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The super-intensive BioFloc Technology (BFT) system has been highlighted as a promising eco-friendly alternative to the traditional shrimp rearing systems. To gain insight into the impact of environmental rearing conditions on shrimp intestinal immunity, we assessed the expression profile of key immunological genes in the midgut of Litopenaeus vannamei shrimp reared in two contrasting culture systems: the indoor super-intensive BFT and the outdoor intensive Green-Water System (GWS). From the 30 analyzed genes, the expression levels of 25 genes were higher in the midgut of shrimp reared in BFT than in GWS. The main functional categories represented in BFT-shrimp were the prophenoloxidase-activating system, immune signaling, antimicrobial peptides, and RNA interference pathway. Comparatively, only the RNAi pathway gene Dicer-1 (LvDcr1) was more expressed in animals from the GWS group. However, despite the differences in gene expression, the total midgut bacterial abundance was similar between the experimental groups. Altogether, our results suggest that the microbial-rich environment offered by the BFT system can be acting as an immunostimulant by altering the immune expression profile of the midgut. The gene expression level found in GWS animals could be related to the chronic presence of the IMNV in the Brazilian Northeast. Knowing the effects of environmental stress factors on the intestinal immune defenses can provide an in-depth understanding of the relationship between cultivated shrimp and the major pathogens affecting the shrimp industry., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Ecological modeling has been used as a tool to estimate potential impacts caused by aquaculture to the surrounding environment. In this work, a mathematical model was applied to estimate the maximum amount of pink shrimp (Farfantepenaeus paulensis) culture units (3,100m2 pen enclosures) that could be installed at two shallow estuarine bays of Patos Lagoon (known as Coreia and Porto do Rei) with no significant effects on either water quality or viability of the culture system. To calibrate the model, information about the culture of Litopenaeus vannamei and F. paulensis as well as field data (influence of netting material, water current speed and nitrogen concentrations) were used. Under a bad scenario (water current velocity of 0.01m s-1 and a mesh clogging effect of 40%), it would be possible to install up to 29 pens at the Coreia bay, and 39 pens at the Porto do Rei bay. Results indicate that the model was useful in determining the maximum number of culture units that could be installed at these bays, and thus have the potential to become an important tool in the definition of environmental management strategies in relation to aquaculture development.

Shrimp farming in the Biofloc Technology System (BFT) is already considered an alternative to the traditional culture. The bioflocs maintain the water quality and can be used as a food supplement for shrimp. The Pacific white shrimp Litopenaeus vannamei forms the basis for most of the production in BFT. However, its culture is limited by the low temperatures. Thus, the BFT culture potential of native species, such as the pink shrimp Farfantepenaeus brasiliensis, should be considered. The present study aimed to compare the cultures of F. brasiliensis and L. vannamei in the grow-out phase in the BFT system. The experiment comprised two treatments: (FB), grown out of F. brasiliensis, and (LV), grown out of L. vannamei. The study lasted 70 days and was conducted at the Marine Station of Aquaculture at the Federal University of Rio Grande, Rio Grande do Sul State, Brazil. The stocking density was 100 shrimp/m² for both species. The shrimp were fed twice a day with commercial food. The physicochemical parameters of the water were monitored throughout the experimental period. The results showed that all physicochemical parameters of the water remained within the tolerated limits for both species. However, during the growth phase in the BFT, it was observed that the L. vannamei shrimp showed a better zootechnical performance than F. brasiliensis. The results indicate that L. vannamei has a higher capacity to catch bioflocs as supplementary food, demonstrating a better response of that species to the BFT system in the grow-out phase compared to F. brasiliensis. [ABSTRACT FROM AUTHOR]

