Search

This study focused on evaluating the effect of different concentrations of nutrients and total suspended solids on the removal rate of nutrients and biocompounds from the macroalgae U. lactuca in an integrated system with the shrimp Penaeus vannamei in biofloc. The experiment lasted 45 days and included five treatments with three replicates each, with percentages of 0 (control), 25, 50, 75, and 100% biofloc inoculum (73.3 ± 5.7 and 325.0 ± 21.2 mg L−1 initial nitrate and solids, respectively, in the 100% inoculum), from a shrimp farm, resulting in different concentrations of solids and nutrients. The macroalgae were introduced into 280 L tanks at a density of 0.88 kg m−2, along with 200 shrimp m−3. The algae were separated by a floating structure. Water quality parameters were measured, and the nutrient removal rate was evaluated. The treatment with 75% inoculum showed a removal rate of 55.0 ± 4.0 and 31.0 ± 10.0% of nitrate and phosphate, respectively. There was no difference in macroalgae growth between the treatments; however, macroalgae grown in 75% inoculum had higher protein, chlorophyll-a, and lower ash values compared with the control. The use of macroalgae in integrated production with shrimp under the conditions of the treatment with 75% biofloc inoculum proved to be viable and sustainable. [ABSTRACT FROM AUTHOR]

In this study, the effect of four temperatures—18, 20, 23 and 26°C—on embryonic development, growth and larval survival of the yellow clam Amarilladesma mactroides was evaluated. In the first phase, the development of the embryos to D‐larva stage was observed until all treatment groups achieved complete transformation. This process lasted approximately 28 h, with the 23 and 26°C groups showing greater transformation speed, completing the stage in 20 h 49 min. In the second phase, D‐larvae were submitted to the four pre‐established temperatures. There was a significant difference in the growth of larvae kept at 26°C when compared to 18 and 20°C. Treatments 18, 20 and 23°C produced viable pediveliger larvae; however, larvae kept at 18 and 20°C showed the fast growth accompanied by the highest survival rate. The results of this study indicate that the embryos of this species are tolerant of a temperature variation from 18 to 26°C, with the effect of this variable being a determinant in the metamorphosis. However, within the experimental conditions adopted, the larvae were dependent on lower temperatures (18 and 20°C) for settling, larger size and higher survival rate. [ABSTRACT FROM AUTHOR]

This study evaluates the bioflocs capacity to assimilate and transfer the bioactive compounds present in açaí to post-larvae of Litopenaeus vannamei cultured in the BFT system. In the first experiment, 21 experimental units (1 l) were randomly distributed among seven treatments (control, 2.5, 5.0, 10.0, 20.0, 40.0, and 80.0 mg açaí L−1) in the BFT system without the inclusion of post-larvae and no water change. Every 24 h, for seven days, the respective concentrations of açaí were added to bioflocs. Initial characteristics of the biofloc used were of 0.13 mg TAN L−1, 0.51 mg N-NO 2 − L−1, 60.5 mg N-NO 3 − L−1, 245 mg CaCO 3 L−1 and 330 mg TSS L−1. In the second experiment, 12 experimental units (20l), all in triplicate, were randomly distributed in four treatments (control, 5.0, 20.0, and 80.0 mg açaí L−1) with 600 post-larvae (twenty-three day-old PL) per tank cultivated in the BFT system for 27 days. The biofloc inoculum used in the second experiment contained 0.52 mg TAN L−1, 0.13 mg N-NO 2 − L−1, 35.70 mg N-NO 3 − L−1, 177.5 mg CaCO 3 L−1 and 330 mg TSS L−1. Water changes during post-larvae cultivation were performed when the concentration of nitrite and total suspended solids in the water exceeded the safe levels of 1.38 mg L−1 and 500 mg L−1, respectively. In the first experiment, an increase in the antioxidant capacity was observed against peroxyl radicals of bioflocs (p < 0.05) at concentrations of 5.0 and 20.0 mg açaí L−1 and a decrease in lipid peroxidation (TBARS) at a concentration of 20.0 mg açaí L−1. In the second experiment, the mean values of the physicochemical parameters of water remained within the range considered adequate for post-larval culture. Shrimp from treatments with açaí showed greater survival, weight gain, and FCR at the concentration of 20.0 mg açaí L−1 (p < 0.05). Bioflocs and shrimp lost antioxidant capacity with increasing açaí concentration (p < 0.05). The TBARS levels of the biofloc were lower at concentrations of 5.0 and 20.0 mg açaí L−1 compared with 80.0 mg açaí L−1 (p < 0.05). It is concluded that bioflocs can assimilate part of the antioxidant compounds, allowing the addition of up to 80.0 mg of lyophilized açaí in BFT systems, and are an alternative to minimize oxidative stress during culture and influence the quality and growth success of post-larvae. • Bioflocs can incorporate exogenously added antioxidants to the BFT system. • Bioflocs enriched with antioxidant act as a vector in the transfer of bioactive molecules. • The application of lyophilized açaí in a BFT system minimizes oxidative stress in shrimp. • The inclusion of açaí in the BFT system increases the survival of post-larvae. [ABSTRACT FROM AUTHOR]