氨氮急性胁迫对大菱鲆幼鱼的毒性效应

Toxic Effects of Acute Ammonia Stress on Young Turbot Scophthalmus maximus

中文关键词: 大菱鲆  氨氮急性胁迫  血浆生理指标

英文关键词: Scophthalmus maximus  Acute ammonia toxicity  Plasma physiological indexes

中文摘要:

      本研究采用96 h半静态毒性实验方法，研究了氨氮对大菱鲆(Scophthalmus maximus)幼鱼的急性毒性效应和血浆生理指标的影响。结果显示，在水温为(19.0±0.5)℃、pH为7.85、盐度为29.5和溶解氧为(7.8±0.2) mg/L的环境条件下，平均体重为(163.90±15.31) g的大菱鲆幼鱼，总氨(TAN)和非离子氨(NH3-N)96 h的半致死浓度(LC50)分别为39.73和0.64 mg/L。氨氮浓度、暴露时间及二者交互作用对血浆肾上腺素(EPI)、皮质醇(Cortisol)、超氧化物歧化酶(SOD)、还原型谷胱甘肽(GSH)、碱性磷酸酶(AKP)和血糖(GLU)含量/活性都存在显著影响；血浆EPI、SOD、GSH、AKP和GLU随氨氮浓度升高响应时间提前，EPI、皮质醇、AKP和GLU随暴露时间延长总体呈现先升后降的趋势；致死高浓度胁迫(TAN浓度70.96和84.11 mg/L)下，血浆SOD和GSH在胁迫期(12 h)内快速升高，GLU快速升高(4 h)后急剧降低(12 h)，暗示氨氮急性致死的原因与氧化应激损伤、生理代谢紊乱和呼吸功能受损有关。本结果可为大菱鲆大规格幼鱼的养殖管理和行为数值模拟提供基础资料。

英文摘要:

      Ammonia can easily form in intensive culture systems due to the ammonification of uneaten food and animal excretions, and usually results in detrimental health effects to teleost. The aim of this study was to provide a reference value for the safe regulation and control of ammonia in the aquaculture of turbot, Scophthalmus maximus, and obtain the corresponding biomarkers of blood physiological indexes under acute ammonia stress. The acute toxicity effects of ammonia on young turbot [average body weight (163.90±15.31) g] were studied with a 96 h half-static toxicity test. The effects of different ammonia concentrations and exposure times on plasma physiological indexes were determined. The results showed that the semi-lethal concentration (LC50) of total ammonia (TAN) and non-ionic ammonia (NH3-N) for 96 h were 39.73 mg/L and 0.64 mg/L, respectively, when the sea water temperature was (19.0±0.5)℃, pH value 7.85, salinity 29.5, and dissolved oxygen (7.8±0.2) mg/L. The plasma epinephrine (EPI), cortisol (cortisol), superoxide dismutase (SOD), reduced glutathione (GSH), alkaline phosphatase (AKP), and blood glucose (GLU) contents or activities were significantly affected by both the ammonia concentration and exposure time. Furthermore, the interaction between ammonia concentration and exposure time also significantly impacted these indexes. The response time of plasma EPI, SOD, GSH, AKP, and GLU advanced with the increasing of ammonia concentration, while EPI, cortisol, AKP, and GLU showed a trend of increasing first and then decreasing with prolonged exposure. These plasma physiological indexes can be used as biomarkers for acute ammonia toxicity. The plasma physiological responses of the high concentration toxic group were characterized by their plasma SOD and GSH rapidly increasing over the exposure period (within 12 h), and GLU rapidly increased at 4 h and decreased sharply before death. The results suggested that the death of juveniles under acute ammonia toxicity may be due to oxidative stress, physiological metabolic disorders, and impaired respiratory function.