Online first articles

Salar de Pedernales basin is located at 3370 meters above sea level in the Atacama Desert, Chile, covering an area of 3620 km². This ecosystem is characterized by high exposure to ultraviolet radiation, low humidity, huge variations in ions content and extreme thermal gradients. Despite these extreme conditions, it has a rich fauna and flora. However, the aquatic biodiversity in the basin remains poorly documented. Our study assessed compositional changes of planktonic and benthic communities across several salt flats (Pedernales S-O, Piedra Parada, La Laguna), natural water courses (wetland and creeks), an artificial stream and lagoon (Pedernales N-E), and their relationship with local physicochemical parameters. Our results show that the Salar de Pedernales basin is a highly heterogeneous ecosystem principally influenced by conductivity, pH, and major ions. Community diversity was high at all locations except for the artificial stream. Microalgae were spatially similar with major changes observed in the disturbed habitats. The composition of the invertebrate communities strongly varied among habitats but displayed distinct composition in the perturbed ones (Salar Pedernales N-E). Distance-based redundancy analysis revealed that phytoplankton and benthos composition were driven by changes in trace metals and nitrate, whereas zooplankton community composition were mainly related to osmotic stress. Our data highlight the remarkable biodiversity of the natural water bodies of the Salar de Pedernales basin and the potential effects of anthropogenic perturbations on the biota in these extreme habitats.