Extremophiles: photosynthetic systems in a high-altitude saline basin (Altiplano, Chile)

Abstract

Studies of different hypersaline systems have revealed various types of limitation. We evaluated the phototrophic microbial assemblages over a whole seasonal cycle (wet vs dry) in the Salar de Alconcha, a high-altitude (4250 m altitude) saline basin. Phototrophic microbial communities were obtained from contrasting ecotypes, and examined for the effects of proximity and salinity variations. We also analyzed pigment profiles pointing to photosynthetic activity. While taxonomic diversity was limited to three algal groups (chlorophytes, diatoms, and cyanobacteria) ecological preferences were highly variable. Physical limitations when the photosynthetic system turn drier (maintaining viability and stability) appear to be the most successful adaptation (constrained assemblages) to the extreme condition in the Altiplano. This suggests that phototrophic microorganisms rarely achieve optimal growth, and could only do so when rain events reduce salinity (e.g. austral summer). However, environmental condition over the salt crust (total salt concentration: 119.74 g l -1 ) was an important driver to algal biomass. Overall, dominated by Dunaliella salina (&18,000 cell ml -1 ) turning the water into a red-orange colored system (b-carotene); aplanospore cysts were observed only during the driest season (austral winter). Our results suggest specific restrictive environments (e.g. environmental dissimilarity in the physical landscape) for phototrophic microbial colonization in highaltitude saline systems quite dependent upon water availability (system on the edge). The present study is a contribution for a better understanding of both the ecology of extreme environments and polyextremophiles communities (phototrophs) that inhabit them. Active salars are considered to be useful analogs of ancient photosynthetic systems, currently very pressured by groundwater extraction. Thus, altering the volume of water through the basin would have negative consequences on the structure and dynamics of local communities, and also in the stability of ecosystem functions.

Geothermal Diatoms: Seasonal Variability in the El Tatio Geothermal Field (Altiplano, Chile)

“…The distribution of H. atacamae, H. coffeaeformis (C. Agardh) Levkov, Denticula elegans Kützing, Denticula thermalis Kützing, and S. chilensis were coincident with the photosynthetic microbial communities described in a near local high-altitude saline basin [35].…”

“…Seasonal change of the most representative genera (>1% total abundance per sample) and size fractions variability. microorganisms are adapted for life there, this result in many of them are unique or rare [35] [39] [40]. Water bodies in different geographic regions often show considerable variability with regard to their diatom richness/composition patterns.…”

Bacterioplankton composition in tropical high-elevation lakes of the Andean plateau

“…1995 ). These ecosystems are located in one of the most extreme environments on Earth (Angel, Vila and Herrera 2016 ) due to the negative water balance, high incident solar UV radiation and extreme daily temperature changes (Dorador et al. 2013 ).…”

A Multidisciplinary Evaluation of Spatial Heterogeneity in the Puquios of the Salar de Llamara, Atacama Desert, Northern Chile

“…These environmental settings are associated with biological communities that are tolerant to extreme conditions 17 , including a reduced group of invertebrates, such as brine shrimps, insects and other planktonic organisms, as well as macrophytes adjacent to the ponds [61][62][63][64][65] . Phototrophs in the desert lagoons are mainly represented by diatoms and cyanobacteria 25,66,67 , with broad representation of phototrophic microbial communities 68 . Diatoms have been well-studied as a result of their abundance in all Northern Chile aquatic systems.…”