Microbial Community Dynamics in Salt Marsh Ecosystems

Salt marshes occupy the dynamic interface between land and sea, subjecting microbial communities to fluctuating salinity, redox gradients and nutrient inputs. These microbes—principally bacteria and archaea, with contributions from fungi—mediate key biogeochemical cycles, including carbon sequestration, nitrogen transformation and sulphur cycling. Tidal inundation, plant–microbe interactions and anthropogenic nutrient enrichment drive shifts in community structure and activity. Advances in high-throughput sequencing, metagenomics and proteomics have revealed both the resident (total) and active fractions of these assemblages, showing how environmental perturbations can reduce functional diversity yet preserve overall community richness via microbial dormancy. Understanding the mechanisms that underpin resilience, succession and metabolic potential in salt marsh sediments is crucial for predicting ecosystem responses to global change and for informing conservation and restoration strategies.

Research from Nature Portfolio

Recent studies have demonstrated that chronic nutrient enrichment can profoundly alter the active component of salt marsh microbial communities. Controlled nitrogen additions led to a doubling of dormant taxa and a concomitant loss of diversity among metabolically active microbes, despite no detectable change in total community composition. This shift highlights the role of dormancy as a buffer against perturbation, enabling the maintenance of overall microbial richness. The findings underscore that nutrient loading does not simply change community membership but redistributes activity across taxa, with implications for nutrient cycling and ecosystem resilience under increasing anthropogenic pressure.

Microbial Community Dynamics in Salt Marsh Ecosystems publication trend

The graph below shows the total number of articles in microbial community dynamics in salt marsh ecosystems across all publications each year (not limited to Nature Index journals).

Technical terms

Biogeochemical cycles: Natural pathways by which elements (e.g. carbon, nitrogen, sulphur) are cycled through biological, geological and chemical processes.

Dormancy: A reversible state of low metabolic activity adopted by microorganisms to survive unfavourable conditions.

Lignocellulose: A complex of lignin and cellulose that constitutes the structural framework of plant biomass, requiring specialised enzymes for decomposition.

Metagenomics: The culture-independent analysis of collective genomes from environmental samples, revealing community composition and functional potential.

Denitrification: A microbial process converting nitrate to gaseous nitrogen species, playing a key role in nitrogen removal from ecosystems.

Rhizosphere: The zone of soil directly influenced by plant roots, characterised by distinct microbial communities and enhanced nutrient exchange.

References

1. Nutrient enrichment induces dormancy and decreases diversity of active bacteria in salt marsh sediments. Nature Communications (2016).
2. Mechanistic strategies of microbial communities regulating lignocellulose deconstruction in a UK salt marsh. Microbiome (2021).
3. Seasonal and Zonal Succession of Bacterial Communities in North Sea Salt Marsh Sediments. Microorganisms (2022).
4. Short-term effect of simulated salt marsh restoration by sand-amendment on sediment bacterial communities. PLOS ONE (2019).