Over Winter Microbial Processes in a Svalbard Snow Pack: An Experimental Approach

Area of Science:

• * Cryosphere microbiology
• * Polar ecosystem dynamics
• * Nutrient cycling

Background:

• * Snow packs are crucial cryosphere components influencing climate and supporting microbial life.
• * Understanding polar winter microbial activity and nutrient cycling remains limited.
• * Current research primarily focuses on the spring ablation season.

Purpose of the Study:

• * To investigate microbial dynamics in a simulated polar winter snow pack.
• * To determine microbial activity and nutrient dependence under subfreezing, dark conditions.
• * To assess the role of mineral particles and dissolved nutrients (nitrogen, phosphorus) on microbial communities.

Main Methods:

• * Incubation of Arctic snow samples (-5°C, dark) for 5 weeks.
• * Addition of glacial mineral particles, dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and combined DIN+DIP.
• * 16S amplicon sequencing and particulate phosphorus analysis.

Main Results:

• * Heterotrophic communities consumed dissolved inorganic nutrients, especially DIN, suggesting potential nitrogen limitation.
• * Microbial community composition differed significantly in the presence of mineral particles.
• * Evidence suggests heterotrophs can utilize particulate phosphorus, potentially explaining the absence of phosphorus limitation.

Conclusions:

• * Polar winter snow packs harbor active microbial communities influencing nutrient dynamics.
• * Nitrogen may be a limiting nutrient for snow microbes, unlike in many aquatic environments.
• * Mineral particles play a role in microbial habitat and nutrient acquisition in snow.
• * Findings impact understanding of nutrient release during snowmelt and its effect on downstream ecosystems.