以体长7.643±0.639mm的日本囊对虾秋繁同生群仔虾为实验对象,以氨氮为胁迫因子,在水温18.0±1.0℃、盐度20、pH 8.1士0.2的条件下,经确认其96h成活率略低于5％的氨氮攻毒质量浓度为52.37mg/L后,以此为氨氮急性攻毒实验质量浓度,借助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(依次为氨氮攻毒0-24h、24-48h、48-72h、72-96 h时段内的死亡群体和氨氮攻毒96 h时的存活群体)间形态表型特征的差异.结果表明:(1)在所涉15项形态性状中,各实验群体间均无显著差异(P＞0.05)的性状仅为总长和第四腹节长;(2)在所涉17项形态比例指标中,各实验群体间均无显著差异(P＞0.05)的指标共计3项,依次为第五腹节长/总长、额剑长/头胸甲长和尾节高/尾节长,各实验群体间的欧氏距离均达到显著水平(P＜0.01),且均有随耐氨氮性能差异的增大而呈显著增大的趋势;(3)经主成分分析,提取到的5个特征值均大于1的主成分,累计贡献率达85.940％,其中第1主成分的贡献率高达46.121％,其载荷绝对值大于0.5的主要影响变量占形态比例指标总数的64.706％;(4)将氨氮急性攻毒处理所获E实验群体定义为选留群,其余实验群体统归为淘汰群,经判别分析,所建的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86.75％,P2分别为88.20％和98.86％,两者综合判别准确率为92.88％.%A study was conducted to investigate the correlation between ammonia endurance and morphological traits of the post larva Marsupenaeus japonicus.Research specimens were kept under the following conditions prior to the experiment:water temperature 18.0±1.0℃,salinity 20,and pH 8.1±0.2.The post larva M.japonicus from the autumn propagation (body length 7.643±0.639mm),and ammonia-N as stress factor.After 96h experiment,when the survival rate of post larva was slightly less than 5％,the ammonia concentration was 52.37％,and taking this concentration as the ammonia acute toxicity experiment concentration.Using microscopic pixel measurement technology and multivariate analysis method to study the different morphological traits of five groups,A,B,C,D,E which represent the death groups of A (0-24h),B (24-48h),C (48-72h),D (72-96h) and the survival group of E (＞96h).The results showed that:(1) Among the 15 morphological traits,there were no significant differences in total length and fourth abdominal segment length between all groups;(2) Among the 17 trait proportions,there were no significant differences in 3 indexes which were fifth abdominal segment length / total length,rostrum length / carapace length,and telson height/telson length.The level of Euclidean distance was extremely significant difference (P＜0.01),and its significant difference increased with the increasing difference endurance to ammonia.(3) The results of the principle component analysis (PCA) showed that there are five principal components to be extracted whose eigenvalues were larger the 1.the accumulative contribution of the five principal components was 85.940％.The accumulative contribution of first principal component was 46.121％,and its absolute loading value was more than 0.5 which accounted for 64.706％ of the total proportion indexes.(4) In discriminate analysis,the groups A,B,C and D were concluded as elimination groups and group E was concluded as retention group.The independent variables were used to establish Fisher classification function equations which could clearly distinguish the individual in elimination groups and retention group.The result showed that the discriminate accuracy rate of individuals in retention group for P1 and P2 were 99％ and 88.20％ respectively.The discriminate accuracy rate of P1 and P2 for the elimination group was 86.75％ and 98.86％ respectively and the synthetic discriminate accuracy rate was 92.88％.
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