DOI: 10.5061/dryad.sxksn03cg
title: Data from: Multiple stressors affect function rather than taxonomic structure of freshwater microbial communities

description: Microbial community responses to environmental stressors are often
 characterised by assessing changes in taxonomic structure, but such
 changes, or lack thereof, may not accurately reflect functional changes
 that are critical to ecosystem processes. While community-level functional
 responses have been studied, these are often done under highly controlled,
 single-stressor scenarios that fail to reflect the complexities of
 multiple interacting environmental stressors in field conditions. We
 conducted a manipulative experiment to investigate the individual and
 combined effects of nutrient enrichment and salinisation – two key,
 interacting stressors in freshwater systems – on the taxonomic structure
 and metabolic function of benthic microbial communities using 1,000 L open
 freshwater ponds established &gt;10 years ago in the field. Microbial
 communities were pre-established on tiles under ambient conditions for 30
 days, and then transferred to ponds with elevated nutrients (+10mg/L N,
 +1mg/L P), elevated salinity (+15g/L NaCl), both stressors combined, or to
 ambient ponds, and community structure and function were measured over 90
 days. We found that both stressors individually impacted community-level
 metabolic function, with distinct differences in the direction and timing
 of these effects. Salinisation decreased metabolic rates within seven days
 before recovering, nutrient enrichment increased metabolic rates after 30
 days, and both stressors combined drove strong decreases in metabolic
 rates and shifted community metabolic profiles independent of time.
 Notably, functional changes occurred without significant alterations in
 bacterial community structure, underscoring the importance of measuring
 functional responses to environmental stressors. These results imply that
 critical microbial functions, including decomposition and organic carbon
 release, are likely to be impaired in freshwater systems under multiple
 stressors, even when taxonomic structure remains relatively stable. This
 dataset contains the raw sequences, environmental metadata, absorbance
 values from the metabolic assay, and the functional metrics from the
 experiment.
description: # Multiple stressors affect function rather than taxonomic structure of
 freshwater microbial communities **Principle Investigator Contact
 Information** ``` Name: Rose Fuggle Institution: University of Sydney
 Email: rose.fuggle@sydney.edu.au ``` **Alternate Contact Information** ```
 Name: Ziggy Marzinelli Institution: University of Sydney Email:
 e.marzinelli@sydney.edu.au ``` #### Dataset Overview This dataset contains
 the data in Fuggle et al 2024 npj biofilms and microbiomes, testing the
 hypothesis that the structure and function of freshwater benthic microbial
 communities are affected by salinisation and nutrient enrichment, and that
 combined stressor effects differ from the sum of individual stressor
 effects. Data was obtained from benthic microbial communities grown on
 tiles in outdoor mesocosms. It includes 1) biofilm in situ functional
 metrics, including oxygen production and consumption, concentration of
 green alage, diatoms and cyanobacteria, total chlorophyll a concentration
 in biofilms, photosynthetic efficiency, 2) 16S rRNA ASV sequences from
 swabbed biofilms, 3) OD590 absorbance values using Ecoplates incubated
 with biofilm suspensions, 4) pond water data including oxygen
 concentrations, chlorophyll a, pH, conductivity, nitrite and phosphate and
 5) csv file with oxygen incubation data calculations. #### Dates of Data
 Collection Data was collected in May - September 2023. #### Data Spatial
 Scope Data was collected from an experimental field site in Toledo, Spain,
 as part of the Iberian Pond Network infrastructure. #### Funding This
 study has received funding from the AQUACOSM-plus project of the European
 Union's Horizon 2020 research and innovation programme under grant
 agreement No. 871081 and Transnational Access project SalNutFun.
 Additional funds were received from The University of Sydney WG Murrell
 funds. ### Files and Folders **Zip File: Sequences.zip** This compressed
 folder contains forward and reverse reads as fasta.gz files for each
 sample. Samples are named as[Treatment]-[Pond]-[Time]. Treatment group
 abbreviations match abbreviations in the manuscript. **File:
 toledo_data_absorbance.csv** This file contains the OD590 absorbance
 values for each carbon source for each sample. Samples are named
 [Treatment]-[Pond]-[Time]-[lab incubation hour]. This data file contains
 OD590 absorbance values that represent microbial or enzymatic activity
 across different carbon sources for each sample. Each column corresponds
 to a carbon compound (e.g., glucose, malic acid, mannose), with separate
 measurements for the maximum slope and mean slope of OD590
 readings—indicating the rate and extent of substrate utilization. **File:
 toledo_data_function.csv** This file contains the functional values for
 each sample. Samples are named as[Treatment]-[Pond]-[Time]. Treatment
 group abbreviations match abbreviations in the manuscript (A = Ambient, S
 = High Salinity, N = Nutrient Enriched, SN = High Salinity + Nutrient
 Enriched, C = Baseline Controls). Days are 1, 7 and 30.
 Concentration_Green_Algae, Concentration_Cyanobacteria and
 Concentration_Diatoms and Biomass are all in the units micromoles of
 chlorophyll-a per square centimetre. PAM_Yield and PAM_F0 are unitless
 values. Copies is the copies of the 16S rRNA gene as determined by qPCR.
 GPP is Gross Primary Productivity, NPP is Net Primary Productity and CR is
 Community Respiration, all presented in the units micromoles of oxygen gas
 per litre (µM/L) per hour. **File: toledo_pond_data.csv** This file
 contains values for pond water. This data file shows measurements of pond
 water quality parameters (Chlorophyll-a, condictivity, pH, Dissolved
 oxygen, nitrites and phosphates)