Macro-nutrient concentrations in Antarctic pack ice: Overall patterns and overlooked processes

• Published in: Elementa: Science of the Anthropocene
• Main Authors: François Fripiat, Klaus M. Meiners, Martin Vancoppenolle, Stathys Papadimitriou, David N. Thomas, Stephen F. Ackley, Kevin R. Arrigo, Gauthier Carnat, Stefano Cozzi, Bruno Delille, Gerhard S. Dieckmann, Robert B. Dunbar, Agneta Fransson, Gerhard Kattner, Hilary Kennedy, Delphine Lannuzel, David R. Munro, Daiki Nomura, Janne-Markus Rintala, Véronique Schoemann, Jacqueline Stefels, Nadja Steiner, Jean-Louis Tison
• Format: Article in Journal/Newspaper
• Language: English
• Published: BioOne 2017
• Subjects: Nutrients; sea ice; Antarctica; geo; envir; Antarctic; Antarc*; Sea ice
• Online Access: https://doi.org/10.1525/elementa.217; https://doaj.org/article/b24837a7f55b4e87a5683ca6f6ee4fd9

Antarctic pack ice is inhabited by a diverse and active microbial community reliant on nutrients for growth. Seeking patterns and overlooked processes, we performed a large-scale compilation of macro-nutrient data (hereafter termed nutrients) in Antarctic pack ice (306 ice-cores collected from 19 research cruises). Dissolved inorganic nitrogen and silicic acid concentrations change with time, as expected from a seasonally productive ecosystem. In winter, salinity-normalized nitrate and silicic acid concentrations (C*) in sea ice are close to seawater concentrations (Cw), indicating little or no biological activity. In spring, nitrate and silicic acid concentrations become partially depleted with respect to seawater (C* Cw). The phosphate excess could be explained by a greater allocation to phosphorus-rich biomolecules during ice algal blooms coupled with convective loss of excess dissolved nitrogen, preferential remineralization of phosphorus, and/or phosphate adsorption onto metal-organic complexes. Ammonium also appears to be efficiently adsorbed onto organic matter, with likely consequences to nitrogen mobility and availability. This dataset supports the view that the sea ice microbial community is highly efficient at processing nutrients but with a dynamic quite different from that in oceanic surface waters calling for focused future investigations.