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Primary vitamin B 12 limitation and widespread stress in Antarctic phytoplankton

Year: 2026
Type: preprint
Abstract: Iron is considered the dominant limiting or colimiting nutrient for phytoplankton growth in the Southern Ocean. However, strong competition and limited biosynthesis capabilities for vitamin B 12 (cobalamin) within the microbial community creates conditions suitable for cobalamin limitation. Through a nutrient enrichment experiment in the Amundsen Sea, we show that growth in a phytoplankton community comprising diatoms and prasinophytes was limited primarily by cobalamin and secondarily by iron. Protein biomarkers across a broad area of the Southern Ocean further indicate widespread cobalamin stress within diatoms and Phaeocystis . As warming-induced melting of ice-shelves increases iron supplies in the coastal Southern Ocean, shifts from iron to cobalamin limitation favor mixotrophic flagellates with low cobalamin requirements, altering community composition and function.
DOI: 10.64898/2026.11.05.764676
Authors: Robert H Lampe, Deepa Rao, Riss M Kell, Rebecca J Chmiel, Nicole L Schanke, Soo Yoon Kim, Lauren E Lees, Francesco Bolinesi, Olga Mangoni, Raffaella Casotti, Cecilia Balestra, Hong Zheng, Dawn M Moran, Andrew E Allen, Matthew R McIlvin, Giacomo R DiTullio, Mak A Saito
Institutions: Woods Hole Oceanographic Institution, College of Charleston, University of California San Diego, University of California, Irvine, University of Naples Federico II, Stazione Zoologica Anton Dohrn, National Institute of Oceanography and Applied Geophysics, J. Craig Venter Institute
Language: English
Subfield: Oceanography
Open Access status: green
OpenAlex ID: W7225414385
Cites: 39
Cited by:
Related to: 10