Sensitivity of Daphnia spinulata (Birabén, 1917) to glyphosate at different salinity levels

Abstract

Daphnia spinulata Birabén, 1917 is an endemic cladoceran species, frequent in the zooplankton communities of the shallow lakes of the Pampean region of Argentina. These lakes have varying salinity levels and, being located in agricultural areas, are frequently subject to pesticide pollution. This study aimed to determine the effects of the herbicide glyphosate (Panzer Gold®) in combination with different salinity levels on the biological parameters of D. spinulata and its recovery ability after a short exposure. Three types of assays were performed: an acute toxicity test, a chronic assessment to determine survival, growth and reproduction, and recovery assays under optimal salinity conditions (1 g L− 1). The LC50-48h of glyphosate was 7.5 mg L− 1 (3.15–11.72). Longevity and the number of offspring and clutches were significantly reduced by glyphosate and high salinity exposure, whether in isolation or combined. The timing of the first offspring did not recover after glyphosate exposure. Our results reveal that D. spinulata is sensitive to the herbicide, which causes stronger negative effects in conditions of higher salinity. Further research is needed to shed further light on the sensitivity of this cladoceran to glyphosate and its variability under other interactive stress factors.