A Comparative Study On The Effects Of Acceleration Mode On Maximum Swimming Speed And Activity Metabolism Of Megalobrama Amblycephala And Silurus Meridionalis

To explore the effects of acceleration modes on the locomotor performance and metabolism characteristics in swimming for the species with different ecological habits and to evaluate the applicable methods for determining the critical swimming speed(U_crit),burst swimming speed(U_burst)and maximum metabolic rate?MMR?for M.amblycephala and S.meridionalis.The water temperature was 25±0.5?.In this study,four acceleration modes composed of different acceleration duration??t?and velocity increment??V??Acceleration mode 1:?V=20 cm/s,?t=2 min;acceleration mode 2,3,4:?V=10 cm/s,?t=20,40 and 60 min?were set up to detect the maximum swimming speed(V_max)and oxygen consumption rate?MO₂?of the experimental fish during their swimming processes and metabolic recovery after the exhaustion were measured.The main results were as follows:1.Under the acceleration mode with velocity increment??V?of 20 cm/s and duration of each acceleration??t?of 2min,V_max in swimming process for both species were significantly higher than those under the other three modes, respectively?P<0.05?.But swimming duration for both species were significantly lower than those under the other three modes?P<0.05?.2.There was no significant difference for the V_max of M.amblycephala among the the other three modes??V=10 cm/s,?t=20,40,and 60min??P>0.05?.Meanwhile, the V_max of the S.meridionalis has a decreasing trend with the increase of the acceleration duration.The U_crit at?t of 20min is significantly higher?P<0.05?than the measured values at?t of 40min and 60min.3.MO₂ of M.amblycephala and S.meridionalis both increased with increasing swimming speed for all acceleration modes.4.MO₂ showed different trends with the increasing swimming speed in U_burst measurements for the two species.The inflection point of correlative curve for MO₂ with swimming speed occurred at velocity of 100 cm/s for the M. amblycephala and MO₂ did not change significantly with increasing velocity in the subsequent acceleration process.But such"plateau period"of MO₂ appeared when the velocity was above 20 cm/s for the S.meridionalis.5.MO₂ of M.amblycephala and S.meridionalis showed a similar trend with their swimming speed among the the other three modes??V=10 cm/s,?t=20,40,and 60min?.6.Under all acceleration modes,the maximum oxygen consumption rates of the two species during swimming process?AMO₂?were significantly higher than the maximum value during the metabolic recovery period?DMO₂??P<0.05?.7.The AMO₂ measured by U_crit method was higher than that observed by U_burst method for M.amblycephala,and the value for S.meridionalis showed an opposite trend.The main conclusion were as follows:1.It is suitable to measure the U_critrit of M.amblycephala using an acceleration mode with?V of 10 cm/s and?t is between 20-60min,and the appropriate acceleration mode for measuring U_crit of S.meridionalis is?V is 10 cm/s and?t is 20min.2.Whether using the U_crit or the U_burst method,the maximum metabolic rate of the two species of fish in the swimming phase was significantly higher than that in the recovery phase.The maximum MO₂ measured during swimming process?AMO₂? should be used as MMR for both species.3.Different methods should be used to measure the MMR of fish with different ecological habits.The M.amblycephala is dominant in the sustain swimming.The determination of MMR is suitable for U_crit method.The S.meridionalis is dominant in the burst swimming and the MMR measurement is suitable for the U_burst method.4.The M.amblycephala can sustain swimming for a long time.But its anaerobic metabolism is relatively weak.But the S.meridionalis show the opposite trend.The differences in locomotor performance and metabolism characteristics in swimming between the two species reflect the trade-off effect of species adaptation to their ecological habits.