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Does microbial stoichiometry modulate eutrophication of aquatic ecosystems?
A K Steenbergh1, P L E Bodelier, M Heldal
1Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), P.O. Box 50, 6700 AB, Wageningen, The Netherlands. a.steenbergh@nioo.knaw.nl
Environmental Microbiology
|December 12, 2012
Summary
Microbial stoichiometry in Baltic Sea sediments reveals high carbon to phosphorus (C:P) ratios in prokaryotes. This finding explains enhanced phosphorus remineralization in low-oxygen marine environments.
Area of Science:
- Environmental Microbiology
- Biogeochemistry
- Marine Ecology
Background:
- Prokaryotic (Bacteria and Archaea) elemental composition influences nutrient cycling during organic matter decomposition.
- Benthic phosphorus fluxes are critical in marine ecosystems, particularly under varying oxygen conditions.
- Existing knowledge gaps regarding microbial stoichiometry in marine sediments.
Purpose of the Study:
- To experimentally determine the carbon, nitrogen, and phosphorus (C:N:P) ratios of individual prokaryotes in marine sediments.
- To investigate the relationship between microbial stoichiometry and benthic nutrient fluxes.
- To understand the role of microbial C:N:P ratios in phosphorus remineralization under different oxygen levels.
Main Methods:
- Collection and incubation of C-limited Baltic Sea sediments under oxic and anoxic conditions.
- Utilized X-ray microanalysis for precise determination of C:N:P ratios in individual prokaryotic cells.
- Comparison of measured microbial C:N:P ratios with the Redfield ratio for marine organic matter.
Main Results:
- Prokaryotic C:P ratios were significantly higher (approx. 400:1) than the Redfield ratio (106:1) in both oxic and anoxic incubations.
- Prokaryotic C:N ratios (approx. 6.4:1) were found to be close to the Redfield ratio.
- These microbial elemental ratios were consistent across both tested oxygen conditions.
Conclusions:
- High microbial C:P ratios in prokaryotes are a key factor controlling benthic nutrient cycling.
- Elevated microbial C:P ratios contribute to the observed enhanced remineralization of phosphorus relative to carbon and nitrogen.
- This stoichiometric imbalance provides a mechanistic explanation for high phosphorus release in low-oxygen marine environments.
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