In recent decades, new aquaculture technologies have been developed and improved, such as the Bio... more In recent decades, new aquaculture technologies have been developed and improved, such as the Biofloc Technology system, which is considered an alternative to the conventional aquaculture model. This study compared the bioeconomic viability of intensive production in nurseries and super-intensive production of shrimp Litopenaeus vannamei bioflocs greenhouses. The investment for implementing the project was US$ 767,190.18 for intensive production and US$ 807,669.16 for super-intensive production. The analyses showed Net Present Value of US$ 363,718.21 and US$ 385,477.42, Equivalent annual value of US$ 59,830.66 and US$ 63,410.00, Net future value of US$ 965,052.69 and US$ 1,022,786.35, Payback Period 4.12 and 4.11, Discounted payback period 5.64 and 5.63, Profitability Index 1.47 and 1.48, Internal Rate of Return 20.49 and 20.55%, and Modified Internal Rate of Return 14.61 and 14.64%. The investment analysis used in this study showed that super-intensive production in a greenhouse is...
ABSTRACT The initial stages of rearing marine shrimp using biofloc technology (BFT) involve the b... more ABSTRACT 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 CaCO3/L. To maintain the alkalinity at the established level, sodium bicarbonate was applied. For the experiments, twelve experimental units (area = 0.20 m2) 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/m2 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.
Biofloc technology (BFT) has been used to rear white shrimp, Litopenaeus vannamei. In this cultur... more 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 (H2O2) can be used as an emergency source of oxygen. This study aimed to determine the lethal concentration and safe level of H2O2 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 H2O2 [29 (100), 58 (200), 116 (400), 174 (600), 232 (800), 290 (1,000) and 348 (1,200) μL H2O2/L (ppm H2O2-29 %/L)] in addition to a control group without addition of H2O2, and the survival rates were monitored for 96 h. The LC50 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 H2O2/L, respectively. The safe level was 14.3 μL H2O2/L, and the highest concentration with survival rates similar to the control group (NOAEC) was 29 μL H2O2/L. In these concentrations, H2O2 can be used as a safe source of oxygen for L. vannamei reared in BFT systems.
The pink shrimp Farfantepenaeus brasiliensis is native in southern Brazil and is potentially suit... more The pink shrimp Farfantepenaeus brasiliensis is native in southern Brazil and is potentially suited for aquaculture. Under intensive culture, the accumulation of nitrogenous compounds results from excretion by the shrimp and from the processes of feed decomposition and nitrification. The objective of this study was to evaluate ammonia, nitrite, and nitrate toxicity effects on oxygen consumption of juvenile pink shrimp. Shrimps (initial weight 0.7 ± 0.15 g) were exposed over a period of 30 days to 50%, 100%, and 200% of the safe levels of total ammonia (TAN = 0.88 mg/L), nitrite (NO2− = 10.59 mg/L), and nitrate (NO3− = 91.20 mg/L) for the species. The specimens were individually collected and placed in respirometry chambers, where the oxygen consumption was measured over a period of two hours. Throughout the experiment there was no significant difference (p > 0.05) among treatments in terms of survival and growth. The pink shrimp juveniles exposed to nitrogen concentrations of 200% of the nitrite and nitrate safe level showed the highest oxygen consumption (p < 0.05).
