Cultivation of the seaweed Ulva spp. With effluent from a shrimp Biofloc rearing system: different species and stocking density

This work evaluated the use of effluent from a marine shrimp biofloc rearing system to cultivate two species of the green seaweed of the genus Ulva. First, the growth of two Ulva species, U. ohnoi and U. fasciata, was evaluated. Second, the best-performing species was cultivated under two different stocking densities (2 g L^-1 and 4 g L^-1) to evaluate both growth and nutrient uptake rates, considering total ammonia nitrogen, nitrate, and orthophosphate. In both cases, environmental variables were monitored, and the cultivation medium, consisting of 25% biofloc water and 75% seawater, was exchanged weelly. Ulva ohnoi grew significantly better, considering all variables evaluated (p <0.05). The smaller stocking density produced a higher specific growth rate (p <0.05). Yield, however, was unaffected (p ?0.05). No significant differences in the nutrient uptake rates were observed (p ?0.05). Overall, this work highlights the importance of species selection for seaweed destined for aquaculture. Additionally, it also optimizes the cultivation of seaweeds, specifically U. ohnoi , using effluent from biofloc systems.