盐度胁迫对不同发育时期菲律宾蛤仔生长和存活的影响

为研究盐度对不同发育时期菲律宾蛤仔Ruditapes philippinarum(以下称蛤仔)生长和存活的影响,在水温24℃条件下,对不同盐度(5、8、11、14、32、38、41、44、47,盐度32为对照组)胁迫下蛤仔幼虫、稚贝和幼贝(壳长10 mm)的生长和存活情况进行了研究。结果表明:盐度胁迫对蛤仔的生长和存活具有显著影响(P0.05),盐度胁迫72 h时,盐度38组蛤仔幼虫、稚贝、幼贝的存活率均最高,分别为97.87%±3.69%、100%、100%,且与其他盐度组有显著性差异(P0.05),而盐度5组蛤仔幼虫、稚贝、幼贝以及盐度8组的幼贝全部死亡;盐度38组蛤仔幼虫及稚贝的生长速度最快,壳长平均日生长分别为(4.83±0.03)μm和(6.81±0.11)μm,仅次于对照组(盐度32),并显著高于其他盐度组(P0.05);蛤仔幼虫、稚贝和幼贝对盐度的耐受范围随着蛤仔受盐度胁迫时间的延长逐渐减小;盐度胁迫21d时,盐度38组幼虫存活率为50.27%±3.76%,显著低于对照组(P0.05),其他各盐度组幼虫全部死亡;盐度胁迫30 d时,盐度38组稚贝存活率为68.75%±5.25%,与对照组无显著性差异(P0.05),其他盐度组稚贝全部死亡;盐度胁迫30 d时,盐度14组幼贝存活率为94.36%±2.03%,与对照组接近(P0.05),而盐度38组存活率为60.00%±14.53%,较对照组显著下降(P0.05),其他盐度组幼贝全部死亡。本试验结果可为蛤仔的生态养殖及抗逆品系的选育提供理论依据。

Influence of salinity stress on growth and survival of Manila clam Ruditapes philippinarum at various developmental stages

The growth and survival of larvae, juvenile, and 1-year old youth( shell length 10 mm) of Manila clam Ruditapes philippinarum were studied at a salinity of 5,8,11,14,32 (control), 38,41,44,and 47 at water tempera-ture of 20 ℃. The results showed that there were significant effects of salinity stress on growth and survival of the clam, with the maximal survival rates(97. 87%±3. 69%, 100%, and 100%) in 72 h in the three stages at salini-ty of 38 ( P<0 . 05 ) and mortality at salinity of 5 . The best daily growth was observed in larvae ( 4 . 83 μm±0 . 03μm) and juveniles (6. 81 μm±0. 11 μm) at a salinity of 38,poorer than that in the control group and significantly better than that in the other groups(P<0. 05). It was found that the range of salinity tolerance was decreased as the clam developed, with survival rate of (50. 27±3. 76)% in 21 day old larvae at a salinity of 38, significantly lower than that in the other groups(P<0. 05), even mortality in the other groups. In 30 days salinity stress, however, the juveniles had survival rate of(68. 75±5. 25)% in a salinity of 38, without significantly different from that in the control group(P>0. 05),even mortality in the other groups. There was survival rate of (94. 36±2. 03)% at a salin-ity of 14 , without significant difference compared to that in the control group ( P>0 . 05 ) , and survival rate of (60. 00±14. 53)% at a salinity of 38, significantly lower than that in the control group (P<0. 05), in the youth clam exposed to salinity stress for 30 days. The findings provided a theoretical basis for eco-breeding of resistant clam strains.