Binder seeding to improve the economic case of UK macroalgal cultivation (Bindweed)

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The emergence of macroalgal cultivation as an aquaculture industry in the UK lags behind many of our neighbours such as Norway, France, Spain and Ireland. Cultivation of macroalgae for food products is profitable and there exists a large unmet market potential, both within the UK and across Europe. Currently, the industry is limited to small-scale cultivators due to the large manual requirement for activities such as outplanting of seedstock. The project Bindweed aims to translate and refine recent research into an innovative new technology that will substantially reduce the cost of macroalgal outplanting for end-users.The current state of the art involves manually winding twine carrying hatchery reared juveniles around longline ropes. The Bindweed method, embeds juvenile macroalgae within a hydrocolloid matrix which can then be directly applied onto cultivation substrates. Juveniles which would traditionally be maintained in the hatchery for several weeks are held in the binder matrix for long enough to allow attachment directly to the substrate before the binder degrades. The Bindweed method is expected to a) increase the space-efficiency of hatchery cultivation 100 times, b) increase the speed of deployment by at least 3 times and c) could be mechanised/automated for use at larger scales further increasing efficiency. In academic trials, the binder method produces a comparable or higher yield of macroalgae than twine, yet the binder method is unreliable. Success of the binder method appears to be related to the physicochemical conditions during initial outplanting, most notably water motion created by waves and/or tides. In the current formulation, shear from high water motion results in the degradation of the binder before the juveniles are able to attach, causing crop failures or reduced seeding densities. The Bindweed project will address the current unreliability through four inter-connected work packages (WP) which will develop the binder from Technological Readiness level 6 to 8 by combining laboratory testing, field monitoring and field experimentation to inform a final economic assessment. WP1 will optimise the binder/material /flow interaction through replicated trials within a controlled flow environment (biological flume). New binder formulations (composition, viscosity and thickness) will be challenged with different flow regimes and combined with novel cultivation substrates aimed at improving retention of juvenile plants. The selection of the flow regimes trailed within flume studies will be informed by environmental monitoring at four macroalgal cultivation sites with different influences of tidal and wave driven flow in WP2. The flow environment within the surface layers (suitable for cultivation) will be characterised in detail to address limitations in traditional monitoring and modelling tools used to assess site suitability for cultivation projects. Surface flow measurements, along with other measured physicochemical conditions including light, temperature, nutrients, pH, and dissolved oxygen will be used to support existing modelling tools to better inform the site selection process. In WP3, outplanting trials at the four cultivation sites will be used to confirm the suitability of the proposed optimised binder formulation and substrate (from WP1) in the real-world. Outplanting success and growth rates will be monitored in parallel with WP3. In WP4, an economic analysis will compare the binder seeding innovation compared to the standard twine seeding method to demonstrate the tangible economic benefits of the project created through the fusion of academic and industrial knowledge. This will be combined with a SWOT analysis, to create a decision tool for UK cultivators.