水体中添加乳酸钙对中华绒螯蟹生长、蜕壳、钙沉积和水质指标的影响OA北大核心CSTPCD

In order to study the effects of calcium lactate to water on the growth,molt,and calcium deposition of juvenile Chinese mitten crab(Eriocheir sinensis),this study conducted a 90-day(two complete molting cycles)rearing experiment on female juvenile crabs with an initial body mass of(4.78±0.51)g.Calcium lactate was added to freshwater at concentrations of 0 mg/L,218 mg/L,436 mg/L and 654 mg/L and the calcium ion content in water is 45.6 mg/L,84.4 mg/L,123.2 mg/L and 163.6 mg/L.(recorded as Treatment 1# to 4#).The results showed:(1)The addition of calcium lactate improved survival rates of juvenile E.sinensis significantly.(2)With the increase in calcium lactate content,there was an upward trend of body mass,weight gain rate,specific growth rate,and hepatopancreas index of juvenile E.sinensis during the first molting cycle,but the differences were not significant.However,during the second molting cycle,the body weight,carapace length and carapace width growth rates of juvenile E.sinensis significantly increased with the calcium lactate addition,and among them,treatment 3# and 4# were significantly higher than treatment 1#.(3)The addition of calcium lactate had no significant effect on the intermolt duration but significantly reduced the rate of limb loss after each molting.(4)In terms of calcium deposition,the addition of calcium lactate significantly increased the calcium content in hemolymph during the first and second molting cycles,as well as calcium content in the muscle during the first molting cycle.(5)Increasing calcium lactate content significantly elevated the expression of es EcR2-mRNA and es RXR-mRNA.(6)Calcium lactate had no significant effect on water pH,ammonia nitrogen and nitrite,but water hardness and alkalinity significantly rose with increasing calcium lactate content.In summary,the addition of 654 mg/L calcium lactate to the water improved the survival,growth performance,calcium deposition in tissues,and expression of molting-related genes in juvenile E.sinensis,as well as reduced the limb loss rate after each molting.