JpGU-AGU Joint Meeting 2020

Presentation information

[J] Poster

A (Atmospheric and Hydrospheric Sciences ) » A-CG Complex & General

[A-CG57] Science in the Arctic Region

convener:Masashi Niwano(Meteorological Research Institute), Shunsuke Tei(Arctic Research Center, Hokkaido University), Tetsu Nakamura(Faculty of Environmental Earth Science, Hokkaido University), Jun Ono(Atmosphere and Ocean Research Institude, The University of Tokyo)

[ACG57-P08] Increasing Zooplankton Biomass Associated with Sea Ice Loss in the Western Arctic Ocean

*Motoyo Itoh1, Minoru Kitamura1, Amane Fujiwara1, Eddy Carmack2, Kazuo Amakasu3, Koichi Ara4, Mario Uchimiya5, Toru Hirawake6, Jonaotaro Onodera1, Shigeto Nishino1, Takashi Kikuchi1 (1.Japan Agency for Marine-Earth Science and Technology, 2.Fisheries and Ocean Canada, Institute of Ocean Science, 3.Tokyo University of Marine Science and Technology, 4.Nihon University, 5.Riken, 6.Hokkaido University)

Keywords:Arctic, sea ice, zooplankton

Sea ice cover is rapidly declining due to global warming accompanied by sea surface temperature warming and an increase in phytoplankton primary production in the western Arctic Ocean. Although these trends are well documented, their influences on marine ecosystems remain unclear because few studies have conducted long-term ecological monitoring at decadal time scales. Using mooring-based acoustic backscattering data collected during periods of both high (2000-2003) and low sea ice coverage (2010-2013) in the Chukchi Sea, western Arctic Ocean, we show that the annual mean zooplankton biomass increased 1.6-fold between the two periods. This biomass change would have increased the grazing pressure on phytoplankton 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.