Identification and ecological assessment of environmental stressors on fish population using genetic biomarkers

为了识别和评估不同种群面临的环境应激源，研究了采自不同地点的鱼类种群间遗传生物标志物的差异。首先，研究了扩增片段长度多态(AFLP)方法在鱼类中的应用，以获得鱼类种群间遗传变异的可靠数据，并发现测量二维数据(荧光强度与基因片段长度)可以满足这一目的。与来自其他栖息地的种群相比，该方法在过去经历过大量鱼类捕杀的小毒蛾种群中测得的遗传变异较小。此外，AFLP方法分类的每个种群的不同基因类型的组成对于那些生活在受到特殊环境应激因素影响的种群来说是特殊的，例如来自农业废水的隔离或农用化学品影响。此外，多环芳烃(PAHs)的污染与每个鱼类种群中不同基因类型的组成有关。换句话说，较高浓度的多环芳烃增加了每个鱼类种群中特定基因的组成。多环芳烃的主要应激源--荧光对不同生境鱼类种群的急性毒性(50%致死浓度和50%有效浓度)有显著差异。这表明，不同生境的环境荧蒽污染程度不同，其对荧菲的耐受性也不同。本研究表明，AFLP方法测定的遗传变异性和基因分型可用于鱼类种群环境应激源的识别和评估。

Difference of genetic biomarkers among fish (Pseudorasbora parvac) populations collected from various sites was examined in order to identify and assess the environmental stressors on each population. First, application of Amplified Fragment Length Polymorphism (AFLP) method to fish was studied for obtaining reliable data on genetic variability among fish populations and measurement of two-dimensional data (strength of fluorescence vs. length of gene fragment) was found to be acceptable for this purpose.The genetic variability measured by the proposed method in Pseudorasbora parvac population which experienced large fish kill in the past was small compared to those taken from other habitats. Also the composition of different genotypes in each population classified by AFLP method was found to be special for those populations that live in sites impacted by special environmental stressors such as isolation or agrochemical impact from agricultural effluent. Furthermore, the pollution by polycyclic aromatic hydrocarbons (PAHs) was found to be related to the composition of different genotypes in each fish population. In other words, higher concentration of PAHs increased the composition of a certain genotype in each fish population. The acute toxicity (50% lethal concentration (LC_<50>) and 50% effective concentration (EC_<50>)) of Pseudorasbora parvac to fluoranthene, which was indicated to be the main stressor among PAHs, was significantly different among the fish populations taken from different habitats. This indicated that tolerance of Pseudorasbora parvac to luoranthene was varied due to the difference of environmental fluoranthene pollution in each habitat.This study showed that genetic variability and genotype measured by AFLP method can be used to identify and assess the environmental stressors to fish population.