Optimising ammonia to improve sustainability in highly buffered recirculating aquaculture systems (RAS)

目前的Flip提案建立在BBSRC与Skretting(全球最大的水产养殖饲料生产商)合作的现有BBSRC产业合作伙伴奖的基础上。后一个IPA项目是基于一种新的饮食操作，这种操作已经被证明在实验室条件下将食物转化为生长的效率提高了20%。它使用活鱼的实验室研究来评估饲养水产养殖鱼类的能量成本和健康影响，然后设计最佳的饮食结构以将这些成本降至最低。它的目的是为鱼节省能量，特别是在进餐后的酸碱和盐平衡方面，并将这些自然干扰对呼吸气体交换和排泄过程的影响降至最低。目前的翻转提案将对上述由BBSRC资助的项目采用类似的办法。然而，尽管目前的BBSRC-IPA项目解决了饮食问题，但这项翻转提案具体解决了新发现的水质变化，这些变化特别与集约化循环水产养殖系统(RAS)有关。目前的翻转提案还与另一个翻转项目(从2015年6月开始)有关，因为这两个项目都源于密集RAS遇到的水质问题。具体地说，是人为提高了水的缓冲能力(作为水pH调节的一部分，提高了NaHCO3)。反过来，这会抑制鱼体内的氨排泄(通过缓冲通常为酸性的鳃边界层)，导致血氨增加，从而导致整个动物性能的不良变化。目前的翻转提议寻求利用学术界和工业界之间的双向交流来解决以前未考虑的因素，这些因素可能对鱼类的生物学和生长效率产生重大影响。通过促进学术和工业人员在各自地点之间的交流，该项目旨在解决与集约化循环水产养殖系统(RAS)相关的水化学方面的这些不理想的变化。它的目的是建立(最好是防止)以前未确认的鱼类能量成本，这些成本与这些水质问题引起的体内氨水平调节有关，这些问题可能损害健康、福利、生长，并最终损害水产养殖的生产效率。这是与安格尔西水产养殖有限公司(AAL)的合作，安格尔西水产养殖有限公司是欧洲最大的海洋RAS，也是英国唯一的鲈鱼养殖场，这种鱼是一种高价值和重要的商业鱼类。这种形式的陆上水产养殖因其在低用水量和最大限度减少废物造成的环境问题方面的可持续性而在全球范围内得到越来越多的推广。然而，水产养殖条件的强度造成了必须解决的水质问题，主要是鱼消耗氧气和排泄二氧化碳，使水酸化。为了解决这个pH问题，RAS操作员添加了大量的碱(氢氧化物或碳酸氢盐)。然而，这种pH补偿措施造成了进一步的水质问题，特别是高碱度(因此也就是缓冲容量)，而二氧化碳只有部分减少。已知这些次级变化会抑制鱼鳃排泄氨，提高体内血液中氨的水平，最终损害鱼类的一般生理和能量，并对其摄食和生长产生负面影响。通过促进知识和技能的双向转移(通过在对方现场直接借调一名学术人员和一名行业交流人员)，这个翻转项目旨在为这些特定的水质问题提供一个具有成本效益的、基于证据的解决方案(S)。此外，我们的目标是将通过学术和产业合作解决问题的文化嵌入到两个组织的结构中，以便能够及时避免或缓解与可持续渔业生产相关的未来问题。

The current FLIP proposal builds upon an existing BBSRC Industrial Partnership Award in collaboration with Skretting (the largest global producer of aquaculture feed). The latter IPA project is based on a novel manipulation of diets that has already been demonstrated to improve the efficiency of converting food into growth by a remarkable 20 % under laboratory conditions. It uses laboratory studies with live fish to assess the energetic costs and health implications of feeding in aquaculture fish, and then to design optimal diet compositions to minimise these costs. It aims to make energetic savings for the fish in particular regarding acid-base and salt balance following a meal, and minimise how these natural disturbances impact upon respiratory gas exchange and excretory processes. The present FLIP proposal will use similar approaches to the above current BBSRC-funded project. However, whereas the current BBSRC-IPA project addresses dietary issues, this FLIP proposal specifically addresses newly discovered water quality changes that are particularly associated with intensive recirculating aquaculture systems (RAS). The present FLIP proposal is also linked to another FLIP project (started June 2015) as both stem from water quality issues experienced by intensive RAS. Specifically the artificially enhanced buffer capacity of the water (raised NaHCO3 as part of the regulation of water pH). In turn this inhibits ammonia excretion in fish (through buffering of the normally acidic gill boundary layer), causing increases in blood ammonia which can result in undesirable changes in whole animal performance. The present FLIP proposal seeks to use a 2-way interchange between academia and industry to address previously unconsidered factors that can have a major influence on the biology and efficiency of growth in fish. By facilitating an interchange of academic and industrial personnel between their respective sites this project aims to address these non-ideal changes in water chemistry associated with intensive recirculating aquaculture systems (RAS). It aims to establish (and ideally prevent) previously unrecognised energetic costs for fish associated with regulation of internal ammonia levels caused by these water quality issues that can impair health, welfare, growth and ultimately the production efficiency in aquaculture. It is a collaboration with Anglesey Aquaculture Ltd (AAL), the largest marine RAS in Europe and the UK's only farm for seabass, a high value and commercially important fish. This form of land-based aquaculture is increasingly promoted worldwide due to its sustainability in terms of low water use and minimising environmental problems from waste products. However, the intensity of the aquaculture conditions creates water quality problems that must be countered, primarily a consumption of oxygen and excretion of carbon dioxide by the fish that acidifies the water. To deal with this pH problem RAS operators add huge amounts of alkali (hydroxide or bicarbonate). However, this pH compensation measure creates a further water quality issue, specifically high alkalinity (and therefore buffer capacity), whilst CO2 is only partially reduced. These secondary changes are known to inhibit the excretion of ammonia by fish gills, raising internal blood levels of ammonia, and ultimately impair the general physiology and energetics of fish, and negatively impacting their feeding and growth. By facilitating a 2-way transfer of knowledge and skills (via direct secondments of one academic and one industry interchanger, at each other's site), this FLIP project aims to provide a cost-effective, evidence-based solution(s) to these specific water quality issues. Furthermore, we aim to embed a culture of problem-solving through academic-industrial collaboration into the fabric of both organisations such that future problems associated with sustainable production of fish can be avoided or mitigated in a timely fashion.