Articles | Volume 13, issue 2
Biogeosciences, 13, 365–374, 2016
https://doi.org/10.5194/bg-13-365-2016

Special issue: Freshwater ecosystems in changing permafrost landscapes

Biogeosciences, 13, 365–374, 2016
https://doi.org/10.5194/bg-13-365-2016

Research article 19 Jan 2016

Research article | 19 Jan 2016

Microbial nutrient limitation in Arctic lakes in a permafrost landscape of southwest Greenland

B. Burpee1, J. E. Saros1, R. M. Northington1, and K. S. Simon2 B. Burpee et al.
  • 1Climate Change Institute, and School of Biology & Ecology, University of Maine, Maine, USA
  • 2School of Environment, University of Auckland, Auckland, New Zealand

Abstract. Permafrost is degrading across regions of the Arctic, which can lead to increases in nutrient concentrations in surface freshwaters. The oligotrophic state of many Arctic lakes suggests that enhanced nutrient inputs may have important effects on these systems, but little is known about microbial nutrient limitation patterns in these lakes. We investigated microbial extracellular enzyme activities (EEAs) to infer seasonal nutrient dynamics and limitation across 24 lakes in southwest Greenland during summer (June and July). From early to late summer, enzyme activities that indicate microbial carbon (C), nitrogen (N), and phosphorus (P) demand increased in both the epilimnia and hypolimnia by 74  % on average. Microbial investment in P acquisition was generally higher than that for N. Interactions among EEAs indicated that microbes were primarily P-limited. Dissolved organic matter (DOM, measured as dissolved organic carbon) was strongly and positively correlated with microbial P demand (R2  =  0.84 in July), while there were no relationships between DOM and microbial N demand. Microbial P limitation in June epilimnia (R2  =  0.67) and July hypolimnia (R2  =  0.57) increased with DOM concentration. The consistency of microbial P limitation from June to July was related to the amount of DOM present, with some low-DOM lakes becoming N-limited in July. Our results suggest that future changes in P or DOM inputs to these lakes are likely to alter microbial nutrient limitation patterns.

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Short summary
This study investigates microbial nutrient limitation patterns across a region of southwest Greenland in relation to environmental factors. Using microbial enzyme activities to infer nutrient limitation patterns, we determined that most lakes are P-limited. Further, P limitation was tightly controlled by lake dissolved organic carbon (DOC) concentration.
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