| Haliotis ovina naturally inhabits in Hainan and Xisha Island in China. Owing to overfishing and climate change in recent years, H. ovina wild resoursedeclined. Therefore, carrying actively out the research of artificial cultivation is of important economic and ecological significance. The present research adopted microscopic observation to explore the embryonic development process. Meanwhile, single and response surface experiment was employed to understand the optimum conditions of embryonic and larval development. Finnally, GABA, serotonin and potassium chloride served as inducer to reveal the inducing mechanism of settlement rate and metamorphosis. The main research results were as follows:H. ovina mature eggs were spherical and rice. Average egg diameter was 0.19±0.02mm. In salinity 32 and temperature 28℃, it took 390min from fertilization to hatching with the average cumulation temperature of 156-182℃·h.The embryonic development process could be divided into 4 stages and 11 development period, according to its form and characteristics. Its development time under the suitable condition were faster than that of Haliotis discus hannailh, and slower than thatof Haliotis diversicolr and Haliotis asinine.The hatching and the survival rate of H. ovina were affected significantly by temperature and salinity （P<0.01）. When the temperature was 28℃, the embryonic development time was the shortest and the hatching rate was the highest. When the temperature was 26℃, the larval development time was the shortest and the survival rate was the highest. The range of suitable temperature for embryonic development was 24～28℃, and the optimal temperature was 26～28℃. The range of suitable temperature for larval development was 26～30℃, and the optimal temperature was 26～28℃. The relationship between temperature and hatching rate, survival rate were as follows:hatching rate （%）=-1.34T2+69.11T-820.08 （R2=0.928）; survival rate（%）=-0.90T2+46.71T-556.4 （R2=0.861）. When the salinity was 24, the embryonic and larval development time were the shortest, but the hatching and survival rate were the lowest. The hatching and survival rate were highest at 30 and 32, respectively. The suitable salinity for embryonic and larval development were 28～32, and the optimal salinity were 30-32. The relationship between salinity and hatching rate, survival rate were as follows:hatching rate （%）=-1.43S2+84.35S-1170.92 （R2=0.938）; survival rate=-0.43S2+29.10S-433.01 （R2=0.993）.In response surface experiment, there was significant effect of temperature and salinity interation on the hatching and the survival rate （P<0.05）. The regression equation were as fellow:Hatching rate （%）=-859.82+61.95T+9.06S-0.39TS-1.01T2+0.06S2 （R2= 0.9508）; Survival rate （%）=-673.69+51.16T+4.57S-0.26TS-0.87T2+0.76S2 （R2= 0.9807）. Based on the Response surface model, the hatching and survival rate reached the maximum （95.32%,81.20%） under temperature 24.61℃ and salinity 32, with the desirability value 0.848. The results indicated that the H. ovina embryonic and larval development had different sensitivity of different temperature and salinity. The high temperature and salt was better toleranced then the low temperature and low salt.4. The effects of GABA, serotonin and potassium chloride were examined to determine the possibility of promoting larval survival, settlement and metamorphosis in H. ovina. The results showed that GABA was able to increase survival, settlement and metamorphosis. Treatment with GABA at 10-4 mol/L for 72 h resulted in the highest settlement （26.27%） and metamorphosis rate （22.26%）, while at 10"6 mol/L for 72 h resulted in the highest survival rate （30.84%）. Settlement and metamorphosis could be induced by serotonin. The highest settlement （20.73%） and metamorphosis rate （20.18%） were detected at serotonin concentration of 10"5 mol/L for 72 h. Potassium chloride could only induce settlement at high concentration （10-3-10-2 mol/L） but had no effect on survival and metamorphosis. The highest settlement rate 11.3%and 16.4%was observed in the 10-3 mol/L group treated for both 24 h and 72 h, respectively. Therefore,10-4 mol/L GABA can be used as an effective inducer in seed culture of H. ovina. |
PDF Full Text Request