Effects of desiccation on survival, metabolism-related enzymes and histological structure of adult red swamp crayfish (Procambarus clarkii)

To investigate the effects of desiccation on adult red swamp crayfish (Procambarus clarkii), we designed a desiccation stress for crayfish for 0, 3, 6, 12, 24, 36, 48, 60, 72, 96, 132 and 144 h under the conditions of (16±1) ℃ and (55±5) % relative humidity (RH). The results show that the half-lethal time (LT₅₀) of male and female crayfish were 148.36 and 144.01 h, respectively. The mass consumption rate increased gradually with the extension of desiccation time; the weight consumption of male reached 16.09% of body mass after 144 h desiccation, while that of female reached 15.87% of body mass after 132 h desiccation. Besides, the histological structure damage of gill, hepatopancreas and muscle was gradually aggravated. Moreover, the activity of lactate dehydrogenase (LDH) in hepatopancreas and muscle first increased and then decreased. The maximum LDH activities of hepatopancreas in female and male were observed at 24^th and 36^th hour, while those of muscle in female and male were observed at 36^th and 48^th hour, respectively. The lactic acid (LA) content of muscle showed similar trend, with LA contents of female and male being the highest after 60 and 48 h desiccation stress, respectively. The succinate dehydrogenase (SDH) activity reduced significantly during desiccating. Furthermore, the desiccation tolerance of adult crayfish reached the limit after 48 h, and the respiratory metabolism gradually transformed from aerobic respiration to anaerobic respiration, accompanied by histological damage. In conclusion, the ability of resist desiccation between male and female is different. Thus, the desiccation time should not exceed 36 h when transporting adult crayfishes.