DOI: 10.5061/dryad.m0cfxppds
title: Benthic bacterial communities are shaped by browning in boreal headwater streams

description: Owing to the rapid progress of high‐throughput sequencing technologies,
 microbial assemblages have gained growing interest in environmental impact
 assessment. However, research on microbial community responses,
 particularly those of benthic biofilm, to browning (increased
 concentrations of dissolved organic carbon [DOC]), is scarce. We used data
 from 55 boreal streams to examine if biofilm bacterial communities exhibit
 changes in diversity and community composition along a gradient of
 browning (3.6–27 mg DOC L−1). Species richness increased slightly with
 increasing DOC, whereas community composition changed markedly across the
 gradient, especially in the active community. Pseudomonadota and
 Bacteroidota were overall dominant bacterial phyla. In the active
 community, Bacteroidota became relatively less abundant and Pseudomonadota
 more abundant with increasing DOC. Nitrate‐N (NO3‐N) and DOC were the most
 important predictors of bacterial community turnover. The greatest change
 in community composition occurred between 75 and 100 μg NO3‐N L−1. For
 DOC, the first change point was at the low‐end of the gradient, followed
 by a major change in strongly brownified waters (&gt; 20 mg L−1).
 Bacterial communities became phylogenetically more similar than expected
 by chance as DOC increased. Concordance between bacterial and benthic
 invertebrate communities was very high, indicating that browning exerts a
 strong control over both taxonomic groups. Our results suggest that
 microbial communities, particularly the active portion of the community,
 may provide a sensitive and reliable tool for stream bioassessment. We
 defined a threshold‐type response in bacterial assemblages to water
 browning but more research is needed on microbial responses to multiple
 simultaneous stressors related to global warming and land‐use
 intensification.
description: Please see the detailed description of sample collection and data
 processing in the article "Benthic bacterial communities are shaped
 by browning in boreal headwater streams". 
  
description: # Benthic biofilm bacteria of 55 northern Finnish streams along a
 dissolved organic carbon gradient Dataset DOI:
 [https://doi.org/10.5061/dryad.m0cfxppds](https://doi.org/10.5061/dryad.m0cfxppds) ## Description of the data and file structure These data were collected as part of a project investigating the impacts of water browning on stream communities. Owing to the rapid progress of high-throughput sequencing technologies, microbial assemblages have gained growing interest in environmental impact assessment. However, research on microbial community responses, particularly those of benthic biofilm, to browning (increased concentrations of dissolved organic carbon, DOC), is scarce. We used data from 55 boreal streams to examine if biofilm bacterial communities exhibit changes in diversity and community composition along a gradient of browning (3.6 to 27 mg DOC L-1). Species richness increased slightly with increasing DOC, whereas community composition changed markedly across the gradient, especially in the active community. Pseudomonadota and Bacteroidota were overall dominant bacterial phyla. In the active community, Bacteroidota became relatively less abundant and Pseudomonadota more abundant with increasing DOC. NO3-N and DOC were the most important predictors of bacterial community turnover. The greatest change in community composition occurred between 75 and 100 µg NO3-N L-1. For DOC, the first change point was at the low-end of the gradient, followed by a major change in strongly brownified waters (&gt;20 mg L-1). Bacterial communities became phylogenetically more similar than expected by chance as DOC increased. Concordance between bacterial and benthic invertebrate communities was very high, indicating that browning exerts a strong control over both taxonomic groups. Our results suggest that microbial communities, particularly the active portion of the community, may provide a sensitive and reliable tool for stream bioassessment. We defined a threshold-type response in bacterial assemblages to water browning but more research is needed on microbial responses to multiple simultaneous stressors related to global warming and land-use intensification. ### Files and variables #### File: Data\_for\_phyloseq\_import.zip **Description:** This file contains a .biom file, a .nwk phylogenetic tree file and a .txt file containing metadata, suitable for upload into the phyloseq R package.  