Abstract Florfenicol (FLO) is the most commonly used antibiotic in aquaculture for various fish bacterial disease treatments. To ensure that low amounts of residue occur in cultured aquatic products, it is important to study the depletion of antibiotics in the process of aquaculture. Recirculating aquaculture system (RAS) is a promising aquaculture model with high water utilization that could effectively reduce nutrient concentrations; however, the fate of antibiotics under recirculating conditions is still unclear. In the present study, European seabass (Dicentrarchus labrax) were fed with FLO-medicated feeds at 10 mg/kg body weight/d for 10 d and the FLO depletion from water and tissues in RAS and flowing aquaculture system (FAS) cultures for 20 d were evaluated. The FLO residues in the RAS and FAS outlet peaked at 3 h and decreased to levels comparable to the pretreatment level at 12 h. With prolonged feeding, FLO was prone to accumulate in the RAS and peaked at 2.06 μg/L at 10 d of treatment, which was significantly higher than that in the FAS. To further compare the contributions among the water treatment units in the RAS, protein skimmer showed the most effective depletion of FLO, and then UV disinfection device and biofilter. Moreover, FLO showed the highest bioconcentration factors (BCF) values in the gill and the BCFs in muscle and liver from fish in the RAS were higher than that in the FAS. The present study reports the FLO depletions in a saltwater RAS for the first time and evaluates the contributions of different treatment units of the RAS on FLO depletion. The results showed the preliminary distribution of FLO in the RAS, which is valuable information for applying antibiotics in aquaculture and the designing water treatment units for RASs.

中文翻译：

---

Dicentrarchus labrax海水循环流动水产养殖系统中含氟苯尼考饲料输送研究

摘要 氟苯尼考（FLO）是水产养殖中最常用的抗生素，用于治疗各种鱼类细菌性疾病。为确保养殖水产品中出现少量残留，研究水产养殖过程中抗生素的消耗非常重要。循环水产养殖系统（RAS）是一种很有前景的水产养殖模式，其水资源利用率高，可以有效降低养分浓度；然而，抗生素在循环条件下的命运仍不清楚。在本研究中，欧洲鲈鱼 (Dicentrarchus labrax) 以 10 毫克/千克体重/天的剂量喂食含 FLO 的饲料，持续 10 天，在 RAS 和流动水产养殖系统 (FAS) 培养中，水和组织中的 FLO 消耗达 20 d 进行了评估。RAS 和 FAS 出口中的 FLO 残留在 3 小时达到峰值，并在 12 小时下降到与预处理水平相当的水平。随着饲喂时间的延长，FLO 容易在 RAS 中积累，并在处理 10 d 时达到 2.06 μg/L 的峰值，显着高于 FAS。为了进一步比较 RAS 中水处理装置之间的贡献，蛋白质分离器显示出最有效的 FLO 消耗，然后是紫外线消毒装置和生物过滤器。此外，FLO 显示鳃中的生物浓缩因子（BCF）值最高，RAS 中鱼的肌肉和肝脏中的 BCF 值高于 FAS。本研究首次报告了咸水 RAS 中 FLO 的消耗，并评估了 RAS 的不同处理单元对 FLO 消耗的贡献。