Nowadays, depletion of oxygen or hypoxia has become a real concerning problem worldwide in freshwater, marine, and estuarine ecosystems and very often co-occurs with xenobiotics. Even though the acute and severe hypoxia is heavily studied in environment and laboratory studies, the in situ combined effects of these stressors on freshwater lake organisms are poorly understood. The current study sought to understand how the combined effects of moderate hypoxia, pesticides and PCBs affect the biochemistry, physiology and organ morphology of Carassius carassius, residing in the Lake Seferani, Dumrea region (Elbasan, Albania), a natural karst freshwater system declared as Nature Monument situated in central Albania. Crucian carp is used as a model organism, because of its residency and ecological relevance to the Lake, as well as for its amenability for the environmental toxicology studies. For this purpose, blood, liver and kidney samples of fish were processed for hematological, biochemical and histopathological analysis. We found a significant increase of blood glucose (GLU), cortisol levels, hematocrit (PCV) and hemoglobin (Hb) which clearly indicate the presence of stress in fish. Based on the histopathological evaluation and organ index results, liver and kidney organs displayed moderate-to-heavy histological-architecture changes. Our results provide a strong evidence that both, hypoxia and the presence of pesticides and PCB congeners found in Seferani Lake, put a heavy load on C. carassius energy metabolism and endocrine system, leading to an elevation of the biochemical and physiological parameters (hemoglobin level, hematocrit, glucose and cortisol), as well as the histopathological alterations. Additionally, in the presence of moderate hypoxia, the toxic effects of pesticides and PCBs on C. carassius are exacerbated. Further studies are needed to evaluate possible effects of pesticide and PCBs toxicity in human health, since crucian carp has an economic value for the population of the zone and it is used often as food sustenance. Elucidation of these kinds of responses can better improve our understanding of response of highly tolerant species, like Carassius carassius, to multiple stressors interactions, helping us to better predict and manage the consequences of the exposure of the freshwater biota to complex stressors in an environment that changes rapidly.

如今，氧气的消耗或缺氧已成为全球淡水，海洋和河口生态系统中一个令人担忧的现实问题，并且经常与异种生物同时发生。即使在环境和实验室研究中已对急性和严重缺氧进行了大量研究，但对于这些压力源对淡水湖泊生物的原位综合作用了解甚少。当前的研究试图了解中度缺氧，农药和多氯联苯的综合影响如何影响of鱼的生物化学，生理和器官形态，居住在杜姆雷亚地区塞弗拉尼湖（阿尔巴尼亚Elbasan）的天然喀斯特淡水系统被称为阿尔巴尼亚中部的自然纪念碑。鱼由于其居所和与湖泊的生态相关性以及对环境毒理学研究的适应性而被用作典范生物。为此，对鱼的血液，肝和肾样本进行了血液，生化和组织病理学分析。我们发现血糖（GLU），皮质醇水平，血细胞比容（PCV）和血红蛋白（Hb）显着增加，这清楚地表明了鱼类中存在压力。根据组织病理学评估和器官指标结果，肝和肾器官显示出中度到重度的组织结构变化。我们的结果提供了有力的证据表明，C. car鱼能量代谢和内分泌系统，导致生化和生理参数（血红蛋白水平，血细胞比容，葡萄糖和皮质醇）升高，以及组织病理学改变。另外，在中度缺氧的情况下，农药和多氯联苯对car鱼的毒性作用加剧。由于cru鱼对这一地区的人口具有经济价值，而且经常被用作食物的来源，因此需要进一步的研究来评估农药和PCBs毒性对人类健康的可能影响。阐明这些反应可以更好地增进我们对高耐受性物种（例如Car鱼）的反应的理解到多个压力源的相互作用，帮助我们更好地预测和管理在瞬息万变的环境中淡水生物群系暴露于复杂压力源的后果。