Undersitanding How Oceanic Environmental Changes Affect Marine Resource Production and Biogeochemical Cycles― The Role of Plankton ―
Covering about 70% of the Earth's surface, the ocean constitutes the largest biosphere on the planet. Filled with water, a medium that differs markedly from air in density, viscosity, and heat capacity, this ever-moving environment has fostered organisms that form ecosystems entirely distinct from those on land. Among them, diverse plankton exemplify life adapted to drifting organisms in the ocean.Thanks to their high turnover rate, plankton collectively produce nearly as much organic matter each year as all terrestrial plants combined. Most fish species depend on plankton during their early life stages, linking plankton directly to fluctuations in fishery resources. Plankton communities also play a pivotal role in the ocean’s absorption of about 30% of anthropogenic CO₂ emissions.
The organisms forming these these plankton communities are generally microscopic and short-lived, undergoing constant succession in response to environmental fluctuations. These shifts ultimately manifest as large-scale impacts—such as changes in fishery productivity and greenhouse-gas concentrations—that affect our daily lives.Understanding the mechanisms of plankton community succession, therefore, is essential for predicting marine ecosystem dynamics. Our laboratory investigates how plankton communities respond to environmental change, including including human impacts, and how these responses influence ecosystems functions, with the ultimate goal of identifying sustainable ways to preserve the ocean’s biodiversity and productivity.
Some of our recent studies are introduced below:
・Yellowfin Tuna in Hawaii Derive the Air — Revealing the Role of Nitrogen-Fixing Organisms in Subtropical Oceanic Fish Production https://www.a.u-tokyo.ac.jp/topics/2018/20181012-1.html
・Rising Coastal Seawater Temperatures in Japan Increase Zooplankton Mortality https://www.a.u-tokyo.ac.jp/topics/topics_20190304-1.html
・Revealing the Distribution of Microplastics in the Surface Waters of the North Pacific Transition Zone https://www.a.u-tokyo.ac.jp/topics/topics_20210713-1.html
Educational approach
Learning from the Ocean: Developing Future Researchers through Field-Based Studies
Although humanity benefits enormously from the ocean, we still lack a full understanding of it and the organisms living within. Because the marine environment is vast, dynamic,and physically challenging for humanss to access, fieldwork is indispensable for studying the plankton ecology.Our laboratory collaborates with various national and international institutions, employing and utilizes research vessels and coastal marine stations to investigate
the dynamics of plankton communities and marine ecosystems. Fieldwork provides a a real-world setting that tests both intellectual and physical abilities. To obtain target samples and data under constantly changing conditions, quick and accurate situational judgment and decisive action are essential. Such work demands rigorous preparation, solid theoretical grounding, and effective teamwork. Because field research often occurs under harsh conditions, such as rough seas or nighttime operations, it also requires endurance, adaptability, and strong communication skills. The the samples and data obtained in the field are unique, and their true value is realized only through analysis and publication. Through this process, our laboratory seeks to cultivate individuals capable of creative, evidence-based problem-solving across diverse scientific fields.
At present, with the open ocean of the Pacific as our main field, we are conducting the following research:
・Elucidating the effects of global warming and anthropogenic pollutants on plankton ecosystems
・Clarifying plankton behavioral ecology using in-situ image analysis techniques
・Reconstructing plankton food web structures through integrated approaches
Vision for industry-academia collaboration
Exploring Appropriate Methods for Marine Environmental Assessment
Through studies on plankton community succession and physiological responses to environmental change, our laboratory seeks to define sustainable modes of ocean utilizing that maintain ecosystem integrity. We contribute to effective marine environmental monitoring by providing advice on observation planning, analytical methods, and data interpretation.In collaboration with industry, we also support the development and refinement of new marine observation instruments and have extensive experience in securing funding for joint research projects. In addition, we maintain more than 120 isolated phytoplankton strains that can be used for environmental assessment and experimental collaborations.
