DOI 10.1016/j.dsr.2020.103263 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.
Phytoplankton community composition, Diatoms, Southern Ocean, Net primary productivity, Carbon dioxide
| File | Pages | Size | Access | |
|---|---|---|---|---|
Publisher's official version | 12 | 1 Mo | ||
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 Ko | ||
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 Ko | ||
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 Ko | ||
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 Ko | ||
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 Mo | ||
Fig. S6. Relationships of summer SAM index (Marshall, 2003) with the integrated PPeu and the averaged wind speed over the study region. | 1 | 44 Ko | ||
Table S1. | - | 17 Ko |
Copy this text