Spatio-temporal distribution of Ephemeroptera (Arthropoda: Insecta) in Yungas rivers of Jujuy (Argentina)

Abstract

The rivers of Reyes basin belong to the Yungas ecoregion (Jujuy-Argentina). To identify the representativeness, richness and spatio-temporal variation of the Ephemeroptera order in the basin, 10 sites were investigated in the longitudinal profile (1380-2200 m a.s.l.) of the rivers Reyes, Lampazar, Quesera, Chinchuli, Guerrero, in two years (2010-2011) and two stages of the hydrological cycle: high waters (March-April: autumn) and low waters (October-November: spring). A high representativeness of the order (76.3%) and families (Baetidae: 72.2%; Leptohyphidae: 3.1%; Leptophlebiidae 1.4% and Caenidae: 0.004%) was observed in relation to total benthos. The spatio- temporal variability of the abundance of eight species was analysed. A change in the seasonal representativeness of the order (87% in autumn and 71% in spring) and species was detected. In situ, physical chemical variables of the water were recorded - temperature, pH, conductivity, dissolved oxygen - which allowed explaining 70% of the spatio - temporal variability of the sites, by means of principal component analysis. The canonical correlation analysis showed that the abundance of the species is significantly related to the physicochemical parameters recorded (R2=0.76; p=0.001). The importance of the Ephemeroptera and the role of each family and species as indicators of particular water conditions were confirmed. Also, the spatio-temporal variation characteristic of the Yungas of Jujuy was recognized, establishing the tolerance range of the species defined by the recorded physicochemical parameters.