Data from: Contrasting effects of rhizosphere and sediment microbiota on seagrass performance in response to a simulated marine heatwave

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.