A two-fold integrated research study was conducted; firstly, to understand the effects of copper (Cu) and zinc (Zn) on the growth and oxidative stress in Nile tilapia, Oreochromis niloticus; secondly, to study the beneficial effects of the duckweed Lemna minor L. as a heavy metal remover in wastewater. Experiments were conducted in mesocosms with and without duckweed. Tilapia fingerlings were exposed to Cu (0.004 and 0.02 mg L−1) and Zn (0.5 and 1.5 mg L−1) and fish fed for four weeks. We evaluated the fish growth performance, the hepatic DNA structure using comet assay, the expression of antioxidative genes (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPx and glutathione-S-transferase, GST) and GPx and GST enzymatic activity. The results showed that Zn exhibited more pronounced toxic effects than Cu. A low dose of Cu did not influence the growth whereas higher doses of Cu and Zn significantly reduced the growth rate of tilapia compared to the control, but the addition of duckweed prevented weight loss. Furthermore, in the presence of a high dose of Cu and Zn, DNA damage decreased, antioxidant gene expressions and enzymatic activities increased. In conclusion, the results suggest that duckweed and Nile tilapia can be suitable candidates in metal remediation wastewater assessment programs.

中文翻译：

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浮萍、浮萍调节尼罗罗非鱼、Oreochromis niloticus 中重金属诱导的氧化应激

进行了一项双重综合研究；首先，了解铜(Cu)和锌(Zn)对尼罗罗非鱼Oreochromis niloticus生长和氧化应激的影响；其次，研究浮萍作为废水中重金属去除剂的有益效果。实验在有浮萍和没有浮萍的中宇宙中进行。罗非鱼鱼种暴露于铜（0.004 和 0.02 毫克 L-1）和锌（0.5 和 1.5 毫克 L-1），鱼被喂食 4 周。我们评估了鱼的生长性能、使用彗星试验的肝脏 DNA 结构、抗氧化基因的表达（超氧化物歧化酶，SOD；过氧化氢酶，CAT；谷胱甘肽过氧化物酶，GPx 和谷胱甘肽-S-转移酶，GST）以及 GPx 和 GST 酶活性。结果表明，Zn 表现出比 Cu 更显着的毒性作用。与对照相比，低剂量的铜不影响罗非鱼的生长，而高剂量的铜和锌显着降低了罗非鱼的生长速度，但浮萍的添加阻止了体重减轻。此外，在高剂量铜和锌的存在下，DNA 损伤减少，抗氧化基因表达和酶活性增加。总之，结果表明浮萍和尼罗罗非鱼可以作为金属修复废水评估计划的合适候选物。