The workshop opened with remarks from Professor Hiroki Tanikawa, Dean of GSES, who drew a natural parallel between the school’s interdisciplinary approach, which integrates environmental, social, and cultural dimensions, and the very nature of watershed management, pointing to the Kiso River Basin as an example. He emphasized the importance of collaboration of various local governments in watershed areas, the role of coordinated governance, shared vision, and inter-municipal cooperation in achieving effective watershed management.

This was followed by the presentation of Dr. Charles John Gunay of University of the Philippines Los Ba?os, School of Environmental Science and Management (UPLB SESAM), on the use of modeling tools for flood and sediment risk assessment. Using case studies such as the Santa Rosa¨CSilang Watershed and the Ogouchi Dam Watershed, he demonstrated how simulations can identify erosion, sediment transport, and high-risk areas. He also shared insights from a -funded project and emphasized the importance of translating technical results into actionable information for decision-makers and communities through participatory approaches.

Ms. Lemuelle Celis of Department of Environment and Natural Resources (DENR) presented the current state of watershed management in the Philippines, highlighting challenges such as overlapping institutional mandates, watershed degradation, and increasing climate vulnerability. She also outlined ongoing initiatives, including improved monitoring systems, integrated management planning, and conservation efforts, while noting the need for greater capacity-building and financial support.

Dr. Taichi Minamitani of JICA discussed the JICA¡¯s approach to flood control in the Philippines, emphasizing the need for proactive investments in disaster risk reduction amid rising economic losses. He outlined strategies to strengthen governance and infrastructure, highlighting long-term efforts in Metro Manila such as river widening and flood diversion. He also noted key challenges in flood control, including limited upstream storage, insufficient river capacity, and urban pressures, underscoring the importance of integrated and forward-looking flood protection planning.

The panel discussion, moderated by Professor Kiichiro Hayashi of Graduate School of Engineering, explored the vital roles of academia, government, non-government and international institutions in addressing the challenges on watershed management. Ms. Celis and Mr. Yamada emphasized the critical role of coordination with local government units and various sectors, as well as the importance of effective data-sharing mechanisms in achieving integrated watershed management. Mr. Yamada also noted that in developing countries, where local capacities may be limited, international cooperation can play a vital role in strengthening watershed management efforts.

Dr. Gunay emphasized the need for improved instrumentation and monitoring in watershed management as a key area for future research. He highlighted the role of academia in providing technical capacity, scientific data, and mentoring, and noted that collaboration between institutions such as University of the Philippines Los Ba?os and ºÚÁϳԹÏÍø can help bridge gaps between technical and non-technical stakeholders, particularly in strengthening government capacity.

Dr. Minamitani emphasized that JICA expects him to promote sustainable river basin management by fostering an understanding of the importance of flood control measures and encouraging relevant organizations to change their behavior. He also called on the academic community to focus not on developing a variety of models, but on producing outputs that contribute to changing the behavior of relevant organizations, so that they can tackle flood control from a scientific perspective with a view to supporting development in each country. He also highlighted the importance of strengthening Japan-Philippines collaboration, improving stakeholder coordination, and building on the Philippines¡¯ strengths in disaster risk reduction and watershed management.

Mr. Toru Uemachi, Director General of JICA Chubu concluded the workshop by expressing appreciation to all participants and highlighting the event as a starting point for broader collaboration, including cross-learning on watershed management between Japan and the Philippines. He reaffirmed JICA¡¯s commitment to supporting joint initiatives and encouraged continued dialogue and partnership between stakeholders from both countries.

The analysis was based on blood samples from over 11,000 seabirds, the first biologically derived estimate of oceanic mercury distribution.

Mercury released into the oceans affects marine environments worldwide. Traditionally, its distribution and quantity have been estimated using marine biogeochemical simulation models.

A recent international study led by Japanese researchers analyzed blood mercury concentrations in more than 11,215 seabirds from 108 species, of which 659 were newly collected samples and over 10,556 were from previous studies. This is the first biologically based estimate of oceanic mercury distribution.

The study found that mercury levels in seabirds vary according to prey trophic level, bird body weight, and foraging depth. The findings were published in .

Mercury emissions into the ocean have risen since the Industrial Revolution, primarily due to increased atmospheric mercury from coal combustion. Mercury travels long distances by wind and enters the ocean through rainfall.

In the ocean, some mercury becomes highly toxic and bioaccumulates in the food chain, ultimately concentrating in the tissues of seabirds that consume fish and zooplankton.

Professor and Researcher Jumpei Okado of , along with Senior Researcher Bungo Nishizawa of the Japan Fisheries Research and Education Agency, led an international study with 12 institutions from four countries.

