| From September 2014 to November 2015, the influence of salinity and temperature stress on the growth and survival of various development stages of Manila Clam and the influence of thermal stress on survival of different shell color of Manila Clam and the crossbreeding syetem juvenile were studied. The main topics of this thesis are as follows.1.The influence of salinity stress on the growth and survival of various development stages of Manila Clam Ruditapes PhilippinarumThe growth and survival of larvae, juvenile, and 1-year adult(10 mm) of Manila Clam Ruditapes Philippinarum were observed at different salinity stress(S=5、8、11、14、38、41、44、47). The results showed that the effects of salinity stress on growth and survival was significant. 72 h, the survival rates of the three stages were highest in the salinity of 38(97.87±3.69%, 100.00%, 100.00%)(p<0.05), however, the larvae, juvenile and 1-year adlut were all dead at salinity of 5; The highest daily growth of larvae was at the salinity of 38(4.83±0.03μm and 6.81±0.11μm); 21 days, the survival rate of larvae in salinity of 38 was 50.27±3.76% while the others were all dead, the group of salinity of 38 was significantly different from the control group(the salinity of 32 was the control group)(p<0.05); 30 days, the survival rate of juvenile in salinity of 38(68.75±5.25%)was significantly different from the control group(p<0.05) while the others were all dead; 30 days the survival rate of adult in salinity of 14 and 38 were 94.36±2.03% and 60.00±14.53%, the group of 14 was not significantly different form the control group(p>0.05) while the group of 38 was significantly different form the control group(p<0.05).2.The influence of temperature stress on the growth and survival of various development stages of Manila Clam Ruditapes PhilippinarumThe growth and survival of larvae, juvenile of Manila Clam were observed at different temperature stress(T=12 ℃、15 ℃、18 ℃、24 ℃、28 ℃、30 ℃、32 ℃、34 ℃、36 ℃ and 38 ℃). The results showed as follows. 72 h, the lowest survival rate of the larvae was at 34 ℃ and the lowest survival rate of the juvenile was at 38 ℃, the rate was 92.91±2.96% and 53.55±7.86%, both of the two rates were significantly different from the other groups(p<0.05), the survival rate of the larvae at the group of 15 ℃, 18 ℃, 24 ℃, 28 ℃ was 100% and the juvenile at 15 ℃, 24 ℃, 28 ℃ was 100%, which were significantly different frem the other groups(p<0.05); 30 days, the survival rates of the larvae at 18 ℃ was 58.39±1.93% and the juvenile at 15 ℃ was 75.23±5.43%, both of the two groups were significantly different from the two controlgroups(p<0.05); The highest daily growth of larvae and juvenile was at 30 ℃(5.34±0.26μm and 14.92±0.32μm); the temperature optima was decreased as the clam was growing.3.The influence of salinity and temperature stress on the survival of juvenile of different shell color strains of Manila Clam Ruditapes PhilippinarumThe survival of juvenile of different shell color strains(Zebra Clam, White Zebra Clam and Orange Clam) of Manila Clam were observed at salinity of 8(55 h), salinity of 47(10 days) and 38 ℃(80 h). The contral group was wild clam. The results showed that among the three ways, the highest survival rate were all Zebra Clam and the lowest survival rate were all wild clam. The survival rate of White Zebra Clam was higher than that of Orange Clam at low and high salinity stress; The survival rate of Orange Clam was higher than that of White Zebra Clam, both of them were not significantly different(p>0.05).4.The influence of thermal stress on the survival of juvenile of complete set line of Manila Clam Ruditapes PhilippinarumChosed 3 families which had 12 combiantions and the growth rate were high(O10O3、O11O3、O12O3、O10Z3、O11Z3、O12Z3、Z10O3、Z11O3、Z12O3、Z10Z3、Z11Z3、Z12Z3) from 12 diallel cross families. We learned that Z10O3 and O12Z3 had the highest growth rate, the daily growth were 15.62±8.89 μm and 15.28±5.19 μm. Each family at the temoerature of 38 ℃(80 h) had a different survival rate. The results showed that OZ had the highest survival rate, the second was ZZ, the survival rate was 65.72±0.64% and 64.18±7.02%, which was significantly different from OO and ZO(p﹤0.05), the heterosis of OZ was 85.70%. The highest survival rate of the 12 combiantions was Z10Z3(70.57±8.64%), which was not significantly different from O10Z3(66.43±3.56%), O11Z3(65.19±7.41%), O12Z3(65.53±9.83%) and Z11Z(65.30±11.06%)( p>0.05). Taken together all these results above, O12Z3 was the most suitable combiantion as the basis for the new strain of thermal stress resistance. |
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