The reduction in alkalinity and pH occurs due to the consumption of inorganic carbon by bacteria ... more The reduction in alkalinity and pH occurs due to the consumption of inorganic carbon by bacteria present in the biofloc. The objective of the study was to evaluate the effects of different doses of calcium hydroxide on the water quality and growth performance of the Litopenaeus vannamei in a biofloc system. The experiment consisted of four treatments with three repetitions for each treatment: Control treatment (TC), in which the pH maintained above 7.2 due to the application of 0.05 g L−1 of calcium hydroxide, and treatments T10, T20 and T40, in which daily doses of calcium hydroxide equivalent to 10, 20 and 40 % of the total amount of feed offered to the shrimp, respectively, were added to the environment. Twelve experimental units (150 L) were stocked with 85 juveniles of L. vannamei (0.18 ± 0.06 g), corresponding to a density of 425 shrimp m−3, and cultivated for 56 days. The values of alkalinity and pH for treatments TC and T10 were similar and significantly lower (p < 0.05) than those for treatments T20 and T40, which differed (p < 0.05) between each other. In terms of growth performance, TC, T10 and T20 performed significantly better (p < 0.05) than T40. There were no significant differences (p > 0.05) in the survival rates. The results obtained indicate that doses of 0.05 g L−1 of calcium hydroxide or daily applications between 10 and 20 % of the total amount of feed offered to the shrimp can be used for the correction of alkalinity and pH.
Abstract The biofloc culture system (BFT) allows for the production of aquatic animals at higher ... more Abstract The biofloc culture system (BFT) allows for the production of aquatic animals at higher stocking densities compared to conventional aquaculture systems and it has been proven to be efficient for shrimp (Litopenaeus vannamei) and mullet (Mugil liza) rearing. Accumulation of nutrients enhances the natural productivity of the system, thus the concentration of total suspended solids (TSS) tends to accumulate during the production cycle, which can deteriorate the water quality and performance of the animals produced. Integrated multi trophic aquaculture (IMTA) can be performed in single or multi tank systems, depending on the interaction of the different species being cultured. The present study aimed to reduce TSS concentration by integrating juvenile mullet into a shrimp BFT system, through the consumption of these solids by the mullet. Three different treatments were used: shrimp monoculture (MONO), single tank (SING -shrimp and mullet cultured in the same tank) and IMTA multi tank (MULT- shrimp and mullet cultured in different tanks). The performance of shrimp was impaired in the SING treatment, while mullet had their best zootechnical performance in this treatment. The presence of the fish modified the nitrification even with the use of biofloc inoculum. The presence of mullet, regardless of the IMTA system used, resulted in lower biofloc concentrations, compared to the monoculture of shrimp, thus confirming that mullet can be used to control solids concentrations originating from shrimp production in a BFT system.
This study analyzes the investment in Penaeus (Litopenaeus) vannamei shrimp production in greenho... more This study analyzes the investment in Penaeus (Litopenaeus) vannamei shrimp production in greenhouses using the biofloc technology system (BFT). Considering bioeconomic variables, a sensitivity analysis was performed with data collected over the course of 10 years to evaluate program efficiency. The parameters considered include a stocking density of 400 shrimp/m2, which reached a productivity rate of 3.84 kg/m2 (69,120 kg/year—three cycles), a final mean weight of 12 g, and a feed conversion rate of 1.3. The results obtained had a net present value (NPV) of US$ 904,947.21, net future value (NFV) of US$ 2,401,094.35, equivalent annual value (EAV) of US$ 148,861.38, payback (PB) of 2 years and 4 months, discounted payback period (DPP) of 2 years and 10 months, profitability index (PI) of 2.59, internal rate of return (IRR) of 41.23%, and a modified internal rate of return (MIRR) of 21.25%. However, shrimp with a final mean weight of 15 g resulted in an NPV of US$ 2,522,150.62, NFV of...
In general, the adverse effect of a chemical compound present in water varies with the concentrat... more In general, the adverse effect of a chemical compound present in water varies with the concentration and time of exposure to the compound, the nature of the chemical species and age of the exposed organisms. Thus, nitrogen does not necessarily cause adverse effects on shrimp, but may, instead, promote sub-lethal effects by long-term exposure. Juvenile Farfantepenaeus brasiliensis (initial mean weight = 0.61 g ± 0.07) were exposed to sub-lethal concentrations of ammonia (0.44 and 0.88 mg L-1), nitrite (5.30 and 10.60 mg L-1) and nitrate (45.60 and 91.20 mg L-1) corresponding to the safe levels for the species. After 40 days of exposure of juveniles to ammonia, nitrite and nitrate, all groups differed significantly (p<0.05) from the control group regarding the growth and survival. Based on the results, it was determined that the shrimp F. brasiliensis was susceptible to nitrogen compounds in concentrations equivalent to supposedly safe levels previously proposed for the specie. Thu...
