Abstract
Microbes drive biogeochemical changes in ecosystems, including carbon (C) and nitrogen (N) cycling. Dam construction has altered riparian ecosystems worldwide, yet we know little about microbial community composition in riparian sediments and how it changes following dam removal and sediment/soil drainage. Here, we evaluate how riparian microbial communities change with increasing depth in the sediment profile for existing dams and over time following dam removal/breach and assess how various physico-chemical sediment properties influence microbial community composition. We studied microbial community structure for 12 riparian sites over a chronosequence of 0-234 years since dam breach. Sediment was collected every 0.3 m to a depth of 4 m. Aerobic taxa involved with N cycling (e.g., Nitrospirota) were dominant in surficial sediments, and increased in deeper sediments as time since dam breach increased. Anaerobic taxa implicated in C cycling (e.g., Bathyarchaeia, Anaerolineaceae) and iron reduction (e.g., Sva0485) were dominant in deeper, anoxic sediments, but declined the fastest post dam breach. These microbial trends provide insights into how riparian biogeochemical functions are impacted by dam inundation and the recovery and restoration of these ecosystems following dam removals.
Data availability
The datasets generated and/or analyzed during the current study are available in the GenBank repository, [accession number PRJNA1346466].
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Acknowledgements
This study was funded by the US Department of Agriculture NIFA grant award # 2023-67019-39835. We would like to thank Jessie Thomas-Blate from American Rivers and the many landowners who provided us access to the milldam sites for sampling. Soil/sediment analysis was provided by Regen Ag Lab and the University of Delaware Soils lab. We also thank Drs. Dorothy Merritts and Robert Walter for their guidance on the study.
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Eric R. Moore (EM) and Shreeram Inamdar (SI) wrote the article. EM, Md. Moklesur Rahman (MR), Matthew Sena (MS), Joseph G. Galella (JG), Bisesh Joshi (BJ), and Alexis Yaculak (AY) collected the data. Marc Peipoch (MP) conducted denitrification enzyme assays and Jinjun Kan (JK) performed high throughput sequencing steps. EM did the data analysis and created the tables and figures. All authors reviewed the manuscript and suggested edits.
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Moore, E.R., Rahman, M.M., Galella, J.G. et al. Distinct changes in riparian sediment microbial communities with depth and time since dam removal.
Sci Rep (2026). https://doi.org/10.1038/s41598-026-37708-3
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DOI: https://doi.org/10.1038/s41598-026-37708-3
Keywords
- Soil microbiome
- Soil drainage
- Dam removal
- Nitrogen cycling
- Anaerobic sediments
- Iron reduction
- Buried hydric soils
Source: Ecology - nature.com
