The Relationship Between Metabolic Characteristics And Swimming Performance,hypoxia Tolerance And Growth Performance In Common Carp

The varying movement capacity,environmental tolerance,and growth performance among individuals is related to energy metabolism of fishes,both of which determine the adaptation of species.This study investigated the individual differences in swimming movement,hypoxia tolerance,and growth performance in fish and their correlation with metabolism.The following three experiments were carried out using common carp as experimental animal.All experimental temperature were set at 25°C,and the sample size of the experimental fish was 30 tails.In experiment I,the individual difference and correlations between metabolic characteristics and swimming ability in common carp were investigated.Thirty common carp were randomly selected to determine their anaerobic exercise,resting metabolic rate?RMR?,and constant acceleration test speed(U_cat),respectively.Other thirty fish individuals were randomly selected to determine their aerobic exercise,RMR,critical swimming speed(U_crit),active metabolic rate?AMR?,and metabolic scope?MS?,respectively.In experiment II,the correlation and repeatability between metabolism and hypoxic tolerance in common carp were investigated.RMR,critical oxygen tension(P_crit),oxygen threshold for the loss of equilibrium?LOE?,and critical oxygen consumption rate(MR_crit)were determined in the common carp,respectively.Then,all individuals were isolated and kept fasting for 21 days,and the above parameters were determined again.In experiment III,the correlation between maintenance metabolism and growth performance in common carp under starvation were investigated.RMR.The experimental fish were fed for 21 days to determine the feeding rate?FR?,feed conversion efficiency?FE?,and growth rate?SGR?.Then,RMR of the fish was determined.After starvation for 21 days,SGR and RMR were determined again.Heart,liver,intestine,unilateral gill,brain,residual viscera,and net body were weighed.The results of the study are as the following.1.The results of experiment I showed that degree of RMR variation was different between the aerobic exercise fish and anaerobic exercise fish,and U_cat was greater than U_crit.RMR was not correlated with U_cat?r=0.175,p=0.356?,while positively correlated with U_crit?r=0.508,p=0.004?.U_crit was positively correlated with both AMR?r=0.509,p=0.004?and MS?r=0.400,p=0.029?.Among the metabolic characteristics,RMR was positively correlated with AMR?r=0.440,p=0.015?,but not with MS?r=0.169,p=0.372?,while AMR was positively correlated with MS?r=0.959,p<0.001?.2.The results of experiment II showed that RMR was significantly correlated with P_crit and LOE prior to starvation?r=0.634,p<0.001 and r=0.407,p=0.026,respectively?.RMR was positively correlated with P_crit post starvation?r=0.541,p=0.002?,but not with LOE?r=0.129,p=0.495?.RMR was not correlated with MR_crit either prior to starvation?r=0.288,p=0.12?or post starvation?r=0.299,p=0.109?,respectively.Starvation resulted in 23.8%reduction in RMR(t₂₉=6.591,p<0.001)and 25.3%increase in P_crit(t₂₉=-2.206,p=0.035).RMR and MR_crit have strong repeatabilities(RMR:r=0.553,p=0.002;MR_crit:r=0.385,p=0.036),while P_crit and LOE have weak repeatabilities(P_crit:r=0.235,p=0.212;LOE:r=0.199,p=0.291).3.The results of experiment II showed that RMR was not correlated with either SGR?r=0.372,p=0.206?or FE?r=0.075,p=0.694?,but correlated with FR?r=0.238,p=0.043?.FR was positively correlated with both SGR?r=0.861,p<0.001?and FE?r=0.632,p<0.001?.FE was positively correlated with SGR?r=0.905,p<0.001?.After starvation,the correlation between RMR and SGR was still not significant?r=0.254,p=0.176?.Starvation resulted in 41.4%reduction in intestine mass(t₁₇=6.495,p<0.001),46.4%reduction in liver mass(t₁₇=5.843,p<0.001),and42.4%reduction in residual viscera mass(t₁₇=-4.397,p<0.001).Other organs were not significantly changed by starvation(heart mass:t₁₇=-2.112,p=0.136;net body mass:t₁₇=-1.374,p=0.187;unilateral gill mass:t₁₇=-1.574,p=0.134;brain mass:t₁₇=0.820,p=0.424).The conclusion of this study were as follows:1.The common carp with a higher maintenance metabolism has a stronger aerobic swimming ability,which can allow a higher energy output,meet the needs of intensive exercise,and a better adaptation to exercise.Individuals with low metabolic level also have a lower exercise capacity and weaker exercise adaptation.2.The common carp with low maintenance metabolism has a better hypoxic tolerance.After starvation,the maintenance metabolism of the common carp decreased,while the effect on the hypoxic tolerance ability was not significant.The maintenance metabolism of the commone carp showed repeatability.3.Under a good feeding condition,the maintenance metabolism of the common carp is positively correlated with food intake,but not correlated with the growth performance,which may be due to that more energy are allocated to digestion,assimilation,or exercise.Starvation reduces the digestive organ mass of common carp and results in negative growth to some degrees.However,the maintain metabolism was not correlated with the growth performance,which could be due to that the individuals keep their energy consumption at high level even during the early development period with a rapid growth.Therefore,environmental resource constraints lead to starvation stress did not influence both maintenance metabolism and growth performance.