Influence of Coastal Oyashio water on massive spring diatom blooms in the Oyashio area of the North Pacific Ocean

Kuroda, Hiroshi; Toya, Yuko; Watanabe, Tsuyoshi; Nishioka, Jun; Hasegawa, Daisuke; Taniuchi, Yukiko; Kuwata, Akira

doi:10.1016/j.pocean.2019.05.004

Cited by 27 publications

(38 citation statements)

References 58 publications

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“…Therefore, we selected those four diatoms as the representative transcripts in this study. Large cell numbers for T. nordenskioeldii , C. socialis , and C. debilis were also observed in the Oyashio region during spring diatom bloom 6,21 , and their relatives were observed in our past sampling in 2015 as described in Supporting Text and Supplementary Fig. S4.…”

Section: Resultssupporting

confidence: 60%

“…The western subarctic Pacific is a preferable field to study cell responses of bloom-forming species because large-scale diatom blooms occur annually in spring in this region 5,20,21 . The hydrography of this region in spring is complex, with dominant water columns: Oyashio Water (OW), Coastal Oyashio Water (COW), and modified Kuroshio Water (MKW) 22 .…”

Section: Introductionmentioning

confidence: 99%

“…The hydrography of this region in spring is complex, with dominant water columns: Oyashio Water (OW), Coastal Oyashio Water (COW), and modified Kuroshio Water (MKW) 22 . Warming by increasing solar radiation and inflow of the low-salinity COW lead to formation of a shallow surface layer and make phytoplankton use nutrients supplied by winter mixing to form massive diatom blooms 21–24 . The alleviation of light limitation due to the mixed layer shoaling and the accumulation of diatom cells due to the weakening of turbulence are also related to onset of diatom blooms 25 .…”

Section: Introductionmentioning

confidence: 99%

“…Here, we performed metatranscriptome analyses of diatom communities during spring blooms in the western North Pacific to reveal bloom-specific cell responses, focusing on differences in depth. We compared two diatom communities obtained from the sea surface (late decline phase of the bloom; 10 m) and subsurface chlorophyll maximum (SCM, initial decline phase of the bloom; 30 m), particularly targeting T. nordenskioeldii and C. debilis , which commonly occur during spring bloom in this region 21 . Moreover, gene expression analysis of nutrient-controlled cultures was conducted to confirm the metatranscriptomic analysis.…”

Section: Introductionmentioning

confidence: 99%

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Depth-dependent transcriptomic response of diatoms during spring bloom in the western subarctic Pacific Ocean

Suzuki

Kataoka

Watanabe

et al. 2019

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Diatoms play important roles in primary production and carbon transportation in various environments. Large-scale diatom bloom occurs worldwide; however, metabolic responses of diatoms to environmental conditions have been little studied. Here, we targeted the Oyashio region of the western subarctic Pacific where diatoms bloom every spring and investigated metabolic response of major diatoms to bloom formation by comparing metatranscriptomes between two depths corresponding to different bloom phases. Thalassiosira nordenskioeldii and Chaetoceros debilis are two commonly occurring species at the study site. The gene expression profile was drastically different between the surface (late decline phase of the bloom; 10 m depth) and the subsurface chlorophyll maximum (SCM, initial decline phase of the bloom; 30 m depth); in particular, both species had high expression of genes for nitrate uptake at the surface, but for ammonia uptake at the SCM. Our culture experiments using T. nordenskioeldii imitating the environmental conditions showed that gene expression for nitrate and ammonia transporters was induced by nitrate addition and active cell division, respectively. These results indicate that the requirement for different nitrogen compounds is a major determinant of diatom species responses during bloom maturing.

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Section: Resultssupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Depth-dependent transcriptomic response of diatoms during spring bloom in the western subarctic Pacific Ocean

Suzuki

Kataoka

Watanabe

et al. 2019

Sci Rep

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“…Pack ice often flows out into the North Pacific through the southern passes of the Kuril Islands, indicating the pack ice could be one of the sources of the highly productive coastal Oyashio waters and influences ocean conditions off the southeast coast of Hokkaido, Japan (Ohtani, 1989;Talley and Nagata, 1995). It is thus likely that ice algae in the Okhotsk sea ice have a seeding effect on the spring phytoplankton bloom of subarctic waters near Japan (Kuroda et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Response to Sea Ice Melt Indicates High Seeding Potential of the Ice Diatom Thalassiosira to Spring Phytoplankton Blooms: A Laboratory Study on an Ice Algal Community From the Sea of Okhotsk

et al. 2020

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Phytoplankton communities in seasonally ice-covered areas are largely affected by ice algae. The Okhotsk Sea is the southernmost sea ice zone in the northern hemisphere with a sizeable seasonal ice cover, thus ice algae of the Okhotsk sea ice have a large potential to seed the early spring bloom. Little is known about the Okhotsk ice algal communities and their seeding effects. We investigated the dynamics of the composition and the photophysiological performances of an Okhotsk ice algal community in a 6day laboratory incubation experiment that simulated the natural ice melt conditions. Centric diatoms, especially Thalassiosira spp., overwhelmingly dominated the ice algal community throughout incubation, whereas pennate diatoms, mostly Navicula and Nitzschia, showed little growth with much higher mortality. The maximum photochemical efficiency of Photosystem II (F v /F m) was the lowest at the beginning of the ice melt, suggesting a suppressed photosynthetic functioning by changes in salinity. The cellular pigment contents decreased by 30% due to osmotic stress, evidenced by deformed plastids under a microscope. The transcript level of the rbcL gene that encodes the large subunit of RubisCO was significantly higher during ice melt and decreased in the no-ice period, suggesting an urgent need for carbon fixation under the melt condition. Full recovery of photosynthesis and growth was also made after complete ice melt. Our results indicated high seeding potential of Thalassiosira to spring blooms owing to their photophysiological plasticity to dynamic salinity changes.

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A review: iron and nutrient supply in the subarctic Pacific and its impact on phytoplankton production

et al. 2021

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One of the most important breakthroughs in oceanography in the last 30 years was the discovery that iron (Fe) controls biological production as a micronutrient, and our understanding of Fe and nutrient biogeochemical dynamics in the ocean has significantly advanced. In this review, we looked back both previous and updated knowledge of the natural Fe supply processes and nutrient dynamics in the subarctic Pacific and its impact on biological production. Although atmospheric dust has been considered to be the most important source of Fe affecting biological production in the subarctic Pacific, other oceanic sources of Fe have been discovered. We propose a coherent explanation for the biological response in subarctic Pacific high nutrient low chlorophyll (HNLC) waters that incorporates knowledge of both the atmospheric Fe supplies and the oceanic Fe supplies. Finally, we extract future directions for Fe oceanographic research in the subarctic Pacific and summarize the uncertain issues identified thus far.

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Influence of Coastal Oyashio water on massive spring diatom blooms in the Oyashio area of the North Pacific Ocean

Cited by 27 publications

References 58 publications

Depth-dependent transcriptomic response of diatoms during spring bloom in the western subarctic Pacific Ocean

Depth-dependent transcriptomic response of diatoms during spring bloom in the western subarctic Pacific Ocean

Response to Sea Ice Melt Indicates High Seeding Potential of the Ice Diatom Thalassiosira to Spring Phytoplankton Blooms: A Laboratory Study on an Ice Algal Community From the Sea of Okhotsk

A review: iron and nutrient supply in the subarctic Pacific and its impact on phytoplankton production

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