High sea ice algal primary production near marine-terminating glaciers linked to turbulence-driven nutrient fluxes across the ice– ocean interface

Abstract:

Sea ice primary production is a key component supplying carbon to higher trophic levels when few other resources are available. In bottom-ice habitats, this production is limited by light availability and nutrient supply from underlying seawater. Reports of low sea ice primary production from Greenland have reinforced the view that landfast ice is regionally unimportant. Here, we document a single early-spring observation of intense algal production in sea ice adjacent to marine terminating glaciers in West Greenland, an environment rarely examined in ice studies. The bloom included abundant pennate diatoms, including Nitzschia frigida , and reached a daily primary production of 146 ± 4.8 mg C m⁻² d⁻¹ and biomass accumulation of 42.4 ± 1.6 mg Chlorophyll a (Chl a ) m⁻², exceeding previous Greenland observations. A biomass-specific production of 5.40 mg C mg Chl a⁻¹ d⁻¹ and maximum quantum yield (ΦPSII_max) of 0.44 indicated an active community. Strong silicic acid depletion in the presence of significant nitrate and phosphate concentrations suggested that silicic acid was the primary limiting nutrient within the ice. We propose that inflow-driven fjord circulation likely enhanced nutrient availability beneath the ice, while turbulence-driven fluxes across the ice-ocean interface represent a plausible mechanism for sustaining the observed high sympagic production during this sampling event. Sea ice in fjords with marine-terminating glaciers may therefore support high early-season production under favorable local conditions.

https://doi.org/10.1038/s41598-026-53846-0