Acute toxicity of salinity to Sinogastromyzon Szechuanensis

Abstract

Abstract We set a salinity gradient, and then measure the tolerance of Sinogastromyzon szechuanensis to salinity at the initial stage and after a period of adaptation. The results show that the half lethal concentrations (LC50) of Sinogastromyzon szechuanensis at 24 h, 48 h, 72 h and 96 h are 10.50 g/L, 10.15 g/L, 9.83 g/L and 9.46 g/L respectively, and the safe concentration is 2.32 g/L. In the early stage of salinity mutation, the respiratory frequency of Sinogastromyzon szechuanensis increases with the increase of salinity. The respiratory frequency of 4 g/L group is 177±10.42 times/min, significantly higher than that of 0g/L group (P<0.05). After 4h of adaptation, when the salinity is 0-7 g/L, the respiratory rate decreases compared with the initial stage, when the salinity is above 7 g/L, the respiratory rate increases significantly compared with the initial stage (P<0.05). The respiratory rate of 2 g/L group is 150.0±5.57 times/min, which is significantly higher than that of 0 g/L group (P<0.05), and the salinity is close to the safe concentration, 2.32 g/L. Under 0∼7 g/L salinity stress, after 4h adaption in each salinity group, the asphyxia point of Sinogastromyzon szechuanensis first decreases and then increases with the increase of salinity, and the asphyxia point of 2 g/L is the lowest, 0.81±0.02 mg/L. After 96 h adaptation, the asphyxia point of Sinogastromyzon szechuanensis in each salinity group decreases, and the asphyxia point of 0-1 g/L is the lowest, 0.60±0.06 mg/L. Conclusion: Sinogastromyzon szechuanensis has a low salinity tolerance, and its asphyxiation point is higher than that of common freshwater fish. Therefore, we suggest controlling the salinity to be 0∼2 g/L, which is helpful to enhance the hypoxia tolerance and survival rate of Sinogastromyzon szechuanensis.