Effects Of Salinities On The Behavior, Energy Metabolism And Haemolymph Physiology On Female Adult Chinese Mitten Crab(Eriocheir Sinensis)

The mature Chinese mitten crab (Eriocheir sinensis) mainly lives in the YangtzeRiver and adjunctive reservoirs. They are in the process of reproductive migration fromthe fresh water habitat to the estuary salt water area after the gonad develops into thefourth period. During the migration, the salinity is one of the biggest factors whicheffects the physiology of E. sinensis. In this study, the sexually matured female Parent E.sinensis was chosen to be researched, based on a video recording analysis method,behaviors were recorded under different salinity water. Meanwhile, connected thebehavior with the physiology to illustrate the mechanism of osmotic pressure regulation.CO2production and ammonia-N excretion ware measured in the experiment. Besides,respiratory quotient, oxygen-nitrogen ratio, energy consumption rate and metabolicsubstrate ratio were investigated to study the effects of salinity on metabolism of thefemale Parent E. sinensis which could provide the theory for production and artificialdischarge in the Yangtze River. Study the relationship between hemolymph biochemicalparameters and salinity in the female Parent E. sinensis to illustrate the theory of energymetabolism and osmotic pressure regulation during migration.1. Study on the behavior and haemolymph physiology to the female Parent E.sinensis under different salinitiesBased on a video recording analysis method, locomotor activity, the thirdmaxillipeds movement, palps flicking, antennule retraction, flicking of antennae,eyestalk movement, closure reaction and abdomen extension were recorded to study theeffects of salinity on behavior of the female parent E. sinensis. The results showed thatthe closure reaction behavior only happened in salinity18and sainity18to30. Theabdomen extension behavior only happened in salinity18to0, and the antennuleretraction behavior didn’t happen in this salinity concentration. The other five behaviorsall reached the maximum level in salinity18to0concentration. The concentrations of E.sinensis were both higher than the enviormental water. The haemolymph iosomolarity,Na~+and Cl~-concentrations increased with the increasing of salinity concentrations and were significantly higher in salinity18to30than the other concentrations (P<0.05).Hemocyanin concentration increased with the declining of salinity concentrations andreached the maximum values in salinity18to0, the minimum values in salinity18to30and showed significant differences (P<0.05). Entering the higher salinity, it enhancedthe behavior of closure reaction and the haemolymph iosomolarity increased; Enteringthe fresh water, it enhanced the behavior of abdomen extension as an additional meansof ion uptake in low salinity.2. Effects of salinity on metabolism of the female Parent E. sinensisFive salinity concentrations (salinity0,6,12,18,24) were set up and oxygenconsumption, CO2production and ammonia-N excretion ware measured in theexperiment. Besides, respiratory quotient, oxygen-nitrogen ratio, energy consumptionrate and metabolic substrate ratio were investigated to study the effects of salinity onmetabolism of the female Parent E. sinensis. The experiment was carried out under thetemperature16±1℃and the body weight of the female Parent Chinese crab was (55.59±6.24)g, the results showed that salinity significantly affected the oxygen consumptionrate and ammonia-N excretion rate (P<0.05). Under the range of salinity0to salinity24,oxygen consumption rate and ammonia-N excretion rate both declined with theincreasing of salinity concentrations. CO2production rate and energy consumption rateshowed the same trend as oxygen consumption rate but showed no significant changescompared with the control group in salinity6（P>0.05）. Under the range of salinity12to salinity24, CO2production rate and energy consumption rate were significantlylower than the control group. Respiratory quotient and oxygen-nitrogen ratio showed nosignificant changes under the different salinity levels（P>0.05）. The maximum energymaterial of metabolic substrate ratio was the lipid and then the protein, carbohydratewas the minimum energy material.3. The relationship between hemolymph biochemical parameters and salinity inthe female Parent E. sinensisSalinity12, salinity25and a control group of fresh water were set up in theexperiment. The samples were respectively taken at0,3,6,12,24,48,72,96, and144hto study the effects of salinity changes on the hemolymph biochemical parameters of thefemale Parent E. sinensis. The results showed that the values of total protein (TP) insalinity concentrations were significantly higher than that of the control group duringthe first6hours (P<0.05) while the values of TP in two salinity concentrations reachedthe same level and kept a little higher than that of the control group after96hours. Thevalues of glucose (GLU) increased with the increasing of salinity concentrations, and the values of GLU both increased firstly and then declined in the salinity concentrations.The values of GLU in salinity25reached the maximum level at72h and weresignificantly higher than the other two groups (P<0.05). The values of triglycerides (TG)in salinity12declined gradually, and were significantly lower than that of control groupduring6-144h (P<0.05) while were significantly lower than that of salinity25after72h(P<0.05). The values of TG in salinity25declined firstly and then increased, andreached the same level as control group after72h. The values of alkaline phosphatase(ALP) both increased firstly and then declined in the two salinity concentrations. Thevalues of lactate dehydrogenase (LDH) in the two salinity concentrations both reachedthe maximum values at3h and reached the minimum at12h. The Parent E. sinensisenhanced the process of energy metabolism to deal with the sudden change of salinityand increased the use of lipids and carbohydrates as energy source meanwhile firstlyregulated protein metabolism in response to the changes of external osmotic pressure.4. Effects of salinity on gill Na~+/K~+-ATPase、haemolymph iosomolarity and ion ofthe female Parent E. sinensisEntering the higher salinity, the haemolymph iosomolarity of E. sinensis in salinity25increased quickly at3h and were significantly higher than control group (P<0.05).The haemolymph iosomolarity increased firstly and then declined, reached themaximum values at72h and then kept a leval significantly higher than the control group(P<0.05). The haemolymph iosomolarity in salinity12showed the same trend assalinity25and reached the maximum values at12h and finally kept a leval a littlehigher than the control group. Na~+and Cl~-concentrations showed the same trend as thehaemolymph iosomolarity. Gill Na~+/K~+-ATPase activity showed the opposite trend asthe haemolymph iosomolarity. The gill Na~+/K~+-ATPase activity declined firstly and thenincreased, finally kept a stable leval. Na~+/K~+-ATPase activity in salinity groups weresignificantly lower than control group after6h (P<0.05) and reached the minimumvalues at48h and then increased and kept a stable leval after72h. Besides, there wereno significant changes in salinity groups (P>0.05). The female Parent E. sinensis werein the process of hyper osmoregulation and showed three stages of stress response,osmotic regulation, and osmotic adaptation.