The Metadata.txt file contains the following variables: * SampleID: The identity code of each sample * SiteID: The identity code of each site * SiteName: The name of the site  * N: The north co-ordinate of the site location * E: The east co-ordinate of the site location * SampleType: The type of sample analysed (all biofilm) * NucleicAcid: The type of nucleic acid extracted (DNA or RNA) * BarcodeSequence: The barcode sequence used for sequencing * LinkerPrimerSequence: The linker primer sequence used for sequencing * Adapter: The adapter sequence used for sequencing * TP: Total phosphorous concentration in µg L-1 * NO3: Nitrate-nitrogen in µg L-1 * NO2: Nitrite-nitrogen in µg L-1 * DOC: Dissolved organic carbon in mg L-1 * Abs436: Absorbance of filtered water samples at 436 nm * Col: Water colour in mg Pt L-1 * EC: Electrical conductivity in S m-1 * pH: The pH value of the water sample * Temp: The water temperature in degrees Celsius * Substrate: The weighted mean of the substrate composition using the Wentworth scale * Substrate.diversity: Simpson diversity index based on the relative cover of each Wentworth class in each quadrat * Moss: Percentage moss cover on the substrate  * Width: The mean width of the stream at the study site in cm * Velocity: Current velocity in cm s−1 * Depth: The mean depth of the stream at the study site in cm * Urban: The percentage of urban land cover in the catchment * Agriculture: The percentage of agricultural land cover in the catchment * Deciduous.forest: The percentage of deciduous forest cover in the catchment * Coniferous.forest: The percentage of coniferous forest cover in the catchment * Mixed.forest: The percentage of mixed forest cover in the catchment (coniferous and deciduous) * Open.peatland: The percentage of open peatland cover in the catchment * Lakes:  The percentage cover of lakes in the catchment * Non-drained: The percentage of non-drained peatland in the catchment * Drainage: The percentage of drained peatland in the catchment * Peat.production: The percentage of peat harvesting area in the catchment * catchment.km2: The area of the catchment in Km-2 #### File: ASV\_matrix\_and\_env.xlsx **Description:** Data sheet of all the environmental variables and amplicon sequence variant (ASV) count data, of both RNA and DNA samples.  ##### Variables * SiteID: The identity code of each site * N: The north co-ordinate of the site location * E: The east co-ordinate of the site location * TP: Total phosphorous concentration in µg L-1 * NO3: Nitrate-nitrogen in µg L-1 * NO2: Nitrite-nitrogen in µg L-1 * DOC: Dissolved organic carbon in mg L-1 * Abs436: Absorbance of filtered water samples at 436 nm * Col: Water colour in mg Pt L-1 * EC: Electrical conductivity in S m-1 * pH: The pH value of the water sample * Temp: The water temperature in degrees Celsius * Substrate: The weighted mean of the substrate composition using the Wentworth scale * Substrate.diversity: Simpson diversity index based on the relative cover of each Wentworth class in each quadrat * Moss: Percentage moss cover on the substrate  * Width: The mean width of the stream at the study site in cm * Velocity: Current velocity in cm s−1 * Depth: The mean depth of the stream at the study site in cm * Urban: The percentage of urban land cover in the catchment * Agriculture: The percentage of agricultural land cover in the catchment * Deciduous.forest: The percentage of deciduous forest cover in the catchment * Coniferous.forest: The percentage of coniferous forest cover in the catchment * Mixed.forest: The percentage of mixed forest cover in the catchment (coniferous and deciduous) * Open.peatland: The percentage of open peatland cover in the catchment * Lakes:  The percentage cover of lakes in the catchment * Non-drained: The percentage of non-drained peatland in the catchment * Drainage: The percentage of drained peatland in the catchment * Peat.production: The percentage of peat harvesting area in the catchment * catchment.km2: The area of the catchment in Km-2 * RNA1 - RNA2708: The number of occurrences at each site of each ASV from RNA samples, numbered 1 to 2708. The absence of an ASV at a site is indicated by a 0 * DNA1 - DNA2708: The number of occurrences at each site of each ASV from DNA samples, numbered 1 to 2708. The absence of an ASV at a site is indicated by a 0 #### File: tax\_table.csv **Description:** This is the taxonomic table containing the taxonomic information of all the Amplicon Sequence Variants (ASVs). ##### Variables * ASV: The identity number of each Amplicon Sequence Variant (ASV) * Domain: The domain the ASV belongs to * Phylum: The phylum the ASV belongs to * Class: The class the ASV belongs to * Order: The order the ASV belongs to * Family: The Family the ASV belongs to * Genus: The genus the ASV belongs to * Species: The species the ASV belongs to Some taxonomic information is not available for many of the ASVs. In these cases there is an NA infilled to the cell, meaning not available.