Intracellular nutrient storage during ice algal spring blooms in the Canadian high Arctic

Nutrient availability influences maximum biomass, speciation, cellular composition, and overall phenology of
Arctic spring ice algal blooms. However, how ice algae obtain nutrients from their environment is not well understood.
Previously documented positive relationships between sea ice nutrient concentrations and algal
biomass implied that ice algae maintain an intracellular nutrient pool. Here, we provide direct evidence
that sea ice diatoms store intracellular nitrate + nitrite and silicic acid well above that available in their ambient
environment. Differential retention of intracellular pools released during standard melt processing techniques
led to an increase in the apparent dissolved N:Si ratio measured in ice melt samples that likely influenced interpretations
of Si-limitation in some previous studies. It is hypothesized that the ability of ice algae to store
intracellular nutrient reserves represents a beneficial adaptation for ice algae to extend blooms under a periodic
tidal-pulsed flux of nutrients to the ice bottom environment.