DOI: 10.5061/dryad.g1jwstqww
title: Data for: Effect of seaweed canopy disturbance on understory microbial communities on rocky shores

description: The collapse of macroalgal habitats is altering the structure of benthic
 communities on rocky shores globally. Nonetheless, how the loss of
 canopy-forming macroalgae influences the structure of epilithic microbial
 communities is yet to be explored. Here, we used experimental field
 manipulations and 16S-rRNA-gene amplicon sequencing to determine the
 effects of macroalgal loss on the understorey bacterial communities and
 their relationship with epiphytic bacteria on macroalgae. Beds of the
 fucoid Hormosira banksii were exposed to different levels of disturbance
 resulting in five treatments: (i) 100% removal of Hormosira individuals,
 (ii) 50% removal, (iii) no removal, (iv) a procedural control that
 mimicked the removal process, but no Hormosira was removed and (v)
 adjacent bare rock. Canopy cover, bacterial communities (epilithic and
 epiphytic) and benthic macroorganisms were monitored for 16 months.
 Results showed that reductions in canopy cover rapidly altered understory
 bacterial diversity and composition. Hormosira canopies in 50% and 100%
 removal plots showed signs of recovery over time, but understory epilithic
 bacterial communities remained distinct throughout the experiment in plots
 that experienced full Hormosira removal. Changes in bacterial communities
 were not related to changes in other benthic macroorganisms. These results
 demonstrate that understory epilithic bacterial communities respond
 rapidly to environmental disturbances at small scales and these changes
 can be long-lasting. A deeper knowledge of the ecological role of
 understory epilithic microbial communities is needed to better understand
 potential cascading effects of disturbances on the functioning of
 macroalgal-dominated systems.
description: # Data for: Effect of seaweed canopy disturbance on understory microbial
 communities on rocky shores Data tables for microbial and macro-organisms
 were collected using amplicon sequencing (16S) of swabs and photographs.
 Bioinformatics and normalisation of data from microbial samples were done
 in two separate groups - a comparison of swabs taken from hormosira’s
 surface (subset of treatments) compared to the benthic substrate, and the
 benthic substrate only (all treatments and times). For details see methods
 of the paper. ## Description of the data and file structure (header
 names). Seven files are included: 1.
 Benthic\_quadrat\_coverage\_analysis.csv percent cover of benthic
 organisms taken from Covalent image analysis. * Column headers:
 Sample\_name (unique ID with concatenation of plot ID, time taken (T2-T4
 shown with T1 naming function absent)); Image\_name; plot ID; time (T1-T4
 as corresponding to manuscript dates of sampling); date (month sampled);
 treatment (of 5 described in ms); plot\_rep (unique name of up to 5
 replicates taken from each plot. Name is a concatenation of treatment,
 plot name and replicate number 1-5 for unique sampling event) * Columns
 8-17 list taxonomic groups that were identified in images: Grazers (ie
 gastropods), Tube worms, Bleached CCA (crustose corraline algae), CCA,
 Sand, Rock, ACR (articulated calcareous red algae), Turf algae, Brown
 laminate algae, H. banksii 2. Hormosira\_substrate\_norm\_asv\_tab.csv ASV
 table for swabs taken on Hormosira surface and benthic substrate * Column
 Headers indicate unique sample name and can be matched to the file
 above/metadata files below 3. Hormosira\_substrate\_taxa\_tab.csv -
 taxonomic assignment tables for swabs taken on Hormosira surface and
 benthic substrate * column headers indicate ASV ID and various taxonomic
 ranks from kingdom-species 4. Hormosira\_substrate\_metadata.csv -
 metadata for swabs taken on Hormosira surface and benthic substrate *
 Column headers Sample name, time sample taken, date sample taken,
 treatment (control, procedural control, 50 percent removal treatments
 only), plot ID, plot replicate for unique sample event, target substrate
 swabbed (i.e Hormosira surface or benthic understory) 5.
 substrate\_metadata - metadata for swabs only taken from benthic substrate
 * same column headers as "Hormosira\_substrate\_metadata.csv"
 except understory treatments only are included (not Hormosira surface) 6.
 substrate\_norm\_asv\_tab.csv - ASV table for swabs taken on benthic
 substrate only * column headers indicate sample name with normalised
 abundance indicated in rows 7. Substrate\_taxa\_tab.csv - Taxonomic
 assignment table for swabs taken from the benthic substrate only. * column
 headers indicate ASV ID and various taxonomic ranks from kingdom-species
 ## Sharing/Access information Please contact the authors for more
 information or access to data code.