Primary productivity and its bio-optical modeling in the Oyashio region, NW Pacific during the spring bloom 2007

Isada, Tomonori; Hattori-Saito, Ai; Saito, Hiroaki; Ikeda, Tsutomu; Suzuki, Koji

doi:10.1016/j.dsr2.2010.03.009

Cited by 28 publications

(16 citation statements)

References 68 publications

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“…Pico‐ and nano‐sized phytoplankton groups were predominant at Stn. A4 during BLOSSOM (Isada et al ). Our CHEMTAX results (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…DFe data during the OECOS cruise were obtained from Nakayama et al (). Daily PAR data above the sea surface were obtained from Isada et al (). Macronutrient (nitrate plus nitrite, phosphate, and silicate) concentrations were measured with a continuous flow analyzer (QuAAtro, Bran + Luebbe).…”

Section: Methodsmentioning

confidence: 99%

“…In the Oyashio region of the WSP, which is located off the coast of Hokkaido Island, Japan, massive diatom blooms occur every spring (Kasai et al ; Chiba et al ; Tsuda et al ; Okamoto et al ; Suzuki et al ). The phytoplankton assemblages during the spring bloom in the Oyashio region possess higher light utilization efficiency of photosynthesis and primary productivity (Shiomoto ; Isada et al , ), which contributes to the highest biological utilization effect on seawater p CO 2 in the world ocean (Takahashi et al ; Chierici et al ) and high biological production (Taniguchi ; Sakurai ; Ikeda et al ; FAO ). Nosaka et al () reported that diatoms during the spring bloom in the Oyashio region are the main producer of transparent exopolymer particles (TEPs) that affect the efficiency of the biological carbon pump.…”

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confidence: 99%

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Responses of phytoplankton assemblages to iron availability and mixing water masses during the spring bloom in the Oyashio region, NW Pacific

Isada

Hattori-Saito

Saito

et al. 2018

Limnology & Oceanography

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Spring phytoplankton blooms play a major role in the carbon biogeochemical cycle of the Oyashio region, western subarctic Pacific, where the seasonal biological drawdown effect on seawater pCO2 is one of the greatest among the world's oceans. However, the bloom often terminates before depleting macronutrients, and the initiation and magnitude of the bloom is heterogeneous. We conducted a high resolution taxonomic and physiological assessment of phytoplankton in relation to the different physicochemical water masses of Coastal Oyashio Water (COW), Oyashio water (OYW), and modified Kuroshio water (MKW) in the Oyashio region from April to June 2007. Massive diatom blooms were found in April. Then, chlorophyll a concentration, cell abundance of diatom taxa, and the maximum photosystem II photochemical efficiency (Fv/Fm) were positively correlated with the mixing ratios of COW, suggesting that the spring bloom in April was strongly affected by the intrusion of COW. In the OYW, intensive blooms occurred from the middle of May under low dissolved iron (DFe) concentration (< 0.26 nM). Redundancy analysis showed that while diatom blooms accompanied by COW were related to DFe concentration, this was not the case in the OYW. These results indicated that diatoms in the OYW possess different iron adaptation strategies compared with diatoms in the water masses affected by COW. This led to the spatial heterogeneity of the Oyashio spring bloom. The results presented here demonstrate that water mass characterization with detailed assessments of phytoplankton taxonomy and physiological status can improve our understanding of marine ecosystems.

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“…Pico‐ and nano‐sized phytoplankton groups were predominant at Stn. A4 during BLOSSOM (Isada et al ). Our CHEMTAX results (Fig.…”

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Responses of phytoplankton assemblages to iron availability and mixing water masses during the spring bloom in the Oyashio region, NW Pacific

Isada

Hattori-Saito

Saito

et al. 2018

Limnology & Oceanography

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“…The western subarctic Pacific (WSP) is the largest CO 2 sink by biological activity among the world's oceans (Takahashi et al, 2002) and has high vertical transport efficiency of particulate organic carbon in spring (Honda, 2003;Kawakami et al, 2004Kawakami et al, , 2015. These distinctive characteristics of the WSP are partly due to the massive spring diatom blooms in the Oyashio region off the Kuril Islands (Isada et al, 2010;Suzuki et al, 2011;Yoshie et al, 2010). The WSP is also known to be an HNLC region in summer and winter (e.g., Fujiki et al, 2014;Hattori-Saito et al, 2010;Suzuki et al, 2009;Tsuda et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Community Composition and Photosynthetic Physiology of Phytoplankton in the Western Subarctic Pacific Near the Kuril Islands With Special Reference to Iron Availability

