Sea lettuce (Ulva ohnoi) cultivation in biofloc technology: growth performance and characterization of bioactive compounds

This work evaluated the biofloc technology cultivation of Ulva ohnoi on its growth performance and biocompounds contents. Ulva ohnoi was cultivated under an initial density of 6 g·L-1 for 28 days using water from a biofloc tank which was exchanged daily at a 90% rate. Temperature, salinity, and illuminance were measured daily. Algae growth and their density was adjusted weekly. Results showed an average plant growth of 1.15%·day-1 (49.5 g·week-1). A significant difference was observed when comparing the initial (2.64 ± 0.3%) and final (4.62 ± 0.2%) ulvan concentration, in addition to a protein increase of 30.2%. No statistical differences were found for concentrations of phenolics and chlorophylls. An increase in flavonoids was observed on days 7 and 14 (0.41 ± 0.04; and 0.41 ± 0.07 μg·g-1 of dry weight), as well as a decrease in carotenoids (41.3%). In conclusion, increases in protein and ulvan were observed after Ulva ohnoi was cultivated in bioflocs