Abstract:The objective of the present research was to investigate the effects of dry exposure on respiratory metabolism in different tissues of Exopalaemon carinicauda. In the trial, E. carinicauda were divided into two experimental groups, namely normal temperature (22-24℃) group and low temperature (4℃) group. Meanwhile, shrimp cultured in seawater were used as the control group. Activities of respiratory metabolism enzymes and content of lactate were measured under dry exposure challenges at 60 min, 90 min, 120 min and 180 min. The investigated enzymes included succinate dehydrogenase (SDH), cytochrome oxidase (CCO), fumarate reductase (FRD) and lactate dehydrogenase (LDH). SDH and CCO are the key enzymes of aerobic metabolism in animals, whereas FRD and LDH are the key enzymes of anaerobic metabolism in animals. In addition, the content of lactate is an indicator of anaerobic metabolism. The results showed that the activities of SDH and CCO in hepatopancreas, gill, and muscle in the normal temperature group decreased significantly than those in the control (P<0.05) with the processes of dry exposure. Activities of FRD, LDH and content of lactate in muscle increased initially and then decreased gradually. And the levels were significantly higher than those in the control (P<0.05). Activities of respiratory metabolism enzymes and content of lactate in low temperature group had no significant difference compared to those in the control group at 60 min. After that, the trends of the enzyme levels in the low temperature group were as similar as the normal temperature group. The changes of enzyme activities were tissue dependent. Activities of respiratory metabolic enzymes in hepatopancreas and gill were higher than those in muscle. The results suggested that anaerobic metabolism increased after dry exposure. By contrast, E. carinicauda can maintain the aerobic metabolism during the early stage of low temperature dry exposure. Furthermore, the hepatopancreas and gill might be more sensitive to dry exposure, whereas reduced temperature could increase the survival rate of E. carinicauda.
