Project Progress: Seaweed cultivation in SIMBA

The use of seaweed for human consumption (and also as a source of phycocolloids including carrageenans and agar) is a centuries-old tradition in many Asian countries. In the western world, however, use of seaweeds has typically been limited to local traditional uses. Lately however, results from scientific research have indicated a whole range of potential applications for seaweeds and have increased possibilities for existing applications for food, feed, cosmetics, nutraceuticals and more. Together with other factors, this has led to an increased demand for seaweeds worldwide.

It soon became clear that collecting natural seaweed alone is insufficient to meet this demand and shifted the focus of both scientists and companies towards seaweed cultivation. In Europe there are several existing commercial cultivation installations operating at varying scales and this number continues to increase. Controlled cultivation will guarantee a much more stable supply of biomass of consistent quality. It also offers the possibility to further develop and improve cultivars and the domestication of new species.

Most recent scientific literature highlights the importance of the microbiome growing on the seaweed thalli for their growth and morphological development. Nevertheless, the extent of these relations and how these can be applied in seaweed cultivation is still poorly understood.

It is precisely at this knowledge gap that SIMBA is intervening. Spanish partner CTAQUA intends to grow sea-lettuce in indoor cylinders, outdoor tanks and in former salt evaporation ponds with open exchange with natural seawater. In collaboration with WP3 leader NIOZ/NWO-I from the Netherlands, partners MATIS from Iceland and the University of Bielefeld in Germany, the development of the microbiome growing on the seaweed Thalli (the plant body of algae that has a simple structure that does not have specialised tissues typical of higher plants, such as a stem, leaves and conducting tissues) will be determined, to compare this among cultivation systems and to study its potential relation with seaweed growth rate and biochemical composition. The final goal is to come to a formulation of the optimal microbiome composition for sustainable Ulva production in outdoor tanks.

Both indoor cultivation and outdoor pond cultivation are already operational at CTAQUA, in the south of Spain. In addition, an outdoor tank cultivation system (photos) has been set up and is currently being optimized and evaluated. Test samples will be taken of the microbial population growing on the seaweed surface as well as in the water to evaluate the draft protocols developed by the NIOZ. The testing period will be completed and evaluated by the end of this year (2019) and actual sampling will start next spring (2020).

Three main outputs (deliverables) are expected from this activity, including a taxonomic and functional description of macroalgae-associated microbiomes during a full growth season and the description of a microbial starter culture for the amendment to macroalgal cultivation. Results will be disseminated to the scientific community, interested companies, and other stakeholders. We expect that the results from these experiments will contribute to the expanding seaweed cultivation industry in Europe.

By: Erik Malta and Myriam Retamero, CTAQUA-Aquaculture Technological Centre, Spain.