Daily variability of bacteria and archaea active composition and their contribution to biogeochemical shifts in a extreme high altitude wetland

Microbial communities changed in association to their physical and chemical environment at different temporal scales, including high frequency variability. Shifts in microbial communities could influence the biogeochemical conditions particularly at sites of intense environmental changes, such as in extreme aquatic ecosystems. Salar de Huasco wetland is an extreme ecosystem located at the high altitude plateau at one of the most arid areas of the Earth, an environment characterized by a notorious daily variability of solar radiation (0- 1100 Wm-2) and temperature (-5 - 20°C). In this study the dynamics of archaea and bacteria composition (sediment and water based on 16S rRNA and rDNA i-tag libraries) and the water biogeochemical conditions, i.e. dissolved organic carbon, nitrogen and phosphorous, nutrients (silicate, phosphate, nitrite and ammonium) and greenhouses gases (carbon dioxide, methane, nitrous oxide) distribution and fluxes, were analyzed along two sampling days in a representative shallow evaporitic pond of the wetland. The results indicate that the meteorological and biogeochemical conditions were different along the day and between the two days sampled, the first day was characterized by higher solar radiation and wind stress and lower temperature than the second. Dissolved organic matter were higher but with a potentially lower lability at day 1 compared with day 2, based on DOC:DON. Nutrient and greenhouse gases changed in association with climatic conditions mainly at day 1, whereas more homogeneous distribution was observed during day 2. Microbial community were variable mainly at the different biomes and templates, Cyanobacteria, Spirochaetae, Chlroflexi and Verrucomicrobia were associated to sediments variability, whereas Proteobacteria, Bacteroidetes and Archaea mainly Thaumarchaeota to the water. Moreover, shifts in potentially different functional groups activity (16S rRNA) were associated with the chemical conditions indicating the presence of key drivers of nitrogen and carbon cycling in the study area.