Hg2+对克隆牙鲆和普通牙鲆的急性毒性

以相同规格的牙鲆Paralichthys olivaceus普通群体为对照,采用静水生物测试法开展了Hg2+对牙鲆克隆群体的急性毒性实验,实验所用幼鱼为130日龄,体长为(12.38±1.13)cm,体质量为(17.97±5.79)g。实验期间,水温为(21±1.2)℃,pH为8.1-8.3,盐度为31.0,硬度6200 mg/L,连续充气保证溶氧充足。研究表明,实验初始阶段,高浓度组克隆牙鲆在容器内躁动不安,上升到水面沿池壁缓慢转圈游动,一段时间后安静伏在池底;而普通牙鲆则仅个别鱼在水面游动,多数静止在池底不动。随中毒程度加深,用玻璃棒触碰普通牙鲆时,其反应剧烈,在水中侧翻、打转、急速游动或上下窜动,而克隆牙鲆则仅沿池底缓慢游动。最终克隆牙鲆和普通牙鲆均身体僵直,失去呼吸能力死亡。Hg2+对克隆牙鲆的24、48、96 h的半致死质量浓度分别为1.50、0.86、0.84 mg/L,而对普通牙鲆的半致死质量浓度则分别为1.93、1.04、0.90 mg/L。结果表明,克隆牙鲆对Hg2+的耐受性弱于普通牙鲆,对Hg2+更加敏感。从死亡过程看,各处理组的克隆牙鲆从出现死亡个体开始,死亡时间集中在8 h内,具有同步性;普通牙鲆则在实验期间陆续出现死亡,持续时间较长,同步性较差。

Acute toxicity of Hg2+ to clonal and common Japanese lounder Paralichthys olivaceus

Clones are defined as groups of genetically identical fish. It is unclear whether clonal fish have identical reactions to toxicants. To address this question we used the static test method to investigate the acute toxicity of Hg^2＋ to clonal and common Japanese flounder, Paralichthys olivaceus. The clonal and common Japanese flounder in the experiments were produced by Beidaihe Central Experiment Station, with the average body length of （ 12. 38 ± 1.13 ） cm and the average body weight of （ 17.97 ±5.79） g. Fully aerated and fihered seawater temperature （ 21± 1.2 ） ℃, pH 8.1 - 8.3, salinity 31.0, and hardness 6200 mg/L] was used in the tests. The results showed that the clonal Japanese flounder treated with high concentration of Hg^2＋ first became anxious, rose to the water surface, and swam around in the aquarium, before they eventually stayed still at the bottom of the aquarium. The majority of common Japanese flounder treated with high concentration of Hg^2＋ remained at the bottom all the time, except for only a few that occasionally swam to the surface. As the poisoning aggravated over the time, the common Japanese flounder began to rotate, swam rapidly or jumped up and down when touched by a glass rod; in the contrast, clonal Japanese flounder swam slowly around the aquarium regardless of the touch. Both the clonal and common Japanese flounder eventually stopped breathing and died with rigid bodies. At 24, 48 and 96 h, the median lethal concentrations of Hg^2＋ to clonal Japanese flounder were 1.50, 0.86, and 0.84 mg/L respectively. The values of common Japanese flounder were 1.93, 1.04, and 0. 90 mg/L respectively. These results suggested that the clonal Japanese flounder was more sensitive to Hg^2＋ than the common Japanese flounder. A trend was ob- served in all groups of clonal Japanese flounder that they mainly died during the 8 hours starting from the occurrence of the first death; however, the death of the common Japanese flounder occurred evenly during the whole experiment.