Why were seabird blood samples used?

Blood samples from seabirds are efficiently collected when they come ashore for breeding. Mercury concentrations in adult birds’ blood at breeding sites reflect their dietary mercury intake from specific ocean areas within the two months prior to sampling.

This method enables a more accurate correlation of mercury levels with specific times and locations than other sample types. Additionally, blood collection causes minimal harm to the birds.

Analysis of seabird blood data

Between 2017 and 2024, researchers collected blood samples from 659 individuals representing 10 seabird species at breeding sites in Japan, Alaska, and New Zealand. They dried and homogenized the samples, then measured total mercury concentrations using atomic absorption spectrometry. Results were standardized to total mercury per gram of dry weight in whole blood for comparison.

Researchers also conducted a systematic review of 106 publications from 1980 to 2025, with over 80% published after 2010, and analyzed data on more than 10,556 adults representing 105 seabird species.

In total, the team analyzed blood mercury concentrations in over 11,215 individuals from 108 seabird species worldwide, covering diverse diets and geographic regions.

The analysis found that seabirds at higher trophic levels, with larger body mass, and those feeding on prey from depths between 200 and 1,000 meters have higher mercury levels.

Statistical analysis showed distinct regional patterns in oceanic mercury contamination. Mercury levels were higher in the North Atlantic, North Pacific, South Pacific below 40 degrees south, and in areas with low productivity, as indicated by reduced chlorophyll a levels. In contrast, mercury levels were much lower in the South Atlantic and Southern Oceans.

The study also found that albatrosses and shearwaters are more exposed to mercury than other seabird species.

Significance and future perspectives

The researchers found that predictions from the seabird-based model and the marine biogeochemical simulation models were only weakly correlated.

“The seabird model is based on empirical measurements from organisms and is therefore considered more reliable than values from marine simulation models,” said Shoji. “Seabirds live in diverse environments, from coastal and tropical zones to polar regions. Their varied feeding patterns make them effective indicators of global ocean health.” ?

This approach offers a promising method to monitor and verify the effectiveness of international mercury emission regulations, such as the Minamata Convention, and to support stronger global efforts to reduce mercury contamination in marine ecosystems.

Paper information

Jumpei Okado, Bungo Nishizawa, Johannes H. Fischer, Olivia C. Rowley, Yukihiko Toquenaga, Yasuaki Niizuma, Chinatsu Nakajima, Futoshi Ujiie, Toru Kawai, Shannon Whelan, Scott A. Hatch, Paco Bustamante, Graeme Elliott, Graham C. Parker, Kalinka Rexer-Huber, Kate Simister, Grace Tocker, Kath Walker, Heiko U. Wittmer, Igor Debski, Akiko Shoji (2026). Global drivers of variation in blood mercury of seabirds revealed by a meta-analysis, Science of The Total Environment.

Funding information

This study was supported by the Japan Society for the Promotion of Science (Grants-in-Aid for Scientific Research awarded to AS: 23KK0116, 22K21355, and 19KK0159), Japan Science and Technology Agency (EXPLORATORY RESEARCH GRANT awarded to AS: JPMJFR241E), and Japan Polar Research Association (2022 and 2023 awarded to CN). Sample collection in Aotearoa New Zealand was supported by the Conservation Services Programme of the Department of Conservation (POP2022¨C08, POP20220¨C7, and POP2022¨C10), the National Geographic Society (WW-249C-17), the Mohamed Bin Zayed Species Conservation Fund (Project 192520234), and Birds New Zealand (Birds NZ Research fund 2017, 2019).

Expert contact:

Akiko Shoji
Graduate School of Environmental Studies, ºÚÁϳԹÏÍø
Email: akiko.shoji@nagoya-u.jp

Media contact:

Naomi Inoue
International Communications Office, ºÚÁϳԹÏÍø
Email: icomm_research@t.mail.nagoya-u.ac.jp

Top image:

This study provides the drivers of variation in mercury concentrations in seabirds and, further, the first biologically based estimate of oceanic mercury distribution, analyzing blood mercury levels in more than 11,215 seabirds from 108 species, including 659 newly collected samples and over 10,556 from prior research. (THg: total mercury)
Credit: Jumpei Okado (modified from Okado et al. 2026, licensed under CC BY 4.0)

It will be held on March 18, 2026 (10:00 AM – 12:00 PM at) ºÚÁϳԹÏÍø, Environmental Studies Building, 1F Lecture Hall, and via Zoom.

Please find the attached promotional material while the registration link and the zoom details are as follows:

Topic: Nagoya-Philippines Watershed Workshop
Time: 18 March 2026, 10:00 AM (Osaka, Sapporo, Tokyo)