Effects Of Cell Size And Metabolic Level On Metabolic Scaling In Two Species Of Carps

The Xiangyun carp?Cyprinus carpio Xiangyunnensis?and the common carp?Cyprinus carpio?were used to study the body mass scaling of metabolic parameters at different temperatures,including size(S_RBC)and metabolic rate(MR_RBC)of red blood cell?RBC?,resting metabolic rate?RMR?,and gill structural parameters.The influence of cell size and metabolic level on RMR was analyzed to test the Cell Metabolism Hypothesis?CMH?.The relationship between the exchange area(S_RBCBC and gill surface area,GSA)and RMR were analyzed to test the Metabolic-Level Boundaries Hypothesis?MLBH?and the Surface Area-Metabolic Demand Hypothesis?SA-MDH?.The results were as follows:1.RMR of the Xiangyun carp and the common carp at 25? positively correlated with body mass?M?by scaling exponents of 0.708 and 1.006,both not significantly different to 2/3 ?p=0.129?or 1?p=0.882?,respectively.RMR of the Xiangyun carp and the common carp at 10? also scaled with M by scaling exponents of 0.629 and 0.863,respectively. The b_RMRMR of the Xiangyun carp was not significantly different to 2/3?p=0.278?,but b_RMR of the common carp was significantly larger than 3/4?p=0.001?.Besides,b_RMRMR and RMR of both the Xiangyun carp and the common carp at 25^o C were significantly greater than those at 10?(b_RMR:Xiangyun carp:p=0.038,common carp:p=0.007;RMR:Xiangyun carp:p=0.013,common carp:p=0.007).2.S_RBCBC of the Xiangyun carp at 25? positively correlated with M?p=0.012?by a scaling exponent of 0.043,but S_RBCBC of the common carp did not correlate with M?p=0.191?.The S_RBC?p=0.006?and RBC length?LC??p<0.001?of the Xiangyun carp were significantly larger than those of the common carp,but there was no significant difference?p=0.913? in the width?WC?.S_RBCBC of the Xiangyun carp at 10? decreased with the increasing M by a scaling exponent of-0.0326,but S_RBCBC of the common carp did not correlate with M?p=0.072?.The S_RBC?p=0.001?,LC?p=0.012?,and WC?p<0.001?of the Xiangyun carp were all significantly larger than those of the common carp,but showed no significant difference between temperatures?Xiangyun carp:p=0.5;common carp:p=0.007?. Besides,the S_RBCBC of the Xiangyun carp and the common carp were not correlated to RMR at each temperature?Xiangyun carp:p=0.212 at 25?,p=0.593 at 10?;common carp:p=0.223,p=0.376 at 10??.3.The size of erythrocyte nuclei(SN_RBC)of the Xiangyun carp and the common carp did not correlated to M at each temperature?Xiangyun carp:p=0.345 at 25?,p=0.135 at 10?; common carp:p=0.384 at 25?,p=0.153 at 10??.The SN_RBCBC of the Xiangyun carp was significantly larger than that of common carp?p<0.001 at 25?;p<0.001 at 10??.4.MR_RBCBC of the Xiangyun carp?p=0.841?and the common carp?p=0.205?did not correlate with M at 25?.MR_RBCBC of the Xiangyun carp at 10^o C did not correlate with M?p=0.074?,but MR_RBCBC of the common carp decreased with increasing M?p=0.001?by a scaling exponent of-0.526.MR_RBCBC of the both two species at 25^o C were greater than those at 10??Xiangyun carp:p=0.009;common carp:p<0.001?.MR_RBCBC of the both two species did not correlate with RMR at each temperature?25?,Xiangyun carp:p=0.302 at 25?,p=0.302 at 10?;common carp:p=0.147 at 25^o C,p=0.147 at 10??.5.GSA of the Xiangyun carp and the common carp increased with increasing M at 25?,and the scaling exponent were 0.906 and 1.043,respectively.GSA of the Xiangyun carp and the common carp also increased with increasing M,and the scaling exponents were 1.004 nd 0.988,respectively.The scaling exponents of the both two species at each temperature ere greater than 2/3?p<0.001?,respectively.But GSA did not correlate with RMR?25?,Xiangyun carp:p=0.053 at 25?,p=0.794 at 10?;common carp:p=0.104 at 5?,p=0.323 at 10??.The conclusions were as follows:1.The Xiangyun carp has a larger S_RBCBC and a higher RMR than those of the common carp.2.The relationships among S_RBC,and b_RMRMR are only partially consistent with the CMH. rythrocytes of fish cannot be simply classified to the rapidly dividing type and the slowly ividing type.3.The relationship between RMR and b_RMRMR of the two species of fish partially supportes the LBH.4.The species with larger S_RBCBC has a smaller b_RMRMR value,which is consistent with the rediction of the SA-MDH.5.Metabolic scaling cannot be explained as the ontogenetic decrease in cell metabolic level.