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Estimating Sediment Denitrification Rates Using Cores and N2O Microsensors
Published on: December 6, 2018
Microbial community composition and denitrifying enzyme activities in salt marsh sediments
Yiping Cao1, Peter G Green, Patricia A Holden
1Donald Bren School of Environmental Science and Management, University of California, Santa Barbara, CA 93106-5131, USA.
Applied and Environmental Microbiology
|November 4, 2008
Summary
Denitrifying microbial communities and enzyme activities in salt marshes are influenced by elevation and carbon content. Despite correlations with environmental factors, denitrifier community composition and function appear uncoupled.
Area of Science:
- Environmental microbiology
- Estuarine ecology
- Biogeochemistry
Background:
- Salt marsh sediments host diverse microbial communities crucial for nutrient cycling.
- Denitrification, a key microbial process, can be impacted by environmental factors like nutrient loading and pollutants.
- Understanding these dynamics is vital for managing coastal ecosystem health.
Purpose of the Study:
- To investigate the influence of environmental factors on denitrifying microbial community composition and denitrification enzyme activities (DEA) in a nutrient-rich California salt marsh.
- To analyze the relationships between microbial community structure, DEA, and environmental variables, including elevation, salinity, nutrients, and metals.
Main Methods:
- Sediment sampling across three elevations and 12 stations with varying conditions.
- Analysis of bacterial (16S rRNA) and denitrifier (nirS) community composition using terminal restriction fragment length polymorphism (TRFLP).
- Measurement of denitrification enzyme activities (DEA), nutrient levels, and eluted metals.
- Multivariate statistical analyses (direct gradient and regression) to determine relationships between variables.
Main Results:
- Microbial community composition and DEA exhibited high variability, strongly influenced by elevation (inundation degree), carbon content, and specific metals.
- Carbon content was closely linked to elevation, with DEA-carbon relationships being elevation-specific.
- Lateral gradients were observed, with stronger associations between community composition and elevation in a marsh subsystem.
- Denitrifier community composition and function showed evidence of being uncoupled, despite correlations with similar environmental factors and metals.
Conclusions:
- Elevation and carbon content are significant drivers of denitrifying microbial communities and their function in this salt marsh.
- The findings highlight the complexity of microbial processes in dynamic estuarine environments.
- The uncoupling of denitrifier community structure and function suggests intricate regulatory mechanisms at play.
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