This work investigates the effect of adding different sources of organic carbon in biofloc systems on water quality, microorganisms' density and zootechnical performance of juvenile Mugil liza raised in the biofloc system indoors over 45 days. Fish (±7.99 g) were stored at a density of 15 fish per tank and fed a commercial feed of 42% protein. The study was arranged in three treatments according to the carbon source: dextrose—DE, liquid molasses—LM and rice bran—RB, and one control with no bioflocs (clear water—CW), all in triplicate. The treatments had no influence (p > 0.05) on the performance parameters of the animals, survival (over 90%), as well on the productivity (between 0.35 and 0.6 kg/m3). Overall mean of total ammonia was lower (p < 0.05) in the biofloc systems than in clear water (CW). Nitrite average was lower (p < 0.05) in the bioflocs fertilized with LM and RB carbon sources, having a concentration of 1.3 ± 1.9 mg/L and 0.6 ± 0.6 mg/L respectively. RB also had the smallest range in nitrite levels throughout the study, from 0.04 to 2.5 mg/L. The LM and RB provided a greater (p < 0.05) abundance of total adhered and coccus bacteria. Water consumption was higher (p < 0.05) in the CW (1.87 m3 per tank) compared with the biofloc treatments (0.41 and 0.44 m3 per tank). Liquid molasses contributed to maintaining water quality compared with clear water, providing savings of around 80% of water. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of different aeration types on water quality, shrimp growth and biofloc composition in a Litopenaeus vannamei culture. The study was conducted with three treatments: (1) PR-propeller aspirator pump aerator; (2) VP-vertical pump aerator; and (3) BL-diffused air blower. The study was performed in a greenhouse with nine 35,000-L rectangular tanks. Water quality parameters (temperature, salinity, dissolved oxygen, pH, ammonia, nitrite, nitrate, settleable and suspended solids) were measured along the 33 experimental days. Moreover, samples were collected to quantify the microorganisms present in the tanks. At the end of the study, samples of the biofloc of each tank were collected to proximal analysis. Throughout the experiment, the temperature, pH, salinity and alkalinity were maintained within the recommended levels for L. vannamei. The propeller treatment showed a concentration of total ammonia above the recommended levels and lower densities of ciliates and flagellates, most likely because of inadequate biofloc formation in this treatment. The final weight was higher in the blower and propeller treatments. However, survival was lower in the propeller treatment compared to the other treatments. The results of this study suggest that diffused air systems (air blower) improve the formation of biofloc and growth performance of L. vannamei. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the contribution of three diatom species on the lipid content of bioflocs, their permanence on the bioflocs and influence on the growth performance of juvenile shrimps. Juveniles of Litopenaeus vannamei were reared (30 days; three replicates per treatment) in biofloc systems inoculated with diatoms Amphora coffeaeformis (A), Cylindrotheca closterium (C), Conticribra weissflogii (W), or biofloc only ( BF, chlorophycean rich). Water quality parameters were monitored daily and the microbiota on days 1, 10, 20 and 30. The lipid content and fatty acid profiles of bioflocs were analyzed at the end of the experiment. Shrimp survival rate (99%) at treatment A was significantly higher than at BF. The bioflocs in A treatment presented the highest lipid content, differing significantly from BF and W. The content of EPA (20:5) (n-3) was significantly higher in A and lower in BF, while linoleic acid (18:2) (n-6) was significantly higher in BF. The results indicate that high cell density of diatoms can be successfully maintained with silicate addition in biofloc systems and that the pennate A. coffeaeformis and the centric C. weissflogii are potentially better suited than the pennate C. closterium as food supplements for shrimp diets in biofloc nurseries system. [ABSTRACT FROM AUTHOR]

The initial stages of rearing marine shrimp using biofloc technology (BFT) involve the biofloc formation process. At the same time, there is an increase in the levels of total suspended solids and a decrease in alkalinity and pH. This reduction of alkalinity and pH occurs due to the consumption of inorganic carbon by the autotrophic bacteria present in the bioflocs and biofilms. The aim of this study was to evaluate the effects of different alkalinities on water quality and the zootechnical performance of the marine shrimp Litopenaeus vannamei in a BFT system. The experiment consisted of four treatments, with three replicates each: 75, 150, 225 and 300 mg CaCO/L. To maintain the alkalinity at the established level, sodium bicarbonate was applied. For the experiments, twelve experimental units (area = 0.20 m) with an effective volume of 50 L were stocked with 30 juvenile L. vannamei (0.20 ± 0.07 g), to achieve a stocking density of 150 shrimps/m and were maintained for an experimental period of 49 days. The 75 treatment presented the highest levels of ammonia and nitrite throughout the study, compared to the 150 and 300 treatments. The results showed that higher alkalinity favors biofloc formation and the establishment of nitrifying bacteria. [ABSTRACT FROM AUTHOR]

