循环水系统中臭氧对大西洋鲑鱼福利影响机理研究

In order to obtain the high-quality seafood, fish welfare is addressed during culture progress. Healthy, clear, comfortable environment is the key to ensure fish welfare. Production of Atlantic salmon (salmo salar) in recirculating aquaculture systems (RAS) based on fish welfare is being considered as the trend of salmon breeding. Because of the low water-renew rate in RAS, kinds of toxic chemicals such as ammonia, colors are easily accumulated. Ozone as a strong oxidant plays an important role in optimizing water quality in RAS while overdose ozone produced oxidants (OPO) are harmful even fatal to aquatic animals. However there is limited information on how ozone impacts welfare of salmon and the perfect dose of ozone in RAS, and how to prevent the stress of overdose ozone in aquaculture. We proposed to investigate the mechanism of how ozonation influences the welfare of Atlantic salmon by the neuroendocrine response, the physiological change, and the effect at the whole-animal level. Firstly, the acute trail of ozone was carried out to analyze the tolerant and half-lethal dose of ozone in seawater. Based on acute toxic trail, the influence of ozonation, which produces OPO in water and the better hydrochemical-microbial environment for fish in RAS on immunity, cortisol, growth, feeding intake, gill tissue,and body color alteration of salmon is studied. It aims to reveal the mechanism of how ozone acutely/ chronically impacts the welfare of salmon. And this study would provide data on the influence of ozone on the aquatic animals, information to the further mechanical study on how ozone harms aquatic animals and guide of ozone utilization in aquaculture.

福利养殖是获得高质量水产品的必要途径，其核心是给养殖对象提供健康舒适的环境。基于鱼类福利的循环水养殖大西洋鲑被认为是未来鲑鱼养殖重要方向。臭氧作为强氧化剂在系统水质优化中具有重要作用，但过量会胁迫养殖动物甚至造成其死亡，一定程度上使臭氧在福利养殖中的应用受到限制。目前，臭氧如何影响大西洋鲑福利、大西洋鲑对臭氧响应机制如何，以期预防臭氧因子不良胁迫却罕有报道。本项目通过研究臭氧对大西洋鲑福利的急性影响，查明臭氧安全、致死浓度范围；通过研究循环系统中水体臭氧残留及优化的水质环境作为胁迫/有益因子对大西洋鲑内分泌、免疫、生理、组织、生长摄食、抗病力、体色变化等特征福利参数的急/慢性拮抗影响，从鲑鱼神经-内分泌、生理-生化-免疫、行为表现应激三级响应系统探究臭氧对鲑鱼福利影响的机理，填补臭氧对水产动物福利影响研究的空白，为臭氧对相关福利指标机制研究提供基础数据和科学依据，为臭氧的应用提供参考意见。

封闭循环水系统具有可控性、高效、环保、稳定和产品优质安全等诸多优点，正成为海水养殖重要生产模式。福利化循环水养殖是获得高质量水产品的必要途径，其核心是给养殖对象提供健康、舒适的环境。其中，臭氧作为强氧化剂在系统水质优化中具有重要作用，但过量会胁迫养殖动物甚至造成其死亡，使臭氧在福利养殖中的应用受到限制。在本基金的资助下，针对海水中臭氧测定方法多样、未有效统一，研究比较了碘化钾-N,N-二乙基-1,4-苯二胺（KI-DPD）分光光度法、靛蓝二磺酸钠褪色法、硼酸碘化钾比色法的重复性、检出限等，从而确定海水中臭氧残留较理想的测定方法，为海水循环水养殖系统臭氧浓度检测提供有效参考。针对海水中残留臭氧对养殖海水鱼类毒性问题，毒性实验发现长周期下即使臭氧残留浓度为0.02mg/LCl2仍会对游泳性鱼例如欧鲈和大西洋鲑造成毒性，引起其摄食量减少、活动能力下降。针对长周期下残留臭氧对养殖鱼类福利影响，从养殖鱼类的神经-内分泌，生理-生化-免疫到行为表现的应激三级响应系统揭示了臭氧对其福利急/慢性影响的规律：残留过量臭氧会破坏鱼类血液中红细胞，影响其气体运输，引起活动能力下降；破坏头肾等器官活力；氧化还原电位定向选择了养殖水环境微生物环境，从而可能影响到鱼类抵挡弧菌感染能力等。基于以上结论及臭氧对循环水系统水质及生物滤器影响，我们初步确认了海水游泳性鱼类的循环水养殖系统最适宜臭氧添加量应在300-320mV，系统臭氧添加量应按照系统日投饵量及投饵节奏有所协同。本研究将有助于充分发挥臭氧对海水游泳性鱼类福利的积极影响，推动循环水系统中福利养殖的开展，为包括大西洋鲑、欧鲈在内的游泳性海水鱼类循环水养殖提供科学依据和指导意见。