University of Oulu

Malazarte, J., Muotka, T., Jyväsjärvi, J., Lehosmaa, K., Nyberg, J., & Huttunen, K.-L. (2022). Bacterial communities in a subarctic stream network: Spatial and seasonal patterns of benthic biofilm and bacterioplankton. Molecular Ecology, 31, 6649– 6663.

Bacterial communities in a subarctic stream network : spatial and seasonal patterns of benthic biofilm and bacterioplankton

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Author: Malazarte, Jacqueline1; Muotka, Timo1; Jyväsjärvi, Jussi1;
Organizations: 1Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.8 MB)
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Language: English
Published: John Wiley & Sons, 2022
Publish Date: 2023-01-02


Water-column bacterial communities are assembled by different mechanisms at different stream network positions, with headwater communities being controlled by mass effects (advection of bacteria from terrestrial soils) while downstream communities are mainly driven by environmental sorting. Conversely, benthic biofilms are colonized largely by the same set of taxa across the entire network. However, direct comparisons of biofilm and bacterioplankton communities along whole stream networks are rare. We used 16S rRNA gene amplicon sequencing to explore the spatiotemporal variability of benthic biofilm (2 weeks old vs. mature biofilm) and water-column communities at different network positions of a subarctic stream from early summer to late autumn. Amplicon sequence variant (ASV) richness of mature biofilm was about 2.5 times higher than that of early biofilm, yet the pattern of seasonality was the same, with the highest richness in midsummer. Biofilm bacterial richness was unrelated to network position whereas bacterioplankton diversity was negatively related to water residence time and distance from the source. This pattern of decreasing diversity along the network was strongest around midsummer and diminished greatly as water level increased towards autumn. Biofilm communities were phylogenetically clustered at all network positions while bacterioplankton assemblages were phylogenetically clustered only at the most downstream site. Both early and mature biofilm communities already differed significantly between upstream (1st order) and midstream (2nd order) sections. Network position was also related to variation in bacterioplankton communities, with upstream sites harbouring substantially more unique taxa (44% of all upstream taxa) than midstream (20%) or downstream (8%) sites. Some of the taxa that were dominant in downstream sections were already present in the upmost headwaters, and even in riparian soils, where they were very rare (relative abundance <0.01%). These patterns in species diversity and taxonomic and phylogenetic community composition of the riverine bacterial metacommunity were particularly strong for water-column communities, whereas both early and mature biofilm exhibited weaker spatial patterns. Our study demonstrated the benefits of studying bacterioplankton and biofilm communities simultaneously to allow testing of ecological hypotheses about biodiversity patterns in freshwater bacteria.

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Series: Molecular ecology
ISSN: 0962-1083
ISSN-E: 1365-294X
ISSN-L: 0962-1083
Volume: 31
Issue: 24
Pages: 6649 - 6663
DOI: 10.1111/mec.16711
Type of Publication: A1 Journal article – refereed
Field of Science: 1181 Ecology, evolutionary biology
Funding: Our research was funded by the Academy of Finland (grant no. 318230) and University of Oulu (Kvantum Institute and Oulanka Foundation).
Academy of Finland Grant Number: 318230
Detailed Information: 318230 (Academy of Finland Funding decision)
Copyright information: © 2022 The Authors. Molecular Ecology published by John Wiley & Sons Ltd. 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.