Effects of Roundup Herbicide at Low Concentration and of Thermal Stress on Physiological and Biochemical Parameters in Amur Sleeper Perccottus glenii Dybowski Juveniles

Abstract

The effects of 30-day exposure to Roundup at concentration of 2 μg/L and of thermal stress on the intestinal glycosidase activities (maltase and amylolytic activities (AA)), brain acetylcholinesterase (AChE) activity and water-soluble protein (WSP) content in juvenile specimens of Amur sleeper Perccottus glenii Dybowski have been studied. Additionally, critical thermal maximum (CTM) and final selected temperature (FST) are determined in fish of control (exposure to 0 μg/L Roundup) and Roundup-exposed groups. After Roundup exposure AA and WSP content were 27 and 31% lower respectively, maltase and AChE activities did not change. An increase in water temperature at a rate of 8°C/h decreased AA by 60%, maltase activity by 18% and WSP content by 28% in fish of the control group; but decreased AA by 76%, AChE activity by 29%, WSP content by 40%, and increased maltase activity by 11% in fish of the Roundup-exposed group. The recovery treatment during 12 days in a thermal gradient with herbicide-free water (temperature range between 14 and 31°C) reduced the inhibitory effect of heating on AA, but increased it the on AChE and WSP content in fish from both control and Roundup-exposed groups (on maltase activity only in the fish of exposed group). No significant differences were noticed in CTM and FST values in fish of control and Roundup-exposed groups.