The Relationships Between Heart-gill Parameters And Physiological Function (Locomotion And Digestion) In 8 Species Of Cyprinidae

Metabolic machinery hypothesis holds that the heart-gill system of fishes is widely related to its physiological function and behavioral output.In order to verify the hypothesis in interspecific level,8 species of cyprinidae,Chinese bream（Parabramis pekinensis）,crucian carp（Carassius auratus）,qingbo（Spinibarbus sinensis）,pale chub（Zacco platypus）,grass carp（Ctenopharyngodon idellus）,Schizothorax prenanti,black carp（Mylopharyngodon piceus）,rock carp（Procypris rabaudi）were selected as the experimental subjects.The routine metabolic rate（RMR）,standard metabolic rate（SMR）,cortisol content,special dynamic action（SDA）,critical swimming speed(U_crit),maximum metabolic rate（MMR）,gill structure parameters and cardiac parameters of the 8 species of cyprinids were measured respectively,and the correlation between cardiac and gill system and physiological function of the 8 species of cyprinids was examined at the interspecies level.The main results of this study are as follows:1.At the interspecific level,cardiac index was positively correlated with gill index（P<0.05）,gill surface area was positively correlated with standard metabolism（P<0.05）,gill surface area was positively correlated with SDA _peak（P=0.047）,and maximum metabolic rate（MMR）and critical swimming speed(U_crit)were positively correlated（P=0.041）.But there was no significant correlation between heart index and energy metabolism or swimming ability.2.The heart index of Chinese bream was the highest and black carp the lowest.The heart index of Chinese bream was significantly higher than that of the qingbo and black carp,pale chub is significantly higher than that of black carp（P<0.05）.Grass carp have the highest ratio of heart length to width,and the lowest ratios of rock carp and crucian carp.Grass carp have a significantly higher heart length to width ratio than the other seven species.The ratio of heart length to width of black carp was significantly higher than that of Chinese bream,rock carp and crucian carp,qingbo is significantly higher than that of the rock carp and crucian carp（P<0.05）.3.Crucian carp had the highest total filament number and pale chub had the lowest（P<0.05）.The average filament length is highest in black carp and grass carp（P<0.05）.The total filament length is the longest in grass carp and the shortest in rock carp（P<0.05）;Gill lamellar frequency of pale chub was the largest and rock carp was minimum,pale chub is significantly higher than that of the other fish.Grass carp,black carp,qingbo and crucian carp were significantly higher than that of the Chinese bream,rock carp,Chinese bream is significantly higher than that of the rock carp（P<0.05）;Branchial area of an average lamellae in Chinese bream was the largest,the smallest was rock carp,Chinese bream was significantly higher than that of the other experimental fish（P<0.05）;The Chinese bream had the largest total surface area,and rock carp had the smallest,Chinese bream is significantly higher than that of the other experimental fish（P<0.05）;Grass carp and crucian carp were significantly higher than that of the black carp,qingbo,pale chub and rock carp（P<0.05）.4.Black carp had the highest RMR and Schizothorax prenanti had the lowest RMR;Chinese bream,grass carp and pale chub were significantly higher than that of the qingbo,rock carp and crucian carp（P<0.05）.The RMR of crucian carp,qingbo and rock carp were significantly higher than that of the Schizothorax prenanti（P<0.05）.SMR of black carp and pale chub were highest,Schizothorax prenanti was the lowest,black carp and pale chub were significantly higher than that of the other fish.The cortisol of Chinese bream,rock carp and Schizothorax prenanti were the highest,crucian carp was the lowest.Chinese bream,rock carp and Schizothorax prenanti were significantly higher than that of the crucian carp,qingbo and grass carp（P<0.05）,black carp and pale chub were significantly higher than that of the crucian carp（P<0.05）.5.The duration of SDA in rock carp was the longest and that was the shortest in black carp and qingbo（P<0.05）.The metabolic peak of Chinese bream is the highest,qingbo and black carp had the lowest metabolic peak.Chinese bream is significantly higher than that of the other experimental fish,crucian carp,grass carp and pale chub were significantly higher than that of the qingbo.The metabolic scope of Schizothorax prenanti,qingbo,grass carp and crucian carp were the highest,while that of black carp was the lowest（P<0.05）.SDA total energy consumption of Chinese bream was the highest,black carp was the lowest（P<0.05）.SDA coefficient of Chinese bream was the highest and black carp was the lowest（P<0.05）.6.The critical swimming speed of qingbo was the highest and the lowest in black carp and grass carp.Qingbo was significantly higher than that of the other 7 species of fish（P<0.05）.The maximum metabolic rate of qingbo was the highest,and that of grass carp and black carp were the lowest（P<0.05）,MO₂of 8 kinds of experimental fish increased significantly with the increase of swimming speed（P<0.05）.The above research results showed that:1.The heart and gill systems of cyprinids have a high consistency with each other,which is conducive to the coordination between them and the more efficient use of energy metabolism and output capacity of the body.At the same time,at the interspecific level,the gill surface area was positively correlated with the standard metabolic rate and the digestibility.The maximum metabolic rate was related to the swimming ability.These results suggest that the"metabolic machinery"hypothesis may exist at the interspecific level.2.At the interspecific level,there was no significant association between cardiac parameters and energy metabolism or swimming ability.It may be because the sample size of 8 species of fish is small,which needs to be further verified by increasing samples in future related studies.3.There are great inter-species differences in heart-gill parameters,energy metabolism,digestion and locomotion performance of cyprinids,which may be closely related to the habitat environment and heredity of the above mentioned cyprinids.