We analyzed the effect of commercial bacterial probiotics on aLitopenaeus vannameibiofloc culture system infected withVibrio parahaemolyticus. Three replicates of two experimental treatments were conducted: a control system (without probiotic) and a system with the application of a multistrain probiotic containingBacillusspp.,Enterococcusspp.,Thiobacillusspp., andParacoccusspp. applied to the water and another multistrain probiotic containingBacillusspp.,Enterococcusspp., andLactobacillusspp. added to the feed. Growth and survival rate were significantly higher in the probiotic treatment group (P< 0.05), and the shrimp in the probiotic group also had a lower (P< 0.05) FCR compared to the shrimp in the control group (1.4 vs. 2.7). [ABSTRACT FROM AUTHOR]

Biofloc technology (BFT) has been used to rear white shrimp, Litopenaeus vannamei. In this culturing system, the absence of aeration causes a rapid drop in dissolved oxygen levels, and hydrogen peroxide (HO) can be used as an emergency source of oxygen. This study aimed to determine the lethal concentration and safe level of HO applied as a source of oxygen for juvenile white shrimp L. vannamei in a BFT system. Juveniles (1.39 ± 0.37 g) were exposed for 2 h to different concentrations of HO [29 (100), 58 (200), 116 (400), 174 (600), 232 (800), 290 (1,000) and 348 (1,200) μL HO/L (ppm HO-29 %/L)] in addition to a control group without addition of HO, and the survival rates were monitored for 96 h. The LC values and 95 % confidence intervals at 24, 48, 72 and 96 h were 235.5 (207-268), 199.1 (172-229), 171.1 (146-198) and 143.3 (120-170) μL HO/L, respectively. The safe level was 14.3 μL HO/L, and the highest concentration with survival rates similar to the control group (NOAEC) was 29 μL HO/L. In these concentrations, HO can be used as a safe source of oxygen for L. vannamei reared in BFT systems. [ABSTRACT FROM AUTHOR]

The present work evaluated the use of molasses as a carbon source during the nursery rearing of Farfantepenaeus brasiliensis in a Biofloc technology system. During a 30 days trial, three replicate tanks were randomly assigned to the following treatments: 1.) molasses (with molasses addition) and 2.) control (without molasses addition). Bacteriological analysis was used to quantify the abundance of presumptive Vibrio spp. between control and molasses treatment. The concentration of this microorganism was lower in molasses compared with control. For the immunological analysis, shrimp haemolymph was collected to determine the total haemocyte count and the total protein concentration. The immunological results were not different between treatments. The performance results of shrimp reared with molasses addition showed that the survival rate (88.87 ± 6.36), the mean final weight (1.22 ± 0.38) and the specific growth rate (0.0309 ± 1.06) were significantly higher compared with control (80.5 ± 2.42; 1.03 ± 0.13; 0.0256 ± 0.97 respectively). Moreover, the addition of molasses contributed to the maintenance of water quality and lower concentration of presumptive Vibrio spp. The control presented an unstable variation of Vibrio spp. reaching values of 80 × 102 CFU/ml, while the highest result of molasses was 20 × 102 CFU/ml, confirming the beneficial effects of molasses addition. [ABSTRACT FROM AUTHOR]

The article focuses on a study which examined the technical feasibility of biofloc culture rearing system (BFT systems) in Brazil. A greenhouse with high density polyethylene (HDPE)-lined tanks was used in this study, while Aquatec™ was the source of the Litopenaeus vannamei post-larvae. Results of the study showed that there were significant differences among stocking density treatments. It also found lower weight and survival for the shrimp cultured at the higher stocking density.

