| Acute toxic effects of benzalkonium bromide on several common hydrocoles in freshwater aquaculture including Daphnia magna, juvenile Megalobrama amblycephala, juvenile Ctenopharyngodon idellus, Cipangopaludina cathayensis, the third stage larvae Eriocheir sinensis and juvenile E. sinensiswere were studied, and safe concentration (SC) was investigated. The results showed that, the lethal concentration 50(LC50) at 24 h, 48 h, 72 h and 96 h on D. magna were 0.56 mg/L, 0.34 mg/L, 0.19 mg/L and 0.13 mg/L, on juvenile M. amblycephala were 1.53 mg/L, 1.44 mg/L, 1.38 mg/L and 1.31 mg/L , on juvenile C. idellus were 4.59 mg/L, 4.42 mg/L, 4.36 mg/L and 4.23 mg/L, on C. cathayensis were 15.21 mg/ L, 10.52 mg/L, 7.76 mg/L and 5.01 mg/L, on the third stage larvae E. sinensis were 10.33 mg/L, 6.73 mg/L, 5.41 mg/L and 5.02 mg/L, and on juvenile E. sinensis were 17.97 mg/L, 12.42 mg/L, 8.67 mg/L and 6.22 mg/L, respectively. The SCs were0.04 mg/L, 0.38 mg/L, 1.23 mg/L, 1.51 mg/L, 0.86 mg/L and 1.78 mg/L, respectively, indicating the toxic resistance of aquatic animals in the experiment to benzalkonium bromide was juvenile E. sinensis > C. cathayensis > juvenile C. idellus > the third stage larvae E. sinensis > juvenile M. amblycephala > D. magna. When benzalkonium bromide with 0.35 mg/L used to prevent and control the fixed ciliate disease in fish water aquaculture, it was not toxic to juvenile M. amblycephala, juvenile C. idellus, C. cathayensis, the third stage larvae E. sinensis and juvenile E. sinensis, but was toxic to D. magna which would die. We could appropriately increase the bait or add other baits in the pond to replenish the loss of D. magna. |
