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Biogeosciences An interactive open-access journal of the European Geosciences Union
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https://doi.org/10.5194/bg-2017-164
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/bg-2017-164
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Submitted as: research article 08 May 2017

Submitted as: research article | 08 May 2017

Review status
This discussion paper is a preprint. It has been under review for the journal Biogeosciences (BG). The revised manuscript was not accepted.

Seasonal effects of photophysiology and chlorophyll a abundance on phytoplankton group-specific primary production in the Kuroshio region as revealed by SeaStar/SeaWiFS

Takafumi Hirata and Koji Suzuki Takafumi Hirata and Koji Suzuki
  • Faculty of Environmental Earth Science, Hokkaido University, Sapporo, 060-0810, Japan

Abstract. To evaluate the group-specific primary production of diatoms, haptophytes, and cyanobacteria in the Kuroshio region, a novel satellite observation methodology using the SeaStar/SeaWiFS satellite instrument was developed. The method used bio-optical relationships between the group-specific production and bio-optical properties such as the photosynthetic quantum yield and chlorophyll a specific optical absorption coefficient of phytoplankton, the last two of which were also estimated together with the group-specific production rather than assumed a priori. A global property of the absorption coefficient of phytoplankton, that the coefficient value at the wavelength of 510 nm was close to their spectral average, was highlighted in the method for a use of multi-spectral ocean color satellite data. Our results showed that the derived quantum yield index was higher for diatoms than haptophytes and cyanobacteria. Furthermore, intraspecific variation in the index, emerged as a latitudinal gradient: the values for cyanobacteria increased towards the higher latitudes. The group-specific primary production in the Kuroshio region showed that the climatological average of 134, 72 and 40 mg C m−2 day−1 for diatoms, haptophytes, and cyanobacteria, respectively. A comparison among variability of the group-specific primary production, the quantum yield index, and the absorption coefficient suggested that, in the Kuroshio region, the primary production due to diatoms was driven by their abundance through the year, whereas that due to cyanobacteria by photophysiology. The production due to haptophytes was seasonally regulated by both abundance and photophysiology.

Takafumi Hirata and Koji Suzuki
Interactive discussion
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AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Interactive discussion
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Takafumi Hirata and Koji Suzuki
Takafumi Hirata and Koji Suzuki
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Short summary
This work delivers a regional estimates of primary production due to diatoms, haptophytes and cyanobacteria around the Kuroshio current. Using a novel methodology, photosynthetic efficiency and abundance of marine phytoplankton are now viewed from a satellite in space. Our see that variability in primary production by diatoms is mainly regulated by their abundance rather than their efficiency, whereas the variability by cyanobacteria is more regulated by their efficiency than their abundance.
This work delivers a regional estimates of primary production due to diatoms, haptophytes and...
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