The effect of different food items on growth and survival was assessed in four feeding experiments conducted consecutively using distinct Farfantepenaeus paulensis (Pérez-Farfante) postlarval growing stages: (1) PL1–PL4 (i.e. from postlarvae 1-day old to postlarvae 4 days old); and (2) PL4–PL10; (3) PL10–PL18 and (4) PL18–PL30. For each trial, 10 feeding treatments were tested in triplicate: Unf, unfed shrimp; Tt, Tetraselmis chuii; Ch, Chaetoceros calcitrans; C, commercial diet; AC, decapsulated Artemia cysts; C+Ph, commercial diet and phytoplankton combination; FA, frozen Artemia nauplii; A, live Artemia nauplii; A+Ph, Artemia nauplii and phytoplankton combination and Mix, mixture of phytoplankton, live Artemia nauplii and commercial diet. Postlarvae feed phytoplankton (i.e. Tt or Ch) exclusively exhibited low growth and survival. The best results for growth and survival were observed in the A, A+Ph and Mix treatments. Frozen Artemia nauplii was found to be suitable for younger postlarvae (PL1–10), whereas AC may be offered from PL4 to PL30. In general, the present findings indicated that even at an early postlarval stage, F. paulensis presents a high degree of carnivory, and a diet containing Artemia is recommended. [ABSTRACT FROM AUTHOR]

Shrimp farming has recently pursued systems that minimize the use of water. A biofloc technology (BFT) culture system contributes to water quality by removing nitrogen compounds, supplementing the shrimp diet and allowing for the use of high stocking densities. In addition, this system enables the culture with minimal water exchange. This study raised Litopenaeus vannamei shrimp in a BFT system at different water depths. Three treatments were compared at 0.40, 0.80 and 1.20 m of water depth (salinity 30). Treatments were randomly assigned to nine 35,500 L lined tanks in a greenhouse. Each tank was stocked with 14,000 animals (400 shrimp m − 2 ). Feed (38% crude protein - CP) was provided three times per day via feeding trays. The study lasted 120 days. The water quality parameters, weight gain, FCR and survival were evaluated. No significant differences were detected for water quality parameters (P > 0.05) except for alkalinity, which was higher in the 1.20 m treatment (P < 0.05). The final weight and survival did not show significant differences (P > 0.05). Final biomass (kg m − 3 ) was significantly higher in the 0.40 m treatment (P < 0.05). The productivity levels were 2.88 (1.2 m), 4.83 (0.80 m) and 8.45 kg m − 3 (0.40 m) at 17 weeks. The 0.40 m treatment used 119 L of water to produce 1.0 kg of shrimp. Based on the results, decreasing the depth of the shrimp tanks to 0.4 m increases the productivity and decreases the use of water per kilogram of shrimp produced. Statement of relevance In the last few years, several researches have been developing technologies to improve Aquaculture production. Shrimp culture achieved high levels of productivities, mainly in semi intensive culture systems in subtropical areas around the world. However, environmental impacts and shrimp diseases have been worldwide spread. In addition, the effluent from aquaculture rich in organic materials and nutrients can cause environmental pollution as well as expenses with pumping water. Thus, the shrimp culture has been directed to biosecurity systems that minimize the use of water. The new proposed culture system, Biofloc Technology Culture Systems (BFT) is characterized by zero water exchange and super-intensive culture of shrimp in enclosed raceways. This system is considered environmentally friendly and avoids nutrient rich waste from polluting coastal waters. The nutrients transformation in biofloc (microorganisms) contribute to the water quality, through the removal of nitrogen compounds, supplements the shrimp diet and allows the use of high stocking densities. Depth as a factor in pond ecosystem management has been given little attention, despite its theoretical importance in autotrophic and heterotrophic systems. Besides of this, the shrimp behavior and water quality parameters could be completely changed according to the amount of water available in the culture system. Therefore, the objective of this study was to compare the growth performance of Litopenaeus vannamei in greenhouse-enclosed raceways with different depths, in BFT culture system. According to the results, water quality parameters were within recommended ranges for shrimp health in terms of dissolved oxygen, pH, temperature and salinity in different depths. The same was detected for nitrification process. Anyway, the amount of water used to produce 1.0 kg of shrimp ranged from 119 to 352 L. The best result was in 0.4 treatment with the production of 8.45 kg m − 3 . Therefore, according to the results from the present study, decreasing the depth of shrimp tanks to 0.4 m increases the productivity and decreases the use of water per kilogram of shrimp produced. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effect of different temperatures on the nursery phase and compensatory growth of pink shrimp, Farfantepenaeus brasiliensis , reared in a biofloc technology (BFT) system. The 30-day nursery phase trial was conducted at 21 °C, 24 °C, 27 °C, 30 °C and 33 °C. At the end of the nursery phase, the shrimp were acclimated at 30 °C (±1 °C) and restocked at 100 juveniles/m 2 to check the compensatory growth during 15 days, with the following treatments: 21 °C (30 °C), 24 °C (30 °C), 27 °C (30 °C), 30 °C (30 °C) and 33 °C (30 °C), in which the first numbers correspond to temperature used in the nursery study and the 30 °C is the temperature used in the compensatory growth study. The mean final weight significantly increased with temperature at the end of the nursery phase ( p < 0.05): 0.10 g (21 °C); 0.18 g (24 °C); 0.27 g (27 °C); 0.34 g (30 °C) and 0.49 g (33 °C). However, survival rates were significantly higher at the lower temperatures (81%, 80% and 80% for 21 °C, 24 °C and 27 °C, respectively) than at the high temperatures (65% for 30 °C and 26% for 33 °C). At the end of the second trial, the 21 °C (30 °C) treatment showed the highest specific growth rate (SGR) compared to the other treatments. This result demonstrates that shrimp in the 21 °C (30 °C) treatment compensated its low growth throughout the nursery phase. Thus, the nursery phase of F. brasiliensis at high stocking density in BFT systems should be conducted at approximately 27 °C. However, this phase can also be carried out at lower temperatures, which can ensure high survival and compensatory growth when the temperature is increased. [ABSTRACT FROM AUTHOR]

