Microbial cell budgets of an Arctic glacier surface quantified using flow cytometry

Area of Science:

• Glaciology
• Microbiology
• Biogeochemistry

Background:

• Estimates of microbial cell and organic detritus fluxes from glacier surfaces remain uncertain.
• Supraglacial environments are increasingly recognized as dynamic ecosystems influencing biogeochemical cycles.

Purpose of the Study:

• To quantify biological particle fluxes from a supraglacial catchment.
• To investigate the relationship between water discharge and biological particle concentrations.
• To assess the balance between biological particle export and input on glacier surfaces.

Main Methods:

• Enumeration of biological particles in supraglacial streamwater over 36 days.
• Analysis of stream cell flux and its relationship with water discharge.
• Measurement of cell concentrations in surface ice cores.
• Estimation of total fluvial export and comparison with estimated inputs.

Main Results:

• A stream cell flux of 1.08 × 10^7 cells m^-2 h^-1 was determined.
• Biological particle concentrations showed a strong inverse, non-linear relationship with water discharge.
• Total fluvial export was approximately 7.5 × 10^14 cells (15.1-72.7 g C), with a significant proportion of small cells (<0.5 μm).
• An apparent storage rate of 8.83 × 10^7 cells m^-2 h^-1 was calculated, indicating retention and potential growth.

Conclusions:

• Glacier surfaces act as sites for physical retention and biological growth of particulates.
• These processes can influence ice mass balance through albedo feedbacks.
• Glacier surfaces can potentially seed deglaciated terrain with microbial cells, genes, and organic matter.
• Further research into glacier surface hydraulics and biological processes is warranted.