Safeguarding fish health - In situ water quality analysis in RAS aquaculture systems using living cell sensors and micro/nanotechnology

A microfluidics-based device as in-situ sensor for water quality in fish production was developed and tested in the project. The device incorporates living Aliivibrio fischeri organisms which causing reduced bioluminescent responses due exposure to stressors causing suboptimal water quality for fish. The responses of the living cell biosensor to water quality stressors such as toxic metals, ammonia and nitrite, all known to causing suboptimal water quality in fish production in recirculating aquaculture systems (RAS), were identified separately and in combination. The results were based on a detailed analysis of the decreasing bioluminescent response of the living cells. Further, the living cell testing platform incorporating microelectronics and micro-biotecnology were presented as a design for the purpose of in-situ monitoring of A. fischeri responses. The results indicate that the technology have potential, but more optimalisations need to be done before the analysis platform could be used commercially to provide early warning of suboptimal water quality in RAS systems. The investigations were conducted in cooperation with a team of experts from Centre of Excellence for Environmental Radioactivity (CERAD CoE), at the Norwegian University of Life Sciences, and Institute for Microsystems (IMS) at the University of South-Eastern Norway. Outcomes of the research are documented in international peer review publications.

The project demonstrated the potential of bioluminescent bacteria to monitoring toxicity of nitrite, un-ionized ammonia, metal cations, and other common stressors in recirculated aquaculture water. A microfluidic chip and a bioelectronic platform were designed and developed for toxicity tests of water from RAS. The project promoted great level of interdisciplinary, involving microbiology, microfluidics, optics, electronics, micro/nanotechnology, etc. Further, the research activities have enhanced international cooperation, with Chinese universities in this case, as well as enhanced collaboration with the private sector. The achieved research results can arouse interest from multiple actors in the aquaculture field, especially companies with vision to implement new sensor technology at RAS facility. The project revealed a new method to improve control of water quality in RAS, with the long term aim of enhancing quality of aquaculture products, while preventing losses in the industry.

Fish production in completely recycled water, such as in a recirculating aquaculture system (RAS), demands permanent control of water quality. Accumulation of excreted metabolites, low dissolved oxygen levels/high CO2 levels, and accumulation of recycling/disinfection by-products pose threat to water quality in RAS, and its deterioration results in deterioration of fish productivity and health. Therefore, continuous monitoring of stressor levels in real time would be a tremendously valuable tool in preventing sudden production decreasing, oxygen depletion or contamination in recirculate fish-production systems. In situ monitoring sensors would thus replace intensive manual sampling for water quality evaluation. This post-doctoral project addresses the need of developing in-situ tools for green RAS, and proposes to solve the R&D challenge of continuous monitoring by investigating a lab-on-a-chip with advanced bio/nanotechnologies and luminous bacteria, that offers broad spectrum of detection and rapid response to toxic levels of key stressors. This project is conducted in close cooperation with Centre of Excellence for Environmental Radioactivity (CERAD, at NMBU), and the proposed research work strengthens the aquaculture research focus in current activities in CERAD. Along with the strategic research areas UMB4 and UMB5 of CERAD, combined toxicity and biological effects in luminous bacteria and model fish exposed to key stressors in RAS will be investigated, and will serve to verify the in-situ monitoring sensors. The cooperation is enhanced by national and international expertise on micro/nanotechnology, water/environmental monitoring and toxicology analysis. The project results will find use in the aquaculture industry, as the implementation of continuous surveillance technology in RAS systems will allow for early warning of toxicity, giving fish producers time to respond before increased levels of key stressors are allowed to negatively affect fish production.