Mattrygghet: Integrated Multitrophic Aquaculture for Sustainable and Safe Food Production

The SAFER-IMTA project draws on key expertise from Norway (Møreforsking AS, MF) and China (Institute of Hydrobiology, IHB, Shenzhen University, SZU) to address the need for a more sustainable and safe aquaculture food production. The project aims to develop advanced land-based systems for the culture of lower trophic species (microalgae, macroalgae and sea cucumber) utilizing both particulate and liquid fractions from carp (China) and salmon (Norway) aquaculture effluents. Biological processes coupled to physical and/or chemical processes are investigated to convert the waste fractions to suitable substrates for sea cucumber and algal production. The safety and quality of lower trophic products in the perspective of their use as food and aquafeed ingredients have been assessed based on their characterization of harmful components and nutritional value. At SZU, anaerobic (AN), facultative anaerobic (FA) and aerobic (AE) digestions of solid aquaculture sludge were evaluated for efficiency of nutrient recovery and suitability for subsequent cultivation of the green microalga Chlorella sorokiniana. The results showed that AN resulted in the highest values of maximum dissolved total nitrogen (N, 82.7 mg L-1) and total ammonia-N (83.9 mg L-1) while AE exhibited highest values of maximum total phosphorus (11.8 mg L-1) and total suspended solid reduction (36.0%). Microbial analysis showed that AN exhibited a distinct bacterial community composition compared to FA and AE. Furthermore, C. sorokiniana grown in effluents from AN for 12 days exhibited optimal biomass production (1.96 g L-1), and highest removal efficiencies of organic matter (COD) (78.3%) and dissolved total N (82.5%). These results suggest that AN has the best potential to recover nutrients from aquaculture sludge for production of C. sorokiniana. At IHB, the effects of light qualities (white light, red light, blue light, and different ratios of red and blue mixed lights) were investigated on C. sorokiniana cultivated in aquaculture wastewater. The results showed that white light promoted growth and resulted in the highest algal dry weight (DW) of 1.64 g L-1, highest biomass productivity of 0.19 g L-1 d-1 and highest heat value of 22.10 MJ kg-1. The highest content of protein (21.54% DW), fatty acids (13.56% DW), and chlorophyll in the microalgae with the highest removal of total organic carbon (TOC, 82.27%) and various organic compounds (i.e. microbial byproduct-like aromatic protein) were observed under blue light. Red light promoted C. sorokiniana to accumulate the highest carbon (556.99 mg L-1) and carbohydrates (55.67% DW). In addition, mixed red and blue lights were beneficial for the removal of TN and NH3-N, consumed by non-microalgal pathways. This study provided insights into the impacts of light qualities on the process of microalgae-based aquaculture wastewater treatment. At MF, particulate sludge from Atlantic salmon aquaculture was assessed as an ingredient for the red sea cucumber (Parastichopus tremulus) aquaculture feeds. Four experimental groups, each consisting of triplicate groups of 5 individuals (average initial biomass 524.6 ± 12.9 g), were fed at a weekly rate of 10% (wet weight). Feeds were prepared using Sargassum algae (control), sludge collected at 2 different times of the year, and sludge anaerobically fermented with lactic acid bacteria (LAB) prepared in collaboration with SZU and IHB. Feed intake was significantly higher for the control feed at all sampling points. However, there was no significant difference between the three experimental feeds. In general, feed intake decreased throughout the experimental period for all feeds, possibly due to seasonal factors. At the end of the trial, all groups had lost weight (final biomass 421.0 ± 50.7 g), but no weight difference was found between the groups. Body wall (gutted weight), presence of intestine and gonad tissue was also assessed. The group fed fermented sludge had a significantly higher gonad index (GI) than the other groups, suggesting that LAB fermentation of sludge could have a positive effect on gonad development. Further, the relevant current and forthcoming regulations and policies pertaining to aquaculture in each country were reviewed to collect and categorize the regulatory framework. The data are currently being analysed to identify constraints and incentives for IMTA in Norway and China. This policy analyses will contribute to understand what types of information are needed for the decision makers to develop an adapted legislation to guide the sustainable and safe development of feed and food products by an innovative IMTA industry.

The global aquaculture sector is expected to grow to feed an increasing world population. Yet, the industry’s relies on limited and unsustainable sources of raw materials for aquafeed production. Additionally, nutrient-rich aquaculture effluents represent an underutilized resource with rising environmental concern. SAFER-IMTA draws on key expertise from Norway (Møreforsking AS) and China (Institute of Hydrobiology, Shenzhen University) to address the need for a more sustainable and safe aquaculture food production. The consortium will build upon existing knowledge to demonstrate the concept of integrated multi-trophic aquaculture (IMTA) to maximize resource utilization and limit environmental impacts from fed aquaculture. The project aims to develop advanced land-based systems for the co-culture of lower trophic species (microalgae, macroalgae and sea cucumber) using both particulate and liquid fractions from carp (China) and salmon (Norway) aquaculture. Biological processes coupled to physical and/or chemical processes will be investigated to convert the waste fractions to suitable substrates for sea cucumber and algal production. The safety and quality of lower trophic products in the perspective of their use as food and aquafeed ingredients will be assessed based on their characterization for harmful compounds (e.g. heavy metals, dioxins, PCBs) and essential nutrients (e.g. proteins, lipids, minerals). Life cycle assessments will provide important information on the environmental footprint of the developed systems. The knowledge generated by the consortium will bring the IMTA production technology further and increase the understanding of societal impacts of its processes and products though stakeholder consultation and regulations surveys. Better understanding of the incentives and barriers for the implementation of IMTA systems along with technological innovation will contribute to the development of sustainable value-chains in the aquaculture sector.