The incidence and dispersal of invasive alien fish species (IAFS) have ecological impacts on biodiversity and environmental health at regional to global scales. We identified links between the presence of largemouth bass (L_b) and bluegill (B_g), and selected indicators of environmental water quality, trophic and tolerance guilds, ecological health factors, and stream order. We used the data collected from national biomonitoring study sites in four major rivers of South Korea. IAFS occurred in eutrophic waters (L_b = total phosphorus: 140 ± 170 µg/L, chlorophyll a: 16.7 ± 27.5 µg/L; B_g = total phosphorus: 160 ± 190 µg/L, chlorophyll a: 19.43 ± 28.05 µg/L) and dominated at higher ambient ratios of total nitrogen to total phosphorus (TN:TP). At TN:TP ≤ 100, the relative abundance of L_b and B_g was highest (95.3% and 96.0%, respectively). Concerning tolerance guilds, L_b (R² = 0.78, p < 0.0001) and B_g (R² = 0.59, p < 0.0001) had positive relationships with tolerant species in all four river watersheds and negative relationships with the percentages of insectivores and omnivores. This indicates the harmful impacts of IAFS on the aquatic food web. These invasive fish species also influenced stream health, particularly in the Nakdong and Yeongsan/Seomjin rivers. Our findings suggest that assessing chemical water quality can help identify the optimal and suboptimal survival and spread ranges of IAFS (L_b and B_g), as they directly influence tolerance and trophic guilds in the aquatic food web. In conclusion, these IAFS could be a major factor in the deteriorating ecosystem health, which had negative relationships with the abundance and occurrence of IAFS. Therefore, approaches that use appropriate water chemistry factors and species tolerance may provide critical insights into the efficient management of river health that has been perturbed by the presence of IAFS.

中文翻译：

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外来鱼类物种的相对丰度和入侵动态与化学条件，生态系统健康，原生鱼类组成和河流秩序有关

外来入侵鱼类的发生和扩散对区域乃至全球范围的生物多样性和环境健康都具有生态影响。我们确定了大嘴鲈（L _b）和蓝_g（B _g）的存在之间的联系，并选择了环境水质，营养和耐受性协会，生态健康因素以及水流次序的指标。我们使用了从韩国四个主要河流的国家生物监测研究站点收集的数据。IAFS发生在富营养化的水中（L _b =总磷：140± 170μg / L，叶绿素a：16.7±27.5μg/ L; B _g=总磷：160±190 µg / L，叶绿素a：19.43±28.05 µg / L），并且在总氮与总磷（TN：TP）的较高环境比下占主导地位。在TN：TP≤100时，L _b和B _g的相对丰度最高（分别为95.3％和96.0％）。关于公差协会，L _b（R ² = 0.78，p <0.0001）和B _g（R ² = 0.59，p<0.0001）与所有四个河流流域的耐性物种呈正相关，与食虫和杂食动物的百分比呈负相关。这表明IAFS对水生食物网的有害影响。这些外来鱼类也影响了溪流的健康，特别是在那洞河和荣山/城津河。我们的研究结果表明，评估化学水质量可以帮助确定IAFS的最佳和次佳存活率和传播范围（L _b和B _g），因为它们直接影响水生食物网中的耐受性和营养协会。总之，这些IAFS可能是生态系统健康状况恶化的一个主要因素，而生态系统健康与IAFS的丰富程度和发生呈负相关。因此，使用适当的水化学因素和物种耐受性的方法可能会为有效管理河流健康提供关键见解，而IAFS的存在已使河流健康受到干扰。