| Carassius auratus gibelio is one kind of fresh fish,which has rich nutrition,delicious taste,strong adaptability,fast growth rate.With the improvement of people’s living standards and the growing awareness of healthy spending,traditional fisheries has been replaced by healthy farming gradually,which requires suitable aquatic environment in farming pond.However,due to more and more high stocking densities and improper water treatment,the changes of water quality indexes such as ammonia,nitrite,dissolved oxygen and pH may affect the growth and quality of farmed fish.Gill bleeding and red gill diseases broke out when the water quality got worsen.Therefore,the regulation of water quality should be enhanced.Building the growth model of C.auratus gibelio in different environment is necessary.To provide basic data for the healthy farming of C.auratus gibelio,the respiratory metabolic and blood physiological response including standard metabolic rate(SMR),maximum metabolic rate(MMR),aerobic scope(AS),specific dynamic action(SDA)and related blood indexes of C.auratus gibelio to four crucial stressors was evaluated by the method of acute exposure.To know the respiratory metabolic response to four crucial stressors,C.auratus gibelio(body weight 15.31 ± 2.28 g,body length 9.03 ± 0.55 cm)were exposed to different concentrations of ammonia(0.5,1,2 mg/L),nitrite(0.5,1,1.5 mg/L),dissolved oxygen(8,4,1.5 mg/L),pH(9.1,9.5,9.9)for 96 h.To know the blood physiological response to four crucial stressors,C.auratus gibelio individuals(body weight 58.79 ± 4.94 g,body length 12.03 ± 0.87 cm)were exposed to different concentrations of ammonia(1,4,7,10 mg/L),nitrite(0.5,1,2,3 mg/L),dissolved oxygen(8,4,1.5mg/L),pH(9.1,9.5 and 9.9).Fifteen individuals were randomly sampled after 24 h,48 h,72 h,96 h stress..1.The results showed that there were positive correlation between SMR and four crucial stressors,which has quadratic regression relationship between SMR and the concentration of ammonia,nitrite in water: y=182.303+49.868x-14.950x2,R2=1.000,P<0.05,y=181.995+67.237x-12.577x2,R2=1.000,P<0.05.There were logarithm regression relationship between SMR and dissolved oxygen in water:y=128.230+25.798 lnx,R2=1.000,P<0.05.There were exponential regressionrelationship between SMR and pH in water: lny=ln49.149+0.168 x,R2=0.993,P<0.05.SMR under the stress of nitrite and pH varied more than ammonia and dissolved oxygen in the study.Under 1.5 mg/L ambient nitrite,SMR increased 40% comparing with the control.Under pH 9.9 environment,SMR increased 41%.The immune function of C.auratus gibelio were broken under the stress of four crucial water quality factors,so they may need more energy to repair and maintain the basic physical function.There are close connection between concentration of ammonia and pH,the concentration of non-ionic ammonia is high when pH is high.Plasma ammonia increased signifacantly under the stress of ammonia and pH.There were cubic regression relationship between the concentration of plasma ammonia and ammonia in water:y=94.028+43.763x-11.511x2+1.062x3,R2=1.000,P<0.05.There were linear regression relationship between the concentration of plasma ammonia and pH in water:y=-587.140+87.427 x,R2=0.993,P<0.05.Under 10 mg/L ambient total ammonia environment,the plasma ammonia concentration was 3.5 times more than the control.Under pH 9.9 environment,the plasma ammonia concentration was 1.6 times more than the control.To prevent ammonia poisoning,more energy was needed to remove ammonia.2.There were negative correlation between MMR and ammonia,nitrite,pH.There were positive correlation between MMR and dissolved oxygen,which has exponential regression relationship between MMR and ammonia in water:lny=ln541.777-0.061 x,R2=0.939,P<0.05.There were quadratic regression relationship between MMR and nitrite in water: y=548.662-143.193x-54.502x2,R2=0.997,P<0.05.There were logarithmic regression relationship between MMR and dissolved oxygen,pH in water: y=326.015+106.736 lnx,R2=0.999,P<0.05,y=1979.531-696.985 lnx,R2=0.997,P<0.05.MMR under the stress of low dissolved oxygen and pH varied more than ammonia and nitrite in the study.Under 1.5 mg/L ambient dissolved oxygen,MMR decreased 33% comparing with the control.Under pH 9.9 environment,MMR decreased 30%.Hemoglobin was significantly affected under the four crucial stressors,there were quadratic regression relationship between the proportion of methemoglobin(MHb/Hb)and nitrite in water: y=0.017+0.072x-0.05x2+0.015x3,R2=0.998,P<0.05.Under 3 mg/L nitrite environment,the proportion of methemoglobin(MHb/Hb)was 9times higher than the control.There were logarithmic regression relationship between the concentration of hemoglobin and dissolved oxygen in water: y=102.703-24.637 lnx,R2=0.999,P<0.05.The hemoglobin concentration was 1.2 times higher than the control under 1.5 mg/L dissolved oxygen environment.There were cubic regression relationship between the concentration of hemoglobin and pH in water:y=-273.320+58.705x-0.283x3,R2=1.000,P<0.05.So the ability of getting oxygen was restricted under the stress of the water quality factors,swimming ability was restricted significantly.Although the concentration of hemoglobin increased under low dissolved oxygen,it’s just the coping mechanism of C.auratus gibelio under low dissolved oxygen.C.auratus gibelio couldn’t get enough oxygen under low oxygen water environment.3.There were negative correlation between AS and ammonia,nitrite,pH.There were positive correlation between AS and dissolved oxygen,which has quadratic regression relationship between AS and ammonia,nitrite,pH in water:y=366.148-109.428x+28.654x2,R2=0.997,P<0.05,y=366.668-210.431x+67.079x2,R2=0.999,P<0.05,y=1774.292-231.940x+6.612x2,R2=1.000,P<0.05.There were logarithmic regression relationship between AS and dissolved oxygen in water:y=197.785+80.938 lnx,R2=0.999,P<0.05.AS under the stress of nitrite and pH varied more than ammonia and dissolved oxygen in the study.Under 1.5 mg/L ambient dissolved oxygen,AS decreased 45% comparing with the control.Under pH 9.9environment,AS decreased 65%.The energy of maintaining the basic physical function increased while the maximum energy decreased,so the energy of completing other aerobic activity was restricted.4.There were positive correlation between the peak of SDA and nitrite,dissolved oxygen,pH,which has inverse regression relationship between the peak of SDA and dissolved oxygen in water: y=357.631-75.278/x,R2=0.996,P<0.05.There were quadratic regression relationship between the peak of SDA and pH in water:y=1143.803-198.25x+12.360x2,R2=1.000,P<0.05.The time of getting the peak metabolic rate delayed under ammonia,nitrie,low dissolved oxygen and pH water,which indicated that the digestion of C.auratus gibelio was affected.However,C.auratus gibelio can finish the whole digestion by delaying the digestion time.These findings indicated that when exposed to high concentration of ammonia,the ammonia excretion of C.auratus gibelio was inhibited.The proportion of methemoglobin increased when exposed to high concentration of nitrite indicated that the oxygen carrying capacity of blood cell decreased.High pH inhibited the ammoniaexcretion and raised plasma ammonia,which caused the reducing of hemoglobin concentration.However,C.auratus gibelio has strong tolerance to hypoxia,compensated by increasing the hemoglobin concentration.These findings of the present study provide basic data for healthy farming of C.auratus gibelio,but the relevant mechanisms still need the further study. |
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