日本囊对虾(Marsupenaeus japonicus)秋繁同生群仔虾不同耐寒性能群体间的形态表型差异

DIFFERENCES OF MORPHOLOGICAL CHARACTERISTICS AMOMG DIFFERENT COLD-TOLERANCE GROUPS OF AUTUMN PROPAGATION POST LARVA COHORT OF MARSUPENAEUS JAPONICUS

以水温16oC、p H 8.1±0.2、盐度20的砂滤海水为实验用水,以体长(7.643±0.639)mm的日本囊对虾(Marsupenaeus japonicus)秋繁同生群仔虾为实验对象,经确认其在水温由16oC瞬降至14oC后并保持96h恒温的最终成活率略低于5%后,以此为水温骤降胁迫处理方式,采取显微扫描像素测量技术和多元分析方法定量研究了A、B、C、D、E实验群体,依次为温降胁迫处理后(0—24)h、(24—48)h、(48—72)h、(72—96)h时段内的死亡群体和温降胁迫处理后96h时的存活群体间形态特征的差异。结果表明:(1)各实验群体在本研究所涉15项形态性状中均无显著差异(P>0.05)仅为第一触角柄长、额剑长和眼径,在所涉17项形态比例指标均无显著差异(P>0.05)仅为尾节高/尾节长;(2)随耐寒性能差异的增大,各实验群体间的欧氏距离也随之增大,且均达到极显著水平(P<0.01);(3)经主成分分析,提取到的4个特征值均大于1的主成分,累计贡献率达87.590%,其中载荷绝对值大于0.80的主要影响变量均仅存在于第1主成分中;(4)将E实验群体定义为耐寒处理选留群,其余实验群体统归为耐寒处理淘汰群,采用逐步导入判别法建立的Fisher分类函数方程组可较清晰地区分淘汰群和选留群个体,其中选留群和淘汰群个体的判别准确率P1分别为99%和88.75%,P2分别为89.80%和98.88%,两者综合判别准确率为93.88%。

We selected the autumn propagation post larva of Marsupenaeus japonicus as experimental subjects with an average initial length of 7.643±0.639 mm. After confirming that the final survival rate was slightly lower than 5% when the water temperature was suddenly changed from 16oC to 14oC and maintained constant temperature of 96 h, which took this as the processing method of suddenly lowering water temperature stress. In this study, the A, B, C, D and E experimental groups were studied quantitatively by microscopic scanning pixel measurement technique and multivariate analysis method, and these groups respectively represent different deaths groups at the time intervals of（0—24）h,（24—48）h,（48—72）h,（72—96）h, and the differences in morphological characteristics of surviving individuals between groups after 96 h. The results showed that：（1） There was no significant difference in the 15 morphological characteristics（P〉0.05） in the experimental groups, except the first antenna length, rostrum length and eye diameter; There was no significant difference in the 17 morphology ratio indexes（P〉0.05）, except telson height/telson length.（2） The Euclidean distance between the experimental groups increased significantly with the increase of cold-tolerance, and reached the extremely significant level（P〈0.01）.（3） Principal component analysis showed four main components whose eigenvalue was greater than 1, and the cumulative contribution rate of 89.590%. The main influencing variables whose absolute value was more than 0.80 were only in the first principal component.（4） The experiment groups of A, B, C and D were classified as cold-tolerance elimination group. The E group was defined as the cold-tolerance retention group. The progressive discrimination method was used to establish the fisher classification function equation groups, which could distinguish clearly from elimination group and retention group. The discrimination accuracy of retention group P1 and P2 were 99% and 89.80% respectively. The discrimination accuracy of elimination group P1 and P2 were 88.75% and 98.88% respectively, the integrative discrimination accuracy being 93.88%.