Effects Of Water Current On Swimming Activity, Growth And Ecophysiological Aspect Of Young Barbodes Schwanenfeldi

Water current,an important environmental factor,can activate sense organ of fish and bring corresponding action mode and response mechanism,which has various ecological effects such as influencing the behavior and physiological development of fish directly or indirectly.This paper reviewed the ecophysiological effects of water velocity on fish was undertaken,and a series of indoor experiments were conducted to investigate the effects of water velocity on rheotaxis behavior,feeding and growth,energy metabolism and budget,hematological parameters, non-special immune factors,biochemical composition,antibiotic residue in tinfoil barb Barbodes schwanenfeldi.The main results were summarized as follows:1) Effects of water velocity on the rheotaxis behavior and swimmming performance of young tinfoil barb B.schwanenfeldiA special device was designed to examine the rheotaxis behavior and swimming performance of young B.schwanenfeldi(weight 125.94±13.87 g) under different water velocities(0,0.1,0.3,0.5 m·s^-1) at 28℃.The experiments were carried out for three phases(90 min,24 h and 45 d).The results showed that the rheotactic frequency(RF) of tinfoil barb increased with increasing water velocity.The tail beat frequency(TBF) at 0.3 and 0.5 m·s^-1 was higher than those at 0 and 0.1 m·s^-1.A linear correlation between TBF and RF was found at each time-point within 90 min.Tinfoil barb altered swimming performance frequently,which was apparently affected by the water current.The time of swimming against the current decreased from above 50%to below 5%,while the time of keeping still increased from below 3%to above 86%with the increasing of water velocity.The TBF was linearly correlation with the swimming speed(â…¤) when the fish moved forward or held still.Moreover,both TBF and RF of the fish challenged with different water velocities were significantly higher than those of the control(0 m·s^-1) in 24 h and 45 d.2) Effects of water velocities on the energy metabolism of young tinfoil barb B.schwanenfeldiExperiments were conducted to determine the effects of water velocity(0,0.1,0.3 and 0.5 m·s^-1) on energy metabolism in young B.schwanenfeldi(weight 125.94±13.87 g).The results demonstrated that the oxygen consumption rate(OCR) in tinfoil barb at the water velocities of 0.3 and 0.5 m·s^-1 were significantly higher than that of the control(0 m·s^-1).OCR reached the peak at 0.3 m·s^-1and it reduced at 0.5 m·s^-1 during the experiment time.The change of respiratory frequency was similar to that of the OCR.The excretion rates of TN and Ur-N both increased with the higher water velocities and peaked at 0.5 m·s^-1,but NH₃-N excretion rate showed little change. The oxygen nitrogen ratios of young fish fluctuated between 28.3～42.0 at different water velocities,with the maximum at 0.3 m·s^-1 and the minimum at 0 m·s^-1.The proportions of carbohydrate and protein decreased with the increasing water velocity but fat increased in substrate energy suply.The carbohydrate and protein were the primary energy substrate at 0.1 m·s^-1,which provided 72.6%of the whole energy.The primary energy substrate was fat and carbohydrate when the water velocity reached 0.1 or 0.3 m·s^-1,which provided 74.1～79.5%of the whole energy.However,the primary energy substrate was fat and protein at 0.5 m·s^-1.3) Effects of water velocities on the growth,feeding and energy budget of young tinfoil barb B.schwanenfeldiBased on the measurement of the ingestion,excretion,metabolism,growth and food conversion of young fish(weight 75.21±2.82g) at different water velocities(0,0.1 and 0.3 m·s^-1) for 45 d,equations of the energy budget in relation to water velocity were established.At 0-0.3 m·s^-1,the ingestion,excretion,metabolism and growth rates of young B.schwanenfeldi increased with increasing water velocity.The metabolism rate decreased and the ingestion and excretion rates increased with increasing culture period.The daily weight gain(DWG) and weight special growth rate(SGR) at 0.1 m·s^-1 was higher than those at 0 and 0.3 m·s.