The objective of this work was to evaluate the effect of the traditional culture system in clear ... more The objective of this work was to evaluate the effect of the traditional culture system in clear water and of the one in microbial flocs on the antioxidant and immunological status of Litopenaeus vannamei shrimp. Samples (gill, hemolymph, and hepatopancreas) were collected on days 15, 30, and 60 of the experimental period. The following immunological parameters were analyzed at each evaluation time: granular and hyaline hemocytes, total protein, and apoptosis. Assays on glutamate-cysteine ligase (GCL) activity and on the concentrations of reduced glutathione (GSH) and thiobarbituric acid reactive substances (TBARS) were also performed. The evaluated immunological parameters did not differ significantly between treatments. Shrimp reared in clear water showed higher levels of lipid peroxidation in the gills and of GCL activity in the hemolymph on days 15 and 30. Shrimp in microbial floc had a higher survival rate, and the water did not have to be renewed during the experimental period...
In general, the adverse effect of a chemical compound present in water varies with the concentrat... more In general, the adverse effect of a chemical compound present in water varies with the concentration and time of exposure to the compound, the nature of the chemical species and age of the exposed organisms. Thus, nitrogen does not necessarily cause adverse effects on shrimp, but may, instead, promote sub-lethal effects by long-term exposure. Juvenile Farfantepenaeus brasiliensis (initial mean weight = 0.61 g ± 0.07) were exposed to sub-lethal concentrations of ammonia (0.44 and 0.88 mg L-1), nitrite (5.30 and 10.60 mg L-1) and nitrate (45.60 and 91.20 mg L-1) corresponding to the safe levels for the species. After 40 days of exposure of juveniles to ammonia, nitrite and nitrate, all groups differed significantly (p<0,05) from the control group regarding the growth and survival. Based on the results, it was determined that the shrimp F. brasiliensis was susceptible to nitrogen compounds in concentrations equivalent to supposedly safe levels previously proposed for the specie. Thu...
Dissertacao(mestrado)-Universidade Federal do Rio Grande, Programa de Pos–Graduacao em Aquicultur... more Dissertacao(mestrado)-Universidade Federal do Rio Grande, Programa de Pos–Graduacao em Aquicultura, Instituto de Oceanografia, 2011.
This study was conducted to evaluate the effects of the feeding rate (0%, 2.5%, 5.0%, 7.5%, and 1... more This study was conducted to evaluate the effects of the feeding rate (0%, 2.5%, 5.0%, 7.5%, and 10% of body weight per day; BW.d−1) on growth performance, nutritional efficiency, and profitability of Nile tilapia (Oreochromis niloticus) juveniles (3.1 ± 0.1 g) using the biofloc technology (BFT) system for 70 days. Fish were randomly stocked (15 fish. Tank−1) in 24 experimental units (50 L), while water quality parameters remained within acceptable limits for the species during the experiment. Animal performance parameters were influenced by feeding rates (P 0.05), which remained around 81%. Final body weight, weight gain, and thermal growth coefficient increased significantly (P
This study aimed to evaluate the effect of alkalinity on food consumption and other performance p... more This study aimed to evaluate the effect of alkalinity on food consumption and other performance parameters of juvenile Litopenaeus vannamei reared in water containing biofloc and clear water. For this purpose, shrimp of 4.06 ± 0.34 g were kept in containers of 3 L of biofloc and clear water during 3 days, with the concentrations of 50, 100 and 200 mg L-1 of alkalinity, plus a Control group, with 5 replicates each group. Food consumption was verified once a day and other performance parameters were evaluated at the end of the experiment. The food consumption and survival rates of the shrimp was not affected by the different levels of alkalinity and clear water and biofloc systems. The best results of weight gain and specific growth rate were observed in the highest concentrations of alkalinity in the biofloc system. Survival, as well as food consumption, was not affected between levels of alkalinity and in clear water and biofloc. The exposure to inappropriate alkalinity concentratio...
