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 (pCO₂^sw) in the Indian sector of the Southern Ocean during austral summer. pCO₂^sw was negatively correlated with total phytoplankton and diatom abundances, as estimated from pigment signatures, in the zone south of the Antarctic Circumpolar Current; however, pCO₂^sw was not correlated with haptophyte abundance. Additionally, a stronger correlation was found between pCO₂^sw and total phytoplankton NPP than between chlorophyll a concentration and pCO₂^sw. We reconstructed pCO₂^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.

南大洋是大气中二氧化碳（CO ₂）的巨大净汇，海洋浮游植物在CO ₂固定中起着至关重要的作用。我们评估了南半球印度洋夏季夏季主要浮游植物群落和净初级生产力（NPP）的变化如何影响地表水CO ₂分压（p CO ₂ ^sw）的变化。根据色素特征估计，在南极绕流洋流以南的区域中，p CO ₂ ^sw与总浮游植物和硅藻的含量呈负相关；但是，p CO ₂ ^sw与触觉植物的丰度无关。此外，与叶绿素a浓度和p CO ₂ ^sw之间的关系相比，p CO ₂ ^sw与总浮游植物NPP之间的相关性更强。我们使用卫星数据在年际尺度上重建了p CO ₂ ^sw，并评估了气海CO ₂通量的年际变化。在1997年至2007年期间，研究区域内的整体CO ₂通量显示出从小源到强汇的巨大变化。集成CO _2的变化通量也与南洋印度洋地区卫星衍生的浮游植物群落的变化相关，优势浮游植物群落的变化可能控制边缘冰区的CO ₂动态。