Pelagic and Sympagic Biogenic Silica Production During Arctic Spring Diatom Bloom in Baffin Bay: Drivers, Limitation, and Fate
Abstract
Silicon (Si) cycling regulates diatom production and export in the Arctic Ocean, yet quantitative constraints on Si sources, recycling, and losses remain limited, particularly in ice-covered systems. In this study, we quantify biogenic silica (bSiO 2 ) production, dissolution, and export during a coastal Arctic spring bloom in Baffin Bay, integrating ice-associated and under-ice pelagic processes using in situ measurements collected during two ice camps of the Green Edge project (2015, 2016). These first direct measurements of sympagic bSiO 2 production ranged from 1.5 to 4.5 mmol Si m -2 and accounted for less than 3% of total seasonal bSiO 2 production. In contrast, under-ice pelagic production was intense, with an early onset, reaching up to 10-12 mmol Si m -2 d -1 and totaling 55-177 mmol Si m -2 over the productive period. Both ice and pelagic diatoms exhibited silicon limitation despite ambient dissolved silica concentrations of 3-6 μmol L -1 . Dissolution of bSiO 2 within the ice sustained a significant part of the production, accounting for up to 19%-35% of diatom Si demand. However, dissolution and measured vertical export fluxes (≤6 mmol Si m -2 ) together accounted for only a small fraction of pelagic bSiO 2 production, implying substantial additional loss pathways such as lateral advection and episodic export events. These results demonstrate a strong decoupling between bSiO 2 production, recycling, and export during Baffin Bay Arctic spring bloom. Our study provides new quantitative constraints on Arctic Si cycle and emphasizes the need to resolve seasonal and spatial variability in Si fluxes to predict future biogeochemical responses to ongoing Arctic change.
Plain Language Summary Diatoms are microalgae capable of growing within and beneath sea-ice under extremely low light and temperature conditions. They provide the energy required to sustain Arctic ecosystems at the end of the polar night and play a key role in climate regulation by exporting a portion of atmospheric carbon to deeper ocean layers. To grow, diatoms require silicon from their environment to form a frustule composed of biogenic silica (bSiO 2 ). In the Arctic, measurements are sparse, and little is known about the oceanic sources and sinks of silicon. As part of the Green Edge project in Baffin Bay, we conducted an extensive monitoring of bSiO 2 production, dissolution, and export by diatoms living in and beneath the ice. Our study revealed that, despite their ecological importance, ice diatoms contribute only ∼3% of the total bSiO 2 produced during the spring bloom. Notably, diatom growth was silicon-limited, even when dissolved silicon concentrations in surface waters were relatively high and while dissolution partially mitigated these limitations. Our results demonstrate a decoupling between diatom growth and their sinking to deep layers. These findings underscore the need to resolve seasonal and spatial variability in the silicon cycle to accurately predict future biogeochemical responses to ongoing Arctic change.
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BibTeX
@article{moriceau2026pelagic,
title = {{Pelagic and Sympagic Biogenic Silica Production During Arctic Spring Diatom Bloom in Baffin Bay: Drivers, Limitation, and Fate}},
author = {B Moriceau and M Gallinari and V Cornet‐barthaux and V Galindo and S Hillion and K Leblanc and J Legras and B Quéguiner and C Lalande and J Ferland and M Babin and A Leynaert},
journal = {Global Biogeochemical Cycles},
year = {2026},
month = oct,
doi = {10.1029/2026gb009170},
url = {https://hal.science/hal-05840703v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Pelagic and Sympagic Biogenic Silica Production During Arctic Spring Diatom Bloom in Baffin Bay: Drivers, Limitation, and Fate
AU - B Moriceau
AU - M Gallinari
AU - V Cornet‐barthaux
AU - V Galindo
AU - S Hillion
AU - K Leblanc
AU - J Legras
AU - B Quéguiner
AU - C Lalande
AU - J Ferland
AU - M Babin
AU - A Leynaert
PY - 2026
DA - 2026/10/27
JO - Global Biogeochemical Cycles
DO - 10.1029/2026gb009170
UR - https://hal.science/hal-05840703v1
AB - Silicon (Si) cycling regulates diatom production and export in the Arctic Ocean, yet quantitative constraints on Si sources, recycling, and losses remain limited, particularly in ice-covered systems. In this study, we quantify biogenic silica (bSiO 2 ) production, dissolution, and export during a coastal Arctic spring bloom in Baffin Bay, integrating ice-associated and under-ice pelagic processes using in situ measurements collected during two ice camps of the Green Edge project (2015, 2016). These first direct measurements of sympagic bSiO 2 production ranged from 1.5 to 4.5 mmol Si m -2 and accounted for less than 3% of total seasonal bSiO 2 production. In contrast, under-ice pelagic production was intense, with an early onset, reaching up to 10-12 mmol Si m -2 d -1 and totaling 55-177 mmol Si m -2 over the productive period. Both ice and pelagic diatoms exhibited silicon limitation despite ambient dissolved silica concentrations of 3-6 μmol L -1 . Dissolution of bSiO 2 within the ice sustained a significant part of the production, accounting for up to 19%-35% of diatom Si demand. However, dissolution and measured vertical export fluxes (≤6 mmol Si m -2 ) together accounted for only a small fraction of pelagic bSiO 2 production, implying substantial additional loss pathways such as lateral advection and episodic export events. These results demonstrate a strong decoupling between bSiO 2 production, recycling, and export during Baffin Bay Arctic spring bloom. Our study provides new quantitative constraints on Arctic Si cycle and emphasizes the need to resolve seasonal and spatial variability in Si fluxes to predict future biogeochemical responses to ongoing Arctic change. Plain Language Summary Diatoms are microalgae capable of growing within and beneath sea-ice under extremely low light and temperature conditions. They provide the energy required to sustain Arctic ecosystems at the end of the polar night and play a key role in climate regulation by exporting a portion of atmospheric carbon to deeper ocean layers. To grow, diatoms require silicon from their environment to form a frustule composed of biogenic silica (bSiO 2 ). In the Arctic, measurements are sparse, and little is known about the oceanic sources and sinks of silicon. As part of the Green Edge project in Baffin Bay, we conducted an extensive monitoring of bSiO 2 production, dissolution, and export by diatoms living in and beneath the ice. Our study revealed that, despite their ecological importance, ice diatoms contribute only ∼3% of the total bSiO 2 produced during the spring bloom. Notably, diatom growth was silicon-limited, even when dissolved silicon concentrations in surface waters were relatively high and while dissolution partially mitigated these limitations. Our results demonstrate a decoupling between diatom growth and their sinking to deep layers. These findings underscore the need to resolve seasonal and spatial variability in the silicon cycle to accurately predict future biogeochemical responses to ongoing Arctic change.
SN - 0886-6236
SN - 1944-8224
ER -