Abstract The purpose of this study was to evaluate the effect of water temperature on the antioxi... more Abstract The purpose of this study was to evaluate the effect of water temperature on the antioxidant (gills, hemolymph and hepatopancreas) and immunological systems (hemolymph) of Litopenaues vannamei reared with no water exchange. A 60-day trial was conducted at different temperatures (15, 21, 27—control and 33 °C), with 3 replicate tanks for each treatment. The immunologic parameters analyzed were as follows: hyaline and granular hemocyte count, total protein and apoptosis. The enzymatic and lipid peroxidation assays consisted of glutamate cysteine ligase (GCL), reduced glutathione (GSH) and thiobarbituric acid-reactive substances (TBARS). There were no significant differences (p > 0.05) in immunological parameters among treatments throughout the experimental period. Shrimp exposed to 15 °C at 30 days exhibited significantly higher GCL activity in gills compared to 21 °C (1166.28%), 27 °C (422.96%) and 33 °C (809.37%). L. vannamei reared at 15 °C had the highest GSH concentration at 30 days. The GSH increase in gills was 390.29, 376.94 and 361.75% at 21, 27 and 33 °C, respectively. On day 30, shrimp subjected to 33 °C had higher TBARS levels (6157.14; 8620.00 and 14,336.66% at 15, 21 and 27 °C, respectively). Shrimp reared at 15 °C exhibited higher activity of the rate-limiting compound for GSH production (GCL) and higher concentrations of this non-enzymatic antioxidant. This increased activity may counteract the overproduction of reactive oxygen species generated by temperature stress. We further noted that at 33 °C, the animals showed higher lipid peroxidation. The lowest stress response was observed in shrimp reared at 27 °C (the control group). Therefore, the extreme temperatures should be avoided. Statement/relevance This study present new results about handling and welfare.
In recent decades, new aquaculture technologies have been developed and improved, such as the Bio... more In recent decades, new aquaculture technologies have been developed and improved, such as the Biofloc Technology system, which is considered an alternative to the conventional aquaculture model. This study compared the bioeconomic viability of intensive production in nurseries and super-intensive production of shrimp Litopenaeus vannamei bioflocs greenhouses. The investment for implementing the project was US$ 767,190.18 for intensive production and US$ 807,669.16 for super-intensive production. The analyses showed Net Present Value of US$ 363,718.21 and US$ 385,477.42, Equivalent annual value of US$ 59,830.66 and US$ 63,410.00, Net future value of US$ 965,052.69 and US$ 1,022,786.35, Payback Period 4.12 and 4.11, Discounted payback period 5.64 and 5.63, Profitability Index 1.47 and 1.48, Internal Rate of Return 20.49 and 20.55%, and Modified Internal Rate of Return 14.61 and 14.64%. The investment analysis used in this study showed that super-intensive production in a greenhouse is...
ABSTRACT The initial stages of rearing marine shrimp using biofloc technology (BFT) involve the b... more ABSTRACT 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 CaCO3/L. To maintain the alkalinity at the established level, sodium bicarbonate was applied. For the experiments, twelve experimental units (area = 0.20 m2) 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/m2 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.
Biofloc technology (BFT) has been used to rear white shrimp, Litopenaeus vannamei. In this cultur... more 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 (H2O2) can be used as an emergency source of oxygen. This study aimed to determine the lethal concentration and safe level of H2O2 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 H2O2 [29 (100), 58 (200), 116 (400), 174 (600), 232 (800), 290 (1,000) and 348 (1,200) μL H2O2/L (ppm H2O2-29 %/L)] in addition to a control group without addition of H2O2, and the survival rates were monitored for 96 h. The LC50 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 H2O2/L, respectively. The safe level was 14.3 μL H2O2/L, and the highest concentration with survival rates similar to the control group (NOAEC) was 29 μL H2O2/L. In these concentrations, H2O2 can be used as a safe source of oxygen for L. vannamei reared in BFT systems.
