Carbon cycle
Dark lakes change how microbes eat land carbon
Open access · cc by · source: Europe PMC
In a dark Ontario lake, more aromatic terrestrial organic matter lowered bacterial production and slightly raised CO2.
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
Structured fields used in claim comparison tables when every cited study has a complete layer.
Key findings
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.
Methodology
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.
Limitations
Two-lake comparison cannot isolate nutrients from light, and mesocosms do not measure whole-lake carbon burial over years.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
Submerged-sediment mesocosms with graded deciduous/coniferous litter in a clear lake (Swan) and a dark lake (Laurentian) near Sudbury found that 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. A two-lake comparison cannot isolate nutrients from light, and the tanks do not measure whole-lake carbon burial over years.
Evidence for the claim as stated.
These mesocosms do not test one carbon-cycle claim. Litter tanks show aromaticity cutting bacterial production 14.5% with lake-colour differences in respiratory cost versus photo-oxidation. Canopy ¹⁵N recovers 3–4× more tracer in wood than soil targeting but does not scale to forest C stocks. Everglades inoculum effects on trunk diameter appear only under unconstrained flooding. Coralline algae are more sensitive to the rate of the pH drop than to low pH as a level, and live thalli at stable pH 7.7 increased daytime calcification. 'Mesocosms show carbon or OA effects' is not a single result.
Evidence for the claim as stated.
Open questions
Tensions this paper is part of
From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.
These mesocosms do not test one carbon-cycle claim. Litter tanks show aromaticity cutting bacterial production 14.5% with lake-colour differences in respiratory cost versus photo-oxidation. Canopy ¹⁵N recovers 3–4× more tracer in wood than soil targeting but does not scale to forest C stocks. Everglades inoculum effects on trunk diameter appear only under unconstrained flooding. Coralline algae are more sensitive to the rate of the pH drop than to low pH as a level, and live thalli at stable pH 7.7 increased daytime calcification. 'Mesocosms show carbon or OA effects' is not a single result.
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