Article (Scientific journals)
Macro-nutrient concentrations in Antarctic pack ice: Overall patterns and overlooked processes
Fripiat, François; Meiners, K.M.; Vancoppenolle, M. et al.
2017In Elementa: Science of the Anthropocene, 5 (13)
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Keywords :
nutrients; sea ice; Antarctica
Abstract :
[en] 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), commensurate with the seasonal build-up of ice microalgae promoted by increased insolation. Stronger and earlier nitrate than silicic acid consumption suggests that a significant fraction of the primary productivity in sea ice is sustained by flagellates. By both consuming and producing ammonium and nitrite, the microbial community maintains these nutrients at relatively low concentrations in spring. With the decrease in insolation beginning in late summer, dissolved inorganic nitrogen and silicic acid concentrations increase, indicating imbalance between their production (increasing or unchanged) and consumption (decreasing) in sea ice. Unlike the depleted concentrations of both nitrate and silicic acid from spring to summer, phosphate accumulates in sea ice (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.
Research center :
FOCUS - Freshwater and OCeanic science Unit of reSearch - ULiège
Disciplines :
Earth sciences & physical geography
Author, co-author :
Fripiat, François ;  Université de Liège > Département de Biologie, Ecologie et Evolution > Département de Biologie, Ecologie et Evolution
Meiners, K.M.
Vancoppenolle, M.
Papadimitriou, S.
Thomas, D.N.
Ackley, S.F.
Arrigo, K.R.
Carnat, G.
Cozzi, S.
Delille, Bruno  ;  Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO)
Dieckmann, G.S.
Dunbar, R.B.
Fransson, A.
Kattner, G.
Kennedy, H.
Lannuzel, D.R.
Munro, D.
Nomura, D.
Rintala, J.-M.
Schoemann, V.
Stefels, J.
Stefels, J.
Steiner, N.
Tison, J.-L.
More authors (14 more) Less
Language :
English
Title :
Macro-nutrient concentrations in Antarctic pack ice: Overall patterns and overlooked processes
Publication date :
29 March 2017
Journal title :
Elementa: Science of the Anthropocene
eISSN :
2325-1026
Publisher :
BioOne, washington, United States - District of Columbia
Volume :
5
Issue :
13
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 27 March 2017

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