Teis Boderskov1, Nina Simonsen2, Kristoffer Larsen-Ledet3, Birgit Olesen3 and Annette Bruhn3
1Department of Ecoscience, Aarhus University, Denmark
2Department of Biological and Chemical Engineering, Aarhus University, Denmark
3Department of Biology, Aarhus University, Denmark
Application of land-based recirculated aquaculture systems (RAS) is promising for expansion of the aquaculture production in Nordic countries (Dalsgaard et al., 2013). Seaweeds can potentially be used in land-based Integrated Multi-Trophic Recirculating Aquaculture Systems (IMRAS) to capture N and P, while creating a source of revenue through seaweed commercialization (Bruhn et al., 2011). However, vast differences in growth characteristics can be found between different local species/strains (Lawton et al., 2021). In the present study, growth rates and C/N contents were compared from a growth experiment, in a high-nutrient pilot scale setup, including 9 different local green algae species/strains. From the 9 tested species/strains, Ulva compressa and Ulvaria obscura was selected for further tests of the effect of temperature (10, 16, 22 and 28 °C) on growth, photosynthesis rates, chlorophyll/carotenoid and C/N-contents. The effect of temperature was significantly different for the two species with highest growth rates at 22 °C for Ulva compressa (18.9 ± 1.2 % DW day-1) and at 10 °C for Ulvaria obscura (16.3 ± 2.6 % DW day-1). After two weeks, the N content was 4.6 ± 0.35 % DW in Ulva compressa and 5.1 ± 0.6 % DW in Ulvaria obscura. Ulva compressa never sporulated during the growth trials, whereas Ulvaria obscura did so at 28 °C. The results show that especially the local selected strain of Ulva compressa could be suitable for cultivation in a land-based RAS system, having consistently high growth rates and N contents.