The pink shrimp Farfantepenaeus brasiliensis is native in southern Brazil and is potentially suit... more The pink shrimp Farfantepenaeus brasiliensis is native in southern Brazil and is potentially suited for aquaculture. Under intensive culture, the accumulation of nitrogenous compounds results from excretion by the shrimp and from the processes of feed decomposition and nitrification. The objective of this study was to evaluate ammonia, nitrite, and nitrate toxicity effects on oxygen consumption of juvenile pink shrimp. Shrimps (initial weight 0.7 ± 0.15 g) were exposed over a period of 30 days to 50%, 100%, and 200% of the safe levels of total ammonia (TAN = 0.88 mg/L), nitrite (NO2− = 10.59 mg/L), and nitrate (NO3− = 91.20 mg/L) for the species. The specimens were individually collected and placed in respirometry chambers, where the oxygen consumption was measured over a period of two hours. Throughout the experiment there was no significant difference (p > 0.05) among treatments in terms of survival and growth. The pink shrimp juveniles exposed to nitrogen concentrations of 200% of the nitrite and nitrate safe level showed the highest oxygen consumption (p < 0.05).
The reduction in alkalinity and pH occurs due to the consumption of inorganic carbon by bacteria ... more The reduction in alkalinity and pH occurs due to the consumption of inorganic carbon by bacteria present in the biofloc. The objective of the study was to evaluate the effects of different doses of calcium hydroxide on the water quality and growth performance of the Litopenaeus vannamei in a biofloc system. The experiment consisted of four treatments with three repetitions for each treatment: Control treatment (TC), in which the pH maintained above 7.2 due to the application of 0.05 g L−1 of calcium hydroxide, and treatments T10, T20 and T40, in which daily doses of calcium hydroxide equivalent to 10, 20 and 40 % of the total amount of feed offered to the shrimp, respectively, were added to the environment. Twelve experimental units (150 L) were stocked with 85 juveniles of L. vannamei (0.18 ± 0.06 g), corresponding to a density of 425 shrimp m−3, and cultivated for 56 days. The values of alkalinity and pH for treatments TC and T10 were similar and significantly lower (p < 0.05) than those for treatments T20 and T40, which differed (p < 0.05) between each other. In terms of growth performance, TC, T10 and T20 performed significantly better (p < 0.05) than T40. There were no significant differences (p > 0.05) in the survival rates. The results obtained indicate that doses of 0.05 g L−1 of calcium hydroxide or daily applications between 10 and 20 % of the total amount of feed offered to the shrimp can be used for the correction of alkalinity and pH.
Abstract The biofloc culture system (BFT) allows for the production of aquatic animals at higher ... more Abstract The biofloc culture system (BFT) allows for the production of aquatic animals at higher stocking densities compared to conventional aquaculture systems and it has been proven to be efficient for shrimp (Litopenaeus vannamei) and mullet (Mugil liza) rearing. Accumulation of nutrients enhances the natural productivity of the system, thus the concentration of total suspended solids (TSS) tends to accumulate during the production cycle, which can deteriorate the water quality and performance of the animals produced. Integrated multi trophic aquaculture (IMTA) can be performed in single or multi tank systems, depending on the interaction of the different species being cultured. The present study aimed to reduce TSS concentration by integrating juvenile mullet into a shrimp BFT system, through the consumption of these solids by the mullet. Three different treatments were used: shrimp monoculture (MONO), single tank (SING -shrimp and mullet cultured in the same tank) and IMTA multi tank (MULT- shrimp and mullet cultured in different tanks). The performance of shrimp was impaired in the SING treatment, while mullet had their best zootechnical performance in this treatment. The presence of the fish modified the nitrification even with the use of biofloc inoculum. The presence of mullet, regardless of the IMTA system used, resulted in lower biofloc concentrations, compared to the monoculture of shrimp, thus confirming that mullet can be used to control solids concentrations originating from shrimp production in a BFT system.
