The biogeochemical role of a microbial biofilm in sea ice: Antarctic landfast sea ice as a case study

Arnout Roukaerts, Florian Deman, Fanny Van der Linden, Gauthier Carnat, Arne Bratkic, Sebastien Moreau, Frank Dehairs, Bruno Delille, Jean-Louis Tison, François Fripiat

Research output: Contribution to journalArticle

Abstract

A paradox is commonly observed in productive sea ice in which an accumulation in the macro-nutrients nitrate and phosphate coincides with an accumulation of autotrophic biomass.This paradox requires a new conceptual
understanding of the biogeochemical processes operating in sea ice. In this study, we investigate this paradox using three time series in Antarctic landfast sea ice, in which massive algal blooms are reported (with particulate organic carbon concentrations up to 2,600 mmol L –1 ) and bulk nutrient concentrations exceed seawater values up to 3 times for nitrate and up to 19 times for phosphate. High-resolution sampling of the bottom 10 cm of the cores shows that high biomass concentrations coexist with high concentrations of nutrients at the subcentimeter scale. Applying a nutrient-phytoplankton-zooplankton-detritus model approach to this sea-ice system, we propose the presence of a microbial biofilm as a working hypothesis to resolve this paradox. By creating microenvironments with distinct biogeochemical dynamics, as well as favoring nutrient adsorption onto embedded decaying organic matter, a biofilm allows the accumulation of remineralization products (nutrients) in proximity to the sympagic (ice-associated) community. In addition to modifying the intrinsic physicochemical properties of the sea ice and providing a substrate for sympagic
community attachment, the biofilm is suggested to play a key role in the flux of matter and energy in this environment.
Original languageEnglish
Article number00134
Pages (from-to)1-14
Number of pages14
JournalElementa: Science of the Anthropocene
Volume9
Issue number1
DOIs
Publication statusPublished - 2021

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