NaHCO3碱度对青鱼幼鱼生存、生长及鳃和肾脏组织结构的影响OA

To clarify the adaptive characteristics of juvenile Mylopharyngodon piceus to saline-alkaline water and fill the research gap in its alkalinity tolerance,the acute median lethal experiment of NaHCO3 alkalinity was con-ducted by the equal logarithmic interval method,and a gradient alkalinity growth experiment was set up in this study to systematically investigate the effects of alkalinity on the survival,growth,and histological structures of gills and kidneys of juvenile M.piceus.The results of acute toxicity experiment showed that the median lethal concentrations(LC50)of alkalinity for juvenile M.piceus at 12,24,48 and 96 h were 63.6 mmol/L,60.3,57.4 and 56.7 mmol/L,respectively,indicating a strong alkalinity tolerance of this fish species.The results of the 60-day growth experiment demonstrated that juvenile M.piceus could survive and grow in water with alka-linity ranging from 0 to 50 mmol/L,and alkalinity exhibited a significant stage-specific effect on their growth.The weight gain rate(612%)in the 5 mmol/L did not differ significantly from that of the freshwater control group(542%).The growth of fish in the 20 mmol/L and 35 mmol/L groups was significantly inhibited,with their weight gain rates decreasing to 249%and 247%,and there was no significant difference between these two groups.The 50 mmol/L group had the strongest inhibitory effect on growth,with a weight gain rate of only 133%.These results suggested that the inhibitory effect on the growth of juvenile M.piceus was exacerbated as al-kalinity increased,with growth inhibition observed at alkalinity levels exceeding 20 mmol/L.Histological obser-vations revealed that compared with the control group(0 mmol/L),the gill lamellae of the 20 mmol/L group became thinner,the adhesion of pavement epithelial cells decreased,and mitochondria-rich cells(MRCs)were distributed unevenly;in the kidney,renal tubule constriction,renal glomerulus atrophy and interstitial cell proliferation were observed.The above histological damages were further aggravated in the 50 mmol/L group,characterized by gill epithelial cell detachment,reduction in the number of MRCs,renal tubule ob-struction and thinning of Bowman's capsule.This study revealed the dose-effect relationship of alkalinity on the survival and growth of juvenile M.piceus as well as the underlying mechanism of organ damage,which provides an important theoretical basis for environmental regulation,resource development and related physiological mechanism research of M.piceus culture in saline-alkaline water.