Toxicity of Commercial Glyphosate on Mobilization, Growth, Reproduction and Catalase Activity of Water Flea Moina macrocopa

Abstract

Glyphosate-based herbicide under the trade name Roundup® has a high account of volume use in Thailand and leaches into aquatic systems causing harmful effects to animals. However, limited studies are available on the effect of Roundup® on physiology, biochemistry and reproduction of freshwater zooplankton. The aim of this study was therefore to assess the impact of Roundup® on zooplankton. Acute toxicity of Roundup® in terms of mobilization and chronic toxicity to growth, antioxidant catalase activity, which is used as a biomaker for oxidative stress, and fecundity of zooplankton were assessed in neonate water fleas (Moina macrocopa) exposed to concentrations < EC25 (2, 20, 200 and 2000 μg/L) of Roundup®
in deionized water for 7 days. The results showed that the 48h-EC50 of Roundup® in M. macrocopa was 3.97 mg/L. The size of water fleas depended on the concentration and time of contact. The body length of neonates significantly increased except on day 7. There was no significant difference in neonate number after exposure to increasing concentration of Roundup®. However, the neonate number of first brood significantly increased at the lowest concentration of Roundup® (2 μg/L). There was a significant difference in catalase activity of neonates following the exposure to chemicals for 48 h at and above the concentration of 200 μg/L. The results indicated that very low contamination of Roundup® in aquatic ecosystems can affect neonates in terms of growth and catalase activity but not in terms of reproduction.