Changes in subsurface chlorophyll-a maximum in the Canada Basin, 2003-2019

The Tenth Symposium on Polar Science/Ordinary sessions: [OB] Polar Biology, Wed. 4 Dec. / 3F Multipurpose conference room, National Institute of Polar Researc

Oxygen isotope ratio, barium and salinity in waters around the North American coast from the Pacific to the Atlantic: Implications for freshwater sources to the Arctic throughflow

In 2002, oxygen isotope ratios of water (H218O/H216O), dissolved barium, and salinity were measured in surface waters around northern North America to identify freshwater sources and to provide a large-scale background for interpretation of regional inputs and processes. Oxygen isotope ratios showed that precipitation, river runoff, and sea ice meltwater were all significant contributors to the freshwater carried by the coastal component of the Arctic throughflow. Precipitation and runoff contributed \u3c40% and \u3e60%, respectively, to the freshwater found in surface waters along the Pacific coast. Sea ice meltwater contributed up to 65% to waters residing near the Mackenzie River and in the Canadian Arctic Archipelago. The salinity-barium relationship, after being corrected for dilution by sea ice meltwater, indicated that freshwater from the Mackenzie River flowed eastward into Amundsen Gulf. It did not, however, continue eastward through Dolphin Union Strait and Coronation Gulf in 2002. In the eastern part of the Canadian Arctic Archipelago, Baffin Bay and the Labrador Sea, barium concentrations in surface waters were low, the result of biological activity and/or local freshwater inputs with low barium concentrations

Sources of dissolved inorganic carbon to the Canada Basin halocline : a multitracer study

Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 121 (2016): 2918–2936, doi:10.1002/2015JC011535.We examine the dissolved inorganic carbon maximum in the Canada Basin halocline using a suite of geochemical tracers to gain insight into the factors that contribute to the persistence of this feature. Hydrographic and geochemical samples were collected in the upper 500 m of the southwestern Canada Basin water column in the summer of 2008 and fall of 2009. These observations were used to identify conservative and nonconservative processes that contribute dissolved inorganic carbon to halocline source waters, including shelf sediment organic matter remineralization, air-sea gas exchange, and sea-ice brine export. Our results indicate that the remineralization of organic matter that occurs along the Bering and Chukchi Sea shelves is the overwhelming contributor of dissolved inorganic carbon to Pacific Winter Water that occupies the middle halocline in the southwestern Canada Basin. Nonconservative contributions from air-sea exchange and sea-ice brine are not significant. The broad salinity range associated with the DIC maximum, compared to the narrow salinity range of the nutrient maximum, is due to mixing between Pacific and Atlantic water and not abiotic addition of DIC.NSERC; Fisheries and Oceans Canada; US National Science Foundation Office of Polar Programs Grant Number: OPP-0424864; Canadian International Polar Year Office2016-11-0

Reports of studies supported by Grant-in-Aid for Research from the Graduate School of Biosphere Science, Hiroshima University

基盤研究サポート Grant-in-Aid for Fundamental Research ・プロバイオティクスを活用した乾乳期からの暑熱緩和ケアによる乳生産技術の開発...河上眞一, 川合美千代, 山本民次 ・安芸津沖および広島湾における海洋酸性化の実態調査...三瓶真 ・福山市田島沖における海苔（ノリ）の色落ちをもたらす要因とその対策に関する研究...小池一

Do Strong Winds Impact Water Mass, Nutrient, and Phytoplankton Distributions in the Ice‐Free Canada Basin in the Fall?

In general, strong wind events can enhance ocean turbulent mixing, followed by episodic nutrient supply to the euphotic zone and phytoplankton blooms. However, it is unclear whether such responses to strong winds occur in the ice‐free Canada Basin, where the seasonal pycnocline is strong and the nutricline is deep. In the present study, we monitored a fixed‐point observation (FPO) station in the Canada Basin for about 3 weeks in the fall of 2014 to examine the oceanic and biological responses to strong winds. At the FPO site, oceanic microstructure measurements, hydrographic surveys, and water sampling were performed with high temporal resolution, recording internal wave propagation, eddy passage, and water mass changes. Strong winds and internal wave propagation significantly enhanced the mixing above and at the seasonal pycnocline, but their effects were diminished at the nutricline, which was much deeper than the seasonal pycnocline. Therefore, wind‐induced mixing did not increase the upward nutrient supply from the nutricline and did not impact phytoplankton (chlorophyll a) distribution in the surface layer of the FPO site. The temporal evolution of the chlorophyll a concentration was most closely related to water mass changes. We also observed prominent subsurface chlorophyll a maxima with abundant large‐sized phytoplankton that were likely carried by warm‐core eddies to the FPO site. Phytoplankton biomass may have been sustained by the high concentration of ammonium within the eddy and ammonium regeneration at the seasonal pycnocline, where particulate organic matter likely accumulated