Abstract: The present study evaluated spermatozoal capacitation in Farfantepenaeus paulensis. This process has direct applications in aquaculture, and it consists of the ionic, biochemical and morphological changes during the period that the spermatophore is stored or adhered to the thelycum. These changes make the spermatozoa capable of fertilization. The morphological changes of spermatozoal capacitation have been previously investigated only in sicyoniids and open-thelycum penaeids. Thus, this study is the first morphological account of a closed-thelycum penaeid. F. paulensis broodstock were captured offshore in southern Brazil, and spermatophores were collected from the terminal ampoule and from the thelycum of sexually mature females that had naturally copulated. The ultrastructure of the spermatozoal capacitation was investigated via transmission electron microscopy. Spermatozoa of F. paulensis show the following changes related to capacitation: (1) the chromatin became less condensed; (2) the acrosomal region became more electron-dense (3) the acrosomal cap became less concave; and (4) the subacrosomal region became much more electron-dense. These results demonstrate that the morphological changes in capacitated spermatozoa of F. paulensis are similar to those previously reported for open-thelycum penaeids, i.e., Litopenaeus species. Further studies on the capacitation process are required, especially to evaluate the interaction between biochemical and morphological changes. Such research could be useful for developing biotechnologies that will allow spermatozoal induction without storing the spermatophore in the thelycum and therefore allow in vitro larval production. [Copyright &y& Elsevier]

Abstract: Nutritional values of microbial floc meal and soy protein concentrate were evaluated as alternative protein sources to fishmeal in diets for Litopenaeus vannamei juveniles. A feeding trial was conducted during 28days to investigate the effects of partial and total replacement of fishmeal with microbial floc meal and soy protein concentrate on feed intake and growth of L. vannamei. Five diets were formulated to contain 38% crude protein and 17kJ/g gross energy. Microbial floc meal was obtained from super-intensive shrimp farm effluent. A control diet (with fishmeal as the main protein source) was compared to four diets containing microbial floc meal and soy protein concentrate at 25%, 50%, 75% and 100% replacement levels and a commercial diet. This feeding trial was conducted in a recirculating aquaculture system, utilizing shrimps weighing 2.48±0.29g. The weight gain, final weight, feed conversion ratio, specific growth rate, protein efficiency ratio and survival were not significantly different among treatments, suggesting that fishmeal can be completely replaced with soy protein concentrate and microbial floc meal without adverse effects on L. vannamei performance. These results suggest that a mixture of soy protein concentrate and microbial floc meal can be utilised as a substitute for fishmeal in diets for L. vannamei juveniles. [Copyright &y& Elsevier]