盐度骤降对不同发育阶段仿刺参存活和生长的影响

Growth and survival of larval and juvenile sea cucumber Apostichopus japonicus exposed to abrupt decline salinity

在2 L烧杯和塑料水槽(50 cm×40 cm×30 cm)中进行了3个试验,研究了盐度骤降对仿刺参Apostichopus japonicus幼体、稚参、幼参存活和生长的影响。1)幼体试验:在水温为24.0~26.0℃下,测定了不同盐度(33(对照)、30、26、22、20、17、13)下幼体在第12、24 h和72 h后的存活率。结果表明:盐度降至13和17时,幼体于第12 h和36 h全部死亡;72 h后,盐度为20组的幼体存活率最低,表明耳状幼体存活和生长的适应盐度为30~26。2)稚参试验:在水温为15.0~13.0℃下,进行不同盐度(33(对照)、30、26、22、20、17、13、9)对稚参(13.5 mg)12、24、72、96 h存活率的影响试验。结果表明:盐度降至9时,12 h时稚参全部死亡;盐度降至13时,24 h时90%的稚参死亡。盐度为30~17时,10 d时稚参的存活率差异不显著(P】0.05);30 d时,盐度为26和盐度为22两组稚参的存活率明显高于其它组(P【0.05);60 d时,盐度为30和盐度为26两组稚参的存活率高于其它组,但差异不显著(P】0.05)。急剧降盐10 d后,将盐度为22、20、17的3组稚参逐渐恢复至盐度为26继续饲养60 d,稚参的存活率与盐度为33、30两组差异不显著(P】0.05),但生长显著缓慢(P【0.05)。3)幼参试验:在水温13.0~10.0℃时,将平均体质量为2.42 g的幼参在盐度为33(对照)、30、26、22条件下饲养60 d,各组幼参的吐肠率为2.23%~11.11%,盐度为33时显著低于盐度30(P【0.05),而与盐度为26、22时差异不显著(P】0.05);但生长却随着盐度的降低而降低,盐度为30、26时,幼参的生长速度分别比盐度为33组减少了5.0%和62.5%,表明盐度为26时为明显抑制生长的拐点。随着盐度的降低,幼参体腔液上清液溶菌酶活力升高,超氧化物歧化酶活力降低。各试验组均未检测出酸性磷酸酶活性。

Effects of abrupt decline salinity on survival and growth of larval and juvenile sea cucumber Apostichopus japonicus were studied in three trials.In the first trial,the auricularia held at a salinity of 33 were directly changed into sea water with a salinity of 33,30,26,22,20,17 or 13 at water temperature of 24-26 ℃.Survival was examined 12 h,36 h and 72 h after the larvae were exposed to the expected salinity.100% mortality occurred 12 h,and 36 h after the auricularia were exposed to a salinity of 17 and 13,respectively,and the minimal survival was observed in the larvae exposed to a salinity of 20,indicating that salinity ranging from 30 to 26 is adaptive for development and survival of the auricularia.In the secondary trial,the juveniles weighing 13.5 mg individual held at a salinity of 33 were directly changed into a plastic tank filled with sea water with a salinity of 33,30,26,22,20,17,13,or 9,and fed common feed at water temperature of 13-15 ℃.It was found that 100% mortality occurred 12 h after the juveniles were exposed to a salinity of 9,90% mortality appeared 24 h after exposure to 13.There were no significant differences in survival in the juveniles exposed to a salinity of 30-17(P>0.05) within 10 days.Within 30 days,however,the juveniles in groups with a salinity of 26 and 22 had significantly higher survival than in other groups(P<0.05).Until 60 days,the juveniles in groups with a salinity of 30 and 26 showed significantly higher survival than in the other groups(P<0.05).The juveniles were acclimated to 2 gradually and fed for 60 days 10 days after they were exposed to 22,20 and 17.They were not found to have significant differences in survival(P>0.05),but significantly poor growth(P<0.05).In the third trial,the juveniles averaging 2.42 g held in a salinity of 33 were directly moved into water with a salinity of 33,30,26 or 22 and ad libitum fed the same feed at water temperature of 13-10 ℃ for 60 days.It was found that 2.23%-11.11% of the juveniles exposed to abrupt decline salinities showed evisceration in the experimental groups,significantly higher in the group with a salinity of 30 than in the group with a salinity of 33(P<0.05).However,the juveniles decreased by 5.0% and 62.5% in growth under 30 and 26 salinity exposure compared to 33 salinity exposure,respectively,indicating that 26 is an abrupt decline salinity for growth.The activity of serum lysozyme increased with increase in salinity while the serum superoxide distmutase(SOD) activity decreased with increase in salinity.No acid phosphatase(ACP) activity was detected in the juveniles exposed to abrupt decline salinities.