北極海カナダ海盆上層における炭酸カルシウム飽和度の季節変動

第6回極域科学シンポジウム分野横断セッション：[IB1] 海氷域における生物地球化学的研究11月17日（火）　国立極地研究所１階交流アトリウ

The rapid response of the Canada Basin to climate forcing : from bellwether to alarm bells

Author Posting. © Oceanography Society, 2011. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 24 no. 3 (2011): 146–159, doi:10.5670/oceanog.2011.66.Sea ice extent in the Arctic Ocean diminished significantly during the first decade of the 2000s, most particularly in the Canada Basin where the loss of both multiyear and first-year ice was greater than in the other three subbasins. Using data collected during basin-wide surveys conducted from 2003–2010 together with data collected during the 1990s and 2000s at one station in the southern Canada Basin, we investigate the response of the Canada Basin water column to this significant decrease in ice cover. Changes were evident from the surface down to the Atlantic layer: some changes were the result of Beaufort Gyre forcing on regional processes, others were the result of Arctic Ocean atmospheric forcing on a hemispheric scale and large-scale advection. These changes have troubling consequences for the ecosystem.We acknowledge support from Fisheries and Oceans Canada, the US National Science Foundation Office of Polar Programs (grant OPP-0424864), and the Canadian International Polar Year office

Enhancement/reduction of biological pump depends on ocean circulation in the sea-ice reduction regions of the Arctic Ocean

http://www.godac.jamstec.go.jp/darwin/cruise/mirai/mr08-04/

Variations in rates of biological production in the Beaufort Gyre as the arctic changes: Rates from 2011 to 2016

Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans 124(6), (2019): 3628-3644, doi:10.1029/2018JC014805.The Arctic Ocean is experiencing profound environmental changes as the climate warms. Understanding how these changes will affect Arctic biological productivity is key for predicting future Arctic ecosystems and the global CO2 balance. Here we use in situ gas measurements to quantify rates of gross oxygen production (GOP, total photosynthesis) and net community production (NCP, net CO2 drawdown by the biological pump) in the mixed layer in summer or fall from 2011 to 2016 in the Beaufort Gyre. NCP and GOP show spatial and temporal variations with higher values linked with lower concentrations of sea ice and increased upper ocean stratification. Mean rates of GOP range from 8 ± 1 to 54 ± 9 mmol O2·m−2·d−1 with the highest mean rates occurring in summer of 2012. Mean rates of NCP ranged from 1.3 ± 0.2 to 2.9 ± 0.5 mmol O2·m−2·d−1. The mean ratio of NCP/GOP, a measure of how efficiently the ecosystem is recycling its nutrients, ranged from 0.04 to 0.17, similar to ratios observed at lower latitudes. Additionally, a large increase in total photosynthesis that occurred in 2012, a year of historically low sea ice coverage, persisted for many years. Taken together, these data provide one of the most complete characterizations of interannual variations of biological productivity in this climatically important region, can serve as a baseline for future changes in rates of production, and give an intriguing glimpse of how this region of the Arctic may respond to future lack of sea ice.We sincerely thank the scientific teams of Fisheries and Oceans Canada's Joint Ocean Ice Studies expedition and Woods Hole Oceanographic Institution's Beaufort Gyre Observing System. The hydrographic, nutrient, and chlorophyll data were collected and made available by the Beaufort Gyre Exploration Program based at the Woods Hole Oceanographic Institution (http://www.whoi.edu/beaufortgyre) in collaboration with researchers from Fisheries and Oceans Canada at the Institute of Ocean Sciences. We thank the captains and crews of the Canadian icebreaker CCGS Louis S. St‐Laurent and Mike Dempsey for sample collection. This paper was improved by the suggestions of Michael DeGrandpre and one anonymous reviewer. We are grateful to Qing Wang at Wellesley College for her assistance with statistics. We thank our funding sources: the National Science Foundation (NSF 1547011, NSF 1302884, NSF 1719280, NSF 1643735) and the support of Fisheries and Oceans Canada. Data presented and discussed in this paper can be found in the Arctic Data Center (http://10.18739/A2W389).2019-10-3

Arctic Ocean Acidification: Results from GRENE and JOIS

第6回極域科学シンポジウム分野横断セッション：[IB1] 海氷域における生物地球化学的研究11月17日（火）　統計数理研究所 セミナー室1（D305