Effects of phytoplankton community composition and productivity on sea surface pCO(2) variations in the Southern Ocean

Type Article
Date 2020-06
Language English
Author(s) Takao Shintaro1, 2, Nakaoka Shin-Ichiro1, Hashihama FuminoriORCID3, Shimada Keishi3, Yoshikawa-Inoue Hisayuki2, Hirawake Toru4, Kanda Jota3, Hashida Gen5, Suzuki KojiORCID2
Affiliation(s) 1 : Natl Inst Environm Studies, 16-2 Onogawa, Tsukuba, Ibaraki 3058506, Japan.
2 : Hokkaido Univ, Fac Environm Earth Sci, Kita Ku, North 10 West 5, Sapporo, Hokkaido 0600810, Japan.
3 : Tokyo Univ Marine Sci & Technol, Minato Ku, 4-5-7 Konan, Tokyo 1088477, Japan.
4 : Hokkaido Univ, Fac Fisheries Sci, 3-1-1 Minato Cho, Hakodate, Hokkaido 0418611, Japan.
5 : Natl Inst Polar Res, 10-3 Midori Cho, Tachikawa, Tokyo 1908518, Japan.
Source Deep-sea Research Part I-oceanographic Research Papers (0967-0637) (Pergamon-elsevier Science Ltd), 2020-06 , Vol. 160 , P. 103263 (12p.)
DOI 10.1016/j.dsr.2020.103263
Keyword(s) Phytoplankton community composition, Diatoms, Southern Ocean, Net primary productivity, Carbon dioxide
Abstract

The Southern Ocean is a vast net sink for atmospheric carbon dioxide (CO2), with marine phytoplankton playing a crucial role in CO2 fixation. We assessed how changes in the dominant phytoplankton community and net primary productivity (NPP) affected variations in the partial pressure of CO2 in surface water (pCO(2)(sw)) in the Indian sector of the Southern Ocean during austral summer. pCO2sw was negatively correlated with total phytoplankton and diatom abundances, as estimated from pigment signatures, in the zone south of the Antarctic Circumpolar Current; however, pCO(2)(sw) was not correlated with haptophyte abundance. Additionally, a stronger correlation was found between pCO(2)(sw) and total phytoplankton NPP than between chlorophyll a concentration and pCO(2)(sw). We reconstructed pCO(2)(sw) at inter-annual scale using satellite data and assessed the inter-annual variability of air-sea CO2 flux. Over the period from 1997 to 2007, the integrated CO2 fluxes over the study region showed very large variations from a small source to a strong sink. Variations in the integrated CO2 fluxes were also correlated with changes in satellite-derived phytoplankton community in the Indian sector of the Southern Ocean and changes in the dominant phytoplankton community may control CO2 dynamics in the marginal ice zone.

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Fig. S1. Temporal changes in satellite chl a concentrations before our cruises. The values of chl a concentration was determined from MODIS/Aqua 8-day composite ... 1 72 KB Open access
Fig. S2. Same as Fig. 8a but for pCO2sw derived from satellite chl a images. White areas represent no satellite data due to cloudiness or sea ice cover. 1 486 KB Open access
Fig. S3. Same as Fig. 9 but for pCO2sw derived from satellite chl a images. The black solid line and shaded area denotes the mean values and standard deviations of satellite pCO2sw values in the area. 1 155 KB Open access
Fig. S4. Comparison between monthly mean pCO2sw estimated from satellite PPeu and in situ pCO2sw along cruise tracks for SOCAT version 2019 (Bakker et al., 2016; Table S1) during austral summer... 1 125 KB Open access
Fig. S5. Anomalies of PPeu distribution during the austral summer (December–February) from 1997/1998 to 2006/2007 in the study area, which was calculated from PPeu data of Takao et al. (2012). 1 1 MB Open access
Fig. S6. Relationships of summer SAM index (Marshall, 2003) with the integrated PPeu and the averaged wind speed over the study region. 1 44 KB Open access
Table S1. 17 KB Open access
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How to cite 

Takao Shintaro, Nakaoka Shin-Ichiro, Hashihama Fuminori, Shimada Keishi, Yoshikawa-Inoue Hisayuki, Hirawake Toru, Kanda Jota, Hashida Gen, Suzuki Koji (2020). Effects of phytoplankton community composition and productivity on sea surface pCO(2) variations in the Southern Ocean. Deep-sea Research Part I-oceanographic Research Papers, 160, 103263 (12p.). Publisher's official version : https://doi.org/10.1016/j.dsr.2020.103263 , Open Access version : https://archimer.ifremer.fr/doc/00676/78836/