University of Oulu

Lehosmaa, K., Muotka, T., Pirttilä, A.M., Jaakola, I., Rossi, P.M. and Jyväsjärvi, J. (2021), Bacterial communities at a groundwater-surface water ecotone: gradual change or abrupt transition points along a contamination gradient?. Environ Microbiol, 23: 6694-6706.

Bacterial communities at a groundwater-surface water ecotone : gradual change or abrupt transition points along a contamination gradient?

Saved in:
Author: Lehosmaa, Kaisa1; Muotka, Timo1; Pirttilä, Anna Maria1;
Organizations: 1Ecology and Genetics Research Unit, University of Oulu, Oulu, FI-90014, Finland
2Water, Energy and Environmental Engineering Research Group, University of Oulu, Oulu, FI-90014, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.6 MB)
Persistent link:
Language: English
Published: John Wiley & Sons, 2021
Publish Date: 2022-02-04


Microbial communities contribute greatly to groundwater quality, but the impacts of land-use practices on bacteria in groundwaters and groundwater-dependent ecosystems remain poorly known. With 16S rRNA gene amplicon sequencing, we assessed bacterial community composition at the groundwater-surface water ecotone of boreal springs impacted by urbanization and agriculture, using spring water nitrate-N as a surrogate of contamination. We also measured the rate of a key ecosystem process, organic matter decomposition. We documented a recurrent pattern across all major bacterial phyla where diversity started to decrease at unexpectedly low nitrate-N concentrations (100–300 μg L−1). At 400 NO3-N μg L−1, 25 bacterial exact sequence variants showed a negative response, resulting in a distinct threshold in bacterial community composition. Chthonomonas, Acetobacterales and Hyphomicrobium were the most sensitive taxa, while only three taxa (Duganella, Undibacterium and Thermoanaerobaculaceae) were enriched due to increased contamination. Decomposition rate responded unimodally to increasing nitrate-N concentration, with a peak rate at ~400 NO3-N μg L−1, parallelly with a major shift in bacterial community composition. Our results emphasize the utility of bacterial communities in the assessment of groundwater-dependent ecosystems. They also call for a careful reconsideration of threshold nitrate values for defining groundwater ecosystem health and protecting their microbial biodiversity.

see all

Series: Environmental microbiology
ISSN: 1462-2912
ISSN-E: 1462-2920
ISSN-L: 1462-2912
Volume: 23
Issue: 11
Pages: 1462 - 2912
DOI: 10.1111/1462-2920.15708
Type of Publication: A1 Journal article – refereed
Field of Science: 1181 Ecology, evolutionary biology
1172 Environmental sciences
Funding: This study was supported by Maj and Tor Nessling Foundation (Project Number 201500223), University of Oulu, Maa-ja Vesitekniikan tuki ry and Academy of Finland (318230).
Academy of Finland Grant Number: 318230
Detailed Information: 318230 (Academy of Finland Funding decision)
Copyright information: © 2021 The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.