CONICET | Buscador de Institutos y Recursos Humanos

Wetlands are ecosystems whose substrate remains flooded or saturated with water most of the time. Saline systems occur especially in regions with arid and semiarid climate, and have great ecological and conservation importance because of the particular fauna they hold. The aim of this study was to analyze the composition of zooplanktonic microcrustacean communities and their relationship with water physical-chemical variables in sites located in the Wetlands of Desaguadero-Salinas del Bebedero, included on the south portion of the RAMSAR site ―Lagunas de Guanacache, Desaguadero y del Bebedero‖, in the province of San Luis. Organisms were collected through filtration of water with a 90 µm of mesh net, in seven sites, on four occasions. Samples were fixed on 70% alcohol, and analyzed to the highest taxonomical level possible, under stereoscopic microscope. Abundance, richness and Shannon-Wiener diversity were estimated, and average values compared between sites. A physical chemical characterization of water samples, obtained in coincidence with microcrustacean sampling, was performed, and their values were correlated with biotic metrics. Salinity varied between 4.2 g.L-1 (Bebedero Lagoon, site D6) and 70.8 g.L-1 (Desaguadero River site D2). A total of 2816 microcrustaceans were quantified, belonging to seven taxa, including copepods of the orders Harpacticoida, Cyclopoida and Calanoida, and cladocers of the species Bosmina huaronensis, Daphnia sp., Moina micrura and Leidigia sp. The most represented groups were copepods (62.2%) of the orders Harpacticoidae (61.1%) and Cyclopodidae (37.4%). There was a tendency for differences of total abundance between sites, having the site streams of Bebedero (site D5) the highest abundance (1145 individuals) and La Horqueta Bridge (site D4) the lowest one (19 individuals). The results obtained evidence a community characterized by a low biological diversity, varying between 0.1 in Desaguadero River (site D0) and 1.4 in Mosmota (site D3), location that also shown the highest richness (7 taxa). Abundance of Calanoida y Bosmina hueronensis taxa were highly correlated to concentrations of the major ions of the system (Cland Na+ ) (p < 0.05), while richness revealed a significant relationship with water turbidity (p = 0.02). These results contribute to the knowledge of planktonic fauna of this poorly studied saline ecosystem, and document the first register of microcrustaceans for the area; they will also contribute, together with other biological and physical-chemical characterizations, to the assessment of the environmental quality of these wetlands.