| China has the highest freshwater pearl production in the world,and Hyriopsis cumingii is one of the most important freshwater pearl breeding species in China.In recent years,freshwater pearl production of Hyriopsis cumingii is far greater than the quality of its pearl,the pursuit is the yield rather than the quality of pearl,so the breeding of Hyriopsis cumingii has become an important task,and the artificial breeding technology of Hyriopsis cumingii has gradually matured,but our research on the growth and development of embryos is still in the preliminary stage,this experiment wants to explore its fertilized egg development site(breeding site)The relationship between the structure and morphology of Hyriopsis cumingii and its breeding can provide basic information for the breeding and artificial breeding of Hyriopsis cumingii.During the breeding period of female Hyriopsis cumingii,the outer gill cavity of pregnant female Hyriopsis cumingii will be filled with fertilized eggs.These fertilized eggs will increase the oxygen consumption,and the outer gill cavity of Hyriopsis cumingii will become crowded,which will reduce the respiratory efficiency of Hyriopsis cumingii and cause anoxia.Anoxia is also one of the environmental conditions that affect the culture of Hyriopsis cumingii.Therefore,the study of female Hyriopsis cumingii under simulated hypoxic environment is carried out Morphological and physiological changes of the outer gill of mussel.Hyriopsis cumingii is a filter feeding bivalve,which can reduce the concentration of algae in the water.This experiment explored the impact of several filter feeding freshwater mussels on the water environment under different culture concentrations,so as to explore the combination of culture and environmental management.The main research contents are as follows:1.Annual changes of the structure and morphology of the outer gill nursery sac of Hyriopsis cumingiiObjective to explore the annual changes of the tissue morphology of the outer gill nursery sac of Hyriopsis cumingii and the effects of hypoxia environment on the tissue morphology and physiological enzyme activities of the outer gill of Hyriopsis cumingii.The results showed that the thickness of the outer gill of mature female Hyriopsis cumingii increased significantly during the breeding period(March to June),and many fertilized eggs in blastocyst stage were found during the breeding period.The thickest part of the gill increased to(1576.52 ± 112.56)μ m,which was higher than that in non breeding period(685.43 ± 32.56)μ M 25)μ m(P < 0.05),and the width of the gill cavity(nursery sac)also increased significantly,which provided a good environment for the growth and development of the fertilized eggs of Hyriopsis cumingii,increased to(754.42 ± 43.23)μ m,which was 332.47% higher than(178.57 ±26.36)μ m in the non breeding period,In December and January,the thickness of gill flap and the width of gill cavity(nursery sac)were the minimum in the same year,which provided the basis for the artificial propagation of Hyriopsis cumingii.2.Effects of hypoxia stress on tissue morphology and enzyme activities of outer gill of Hyriopsis cumingiiAfter 5 days of hypoxia stress,the cilia on the lateral gill of Hyriopsis cumingii increased to(76.45 ± 6.37)μ m,79.58% higher than that of the control group(P < 0.05),and the aqueduct tissue of Hyriopsis cumingii increased to(203.52 ± 8.53)μm,248.73% higher than that of the control group(P < 0.05)Qi.Under hypoxia stress,the LDH activity in response to anaerobic respiration metabolic intensity was significantly higher than that in control group(P < 0.05).The highest value of(360.38± 4.07)U / mgprot in experimental group was 131.1% higher than that in control group(155.94 ± 4.92)U / mgprot.The SDH activity in response to aerobic respiration metabolic intensity was significantly lower than that in control group(P < 0.05).The lowest value of(41.79 ± 1.22)U / mgprot in experimental group was 70.28 ± 4.92)Compared with the control group(9.36 ± 0.96)U / mgprot,the highest value of the experimental group(17.91 ± 1.49)U / mgprot was increased by 91.34%,while the activity of antioxidant enzyme SOD was significantly lower(P < 0.05),lower than the lowest value of the control group(6.59 ± 0.57)U / mgprot,decreased by 68%compared with the control group(21.19 ± 1.46)U / mgprot 9%,indicating that Hyriopsis cumingii can adjust its outer gill structure to fight against hypoxia environment,and the antioxidant system enzyme activity of Hyriopsis cumingii has obvious response to hypoxia environment.3.Effects of Hyriopsis cumingii,Anodonta dorsalis and Cristaria plicata on water quality under single stocking conditionThree kinds of freshwater mussels(Hyriopsis cumingii,Anodonta woodiana,Cristaria plicata)were reared in a water tank in the laboratory,After 7 days of experiment,The results showed that the concentrations of total nitrogen and ammonia nitrogen in the three experimental groups were significantly higher than those in the control group,and the increase of total phosphorus was relatively slow.Among them,In the low biomass Hyriopsis cumingii group,the highest total nitrogen concentration increased by 60.97%,while the highest total phosphorus concentration increased by17.78% and 46.1%,respectively.Compared with the control group,the concentration was significantly increased by 98.48% and 121.12%;Compared with the control group,the highest concentration of total nitrogen,total phosphorus and ammonia nitrogen in the two experimental groups were significantly increased by 50% and 175.61%,20.86% and 39.13%,109.09% and 200% respectively;the highest total nitrogen concentration of the two test groups of Anodonta woodiana was significantly increased by 41.46% and 190.24% compared with the control group.The total phosphorus concentration of the low biomass group was not significantly higher than that of the control group.Difference,the high biomass group significantly increased by 41.73%,and the ammonia nitrogen concentration was significantly increased by 116.67% and133.33% compared with the control group.There was no significant difference in the phosphorus metabolism rate among the three species,but the high biomass group was significantly higher than the low biomass group,while the ammonia nitrogen metabolism rate was in the order of Crista plicata > Anodonta dorsalis > Hyriopsis cumingii.Among the three groups,the turbidity decreased significantly.Anodonta dorsalis was the most significant,followed by Hyriopsis cumingii,followed by Crista plicata.The results of gill sections of three species of Hyriopsis cumingii showed that the branchial aqueduct tissue of Anodonta dorsalis was the widest,32.34% larger than that of Hyriopsis cumingii and 48.11% larger than that of Crista plicata.The results show that these three mussels will aggravate the metabolism of nitrogen and phosphorus in the water,increase the nutrient content in the water,and the high culture density will aggravate this phenomenon,but they will significantly reduce the turbidity of the water through the filtration effect.Therefore,in the actual culture process,they can cooperate with emergent plants to absorb nutrients and jointly improve the water quality. |
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