Size-fractionated primary production in the Kuroshio Extension and adjacent regions in spring

Nishibe, Yuta; Takahashi, Kazutaka; Shiozaki, Takuhei; Kakehi, Shigeho; Saito, Hiroaki; Furuya, Ken

doi:10.1007/s10872-014-0258-0

Cited by 27 publications

(16 citation statements)

References 30 publications

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“…High production based on high nutrients is often reported around the Kuroshio Extension front (Kaneko, Yasuda, Komatsu, & Itoh, ; Nishibe et al., ; Okazaki, Nakata, & Kimura, ; Shiozaki et al., ; Yamazaki, Iwamatsu, Hasegawa, & Nagai, ). Nutrient concentrations and copepod abundances were high in the stations in G4; juvenile copepods in particular were extremely abundant.…”

Section: Discussionmentioning

confidence: 99%

“…Only the juvenile identified to species were used for the lower graph fertilization: 30-36 hr for Japanese sardine (Matsuoka, Miyaji, & Katoh, 1995) and 39-40 hr for chub mackerel (Murata et al, 2005). High production based on high nutrients is often reported around the Kuroshio Extension front (Kaneko, Yasuda, Komatsu, & Itoh, 2013;Nishibe et al, 2015;Okazaki, Nakata, & Kimura, 2002;Shiozaki et al, 2014;Yamazaki, Iwamatsu, Hasegawa, & Nagai, 2009). Nutrient concentrations and copepod abundances were high in the stations in G4; juvenile copepods in particular were extremely abundant.…”

Section: Discussionmentioning

confidence: 99%

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Environmental characteristics of spawning and nursery grounds of Japanese sardine and mackerels in the Kuroshio and Kuroshio Extension area

Sogawa

Hidaka

Kamimura

et al. 2019

Fisheries Oceanography

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The sustainable use of marine resources requires understanding the surrounding ecosystem and elucidating mechanisms of variation. However, we still lack a comprehensive understanding of environmental variation in the spawning and nursery grounds of important fisheries species Japanese sardine (Sardinops melanostictus) and mackerels (Scomber japonicus and Scomber australasicus) in the northwest Pacific. Here, we investigate detailed physical, chemical, and biological environment variations in the spawning and nursery grounds along the Kuroshio and Kuroshio Extension area from intensive investigation in spawning season (April) of 2013. We found similar water mass property and copepod community in the egg‐rich Kuroshio area and the larvae‐rich downstream Kuroshio Extension area, indicating environmental variability is small during transportation and development processes. The egg‐rich northern Izu Islands region showed high copepod abundance, although low nutrient and chlorophyll concentrations were observed. Eggs were scarce or absent in the second survey 10 days after abundant eggs were observed in the region, along with differences in water property and copepod community. This indicates that not only the location but also the specific water characteristic and copepod community are a determining factor for spawning. Indicator communities of copepod found in our study (indicator community of transportation process from spawning ground, of non‐spawning ground, and of reproductive area in the Kuroshio Extension area) would be a key factor for recruitment prediction.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Environmental characteristics of spawning and nursery grounds of Japanese sardine and mackerels in the Kuroshio and Kuroshio Extension area

Sogawa

Hidaka

Kamimura

et al. 2019

Fisheries Oceanography

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“…The new NPIW is formed in the same region and is a mixture of relatively fresh and recently ventilated Oyashio water and high-salinity Kuroshio water (Yasuda et al, 1996;Talley, 1997;Qiu and Chen, 2011). The mixed water region in the KE has been characterized as an important sink of anthropogenic CO 2 in the northwestern North Pacific (Tsunogai et al, 1993), and it is a key area for understanding regional climate and ecosystem variations and biogeochemical cycles (Yasuda, 2003;Wu et al, 2012;Hu et al, 2015;Nishibe et al, 2017).…”

Section: Study Areasmentioning

confidence: 99%

Dissolved organic carbon dynamics in the East China Sea and the northwest Pacific Ocean

Ding

Wang

2019

Ocean Sci.

