Comparison of carbon cycle between the western Pacific subarctic and subtropical time-series stations: highlights of the K2S1 project

Honda, Makio C.; Wakita, Masashi; Matsumoto, Kazuhiko; Fujiki, Tetsuichi; Siswanto, Eko; Sasaoka, Kosei; Kawakami, Hiroyoshi; Mino, Yoshihisa; Sukigara, Chiho; Kitamura, Minoru; Sasai, Yoshikazu; Smith, S. Lan; Hashioka, Taketo; Yoshikawa, Chisato; Kimoto, Katsunori; Watanabe, Shuichi; Kobari, Toru; Nagata, Toshi; Hamasaki, Koji; Kaneko, Ryo; Uchimiya, Mario; Fukuda, Hideki; Abe, Osamu; Saino, Toshiro

doi:10.1007/s10872-017-0423-3

Cited by 34 publications

(43 citation statements)

References 123 publications

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“…Previous studies (e.g., Honda et al, ) have shown that POC from the surface mixed layer is efficiently exported to the deep sea at Station K2. In other words, POC is degraded at lesser rate at Station K2 compared to that in other areas.…”

Section: Discussionmentioning

confidence: 86%

Phaeodaria: An Important Carrier of Particulate Organic Carbon in the Mesopelagic Twilight Zone of the North Pacific Ocean

Ikenoue

Kimoto

Okazaki

et al. 2019

Global Biogeochemical Cycles

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Phaeodaria, which comprise one group of large, single‐celled eukaryotic zooplankton, have been largely ignored by past marine biological studies because Phaeodaria and their delicate skeletons are liable to collapse. As a result, collection and quantification of specimens are difficult, and seasonal changes of phaeodarian abundance have not been thoroughly studied. The transport of biogenic elements by sinking phaeodarians has been estimated for only a few representative species. Sinking particles >1 mm in size and swimmers have traditionally been excluded when estimating sinking particle fluxes. The focus of this study is the large number of phaeodarians among the >1‐mm sinking particles collected in the western North Pacific from June 2014 to July 2015. Careful sorting by microscopic examination and chemical analyses revealed that phaeodarians accounted for up to about 10% of the organic carbon in all sinking particles and accounted for a mean of 33% of the organic carbon in the >1‐mm sinking particles. The high‐standing stocks of phaeodarians at depths of 150–1,000 m in the mesopelagic twilight zone suggested that particles sinking from the euphotic zone as aggregates and fecal pellets can be efficiently exported to the deep sea by the ballasting effect of large phaeodarian particles rich in organic carbon.

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Section: Discussionmentioning

confidence: 86%

Phaeodaria: An Important Carrier of Particulate Organic Carbon in the Mesopelagic Twilight Zone of the North Pacific Ocean

Ikenoue

Kimoto

Okazaki

et al. 2019

Global Biogeochemical Cycles

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“…Sta. S1 was established in 2010 for a comparative study of the ecosystem and biochemistry of the subarctic gyre and subtropical region of the western North Pacific (K2S1 project; see Honda et al ). Measurements with the profiling buoy system were successfully made at 03:00 h local time (nighttime) and 12:00 h local time (daytime) every 6 d from 08 July 2012 to 17 March 2013 except on 17 December 2012.…”

Section: Methodsmentioning

confidence: 99%

Time‐series observations of photosynthetic oxygen production in the subtropical western North Pacific by an underwater profiling buoy system

