Dark lakes change how microbes eat land carbon
In a dark Ontario lake, more aromatic terrestrial organic matter lowered bacterial production and slightly raised CO2.
Source
Feasting on terrestrial organic matter: Dining in a dark lake changes microbial decomposition
Study at a glance
- Design
- Animal / in-vitro — Sediment mesocosms with graded litter in clear vs dark lakes near Sudbury
- N
- N=48 · 24 mesocosms per lake × 2 lakes
- Population
- Benthic microbial communities in Swan Lake and Lake Laurentian, Ontario
- Outcome
- Bacterial production, enzymes, and CO2 response to terrestrial organic-matter aromaticity
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Inspect source passages
Dark lakes change how microbes eat land carbon
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
The clear lake had 13.6% less available N and 15.0% less available P relative to C than the dark lake.
the clear lake always had 13.6% and 15.0% less available N and P, respectively, relative to C
Which two lakes were used?
two lakes near Sudbury, Ontario Canada: Lake Laurentian
What they did
Submerged sediment mesocosms with graded deciduous/coniferous litter in a clear lake (Swan) and a dark lake (Laurentian) near Sudbury, then measured bacterial production, enzymes, CO2, and metagenomes.
What they found
A 25% rise in aromaticity cut bacterial production 14.5%; the dark lake paid a respiratory cost, while the clearer lake was more nutrient-limited and more photo-oxidizing.
The limits
What it doesn't show
Two-lake comparison cannot isolate nutrients from light, and mesocosms do not measure whole-lake carbon burial over years.
Key terms
- t-OM
- Terrestrially derived organic matter washed or falling into lakes.
- SUVA
- Specific UV absorbance indicating how aromatic dissolved organic matter is.
- Bacterial production (BP)
- Rate at which sediment bacteria build new biomass.
- EEA
- Extracellular enzyme activity used to break down complex organics.
- LMW vs HMW
- Low- versus high-molecular-weight organic compounds.
- Mesocosm
- Field container of sediment exposed to natural lake water.
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The dark lake was:
Common questions
Where?
Two lakes near Sudbury, Ontario.
Lakes?
Clear Swan Lake and dark Lake Laurentian.
Aromaticity effect?
25% more aromaticity cut BP 14.5%.
When deployed?
July 2015.
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