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Abstract. Oceanic dissolved organic carbon (DOC) represents one of the largest carbon reservoirs on Earth, and its distribution and biogeochemical cycles play important roles in carbon cycling and other biogeochemical processes in the ocean. We report the distribution and concentrations of DOC for water samples collected from the shelf-edge and slope regions in the East China Sea (ECS) and the Kuroshio Extension (KE) in the northwestern North Pacific during two cruises in 2014–2015. The DOC concentrations were 45–88 µM in the ECS and 35–65 µM in the KE. In addition to biological processes that are estimated to account for 7 % and 8 %–20 % in shaping the DOC distribution in the ECS and KE regions, respectively, the DOC distribution is largely controlled by hydrodynamic mixing of different water masses. By comparing the DOC results with dissolved inorganic carbon (DIC) and dissolved inorganic radiocarbon (Δ14C-DIC) measured from the same water samples, we further demonstrate that the intrusion of the Kuroshio Current could dilute the DOC concentrations at stations in the outer shelf and slope regions of the ECS. The concentrations of DOC in the KE were significantly lower in surface waters than in the ECS, and a relatively low and stable DOC level (∼40 µM) was found in deep water (below 1500 m) at all stations. Based on the previously reported DIC and Δ14C-DIC values for the stations, the observed spatial variations of DOC in the upper 700 m among the stations in the KE were mainly influenced by mixing of the two water masses carried by the Kuroshio and Oyashio, the two dominant western boundary currents in the region. The hydrodynamic processes are thus important factors in the distribution and dynamics of DOC in the KE region.

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“…Guo et al, 2012;Yatsu et al, 2013). A low primary productivity in the Kuroshio Extension region during the springtime was also indicated by the low availability of nitrate in the seawater (Nishibe et al, 2015).…”

Section: Nutrient Limitation In the Nwpo And Ysmentioning

confidence: 99%

Phytoplankton growth response to Asian dust addition in the northwest Pacific Ocean versus the Yellow Sea

et al. 2018

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Abstract. In this study, five on-board microcosm experiments were performed in the subtropical gyre, the Kuroshio Extension region of the northwest Pacific Ocean (NWPO), and the Yellow Sea (YS) in order to investigate phytoplankton growth following the addition of artificially modified mineral dust (AM dust) and various nutrients (nitrogen (N), phosphorus (P), iron (Fe), N + P, and N + P + Fe). The two experiments carried out with AM-dust addition in the subtropical gyre showed a maximum chlorophyll a (Chl a) concentration increase of 1.7-and 2.8-fold, while the cell abundance of large-sized phytoplankton (> 5 µm) showed a 1.8-and 3.9-fold increase, respectively, relative to the controls. However, in the Kuroshio Extension region and the YS, the increases in maximum Chl a and cell abundance of largesized phytoplankton following AM-dust addition were at most 1.3-fold and 1.7-fold larger than those in the controls, respectively. A net conversion efficiency index (NCEI) newly proposed in this study, size-fractionated Chl a, and the abundance of large-sized phytoplankton were analysed to determine which nutrients contribute to supporting phytoplankton growth. Our results demonstrate that a combination of nutrients, N-P or N + P + Fe, is responsible for phytoplankton growth in the subtropical gyre following AM-dust addition. Single nutrient addition, i.e., N in the Kuroshio Extension region and P or N in the YS, controls the phytoplankton growth following AM-dust addition. In the AM-dust-addition experiments, in which the increased N-P or P was identified to determine phytoplankton growth, the dissolved inorganic P from AM dust (8.6 nmol L −1 ) was much lower than the theoretically estimated minimum P demand (∼ 20 nmol L −1 ) for phytoplankton growth. These observations suggest that additional supply augments the bioavailable P stock in incubated seawater with AM-dust addition, most likely due to an enhanced solubility of P from AM dust or the remineralization of the dissolved organic P.

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Size-fractionated primary production in the Kuroshio Extension and adjacent regions in spring

Cited by 27 publications

References 30 publications

Environmental characteristics of spawning and nursery grounds of Japanese sardine and mackerels in the Kuroshio and Kuroshio Extension area

Environmental characteristics of spawning and nursery grounds of Japanese sardine and mackerels in the Kuroshio and Kuroshio Extension area

Dissolved organic carbon dynamics in the East China Sea and the northwest Pacific Ocean

Phytoplankton growth response to Asian dust addition in the northwest Pacific Ocean versus the Yellow Sea

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