Fujiki

Inoue

Honda

et al. 2019

Limnology & Oceanography

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We conducted time-series observations in the northwestern part of the North Pacific subtropical gyre (30 N, 145 E) from July 2012 to March 2013 using a profiling buoy system equipped with a fast repetition rate fluorometer and dissolved oxygen (DO) sensor in order to understand vertical and temporal variations in gross oxygen production (GOP) by phytoplankton and its contribution to the oxygen cycle in the upper ocean. Under stratified conditions (July-November), daily GOP slightly exceeded 2 mmol O 2 m −3 d −1 and only in near-surface waters. However, during periods of vertical mixing (December-March) when phytoplankton blooms occurred, daily GOP increased in the upper 30 m and often exceeded 5 mmol O 2 m −3 d −1 . The depth-integrated daily GOP within the euphotic layer ( Ð GOP EL ) was relatively low (84.0 AE 23.6 mmol O 2 m −2 d −1 ) during stratification, but increased gradually with vertical mixing and reached 460 mmol O 2 m −2 d −1 on 17 March 2013. Additionally, during stratified conditions, a subsurface oxygen maximum (SOM) formed below the mixed-layer depth (MLD) because the steep density gradient constrained upward diffusion of oxygen produced below the MLD. During the period of vertical mixing, the SOM disappeared, and DO concentrations within the upper 100 m increased through both increasing Ð GOP EL and atmospheric oxygen uptake. Using our buoy observations and air-sea gas flux model, we estimated that 24% AE 7% of Ð GOP EL was emitted to the atmosphere during the stratification period, and Ð GOP EL during the mixing period was about 2.4 times the rate of oxygen uptake by the ocean from the atmosphere. 18 O spike (Bender et al. 1987) incubation methods. These methods rely on the change in oxygen concentrations or the evolution of 18 O 2 from 18 O-H 2 O during water splitting in incubation bottles containing the phytoplankton. However, despite its recognized importance, information on

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“…2a). The upper boundaries of the North Pacific deep water (NPDW; r h , 27.69) and the lower circumpolar deep water (LCDW; r h , 27.77) (Kawabe and Fujio 2010;Wakita et al 2010) were located at depths of 2000 m and 3500 m, respectively (Fig. 2b).…”

Section: Overview Of Oceanographic Features and Prokaryotic Parametersmentioning

confidence: 99%

“…Here, we present data collected during the “K2S1 project,” which was conducted at two stations in the subarctic and subtropical western North Pacific. This project involved extensive time‐series observations of the physical and biogeochemical properties of two disparate regions, in order to extend our understanding of the mechanisms controlling the carbon cycle in the western North Pacific (Honda et al ). During the project, we examined the full‐depth distributions of prokaryotic production and abundance on five occasions, covering a full seasonal cycle.…”

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confidence: 99%

Balancing organic carbon supply and consumption in the ocean's interior: Evidence from repeated biogeochemical observations conducted in the subarctic and subtropical western North Pacific

Uchimiya

Fukuda

Wakita

et al. 2018

Limnology & Oceanography

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The heterotrophic prokaryotic carbon demand (PCD) in the ocean's interior often substantially exceeds (by up to two orders of magnitude) the amount of organic carbon supplied by sinking particulate organic carbon (POC). A hypothesis to explain this carbon imbalance proposes that some non‐steady‐state processes have not been considered in previous studies based on snapshot data. To test this hypothesis, we collected time‐series (2.5 yr) data on sinking POC fluxes using moored sediment traps (trap deployment depths: 200 m, 500 m, and 4810 m) and compared them with the PCD data collected seasonally at two stations in the subarctic and subtropical western North Pacific. The POC supplies (ΔPOC) in the 200–500 m and 500–4810 m layers were estimated with a correction, when appropriate, for the non‐steady‐state effect arising from the change in the POC flux during the transit of POC between the upper and deeper traps. In the 200–500 m layer, ΔPOC generally exceeded or equaled PCD. In contrast, in the 500–4810 m layer, PCD generally exceeded ΔPOC by up to sevenfold. However, on a yearly basis, this carbon imbalance in the deeper layer decreased, with PCD balancing ΔPOC within a factor of 2. Therefore, the enigma of the high PCD relative to the POC flux in deep water is partially resolved by assuming a temporal uncoupling between supply and consumption, which partly equilibrates the carbon budget over a longer (yearly) time scale.

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Comparison of carbon cycle between the western Pacific subarctic and subtropical time-series stations: highlights of the K2S1 project

Cited by 34 publications

References 123 publications

Phaeodaria: An Important Carrier of Particulate Organic Carbon in the Mesopelagic Twilight Zone of the North Pacific Ocean

Phaeodaria: An Important Carrier of Particulate Organic Carbon in the Mesopelagic Twilight Zone of the North Pacific Ocean

Time‐series observations of photosynthetic oxygen production in the subtropical western North Pacific by an underwater profiling buoy system

Balancing organic carbon supply and consumption in the ocean's interior: Evidence from repeated biogeochemical observations conducted in the subarctic and subtropical western North Pacific

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