Antarctic meltwater-induced dynamical changes in phytoplankton in the Southern Ocean

• Published in: Environmental Research Letters
• Main Authors: Ji-Hoon Oh, Kyung Min Noh, Hyung-Gyu Lim, Emilia Kyung Jin, Sang-Yoon Jun, Jong-Seong Kug
• Format: Article in Journal/Newspaper
• Language: English
• Published: IOP Publishing 2022
• Subjects: Antarctic meltwater; Antarctic ice-sheet/shelf; Southern Ocean; chlorophyll; phytoplankton; Environmental technology. Sanitary engineering; TD1-1066; Environmental sciences; GE1-350; Science; Q; Physics; QC1-999; Antarctic; Antarctic Ocean; The Antarctic; Antarc*; Ice Sheet
• Online Access: https://doi.org/10.1088/1748-9326/ac444e; https://doaj.org/article/81a25b5b233a492aa706dd2d0b94fddb

It has been suggested that the freshwater flux due to the recent melting of the Antarctic ice-sheet/shelf will suppress ventilation in the Southern Ocean (SO). In this study, we performed idealized earth-system simulations to examine the impacts of Antarctic meltwater on the biomass of surface phytoplankton in the Antarctic Ocean. The enhanced stratification due to the meltwater leads to a decrease in surface nitrate concentration, but an increase in the surface concentration of dissolved iron. These changes are associated with the reduced upwelling of nitrate-rich deep water and the trapped iron exported from terrestrial sediment. Because of the limited iron availability in the SO, the trapped iron in surface water enhances the chlorophyll concentration in the open ocean. However, in the marginal sea along the Antarctic coastline where the iron is relatively sufficient, a nitrate reduction induces a chlorophyll decrease, indicating a regime shift from iron-limited to nitrate-limited conditions.