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Aquatic animals are vulnerable to arsenic (As) toxicity. However, rarely does a contaminant occur alone in the aquatic environment. For this reason, this study was conducted to evaluate whether titanium dioxide nanoparticles (nTiO2) can interfere with the effects induced by As in Litopenaeus vannamei. Arsenic accumulation and metabolic capacity; expression and enzymatic activity of GSTΩ (glutathione-S-transferase omega isoform); antioxidant responses such as GSH, GR, and GST (reduced glutathione levels, glutathione reductase, and glutathione-S-transferase activity, respectively); and lipid peroxidation in the gills and hepatopancreas of shrimp were evaluated. The results are summarized as follows: (1) higher accumulation of As occurred in both tissues after exposure to As alone; (2) co-exposure to nTiO2 affected the capacity to metabolize As; (3) GSTΩ gene expression was not modified, but its activity was decreased by co-exposure to both contaminants; (4) As alone increased the GSH levels in the hepatopancreas, and co-exposure to nTiO2 reduced these levels in both tissues; (5) a decrease in the GST activity in the gills occurred with all treatments; (6) in the gills, GR activity was increased by As, and nTiO2 reversed this increase, whereas in the hepatopancreas co-exposure inhibited enzyme activity; (7) only in the hepatopancreas lipid damage was observed when animals were exposed to As or nTiO2 but not in co-exposure. The results showed that the As induces toxic effects in both tissues of shrimp and that co-exposure to nTiO2 can potentiate these effects and decrease the capacity to metabolize As, favoring the accumulation of more toxic compounds. [ABSTRACT FROM AUTHOR]

The processing of fish in general entails quantities of by-products, such as exoskeleton and cephalothorax of shrimp, which may reach 70%. Protein recovered from by-products has been investigated in recent years for its ability to offer more nutritious foods and improved functional properties. The objective of the present study was the use of the pH shifting process to recover proteins from solubilization and precipitation that are present in the by-products (heads and shells) of white shrimp (Litopenaeus vannamei). The proximal composition of the by-products presented 58.5% protein (d.b). The isoelectric point used to precipitate the protein was defined at pH 4. The protein concentrate presented 73.1% of protein. The yield of the protein concentrate mass resulted in 47.8% (w.b). The greatest solubility found for the protein concentrate was 51.3% at pH 8. The oil and water retention capacity resulted in values of 8.5 and 2.5 mL/g of protein, respectively, and the highest emulsifying capacity was found at pH 8. The by-products and concentrate amino acids profiles confirmed the presence of 16 amino acids. In general, the shrimp protein concentrate obtained showed the potential to be included as an ingredient in food formulations. [ABSTRACT FROM AUTHOR]

Blooms of the toxic cyanobacteriumNodularia spumigenaoccur in various locations worldwide, but have not been observed in Brazil until recently. ThreeNodulariastrains were isolated from summer blooms in experimental shrimp production ponds ofPenaeus vannameiin Rio Grande, in southern Brazil; these strains were characterized by morphology, phylogeny, growth rate and toxicity. The strains were identified asN. spumigenabased on the size of vegetative cells, heterocytes and akinetes under a light microscope and based on the number of gas vesicles per μm2under a transmission electron microscope. The 16S rRNA gene sequences of the three strains showed high identity (> 99%) withN. spumigenasequences available on the NCBI database but were grouped closer in the phylogenetic tree withN. spumigenastrains from Australia and USA than those from the Baltic Sea. The growth rate in batch culture varied between 0.2 and 0.6 μ d−1based on cell density, optical density and chlorophyll-a content. The three strains produced the hepatotoxin nodularin (ELISA plate kit) with similar toxicity values (4.8–4.9 µg l−1). We conclude that the three isolated strains areN. spumigenawith similar rates of growth and nodularin production. The presence ofN. spumigenanow represents a potential problem in aquaculture and estuarine environments in Brazil. [ABSTRACT FROM PUBLISHER]

