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Systematic microbial production of optically active dissolved organic matter in subarctic lake water

Berggren, Martin LU ; Gudasz, Cristian ; Guillemette, Francois ; Hensgens, Geert LU ; Ye, Linlin LU and Karlsson, Jan (2019) In Limnology and Oceanography
Abstract

The ecology and biogeochemistry of lakes in the subarctic region are particularly sensitive to changes in the abundance and optical properties of dissolved organic matter (DOM). External input of colored DOM to these lakes is an extensively researched topic, but little is known about potential reciprocal feedbacks between the optical properties of DOM and internal microbial processes in the water. We performed 28-day dark laboratory incubation trials on water from 101 subarctic tundra lakes in northern Sweden, measuring the microbial decay of DOM and the resulting dynamics in colored (CDOM) and fluorescent (FDOM) DOM components. While losses in dissolved oxygen during the incubations corresponded to a 20% decrease in mean DOM,... (More)

The ecology and biogeochemistry of lakes in the subarctic region are particularly sensitive to changes in the abundance and optical properties of dissolved organic matter (DOM). External input of colored DOM to these lakes is an extensively researched topic, but little is known about potential reciprocal feedbacks between the optical properties of DOM and internal microbial processes in the water. We performed 28-day dark laboratory incubation trials on water from 101 subarctic tundra lakes in northern Sweden, measuring the microbial decay of DOM and the resulting dynamics in colored (CDOM) and fluorescent (FDOM) DOM components. While losses in dissolved oxygen during the incubations corresponded to a 20% decrease in mean DOM, conversely the mean CDOM and total FDOM increased by 22% and 30%, respectively. However, the patterns in microbial transformation of the DOM were not the same in all lakes. Notably, along the gradient of increasing ambient CDOM (water brownness), the lakes showed decreased microbial production of protein-like fluorescence, lowered DOM turnover rates and decreasing bacterial growth per unit of DOM. These trends indicate that browning of subarctic lakes systematically change the way that bacteria interact with the ambient DOM pool. Our study underscores that there is no unidirectional causal link between microbial processes and DOM optical properties, but rather reciprocal dependence between the two.

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author
organization
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Contribution to journal
publication status
epub
subject
in
Limnology and Oceanography
publisher
ASLO
external identifiers
  • scopus:85074762468
ISSN
1939-5590
DOI
10.1002/lno.11362
language
English
LU publication?
yes
id
c363e02e-efc1-4f8b-893b-31ff7ff56782
date added to LUP
2019-12-09 11:29:12
date last changed
2020-05-26 05:36:36
@article{c363e02e-efc1-4f8b-893b-31ff7ff56782,
  abstract     = {<p>The ecology and biogeochemistry of lakes in the subarctic region are particularly sensitive to changes in the abundance and optical properties of dissolved organic matter (DOM). External input of colored DOM to these lakes is an extensively researched topic, but little is known about potential reciprocal feedbacks between the optical properties of DOM and internal microbial processes in the water. We performed 28-day dark laboratory incubation trials on water from 101 subarctic tundra lakes in northern Sweden, measuring the microbial decay of DOM and the resulting dynamics in colored (CDOM) and fluorescent (FDOM) DOM components. While losses in dissolved oxygen during the incubations corresponded to a 20% decrease in mean DOM, conversely the mean CDOM and total FDOM increased by 22% and 30%, respectively. However, the patterns in microbial transformation of the DOM were not the same in all lakes. Notably, along the gradient of increasing ambient CDOM (water brownness), the lakes showed decreased microbial production of protein-like fluorescence, lowered DOM turnover rates and decreasing bacterial growth per unit of DOM. These trends indicate that browning of subarctic lakes systematically change the way that bacteria interact with the ambient DOM pool. Our study underscores that there is no unidirectional causal link between microbial processes and DOM optical properties, but rather reciprocal dependence between the two.</p>},
  author       = {Berggren, Martin and Gudasz, Cristian and Guillemette, Francois and Hensgens, Geert and Ye, Linlin and Karlsson, Jan},
  issn         = {1939-5590},
  language     = {eng},
  month        = {11},
  publisher    = {ASLO},
  series       = {Limnology and Oceanography},
  title        = {Systematic microbial production of optically active dissolved organic matter in subarctic lake water},
  url          = {http://dx.doi.org/10.1002/lno.11362},
  doi          = {10.1002/lno.11362},
  year         = {2019},
}