The objective of this study was to evaluate the effect of the addition of Navicula sp. on the growth and fatty acids profile of Litopenaeus vannamei postlarvae in a biofloc system (BFT). Four treatments were used: BFT; BFT 2.5N (addition of 2.5 × 10⁴ cells/ml of Navicula sp.); BFT 5N (addition of 5 × 10⁴ cells/ml of Navicula sp.) and BFT 10N (addition of 10 × 10⁴ cells/ml of Navicula sp.), all in triplicate. The shrimp (1 ± 0.01 mg) were stocked at a density of 3,000 postlarvae/m³ and fed with commercial feed. The diatom was added every 10 days, and at the end of 42 days, shrimp performance, water quality and proximal composition were evaluated. The BFT 5N and BFT 10N treatments had higher performance values, highlighting the values of productivity (2.30 and 2.42 kg/m³) and specific growth rate (15.92 and 16.08%/day), which were higher than the other treatments. In addition, the highest levels of fatty acids were observed in treatments with diatom (BFT 5N and BFT 10N), indicating the benefits of Navicula sp. on growth enhancement and fatty acid content of L. vannamei postlarvae grown in biofloc systems.

The objective of this study was to investigate the effluent treatment from Nile tilapia farming in a biofloc system with a consortium of microalgae (Chlorella vulgaris) and zooplankton (Daphnia similis). Thus, integrated cultures of C. vulgaris and D. similis were performed in two forms of wastewater treatment: sedimentation (S) and non-sedimentation (NS), in four different salinities (1, 2, 3 and 4 g L⁻¹). Water quality, growth of D. similis, behaviour of C. vulgaris, efficiency of removal of nitrogen compounds, orthophosphate, and total suspended solids (TSS) were measured. D. similis had higher density in 3NS (p < 0.05), while population die-off occurred in 4S and 4NS. The 2S and 1NS combinations stood out in bioremediation, achieving removal of up to 70.37% nitrate, 75.74% orthophosphate, and 90.74% TSS. 2S and 3S cultures became self-sufficient from day 21. Thus, the Chlorella-Daphnia consortium using 3NS allowed better production of D. similis, whereas salinities 2 g L⁻¹ (S) and 1 g L⁻¹ (NS) provided better bioremediation, and the use of S wastewater improved the sustainability of the system. These results contribute to a better evaluation of cultures in consortia of organisms for the treatment of aquaculture wastewater and the production of live feed for aquaculture. GRAPHICAL ABSTRACT

The aquaculture industry requires green solutions to solve several environmental challenges, including adequate wastewater remediation and natural drug applications to treat bacteria- and virus-related diseases. This study investigated the feasibility of cultivating the dinoflagellate Durusdinium glynnii in aquaculture wastewater from shrimp rearing in a synbiotic system (AWW-SS), with different dilutions of f/2 medium (FM). Interestingly, D. glynnii demonstrated enhanced growth in all AWW–SS treatments compared to the control (FM). The highest growth rates were achieved at AWW-SS:FM dilutions of 75:25 and 50:50. The removal of total nitrogen and total phosphorus reached 50.1 and 71.7%, respectively, of the crude AWW–SS. Biomass extracts of D. glynnii grown with AWW–SS were able to inhibit the growth of the bacteria Vibrio parahaemolyticus (inhibition zone of 10.0 ± 1.7 mm) and V. vulnificus (inhibition zone of 11.7 ± 1.5 mm). The presented results demonstrate that the dinoflagellate D. glynnii is a potential candidate for the development of circularity for sustainable aquaculture production, particularly by producing anti–Vibrio compounds at a near-zero cost.

The addition of Navicula sp. to shrimp nurseries can improve the growth of Penaeus vannamei reared in biofloc systems. However, the contribution of microalgae to the biofloc formation and the effective contribution to shrimp nutrition remain unknown. In this study, Navicula sp. was added to biofloc nursery systems of P. vannamei at distinct time frequencies for evaluating its nutritional contribution to shrimp growth. Nursery rearing was carried out in bioflocs for 35 days at a stocking density of 3000 post-larvae m(-3). Shrimp were fed using a commercial feed plus fresh culture of Navicula sp. at different frequencies: no addition of Navicula sp. (WN - control), the addition of 10 x 10(4) cells mL(-1) of the diatom every 5, 10 and 15 days (N5, N10 and N15, respectively). Food sources relative contribution to P. vannamei development was estimated using a Bayesian mixture model. The isotopic discrimination factor (Delta N-15 and Delta C-13) for each food source was determined experimentally. After 35 days of culture, survival (similar to 93 %) was similar across all treatments but there was a significant difference in weight gain and feed conversion ratio. The N10 treatment (0.50 +/- 0.05 g, 0.99 +/- 0.01) exhibited better growth parameters when compared to the WN treatment (0.33 +/- 0.07 g, 11.46 +/- 0.30). Biofloc was the food source most assimilated by shrimp followed by Navicula sp. and commercial feed. Contribution of Navicula sp. was higher in the N5 treatment. In the treatments with diatom addition, an inverse correlation was observed between the relative contributions of biofloc and Navicula sp., indicating that Navicula sp. is not in the biofloc composition, but it is directly consumed by P. vannamei post-larvae. Biofloc and Navicula sp. exhibited larger contributions to the growth of shrimp, reinforcing the importance of natural food sources to the aquaculture of P. vannamei post-larvae.