Decadal changes in ocean climate and zooplankton biomass associated with recent sea ice reduction in the Arctic Ocean

2020 Fiscal Year Final Research Report

• Project/Area Number: 16K00533
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Environmental dynamic analysis
• Research Institution: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: ITOH Motoyo 国立研究開発法人海洋研究開発機構, 地球環境部門(北極環境変動総合研究センター), 副主任研究員 (60373453)
• Project Period (FY): 2016-04-01 – 2021-03-31
• Keywords: 北極海 / 海洋物理 / 海洋生態 / 環境変動

Outline of Final Research Achievements

Sea ice cover is rapidly declining due to global warming in the Arctic Ocean. However, their influences on marine ecosystems remain unclear because few studies have conducted long-term ecological monitoring at decadal time scales. Mooring-based acoustic backscattering data collected during periods of both high (2000-03) and low sea ice coverage (2010-13) in Barrow Canyon, are used to show that the annual mean zooplankton biomass increased 1.6 hold between the two periods. Our calculations suggest that this biomass change would have increased the grazing pressure by zooplankton, which, in turn, decreased the supply of sinking carbon to benthic organisms during summer, even though phytoplankton production would have increased. Thus, the Chukchi Sea ecosystem is now shifting away from a pelagic-benthic coupled ecosystem towards one that is pelagic-dominated, in which the primary production is not directly connected to the benthic carbon cycle due to increased pelagic zooplankton grazing.

Free Research Field

極域海洋学

Academic Significance and Societal Importance of the Research Achievements

本研究で示された動物プランクトン量の増加は摂餌圧の変化を通して、海洋生態系の食物連鎖網に影響を与える。動物プランクトンは、太平洋側北極海の主要な魚類である北極タラ、サケの餌となるため、漁業資源の変動にも影響する可能性がある。バロー海底谷で観測された、動物プランクトン量の増加、植物プランクトンへの摂餌圧の増加、底生生物への有機物供給量の減少は、海氷減少が発端となって起こっている。そのため、今後も更なる海氷減少が予測される北極海での食物連鎖網の変化の端緒を捉えた可能性がある。