DOI: 10.5061/dryad.m37pvmddb
title: Data from: Contrasting effects of rhizosphere and sediment microbiota on seagrass performance in response to a simulated marine heatwave

description: Climate change-induced temperature stress is drastically affecting the
 health and survival of plants across terrestrial and aquatic ecosystems.
 For terrestrial plants, below-ground microbes can enhance plant
 performance in response to environmental stress and recent evidence
 suggests a similar role for marine plants. Despite this, the potential for
 below-ground microbes to enhance marine plant resilience against climate
 change-induced marine heatwaves (MHWs), an ocean temperature stress that
 is increasing in frequency and intensity globally, remains unclear. We
 experimentally manipulated microbial communities in the Zostera
 muelleri rhizosphere and bulk sediment through root sterilisation and
 sediment autoclaving to determine their influence on seagrass growth and
 survival under two marine heatwave scenarios (recent MHW profile and an
 end-of-century scenario). Seagrasses with an experimentally disrupted
 rhizosphere microbiome showed reduced growth under all temperature and
 sediment treatments. In contrast, an intact bulk sediment microbiome
 hindered plant growth under the future marine heatwave scenario and
 disruption of these communities had a positive effect on plant
 performance. Future marine heatwave treatments had a lower relative
 abundance of potentially beneficial microbes in bulk sediments (i.e.,
 Akkermansiaceae) and were enriched with potential plant pathogens (i.e.,
 Xanthomonadaceae). In addition, the rhizosphere of plants in intact bulk
 sediments showed a lower relative abundance of potential plant-growth
 promoting bacteria. Synthesis. This study provides experimental evidence
 that marine heatwaves can negatively affect seagrass performance via
 changes in bulk sediment microbiota and that the benefits provided by
 rhizosphere microbiota to plants may not be enough to overcome such
 effects. Our experiment highlights for the first time the importance of
 below-ground microbes in seagrass responses to heat stress. Furthermore,
 our findings emphasise the need to consider microbial interactions in
 future seagrass research and suggest that shifts in microbial communities
 could play a key role in seagrass resilience to climate change.
 Furthermore, these insights may be crucial for restoration efforts, as
 integrating microbial communities into seagrass management strategies may
 enhance the success of restoration initiatives under changing
 environmental conditions.
description: The experiment was designed to evaluate the effects of sediment
 microbiota, rhizosphere microbiota and marine heatwaves on the growth and
 survival of the seagrass <em>Zostera muelleri</em>. Sediments
 from a seagrass meadow were collected and processed to create treatments
 with intact and disrupted (sterilised) microbiota. Seagrass shoots were
 also collected, standardised, and treated to either maintain or disrupt
 root-associated microbes.  Seagrass shoots were planted in the pots, which
 were then deployed in pots at the aquarium facilities of the Sydney
 Institute of Marine Sciences (SIMS) under three different temperature
 treatments. 
description: # Data from: Contrasting effects of rhizosphere and sediment microbiota on
 seagrass performance in response to a simulated marine heatwave
 [https://doi.org/10.5061/dryad.m37pvmddb](https://doi.org/10.5061/dryad.m37pvmddb) ## Description of the data and file structure The experiment was designed to assess the effects of sediment microbiota, marine heatwaves, and root-associated microbes on the growth and survival of the seagrass *Zostera muelleri*. Sediments from a seagrass meadow were collected and processed to create treatments with intact and disrupted (sterilized) microbiota. Seagrass shoots were also collected, standardized, and treated to either maintain or disrupt root-associated microbes. Plants were then exposed to three temperature treatments: ambient, current marine heatwave conditions, and future extreme marine heatwave conditions in a mesocosm experiment. Seagrass growth and survival were recorded. Samples from rhizosphere and bulk sediment were taken for bacterial community analyses. ### Files and variables #### File: Rawdata\_Seagrass-growth\_ZosteraMHW\.csv This dataset contains growth and physiological data for the seagrass Zostera muelleri exposed to different sediment microbial treatments and simulated marine heatwave conditions. Plants were sampled at two time points (11 and 22 days). Variables include leaf and root growth, total and dead leaf counts, and chlorophyll fluorescence measurements (e.g. Fv/Fm, Y(II)). Treatments included intact vs. disrupted sediment and root systems, and three temperature regimes (23°C, 26°C, and 29°C). ##### Variables * PotID: Number of the experimental unit * Sediment: Sediment treatments: (+) = intact sediment; (-) = disrupted sediment * Root: Root treatments: (+) = intact roots; (-) = disrupted roots * Temperature: Temperature treatments: control = 23 degrees, MHW = 26 degrees, MHW+ = 29 degrees (Celcius) * Harvesttime: Time point at which the plant was sampled: T1 = after 11 days, T2 = after 22 days * percentagegreenleaves: Percentage of leaves that were green and healthy per plant * numberdeadleaves: Percentage of leaves that were dead per plant * numbertotalleaves: Total amount of leaves on each plant * lengthleaf: Length of the longest leaf on plant (mm) * growthleaf: Length of the longest leaf on plant minus starting length of 100 mm (mm) * lengthroot:  Length of the roots on a plant (mm) * growthroot: Length of the roots on plant minus starting length of 50 mm (mm) * Fm: Maximum fluorescence * Fv: Variable fluorescence * Y: Effective quantum yield of photosystem II (PSII) * FvFm: Fv/Fm ratio: indicator of the maximum quantum efficiency of PSII photochemistry #### File: Rawdata\_Seagrass-survival\_ZosteraMHW\.csv This dataset reports shoot survival of the seagrass Zostera muelleri in response to experimental sediment microbial treatments and temperature stress simulating a marine heatwave. Plants were sampled at two time points (11 and 22 days). Variables include initial shoot number, number of surviving shoots, and shoot survival percentage. Treatments included intact vs. disrupted sediment and root systems, and three temperature regimes (23°C, 26°C, and 29°C). ##### Variables * PotID: Number of the experimental unit * Sediment: Sediment treatments: (+) = intact sediment; (-) = disrupted sediment * Root: Root treatments: (+) = intact roots; (-) = disrupted roots * Temperature: Temperature treatments: control = 23 degrees, MHW = 26 degrees, MHW+ = 29 degrees (Celcius) * Harvesttime: Time point at which the plant was sampled: T1 = after 11 days, T2 = after 22 days * numberalive: Number of shoots in each pot that were alive at the time of sampling * totalshoots: Total number of shoots in each pot at the start of the experiment * percentagealive: Percentage of plants in each pot that were alive at the time of sampling (%)