将初始体质量(3.87±0.32)g的一龄青海湖裸鲤(Gymnocypris przewalskii)幼鱼饲养在55 cm × 40 cm × 34 cm冷水鱼循环水族箱中,设淡水对照组(CK)和盐度5.0、7.5、10.0、12.5和15.0组共6组,每组3个重复,每箱10尾.实验盐度用海量星海水素配制,养殖69 d检测其生长性能等指标,旨在为科学养殖青海湖裸鲤幼鱼提供科学依据.结果显示:随盐度的升高,青海湖裸鲤幼鱼增重率(WGR)与特定生长率(SGR)逐渐降低,但盐度12.5组略有回升;日均增重率(ADG)呈先升高后降低的趋势,5.0组最高;体长特定生长率(SGRL)呈先降低再升高再降低的趋势;肥满度(CF)先升高再降低,5.0组最小;存活率(SR)无明显变化(90％以上).盐度在0～10.0范围内,幼鱼鳃小片间隔逐渐减小;盐度超过10.0后,鳃组织退化,鳃小片弯曲程度加剧,上皮细胞脱落、坏死,泌氯细胞数量增多、体积增大,鳃小片长度变短、宽度减小、间隔增大.不同盐度处理均显著提高了糖原含量以及果糖-1,6-二磷酸醛缩酶(FBA)活性(P＜0.05),5.0组肝糖原含量最高,10.0组肌糖原含量最高;10.0组肝中FBA活性最高,15.0组肌中FBA活性最高,首次确认FBA参与青海湖裸鲤的耐盐过程.综上所述,盐度在0～5.0时青海湖裸鲤幼鱼的生长性能最佳,盐度超过10.0对青海湖裸鲤幼鱼鳃组织影响显著,说明盐度处理增强了幼鱼糖代谢过程.本研究结果为青海湖裸鲤的人工养殖提供了新思路.
Effect of Salinity on Growth,Gill Histology and Glucose Metabolism-related Indicators of Gymnocypris przewalskii Juveniles
Juvenile Gymnocypris przewalskii with initial body weight of(3.87±0.32)g were reared in cold-water fish circulating aquaria of 55 cm× 40 cm× 34 cm at stocking density of 10 individuals per aquarium with freshwater(control group,CK)and salinity of 5.0,7.5,10.0,12.5 and 15.0,three replicates per group.The test salinity was prepared with massive seawater elements,and the growth performance of G.przewalskii was detected for 69 d,aiming to provide scientific basis for scientific breeding of nudibranchs in Qinghai Lake.The results showed that there were gradual decrease in weight gain rate(WGR)and specific growth rate(SGR)in G.przewalskii juveniles with increasing salt concentration,with slightly increase in the 12.5 group,increase and then decrease in the average daily weight gain rate(ADR),and maximum in the 5.0 group.The spedific growth rate of length(SGRL)was shown to be a trend of decreasing and then increasing and then decreasing,and condition factor(CF)to be a trend of increasing and then decreasing,with the minimal in the 5.0 group,without significant change in survival rate(SR)(over 90％).The gradual decrease was observed in space between secondary gill lamella of G.przewalskii juveniles at the salinity from 0 to 10.0,in the salinity over 10.0 group,the gill tissue of the juveniles became degraded,mainly manifested by the increase in bending of secondary gill lamella,the loss and necrosis of epithelial cells,the increase in the number and volume of secretory chloride cells.The short and width secondary gill lamella were found,with increase in the interval in high salinity group.Significantly(P＜0.05)increase in glycogen content and fructose-1,6-bisphosphate aldolase(FBA)activity was observed in different salinity treatments,with the maximal liver glycogen content in the 5.0 group and the maximal muscle glycogen content in the 10.0 group,with the maximal FBA activity in liver in the 10.0 group and in muscle in the 15.0 group.The involvement of FBA in the salt tolerance process of G.przewalski was first approved.In conclusion,the best growth performance of G.przewalskii juveniles were observed at salinities ranging from 0 to 5.0,and high salinities(over 10.0)significantly affected the gill tissue morphology of G.przewalskii juveniles.Salinity treatment enhanced the process of glucose metabolism in juveniles,which provides new ideas for the artificial farming of G.przewalskii juveniles.
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