Microbial cell budgets of an A rctic glacier surface quantified using flow cytometry

Abstract

Summary Uncertainty surrounds estimates of microbial cell and organic detritus fluxes from glacier surfaces. Here, we present the first enumeration of biological particles draining from a supraglacial catchment, on M idtre L ovénbreen ( S valbard) over 36 days. A stream cell flux of 1.08 × 10 7 cells m −2 h −1 was found, with strong inverse, non‐linear associations between water discharge and biological particle concentrations. Over the study period, a significant decrease in cell‐like particles exhibiting 530 nm autofluorescence was noted. The observed total fluvial export of ∼ 7.5 × 10 14 cells equates to 15.1–72.7 g C , and a large proportion of these cells were small ( 7 cells m −2 h −1 . Analysis of surface ice cores revealed cell concentrations comparable to previous studies (6 × 10 4 cells ml −1 ) but, critically, showed no variation with depth in the uppermost 1 m. The physical retention and growth of particulates at glacier surfaces has two implications: to contribute to ice mass thinning through feedbacks altering surface albedo, and to potentially seed recently deglaciated terrain with cells, genes and labile organic matter. This highlights the merit of further study into glacier surface hydraulics and biological processes.

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