Chlorophyll a concentration is the most common indicator of phytoplankton biomass, basically regulated by macro-nutrients and light intensity. Therefore, long-term monitoring of these parameters provides fundamental information on ecosystem changes with climate change. As part of the monitoring programs of the Japanese Antarctic Research Expedition (JARE), water temperature, salinity, chlorophyll-a concentration, macro-nutrients (nitrate, nitrite, phosphate, and silicic acid), and photosynthetically active radiation at the sea surface have been measured onboard the icebreakers Shirase and Fuji by JARE-7 during the 1965/66 season and by JARE-14 during the 1972/73 season, respectively. This report presents the latest data collected during the Shirase cruise in the 2017/18 season.
A 2020 study studied this question.