This study analyzes the investment in Penaeus (Litopenaeus) vannamei shrimp production in greenho... more This study analyzes the investment in Penaeus (Litopenaeus) vannamei shrimp production in greenhouses using the biofloc technology system (BFT). Considering bioeconomic variables, a sensitivity analysis was performed with data collected over the course of 10 years to evaluate program efficiency. The parameters considered include a stocking density of 400 shrimp/m2, which reached a productivity rate of 3.84 kg/m2 (69,120 kg/year—three cycles), a final mean weight of 12 g, and a feed conversion rate of 1.3. The results obtained had a net present value (NPV) of US$ 904,947.21, net future value (NFV) of US$ 2,401,094.35, equivalent annual value (EAV) of US$ 148,861.38, payback (PB) of 2 years and 4 months, discounted payback period (DPP) of 2 years and 10 months, profitability index (PI) of 2.59, internal rate of return (IRR) of 41.23%, and a modified internal rate of return (MIRR) of 21.25%. However, shrimp with a final mean weight of 15 g resulted in an NPV of US$ 2,522,150.62, NFV of...
In general, the adverse effect of a chemical compound present in water varies with the concentrat... more In general, the adverse effect of a chemical compound present in water varies with the concentration and time of exposure to the compound, the nature of the chemical species and age of the exposed organisms. Thus, nitrogen does not necessarily cause adverse effects on shrimp, but may, instead, promote sub-lethal effects by long-term exposure. Juvenile Farfantepenaeus brasiliensis (initial mean weight = 0.61 g ± 0.07) were exposed to sub-lethal concentrations of ammonia (0.44 and 0.88 mg L-1), nitrite (5.30 and 10.60 mg L-1) and nitrate (45.60 and 91.20 mg L-1) corresponding to the safe levels for the species. After 40 days of exposure of juveniles to ammonia, nitrite and nitrate, all groups differed significantly (p<0.05) from the control group regarding the growth and survival. Based on the results, it was determined that the shrimp F. brasiliensis was susceptible to nitrogen compounds in concentrations equivalent to supposedly safe levels previously proposed for the specie. Thu...
The objective of this work was to evaluate the effect of the traditional culture system in clear ... more The objective of this work was to evaluate the effect of the traditional culture system in clear water and of the one in microbial flocs on the antioxidant and immunological status of Litopenaeus vannamei shrimp. Samples (gill, hemolymph, and hepatopancreas) were collected on days 15, 30, and 60 of the experimental period. The following immunological parameters were analyzed at each evaluation time: granular and hyaline hemocytes, total protein, and apoptosis. Assays on glutamate-cysteine ligase (GCL) activity and on the concentrations of reduced glutathione (GSH) and thiobarbituric acid reactive substances (TBARS) were also performed. The evaluated immunological parameters did not differ significantly between treatments. Shrimp reared in clear water showed higher levels of lipid peroxidation in the gills and of GCL activity in the hemolymph on days 15 and 30. Shrimp in microbial floc had a higher survival rate, and the water did not have to be renewed during the experimental period...
In general, the adverse effect of a chemical compound present in water varies with the concentrat... more In general, the adverse effect of a chemical compound present in water varies with the concentration and time of exposure to the compound, the nature of the chemical species and age of the exposed organisms. Thus, nitrogen does not necessarily cause adverse effects on shrimp, but may, instead, promote sub-lethal effects by long-term exposure. Juvenile Farfantepenaeus brasiliensis (initial mean weight = 0.61 g ± 0.07) were exposed to sub-lethal concentrations of ammonia (0.44 and 0.88 mg L-1), nitrite (5.30 and 10.60 mg L-1) and nitrate (45.60 and 91.20 mg L-1) corresponding to the safe levels for the species. After 40 days of exposure of juveniles to ammonia, nitrite and nitrate, all groups differed significantly (p<0,05) from the control group regarding the growth and survival. Based on the results, it was determined that the shrimp F. brasiliensis was susceptible to nitrogen compounds in concentrations equivalent to supposedly safe levels previously proposed for the specie. Thu...
