Acknowledgements
We express our heartfelt thanks to the sea ice team, members of the Japanese Antarctic Research Expedition, the crew of the Japan Maritime Self-Defense Force icebreaker Shirase , and cruise members for their support in conducting field work. We thank Prof. K. Kawashima, K. Murakami, H. Nakajima, M. Kiuchi, T. Ishino, and T. P. Tamura for their support in the low temperature room, M. Hirabayashi for oxygen isotopic analyses, and A. Ooki for nutrient analyses. We benefitted greatly from advice and useful comments on the nutrient data offered by A. Ooki and T. Ishino. This work was supported by grants from the Japan Society for the Promotion of Science (#17H04715, #17H04710, #17H06317, #17H06322, #18F18794, #20H04345, #21H04931),
the Science Program of the Japanese Antarctic Research Expedition (JARE) as Prioritized Research AJ0902 (ROBOTICA), the National Institute of Polar Research (NIPR) through Project Research KP-303 and General Collaboration Project #28-14, #2-13 and the grant for young scientist, the Center for the Promotion of Integrated Sciences of SOKENDAI, and the Joint Research Program of the Institute of Low Temperature Science, Hokkaido University. The data used in this study are available in the supplementary information (Table S1) and are archived in the data repository of the National Institute of Polar Research, Tokyo, Japan (https://ads.nipr.ac.jp), is underway.