Microbial nutrient limitation in Arctic lakes in a permafrost landscape of southwest Greenland
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 nut...
Main Authors: | , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2016-01-01
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Series: | Biogeosciences |
Online Access: | http://www.biogeosciences.net/13/365/2016/bg-13-365-2016.pdf |
Summary: | 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 (<i>R</i><sup>2</sup> = 0.84 in July),
while there were no relationships between DOM and microbial N demand.
Microbial P limitation in June epilimnia (<i>R</i><sup>2</sup> = 0.67) and July
hypolimnia (<i>R</i><sup>2</sup> = 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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ISSN: | 1726-4170 1726-4189 |