Extreme temperatures from marine heatwaves may seriously affect the growth and immunity of aquaculture species and trigger disease outbreaks. Vitamin C supplements in the diets can improve the performance of farmed fish. However, it is unknown how extreme temperatures may alter the effects of dietary vitamin C on fish. To address the issues, we cultured juvenile Waigieu seaperch, Psammoperca waigiensis, with one of three dietary vitamin C levels (0, 100 and 400 mg/kg diet) and two temperatures (28 and 32째C). We comprehensively assessed the growth, food utilization, immunity and pathogen resistance of P. waigiensis. Extreme temperature reduced survival, growth, feed utilization, protein and lipid contents, and immunological parameters. Fish fed with dietary vitamin C significantly improved growth, feed utilization, body protein, lipid contents, and haematological and immunological parameters in a dose-dependent manner. Vitamin C effects on these parameters were similar across two temperatures. Fish challenged with Streptococcus iniae showed faster mortality at 32째C than at 28째C. Fish fed with dietary vitamin C had lower mortality, especially at 28째C. These results illustrate that extreme temperature weakened dietary vitamin C effect on the fish resistance to bacteria, challenging fish production under the increasing prevalence and severity of marine heatwaves.

中文翻译：

---

极端温度不同程度地改变了日粮维生素 C 对 Waigieu seaperch、Psammoperca waiigiensis 生长、免疫和病原体抗性的影响

海洋热浪带来的极端温度可能会严重影响水产养殖物种的生长和免疫力，并引发疾病爆发。饮食中的维生素 C 补充剂可以提高养殖鱼类的性能。然而，尚不清楚极端温度会如何改变膳食维生素 C 对鱼类的影响。为了解决这些问题，我们培养幼Waigieu鲈鱼，Psammoperca waigiensis，具有以下三种膳食维生素C水平（0，100和400毫克/千克饮食）和两种温度（28和32 째 C）。我们综合评估了P的生长、食物利用、免疫和病原体抗性。外江人. 极端温度会降低存活率、生长、饲料利用率、蛋白质和脂质含量以及免疫参数。用膳食维生素 C 喂养的鱼以剂量依赖性方式显着改善生长、饲料利用率、身体蛋白质、脂质含量以及血液学和免疫学参数。维生素 C 对这些参数的影响在两个温度下相似。用海豚链球菌 攻击的鱼在 32°C 比在 28°C 显示出更快的死亡率。用膳食维生素 C 喂养的鱼死亡率较低，尤其是在 28°C 时。这些结果表明，极端温度削弱了膳食维生素 C 对鱼类对细菌抵抗力的影响，在海洋热浪日益流行和严重的情况下对鱼类生产提出了挑战。