Developing the seaweed and plant components of integrated multi-trophic aquaculture and aquaponics and their applications within a biorefinery approach

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Aquaculture will have an increasing share in tomorrow's food production systems. However, the Blue Revolution needs to become greener by developing innovative technologies and practices with increased environmental sustainability, economic stability and societal acceptability, such as Integrated Multi-Trophic Aquaculture (IMTA). With IMTA, farmers cultivate species from different trophic levels with complementary ecosystem functions. They combine fed species (fish) with extractive species (seaweeds, aquatic plants, shellfish and other invertebrates) to take advantage of synergistic interactions among them, while biomitigation operates. During this Discovery Grant we will work on three improvements of IMTA systems. Developing the cultivation of the seaweed Palmaria palmata (dulse) as a summer inorganic extractive component of an IMTA system We developed the cultivation of kelps as the inorganic extractive component, from fall until early summer. But the need to increase biomitigation during summer led us to investigate the possibility of cultivating dulse. While dulse has been harvested for human consumption for centuries, its large-scale cultivation has never been successful. The problem is that dulse has a complex life cycle and individuals are most of the time non-reproductive, suggesting there may be an unknown asexual phase. We will investigate this possibility using molecular and spectroscopic markers. This could simplify cultivation by eliminating the need for sexual reproduction to create multiple generations in culture, thereby reducing pressure on natural populations. Developing freshwater IMTA The IMTA concept is not confined to marine systems. Its principles can also be applied to land-based, closed-containment freshwater systems (FIMTA, or aquaponics). If salmon spend 1.5-2 years in seawater pens, it is after they have spent 1-1.5 years in freshwater hatcheries. Developing FIMTA will aid in reducing water usage and waste production, and in product diversification. Using plants to reduce phosphorus levels in effluents will help farmers meet water quality guidelines and prevent eutrophication in the environment. People often describe aquaponics as the combination of animal aquaculture and plant cultivation. However, there is a key microbial link between the two, about which very little is known. We will identify these microbial communities, their changes over time and their role in nutrient cycling. Adding value to seaweeds through the Integrated Sequential Biorefinery (ISBR) approach Business models have to evolve from the “one species - one process - one product” approach to embrace the ISBR “one species - several processes - several products” concept, in which the residues of one process become the valuable products of the next step. We will develop several analytical and bioactivity platforms to transform seaweed residues into valuable new products.