M Alishahi - Department or Clinical Sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
Sh Jalilian - DVM Student, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
A.H Homayounkhah - DVM Student, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
M Mesbah - Department or Clinical Sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran

The usage of pollutant biomarkers has an important role to evaluation of pollution on ecosystems. The herbicides are widely used in agriculture and they are important echo-pollutant in aquatic ecosystems. Evaluation of herbicides pollution in aquatic environments needs the great concern. Daphnia magna is an important bio-indicator of toxicity and pollution in aquatic environments. Then in this study the acute toxicity of two widely used herbicides: ۲,۴-Dichlorophenoxyacetic acid (۲, ۴-D) and Trifluralin (Terflan) were investigated. The acute toxicity test of herbicides was conducted following the Organization for Economic Cooperation and Development (OECD) under static-renewal test. Daphnia exposed to serial dilution of each herbicide in triplicate for ۴۸ hours, Mortality after ۱۲, ۲۴, ۳۶ and ۴۸, were recorded and analysed using Probit software. Maximum Acceptable Concentration (MAC) measured for each herbicide. Results showed that acute toxicity of two herbicides were significantly different using daphnia magna. The ۴۸h LC۵۰ of ۲,۴-D and Trifluralin in Daphnia were ۱۹.۴ and ۲.۳ mg/L respectively. It means that toxicity of terflan is approximately ۹ time higher than ۲, ۴-D. The mortality rate of daphnia enhanced along with increasing concentration of both herbicides as well as exposure duration. Comparatively ۲,۴-D showed significantly lower toxicity in daphnia compare with Terflan. Due to the widespread and increasing use of two effective herbicides (۲,۴-D and terflan) in agriculture industry along with significantly lower toxicity of ۲,۴- D on daphnia, as a reliable echo toxicity bio-indicator it can be concluded that ۲, ۴-D is highly recommendable as an environmentally friendly herbicide in agriculture and aquaculture.

Trifluralin, ۲,۴-Dichlorophenoxyacetic acid (۲, ۴-D), Daphnia magna, Acute toxicity