Effect of Salinity and pH Changes on the Toxicity of Abamectin in Artemia franciscana using Response Surface Methodology

The excessive increase in pesticides consumption has made concerns about aquatic ecosystems. Hence, the present study focused on the toxicity level of Abamectin as a widely used pesticide in Artemia franciscana. The lethality of Abamectin at different pHs and salinity was investigated to simulate the real natural status of A. franciscana. The salinity ranges of 10-255 and 10-130 g.l-1 with the pH range of 4-11 for water with a constant Lethal concentration 50 (LC50) (0.145 μg.l-1 from the toxicity test) were considered and evaluated using response surface methodology (RSM). A significant variation in Artemia mortality was observed at 0.145 μg.l-1 of Abamectin in the salinity ranges of 10-255 g.l-1, irrespective of the effect of pH. In the second phase of the experiment, a significant variation of mortality was observed in the level of LC50 in the salinity range of 10-130 g.l-1, which was associated with pH shifts (p<0.05). In addition, R2 adjusted, and predicted R2 of the model were equal to 0.985, 0.976, and 0.96, respectively. The reduction in the pH from 7.5 and the salinity from 30 g.l-1 intensified the lethal effects of Abamectin. The simultaneous increase in pH and salinity decreased the mortality level. Also, the increase in salinity raised the mortality rate. These findings may reflect the stressor effects induced by the change of physicochemical parameters on the tolerance of A. ftanciscana,s in confronting pollution exposure. Hence, it can be concluded that a severe decrement in salinity and pH can intensify the LC50, which exerts an adverse impact on osmoregulation and high energy demand.