Long-Term Pollution Does Not Inhibit Denitrification and DNRA by Adapted Benthic Microbial Communities
Elias Broman1,2,3, Mohanad Abdelgadir4, Stefano Bonaglia5
1Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91, Stockholm, Sweden. elias.broman@su.se.
Microbial Ecology
|May 24, 2023
Summary
Nitrogen cycling processes like denitrification and dissimilatory nitrate reduction to ammonium (DNRA) in Baltic Sea sediments were unaffected by long-term pollution. Microbial communities showed adaptation to metals, suggesting eutrophication is a greater influence than historic contaminants.
Area of Science:
- Environmental Microbiology
- Biogeochemistry
- Marine Ecology
Background:
- Microbial nitrogen (N) cycling, including denitrification and dissimilatory nitrate reduction to ammonium (DNRA), is crucial for aquatic ecosystems.
- The impact of long-term pollution, specifically hydrophobic organic compounds (HOCs) and metals, on these vital microbial processes remains incompletely understood.
Purpose of the Study:
- To investigate the effects of long-term pollution on denitrification and DNRA rates in Baltic Sea sediments.
- To analyze the taxonomic structure and N-cycling gene abundance of microbial communities in response to pollution.
Main Methods:
- Sediment sampling from a long-term polluted site in Oskarshamn (Baltic Sea).
- Measurement of denitrification and DNRA rates.
- Metagenomic analysis of microbial community taxonomic structure and N-cycling genes.
Main Results:
- Denitrification and DNRA rates were comparable to reference and unpolluted sites, indicating no significant impact from long-term pollution.
- Metagenomic data suggested microbial community adaptation to metal pollution.
- N-cycling microbial communities showed resilience to historic metal and HOC pollution.
Conclusions:
- Denitrification and DNRA rates in Baltic Sea sediments are more sensitive to eutrophication and organic enrichment than to historical metal and HOC contamination.
- N-cycling microbial communities exhibit adaptive strategies to cope with metal pollution.
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