The Thermal Adaptation Characteristic And The Effect Of Temperature On Blood Parameters Of The Salamander Batrachuperus Tibetanus (Schmidt, 1925) (Amphibia: Hynobiidae)

Any environmental disturbance, such as a change of habitat temperature, can be considered to be a potential source of stress, and can theoretically be detected by changes of hormone or substrate concentrations in plasma. Hematological parameters are increasingly used as indicators for identification of stress response to endogenous or exogenous changes in fish and other aquatic animals. A change in plasma chemical properties may be an adaptation to a new environment such as another thermal condition or may be caused by a malfunction of self-regulatory mechanisms. Most literatures on the chemical properties of blood are focused on fish. However, at present, very few studies on plasma cortisol and ion were made in salamander, as is evident from the extensive reviews of the subject of fish blood.Stream salamander Batrachuperus tibetanus (Schmidt, 1925) (Amphibia: Hynobiidae) is a kind of aquatic amphibian. The resources of B. tibetanus decreases dramatically these years due to over exploitation, the disturbance of habitat and climate change. This species has been listed in "China Red Data Book of Endangered Animals". It is necessary and imperative to provide reference values for an assessment of the status of this species in both normal and stress conditions.What are the characteristics of thermal adaptation of B. tibetanus? What is the normal value of blood parameters of B. tibetanus? How does B. tibetanus respond to different temperature regimes in the blood parameters? These questions have never been studied. The present study aimed to understand characteristics of thermal adaptation of B. tibetanus and how it responds to different temperature regimes in the blood parameters.In order to understand characteristics of thermal adaptation of B. tibetanus, the preferred temperature, critical minimum avoidance temperature and critical maximum avoidance temperature were measured using a thermal gradient apparatus. The results showed that B. tibetanus had a wide preferred temperature range, the preferred temperature in both the adult and the juvenile ranged from 6℃to 18℃, the critical minimum avoidance temperature and the critical maximum avoidance temperature in the adult were 2.37±0.33℃and 24.03±0.68℃respectively, and were 1.95±0.41℃and 22.83±0.79℃respectively in the juvenile. There were no significant difference between the adult and the juvenile.To better understand how B. tibetanus responds to different temperature regimes in the blood parameters and to estimate the change in plasma cortisol level in this species exposed to different temperatures, the animals were stochastically divided into three groups and exposed respectively to 4.6℃, 14.6℃(control group) and 19.6℃for 12 days. Hematocrit value was measured with a minim tubule. The concentrations of glucose, total protein, albumin, triacylglycerol and Ca²⁺ were measured using automatic analyzer; concentrations of K⁺, Na⁺ and Cl^- were measured using the electrolyte analyser; plasma cortisol level was measured with radioimmunoassay. There was no significant difference between the plasma cortisol level of the control group and the experiment groups. Glucose level at 4.6℃and 19.6℃was significantly lower than glucose level at 14.6℃. The plasma triacylglycerol level was significantly influenced by temperature, and the plasma triacylglycerol level very significantly decreased at 19.6℃, while significantly increased at 4.6℃when compared with the control group. The concentration of total protein, albumin, globulin and the ratio between albumin and globulin were not significantly influenced by temperature when compared with control group. There was no significant change in concentration of Ca²⁺ at different temperatures. The concentration of K⁺ was significantly influenced by temperature. Plasma K⁺ level significantly increased at 19.6℃when compared with the control group, while there was no significant change in the concentration of plasma K⁺ level between the control group and the group at 4.6℃. The plasma Na⁺ level and Cl^- level were significantly influenced by temperature, the plasma Na⁺ level and Cl^- level very significantly increased at 4.6℃, while the plasma Na⁺ and Cl^- levels significantly decreased at 19.6℃. Na⁺: Cl^- ratio was significantly influenced by temperature, the ratio at 4.6℃was significantly lower than that at 14.6℃, while there was no significant difference between the ratio at 14.6℃and the ratio at 19.6℃. It could be concluded that glucose, triacylglycerol, Na⁺ and Cl^- levels could be considered as indicators of thermal stress in B. tibetanus; plasma cortisol, albumin, globulin, Ca²⁺ levels, and albumin/globulin ratio are not significantly influenced by suboptimal temperature.