| The morphological characters of embryo, larva, juvenile and fingerling stages ofInimicus japonicas were described in this study. At22.0℃and salinity29, thespawning takes place about40h after artificial fertilization. The fertilized eggs werespherical, separate and buoyant with a diameter of1.40mm, without the oil globule.There was a chap on the yolk at the animal pole. At20.0~21.0℃and salinity29, theembryo developed to the stages of gastrula ion and there were pigment point arise about32h after fertilization, the pectoral bud swelling at the muscular response stage about60h after fertilization, hatching at62h after fertilization. The total lengths of the newlyhatched larvae were3.9mm. The first feeding occur for3day post hatching and theoral fissure were0.44mm, the yolk sac disappeared at6day post hatching. From firstday to each fin completely forms, it is called larval stage (from1dph to10dph); whenthe2fin ray which above the pectoral fin were free, it is called juvenile stage (from11dph to25dph); when the whole body is covered the pigment plaques, we call itfingerling stages (from26dph to40dph).The changes on lipid characteristics and fatty acid contents of fertilized egg,blastula stage, embryo formed, tail-bud stage, muscular response stage and yolk-saclarvae of I. japonicas during early development stage were also investigated in thisstudy. The results indicated that the lipid class of the embryonic and yolk-sac larvaewere polar lipids, which in total lipids content of72.20~79.07%. The content ofneutral lipids rising first dropped in the bud when peak period during the embryonicdevelopment, during the yolk sac development were no significant change. Polar lipidscontent with embryos and yolk sac series development gradually declined, but inembryonic development and the yolk sac during the period were no significant change.Total lipids content change trend as well as the polar lipids, and the content of3daypost hatching larvae were11.66%. Lipids during embryonic development are mainlyused for the construction of the organization. The polar lipids as a major energy materialduring the yolk sac larvae development and the neuter lipids get relative retention. The dominating fatty acids in neutral lipids of I. japonicas embryos and yolk-saclarvae were16:0，DHA，18:1n-9，18:0，16:1n-5，EPA, while in polar lipids were DHA，16:0，ARA，EPA，18:0，18:1n-9. The main fatty acids in neutral lipids such as saturatedfatty acids (SFA),monounsaturated fatty acid (MUFA), polyunsaturated fatty acid(PUFA) and n-3PUFA, n-6PUFA content during the development of embryo risegradually, then present different degree of decline in the yolk-sac larvae development.The main fatty acids in polar lipids such as SFA, MUFA, PUFA and n-3PUFA, n-6PUFA content during the embryonic development period is volatility changes, inaddition to MUFA peak appeared in the embryo formed and muscular response stage,the others each peak fatty acids all appear at blastula stage and muscular response stage.All of the fatty acids in yolk sac larvae during development were slow drop. There didexist that DHA shifted from the polar lipids to the neuter lipids during the earlydevelopment of I. japonicas, and the demand of ARA of the yolk-sac larvae was higherthan the EPA.The effects of the rotifer and Artemia nauplii enriched by two different kinds ofenrichments on growth, survival and fatty acids composition in I. japonicas larvae werestudied. The results showed that: the liver oil group19.43%survival rate was thehighest and there was no significantly difference with the control group18.20%. Thesurvival rate of spermary oil group12.83%which was significantly below the liver oilgroup and control group. The overall length of the larvae of the spermary oil group5.21mm, significantly lower than those of the control group was6.03mm and5.64mm liveroil group; however, there was no significantly difference between the control group andliver oil group.With two different kinds of enrichment enhanced, the neuter lipids content of10dph larvae were significantly higher than those in the control group and the3dph;There was no significant differences between the control group and enrichment group ofthe polar lipids content of10dph larvae, but each enrichment group and control group’spolar lipids content were significantly lower than3dph larvae. The content of ARA、 EPA、DHA and n-3PUFA in the neuter lipids of liver oil group were significantly higherthan those in the control group and the spermary oil group. The ratio of EPA/ARA inthe neuter lipids of liver oil group and the spermary oil group were1.78and2.64,significantly higher than those in the control group1.00and3dph larvae0.77. All theratio of EPA/ARA in the polar lipids was higher than the ratio of the3dph larvae. Theresults show that while DHA/EPA ratio for2, EPA/ARA too high was harmful for the I.japonicas larvae’s growth and survival, reference the yolk-sac larvae’s fatty acidcomposition; we judged the EPA/ARA value of0.7is relatively appropriate.The changes on lipid characteristics and fatty acid contents of yolk-sac larvae ofEpinephelus awoara, Trachinotus ovatus and Pseudosciaena crocea during earlydevelopment stage were investigated in this study. The newly hatched larvae and1d,2d,3d post hatching larvae of E. awoara, T. ovatus and P. crocea were sampled andtheir lipid content and fatty acid profiles were assayed. The results indicated that thelipid class of the therr larvae was different. The neutral lipid/polar lipid ratio in yolk saclarvae of E. awoara was between0.97and1.22. While it was between1.88and3.21inyolk-sac larvae of T. ovatus, and from2.63to2.62of P. crocea. The total lipids of thethree larvae decreased as the development of yolk sac larvae and the main consumedlipid was neutral lipid in all of the larvae. The contents of main fatty acids in neutrallipid decreased significantly at2days post hatching in E. awoara larvae and at1daypost hatching in T. ovatus larvae, at3day post hatching in P. crocea larvae respectively.While the contents of main fatty acids in polar lipid increased significantly at1day posthatching in all of the larvae. It is therefore suggested that the lipid characteristics andfatty acid contents were difference between the marine fish which contain the oilglobule and without. |
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