Abstract: The acute toxicity of atrazine to Carassius auratus and the effects of low level atrazine on serum estradiol contents in male C. auratus at different affecting time and exposure concentrations were studied under laboratory conditions. The results showed that the LC₅₀ of atrazine to C. auratus in 24 h, 48 h and 96 h was 229.33, 146.17 and 105.94 mg·L^-1, respectively, and the safety concentration of atrazine to C. auratus was 10.59 mg·L^-1. Under long term (24 days) exposure, low concentration (0.1-5.0 mg·L^-1) atrazine could induce the synthesis of serum estradiol in male C. auratus. The strongest inducing effect was happened when the concentration of atrazine was 1.0 mg·L^-1, and the content of serum estradiol was increased by 84.1%, compared with the control. However, the synthesis of serum estradiol was inhibited at higher concentration (10.0 mg·L^-1) of atrazine. At 5.0 mg·L^-1 of atrazine, the serum estradiol content in male C. auratus at any affecting time was higher than the control, which was increased by 50% on the 14th day, reaching the highest value. The variation of serum estradiol content could directly affect the reproductive function of male C. auratus, and thus, the male C. auratus whose serum estradiol content had changed significantly due to the enrichment of atrazine in its body was likely to have reproductive problems to some extent.

Key words: Wheat-corn intercropping agroecosystem, Features of energy flow