(-1).No significant difference was observed in the food conversion rate(FCR) of the young fish at 0 and 0.1 m·s^-1,but thery were both significantly higher than that of the fish at 0.3 m·s^-1.The energy budget equations were established during the experiment period included: 0 m·s^-1:100.0 C=44.8 F+4.7 U+36.6 R+13.9 G 0.1 m·s^-1:100.0 C=37.9 F+5.1 U+40.1 R+16.4 G 0.3 m·s^-1:100.0 C=41.9 F+6.1 U+47.1 R+4.9 GTo sum up,the ratio of energies used for metabolism and excretion increased with increasing water velocity.The growth energy was maximal and the faecal production energy was minimal under 0.1 m·s^-1,which were the reverse under 0.3 m·s^-1.4) Effects of water velocities on blood parameters and non-specific immunity of young tinfoil barb B.schwanenfeldi The blood parameters and immune function of young Barbodes schwanenfeldi(weight 75.21±2.82g) were examined at different water velocities(0,0.1 and 0.3 m·s^-1) for 45 d.The results showed that water velocities affected the hematological parameters of young tinfoil barb. The quantity of RBC,HCT,MCH and MCHC increased significantly with increasing water velocity and duration,while MCV decreased markedly and WBC showed no obvious change. Moreover,the biochemical composition of serum changed in response to the different water velocities.Plasma glucose remained unchangeable before the middle of the experiment time,but it increased significantly under 0.3 m·s^-1 at the end of the experiment.The total protein(TP) and the globulin protein(GP) content in 0.3 m·s^-1 group were higher greatly than those of the control, but the change of albumin protein was not remarkable.The contents of total glyceride(TG) and total cholesterol(TC) remained stable in the middle(23 d) of the experiment,and they dropped significantly at the end(45 d) of the experiment(P＜0.05).The water current also influenced activities the transaminase and phosphatase.The activities of LDH,AST,ALT and AKP increased with increasing water velocity within the period of 1-45 days.The immunity of fish was affected by the water velocity.At different water velocites,the weight of immune organs (spleen) did not change significantly but the quantity of NBT positive cells increased markedly. The quantity of NBT positive cells of fish at 0.1 and 0.3 m·s^-1group were higher than that of the control.However,no remarkable difference was found in the 0.1 and 0.3 m·s^-1 groups after 45 days.The activities of lysozyme and superoxide dismutase both increased obviously with increasing water velocity,which peaked in 0.3 m·s^-1 group.5) Effects of water velocities on the biochemical composition of young tinfoil barb B. schwanenfeldiThe water velocity significantly affected the biochemical composition of young B. schwanenfeldi(weight 75.21+2.82 g).After water velocity treatments(0,0.1 and 0.3m·s^-1) for 45 d, no significant difference in the processing indices and water content in muscle was observed among the treatments with various water velocities.The protein content of fish muscle increased greatly with the increase of water velocity,while the lipid content of muscle dropped with the increasing water velocity.There was no significant difference in the contents of amino acids at the mid-time of the experiment,but the content of Asp,Glu,Gly,Ala,leu and Lys of the fish treated with the water velocity of 0.3 m·s^-1 were significantly higher than that of control at the end of experiment.Moreover,the content of delicious amino acids increased greatly with the increase of water velocity.Water current also affected fatty acids content greatly.At the mid-time of the experiment,the SFA congtent except C18:2n-6 in the group treated with 0.1 m·s^-1 water velocity and C15:0, C16:1,C18:2n-6 and C20:5n-3 in the group treated with 0.3 m·s^-1 water velocity decreased obviously compared to that in the control group,but all the UFA content increased.At the end of experiment,the contents of SFA except C16:0 and C18:2n-6 in the 0.1 m·s^-1 water velocity treated gruoup and C16:0,C16:1 and C18:2n-6 in the 0.3 m·s^-1 water velocity treated gruoup were all markedly lower than that of the control,but contents of UFA were significantly higher. Furthermore,the contents of EPA,DHA and ALA also rose greatly up while water velocity increased at the end of the experiment(P＜0.05).6) Effects of water velocities on the residue of NFLX-HCL of young tinfoil barb B. schwanenfeldiThe NFLX-HCL mixed with feed were given to the young fish(weight 90.3±10.1 g) at a dose of 50 mg·kg^-1 weight for consecutive 7 days at different water velocities(0 and 0.3 m·s^-1). The muscle was sampled and the content of NFLX-HCL was examined at different time-points during the experiment period of 27 days.The results showed that the drug was eliminated from the muscle at a quite different speed when the fish were treated with different water velocities.The content of NFLC-HCL in muscle offish at 0.3 m·s^-1 water velocity were lower that of the control(p＜0.05).When the drug feeding were stopped,no medicine residue in the muscle offish treated with 0.3 m·s^-1 water velocity was detected on the 6th day,while its content became undetectable on the 12th day in the control group(0 m·s^-1).