The tolerance of aquatic organisms to stressors is widely used to monitor and evaluate the condition of freshwater ecosystems. Tolerance values (TV) derived from analyses of the relationship between species and their environment are considered to be more objective than those that rely on expert opinion. We used principal component analysis (PCA) to derive a generalized stressor gradient based on physicochemical characteristics and physical habitat quality and structure. Scores of the first principal component axis (PC1) were used to estimate TV for 37 fish species collected from 54 sites in the Karun River basin, Iran. PCA of 17 variables identified stressors that were influential such as total phosphate, total nitrogen, total coliform, and habitat and morphological score. The species were separated into three categories on the stressor gradient: sensitive (18.9%), semi-tolerant (48.6%), and tolerant species (32.4%). Based on these results we developed the Karun Fish Tolerance Index (KFTI) and demonstrated that it performed well in separating the least, moderate, and most disturbed sites in the study area. The discrimination efficiency of the KFTI was 82.5%, which makes it a robust management tool for the protection and conservation of streams and rivers in the Karun River watershed. TV developed here reflect objective characteristics of the sensitivity of fish species to the predominant stressors in the Karun and similar systems.

中文翻译：

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使用基于鱼类的耐受指数对中东河流域进行环境影响评估和保护规划

水生生物对应激源的耐受性被广泛用于监测和评估淡水生态系统的状况。通过分析物种与其环境之间的关系得出的耐受值（TV）被认为比依赖专家意见的耐受值更客观。我们使用主成分分析（PCA）根据物理化学特征和物理栖息地质量和结构得出广义压力源梯度。第一主成分轴 (PC1) 的分数用于估计从伊朗卡伦河流域 54 个地点收集的 37 种鱼类的 TV。17 个变量的 PCA 确定了有影响的压力源，例如总磷酸盐、总氮、总大肠菌群以及栖息地和形态评分。根据应激梯度将物种分为三类：敏感物种（18.9%）、半耐受物种（48.6%）和耐受物种（32.4%）。根据这些结果，我们制定了卡伦鱼耐受性指数 (KFTI)，并证明它在区分研究区域中最少、中等和最受干扰的地点方面表现良好。KFTI 的区分效率为 82.5%，这使其成为卡伦河流域溪流和河流保护和养护的强大管理工具。这里开发的电视反映了鱼类对卡伦和类似系统中主要压力源的敏感性的客观特征。