et al. 2020

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The western subarctic Pacific (WSP) is known as one of the most productive regions among the world's oceans in spring. However, its oceanic waters are also known as a high‐nutrient, low‐chlorophyll region during summer due to low iron (Fe) availability in seawater. Indeed, recent studies have demonstrated that the distribution of Fe in the WSP is complex and heterogeneous. This study thus investigated the effects of Fe availability on the community composition and photophysiology of surface phytoplankton from coastal to offshore waters in the WSP in the summer of 2014. Although relatively high concentrations (>2 mg/m3) of chlorophyll (chl) a were found in the Sea of Okhotsk and some coastal waters, low chl a concentrations (<1 mg/m3) were commonly observed in offshore waters. Based on dissolved Fe and macronutrient concentrations, we deduced that low Fe availability limited phytoplankton growth in offshore waters, whereas low silicate and/or nitrate levels limited growth in the shelf areas. Scanning electron microscopy also revealed that the centric diatom Chaetoceros exclusively dominated the diatom assemblages in the shelf and coexisted with pennate diatoms in offshore waters, respectively. Primary productivity in surface waters was negatively correlated with the bottom of the euphotic layer or the light saturation index of the photosynthesis‐irradiance curve, which indicates that the phytoplankton assemblages were well acclimated to in situ light conditions regardless of the water masses.

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“…These blooms are generally triggered by water-column stratification during the transition from winter to spring (Kasai et al, 1997). The chlorophyll (Chl) a concentration and primary production integrated within the water column can reach 500 mg Chl a m −2 (Kasai et al, 1998) and 3,200 mg C m −2 d −1 (Isada et al, 2010), respectively. The enormous spring blooms cause an increase in meso-and macrozooplankton biomass and fishery production in the Northwest Pacific (Sakurai, 2007;Ikeda et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Dynamics and Origin of Transparent Exopolymer Particles in the Oyashio Region of the Western Subarctic Pacific during the Spring Diatom Bloom

2017

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The seasonal biological drawdown of the partial pressure of CO 2 (pCO 2 ) in the surface waters of the Oyashio region of the western subarctic Pacific is one of the greatest among the world's oceans. This is attributable to spring diatom blooms. Transparent exopolymer particles (TEPs) are known to affect efficiency of the biological carbon pump, and higher TEP levels are frequently associated with massive diatom blooms. However, TEP dynamics in the Oyashio region remain unclear. We investigated the TEP distribution from three cruises during the spring diatom bloom periods in 2010 and 2011. TEP concentrations varied from < 15 to 196 ± 71 µg xanthan gum equiv. L −1 above 300 m and generally declined with depth. Vertical TEP concentrations were significantly related not only to chlorophyll a concentrations but also to bacterial abundance. Average TEP concentrations within the mixed layer (> 30 m) were significantly higher during the bloom (155 ± 12 µg xanthan gum equiv. L −1 ) than in the post-bloom phase (90 ± 32 µg xanthan gum equiv. L −1 ). In contrast, bacteria abundance within the mixed layer changed little during the bloom to post-bloom phases. These results suggest that the abundance of phytoplankton greatly contributed to dynamics of the TEP distribution. To evaluate the ability of the phytoplankton to produce TEP, an axenic strain of the diatom Thalassiosira nordenskioeldii, which is a representative species of Oyashio blooms, was examined within a batch culture system. Cell abundance-normalized TEP and dissolved organic carbon (DOC) production rates changed simultaneously with growth of the strain. Although these production rates were significantly higher in the stationary phase than in the exponential growth period, values of the TEP/DOC ratio changed little throughout incubation. These findings suggest that TEP production in the Oyashio region may be enhanced by an increase in DOC production from spring diatoms.

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Primary productivity and its bio-optical modeling in the Oyashio region, NW Pacific during the spring bloom 2007

Cited by 28 publications

References 68 publications

Responses of phytoplankton assemblages to iron availability and mixing water masses during the spring bloom in the Oyashio region, NW Pacific

Responses of phytoplankton assemblages to iron availability and mixing water masses during the spring bloom in the Oyashio region, NW Pacific

Community Composition and Photosynthetic Physiology of Phytoplankton in the Western Subarctic Pacific Near the Kuril Islands With Special Reference to Iron Availability

Dynamics and Origin of Transparent Exopolymer Particles in the Oyashio Region of the Western Subarctic Pacific during the Spring Diatom Bloom

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