DE-RISKING RAS - Developing best practice for RAS bio-filters: regular 'maintenance' dosing vs. seed only dosing

2019冠状病毒病大流行凸显了缩短粮食供应链的必要性。目前，英国消费的53%的食物是在这里生产的，但我们是海鲜的净进口国。然而，由于海洋鱼类资源目前被过度捕捞，英国海产品生产的可持续增长作为任何绿色复苏的关键部分将不得不来自水产养殖。循环型水产养殖系统（RAS）是一种陆上、基于水箱的水产养殖系统，其中的水通过包括生物过滤器在内的水修复系统进行再利用。开发RAS是为了解决传统水产养殖所造成的问题：环境退化、疾病或寄生虫的风险（例如大西洋鲑鱼的海虱）以及远离最终市场导致运输成本和排放高的地点。通过封闭的系统和受控的条件，RAS可以解决这些问题，并为英国消费者提供更可持续的海鲜来源。然而，为了实现这一目标，RAS需要克服一些关键的挑战。其中最重要的是硫化氢（H2S）的风险——RAS系统中的一种强效毒素。毒素峰值的威胁以及由此造成的昂贵种群的损失限制了RAS的生长；相反，解决这一问题的行之有效的方法将有助于扩大这种替代传统水产养殖的可持续方法。目前RAS操作员的主要方法是在启动系统时用细菌“播种”一个生物过滤器，期望细菌的生长有助于控制系统中产生的毒素，如氨或亚硝酸盐。这种“播种后退一步”的方法可能导致细菌种类的次优组合，随后毒素激增。例如，当硫酸盐还原菌（如弧菌）在RAS的生物过滤器中积累时，它们会产生H2S。该项目旨在证明一种创新的新方法——“维持剂量”的有效性。我们的目标是证明在RAS生物过滤器中定期添加特定选择的细菌可以提供以下主要好处：*与只使用初始应用相比，微生物组更可预测和控制；*防止弧菌的增殖，从而降低H2S的风险；*防止土臭素和MIB（海产品中常见的污染物，导致“异味”）的存在。在英国或世界各地的RAS设施中，“维护剂量”都不是常见的做法。证明这种创新方法具有上述物质利益将有助于它成为该行业的“标准做法”，从而促进可持续RAS作为传统水产养殖的替代方案的扩展。英国大虾（GBP）和Nova Q率先采用了这种“维持剂量”方法，并在GBP的商业对虾养殖场取得了成功的结果。然而，没有公开的、重复的试验来提供数据来支持这些结果。该项目旨在填补这一空白。Great British Aquatech （GBP的研发子公司）和Nova Q与苏格兰首屈一指的独立海洋科学组织-苏格兰海洋科学协会（SAMS）合作开展该项目。

The Covid pandemic has shone a light on the need for shorter food supply chains. Currently 53% of food consumed in the UK is produced here, but we are a net importer of seafood. However, with marine fish stocks currently over fished, sustainable growth in UK seafood production as a key part of any Green Recovery will have to come from aquaculture.Recirculating Aquaculture Systems (RAS) are an on-land, tank-based aquaculture system, where water is reused having been put through water remediation systems including bio-filters.RAS are being developed as a potential solution to the issues posed by conventional aquaculture: environmental degradation, the risk of disease or parasites (sea-lice in Atlantic Salmon, for instance), and locations far from final markets leading to high transport costs and emissions.With closed systems and controlled conditions, RAS can solve these problems and provide a more sustainable source of seafood for UK consumers.However, to achieve this, RAS need to overcome key challenges. Foremost among these is the risk of Hydrogen Sulphide (H2S) - a potent toxin in RAS systems. The threat of toxin spikes and so the loss of expensive stock has limited the growth of RAS; conversely, a proven method for solving this problem would help the expansion of this sustainable alternative to conventional aquaculture.The dominant current approach by RAS operators is to 'seed' a bio-filter with bacteria when they start a system, in the expectation that the bacteria that develop with help to control toxins produced in the system, such as ammonia or nitrite. This 'seed and step back' approach can lead to sub-optimal combinations of bacteria species developing, with subsequent spikes in toxins. For instance, when sulphate reducing bacteria (e.g. _Vibrio sp._) are allowed to accumulate in the bio-filters of RAS, they will produce H2S.This project aims to prove the validity of an innovative new approach - 'maintenance dosing'. We aim to prove that the addition of regular applications of specifically chosen bacteria to a RAS bio-filter provides the following key benefits:* more predictable and controlled micro-biome when compared to only applying a starting application;* prevents the proliferation of _Vibrio sp._, therefore reducing the risk of H2S;* prevents the presence of Geosmin and MIB (common contaminants in seafood, resulting in 'off-flavour' taste).'Maintenance dosing' is not common practice in RAS facilities either in the UK or Worldwide. Proof that this innovative approach had the material benefits outlined above would help it become 'standard practice' in the industry, and so facilitate the expansion of sustainable RAS as an alternative to conventional aquaculture.Great British Prawns (GBP) and Nova Q have pioneered this 'maintenance dosing' approach, with successful results achieved in GBP's commercial prawn farm. However, no publicly available, replicated trials have been conducted to provide the data to support these results. This project aims to fill that gap. Great British Aquatech (GBP's R&D subsidiary) and Nova Q have partnered with Scotland's premier independent marine science organisation - the Scottish Association for Marine Science (SAMS) - to conduct this project.