS)
2023 (BS)
2023 (BS)
2023 (BS), 2025 (MS)
2020 (BS), 2022 (MS)
2021 (BS)
2021 (BS)
2021 (PhD)
2020 (PhD), 2017 (MS)
2021 (PhD)
2020 (MS), 2018 (BS)
2020 (MS), 2023 (PhD)
2020 (BS)
2020 (BS)
2019 (MS)
2021 (MS), 2019 (BS)
2019 (BS)
2021 (MS), 2019 (BS)
2018 (MS)
2017 (MS), 2015 (BS)
2016 (BS)
2015 (BS)
2015 (Shanghai Ocean University Exchange Student)
2014 (MS), 2012 (BS)
2014 (BS)
2012 (BS)
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