Diatom and Invertebrate Assemblages in High Altitude Saline Wetlands of the Argentinian Puna and their Relation to Environmental Factors

Abstract

Aquatic biota in high altitude Andean wetlands is exposed to extreme environmental conditions that influence ecological parameters at population and community levels. We analyzed changes in occurrence, taxa richness and relative abundance of diatom and invertebrate assemblages in four saline wetlands located at the same altitude (approx. 3,330 masl), in the Salar de Antofalla (Catamarca, Argentina).Biological samples were taken seasonally during a 1-year period, together with water variables, which were used in ordination techniques to characterize the sites.Water ionic content and biological variables, such as microcrustacean abundance and diatom richness, were evaluated as possible factors affecting the assemblages' distribution. The wetlands ranged from meso-to hyperhaline habitats and showed distinctive morphological, physical and chemical characteristics. Diatoms (42 taxa) and invertebrates (15 taxa) were collected from all sites, and diatom taxa richness was negatively correlated with water conductivity. According to multivariate analysis, the distribution of both communities was significantly explained by water hardness, whereas copepod abundance also influenced the diatom flora. We conclude that, at the same altitude and, consequently, UV radiation exposure, variables related to ionic content and/or biological parameters of the aquatic habitat may act as determinants of the biota distribution in these extreme environments.