Subproject A03 Evaluation of Ecosystem Functions
Group A03-1 Spatio-temporal Dynamics of Highly Migratory Top Predators over Ocean Provinces
Most oceanic top predators are highly migratory species that affect the productivity and nutrient cycles of different regions during the course of their life cycles. They also change the trophic position and function in the food web as they grow from juveniles to adults. Consequently, they are important keystone and indicator species of marine ecosystems and provide valuable ecosystem services as food and economic resources. The abundance of oceanic top predators shows annual and decadal variability due to environmental change, fishery and other anthropogenic activities. Their dynamics exert top-down effects on regional ecosystems through trophic cascades. Therefore, better understanding of the dynamics of top predators is indispensable for the sustainable utilization and management of the oceanic ecosystem under the changing environment.
Regarding the subject of predators, our group focuses on the higher trophic level (HTL) species of the western North Pacific. Blue shark, skipjack tuna, albacore, pomfret, salmon, and squid are the main species of the HTL community. We integrate the analyses of historical data (survey data and fishery data) and recent biological specimens to articulate the structure (size structure, species structure, diversity) and function (trophic dynamics) of the oceanic food web and its spatiotemporal variation from the viewpoint of climate change and fishery impacts.
In addition, special attention is paid to two key species, neon flying squid (Ommastrephes bartramii) and salmonids. Neon flying squid is an annual species that accomplishes its life cycle in one year. Young squids are relatively non-migratory, so their survival and growth reflect the environmental conditions of the nursery area. Once they grow up they occupy a higher trophic position in the food web, and their abundance is affected by fishery. Neon flying squid can be a good ecosystem indicator since their population dynamics are affected by climate change and fishery impact at different life stages. Salmonids are highly migratory anadromous fish. As they grow and migrate, they utilize the local productivity and transport nutrients from subregion to subregion up to their final destination, the spawning river. Salmonids are cold-water species susceptible to global warming. We intend to develop a migration model of salmonid species to understand their role in regional nutrition cycles and to project the impact of climate change on salmon migration and material circulation in the North Pacific.
Group A03-2 Economic Valuations on Ocean Ecosystem Services
Our group aims to provide proper estimations on the economic values of the oceans. These values include estimated monetary equivalents for potential productions of marketable goods such as fish and fishery products from the ocean areas. They also include non-market values from ecosystem services in the ocean. The focus of this study is directed to all four categories of ecosystem services (namely, supporting services, provisioning services, regulating services, and cultural services), which were identified in the Millennium Ecosystem Assessment (MA) report in 2005, and new assessments for each service will be conducted to provide their re-estimated monetary values. The study also attempts to assess the costs and the benefits of geo-engineering. Assessments are based on conjoint analyses or other research techniques. The results of the study will be reported to other study teams in the project, and are expected to provide vital inputs to design and develop further scientific studies.