Sophie Steinhagen1, Swantje Enge1, Gunnar Cervin1, Karin Larsson2, Ulrica Edlund3, Alina E.M. Schmidt3, Barbro Kollander4, Henrik Pavia1, Ingrid Undeland2, Gunilla B. Toth1
1 Department of Marine Sciences-Tjärnö, University of Gothenburg, SE-452 96 Strömstad, Sweden
2 Department of Biology and Biological Engineering-Food and Nutrition Science, Chalmers University of Technology, Gothenburg, Sweden
3 Fibre and Polymer Technology, KTH Royal Institute of Technology, SE-100 44, Stockholm, Sweden
4National Food Agency (NFA), P.O. Box 622, SE-75126 Uppsala, Sweden
Compared to Asia, seaweed aquaculture is in its infancy in Western Europe. However, due to the multi-applicable usage of this renewable resource there is a rapidly growing interest in efficient production technologies to foster a large-scale industrial production of seaweed biomass. Especially the sustainable oceanic cultivation of seaweeds is attractive as it does not compete with terrestrial crops for space and freshwater, and as extractive organisms seaweeds do not afford fertilization whilst providing high biomass yields.
This study monitored the effect of seasonality on the overall biomass performance (growth, biomass yield), chemical composition (fatty acid, protein, carbohydrate, pigment, phenolic, biochar, ash, and element composition), fertility (total amount of fertile thallus tissue), and biofouling (total coverage) of Swedish off-shore cultivated Ulva fenestrata, in order to find suitable harvest times for biorefinery purposes. Specimens of U. fenestrata were cultivated in an off-shore seafarm in the Kosterfjord, Sweden from October to five different harvesting points in April, May and June. Statistical analyses confirmed that there was a significant
difference in overall biomass performance and biochemical composition among the time points. Our study confirmed the large scale off-shore cultivation potential of northern hemisphere U. fenestrata and underpins suitable harvest time points to facilitate industrial valorization processes of the off-shore cultivated biomass. Together, these results indicate that seasonality and the selection of harvest periods are crucial factors to consider in order to facilitate high yields, respective quality as well as desired biochemical traits in future oceanic Ulva farms.