Vertical organisation of microbial communities in Salineta hypersaline wetland, Spain

Microbial communities inhabiting hypersaline wetlands, well adapted to the environmental fluctuations due to flooding and desiccation events, play a key role in the biogeochemical cycles, ensuring ecosystem service. In order to better understand the ecosystem functioning we studied soils microbial communities of Salineta wetland (NE Spain) in dry and wet seasons in three different landscape stations representing situations characteristic of ephemeral saline lakes: S1 soil always submerged, S2 soil intermittently flooded and S3 soil with halophytes. Microbial community composition were determined according to different redox layers by 16S rRNA gene barcoding. We observed reversed redox gradient, negative at the surface and positive in depth, which was identify by PERMANOVA as the main factor explaining microbial distribution. The Proteobacteria, Gemmatimonadetes and Euryarchaeota phyla were dominant in all stations. Linear discriminant analysis effect size (LEfSe) revealed that the uppper soil surface layer was characterized by the predominance of halophilic archaeal operational taxonomic units (OTUs) while the subsurface soil layer was dominated by Bacillus related OTU. Additionally, the potential functional capabilities involved in carbon, nitrogen and sulfur cycles according to redox stratification were similar in all samples suggesting a functional redundancy. Such findings highlight the importance of biomonitoring and management of these wetlands whose extreme aridity and salinity conditions are exposed to irreversible changes due to human activities.