Dissertacao(mestrado)-Universidade Federal do Rio Grande, Programa de Pos–Graduacao em Aquicultur... more Dissertacao(mestrado)-Universidade Federal do Rio Grande, Programa de Pos–Graduacao em Aquicultura, Instituto de Oceanografia, 2011.
This study was conducted to evaluate the effects of the feeding rate (0%, 2.5%, 5.0%, 7.5%, and 1... more This study was conducted to evaluate the effects of the feeding rate (0%, 2.5%, 5.0%, 7.5%, and 10% of body weight per day; BW.d−1) on growth performance, nutritional efficiency, and profitability of Nile tilapia (Oreochromis niloticus) juveniles (3.1 ± 0.1 g) using the biofloc technology (BFT) system for 70 days. Fish were randomly stocked (15 fish. Tank−1) in 24 experimental units (50 L), while water quality parameters remained within acceptable limits for the species during the experiment. Animal performance parameters were influenced by feeding rates (P 0.05), which remained around 81%. Final body weight, weight gain, and thermal growth coefficient increased significantly (P
This study aimed to evaluate the effect of alkalinity on food consumption and other performance p... more This study aimed to evaluate the effect of alkalinity on food consumption and other performance parameters of juvenile Litopenaeus vannamei reared in water containing biofloc and clear water. For this purpose, shrimp of 4.06 ± 0.34 g were kept in containers of 3 L of biofloc and clear water during 3 days, with the concentrations of 50, 100 and 200 mg L-1 of alkalinity, plus a Control group, with 5 replicates each group. Food consumption was verified once a day and other performance parameters were evaluated at the end of the experiment. The food consumption and survival rates of the shrimp was not affected by the different levels of alkalinity and clear water and biofloc systems. The best results of weight gain and specific growth rate were observed in the highest concentrations of alkalinity in the biofloc system. Survival, as well as food consumption, was not affected between levels of alkalinity and in clear water and biofloc. The exposure to inappropriate alkalinity concentratio...
Abstract The purpose of this study was to evaluate the effect of water temperature on the antioxi... more Abstract The purpose of this study was to evaluate the effect of water temperature on the antioxidant (gills, hemolymph and hepatopancreas) and immunological systems (hemolymph) of Litopenaues vannamei reared with no water exchange. A 60-day trial was conducted at different temperatures (15, 21, 27—control and 33 °C), with 3 replicate tanks for each treatment. The immunologic parameters analyzed were as follows: hyaline and granular hemocyte count, total protein and apoptosis. The enzymatic and lipid peroxidation assays consisted of glutamate cysteine ligase (GCL), reduced glutathione (GSH) and thiobarbituric acid-reactive substances (TBARS). There were no significant differences (p > 0.05) in immunological parameters among treatments throughout the experimental period. Shrimp exposed to 15 °C at 30 days exhibited significantly higher GCL activity in gills compared to 21 °C (1166.28%), 27 °C (422.96%) and 33 °C (809.37%). L. vannamei reared at 15 °C had the highest GSH concentration at 30 days. The GSH increase in gills was 390.29, 376.94 and 361.75% at 21, 27 and 33 °C, respectively. On day 30, shrimp subjected to 33 °C had higher TBARS levels (6157.14; 8620.00 and 14,336.66% at 15, 21 and 27 °C, respectively). Shrimp reared at 15 °C exhibited higher activity of the rate-limiting compound for GSH production (GCL) and higher concentrations of this non-enzymatic antioxidant. This increased activity may counteract the overproduction of reactive oxygen species generated by temperature stress. We further noted that at 33 °C, the animals showed higher lipid peroxidation. The lowest stress response was observed in shrimp reared at 27 °C (the control group). Therefore, the extreme temperatures should be avoided. Statement/relevance This study present new results about handling and welfare.
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