Elevated concentrations of dissolved carbon dioxide (CO2) and reduced pH levels are observed during the culture and transportation of aquatic organisms. Studies on the toxicity effects of CO2in penaeid shrimp are scarce when compared to the amount of research in fish. The objective of the present study was to determine the lethal concentration and safety levels of CO2for juvenile white shrimpLitopenaeus vannamei. Juveniles (1.76 ± 0.36 g) were exposed for 96 h to one of six concentrations of dissolved CO2(14.5, 23.8, 59.0, 88.0, 115.0, and 175.0 mg/L) or a control condition (without the addition of CO2), and their survival was monitored for 96 h. The LC50values with 95% confidence limits at 24, 48, 72, and 96 h were 130.05 (104.2–162.1), 77.2 (73.8–80.02), 69.65 (65.47–74.32), and 59.12 (53.08–66.07) mg/L of CO2, respectively. The calculated safety level was 5.9 mg/L of CO2, and the highest concentration that did not induce significantly higher mortality than that observed in controls (NOEC) was 23.8 mg/L of CO2. We recommend that CO2levels should be kept below the safety level obtained in this study. [ABSTRACT FROM PUBLISHER]

A failure in the aeration system ofLitopenaeus vannameirearing with biofloc technology can decrease the oxygen concentrations rapidly and also increase the carbon dioxide (CO2) concentrations at the same rate. We report here an evaluation of the effect of CO2on the oxygen consumption ofL. vannamei. We used a continuous-flow respirometer with water recirculation equipped with a digital fiber-optic oximeter. Eight juveniles ofL. vannamei(12.1 ± 1. 4 g) were used in each treatment with one per respiratory chamber (0.6 L). The shrimp were exposed to six concentrations of CO2(5, 30, 60, 95, 150, and 300 mgCO2/L) with an acute exposure time of six hours. Upon treatment with 5–30 mgCO2/L, we observed a consumption of oxygen of 0.233 ± 0.129 and 0.33 ± 0.072 mgO2/g/h, respectively. Upon treatment with 60 mgCO2/L, an increase was observed in the oxygen consumption (0.521 ± 0.098 mgO2/g/h). Upon treatment with 95, 150, and 300 mgCO2/L however, the shrimp decreased their oxygen consumption and lost their equilibrium. The CO2should therefore be maintained at a maximum of 5 mgCO2/L during shrimp rearing. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the effects of nitrite on the growth and survival of the white shrimpL. vannameiin two different salinities. Nitrite concentrations tested in salinity 8 g/L were 0 (control), 2.5, 5.0, 10.0, and 20.0 mg NO2−-N/L, and in salinity 24 g/L were 0 (control), 5.0, 10.0, 20.0, and 40.0 mg NO2−-N/L. For these experiments, 30 experimental units with 30 L of useful volume were stocked with 20 juvenileL. vannamei(8.0 ± 0.50 g), corresponding to a stocking density of 100 shrimp/m2, and cultivated for an experimental period of 30 days. A significant difference was found between the control and treatment groups with respect to growth and survival. The 2.5 mg NO2−-N/L treatment showed the best performance indexes in salinity 8 g/L, while the best growth performance indexes were found in the control and 5.0 mg NO2−-N/L treatments in salinity 24 g/L. Total mortality was observed in the 10 and 20 mg NO2−-N/L treatment groups from salinity 8 g/L and in the 40 mg NO2−-N/L treatment group in salinity 24 g/L. This study determined that concentrations of nitrite of up to 2.5 and 10 mg/L are acceptable for the rearing ofL. vannameiin salinities of 8 and 24 g/L, respectively. [ABSTRACT FROM PUBLISHER]

The White Shrimp (Litopenaeus vannamei) is reared in several types of systems. Changes in pH in some can produce sub-lethal effects that result in poor growth and survival. The aim of the present study was to determine the acidic and basic pH 50% lethal limits after 96 h exposure (pH50–96 h) and to evaluate the sub-lethal effects of pH on oxidative stress parameters in juvenileL. vannamei. The experimental design comprised nine treatments with three replications of each. The nine treatments consisted of pH 10.5, 10.0, 9.5, 9.0, 7.0, 5.0, 4.5, 4.0 and 3.5. The treatment at 7.0 was used as the control. The sub-lethal pH tests were: basic pH 9.5, neutral pH 7.0 (control) and acidic pH 4.5. For each experimental pH and sampling point, the hemolymph of six shrimp was collected to determine catalase and glutathione S-transferase’s activities and total antioxidant capacity. The values of lethal pH50at 24, 48, 72 and 96 h for juvenileL. vannameihad basic pH values equal to 9.82, 9.62, 9.59 and 9.58 and acidic pH values of 3.86, 3.92, 3.94 and 4.04, respectively. The shrimp exposed to basic and acidic pH levels showed antioxidant responses with changes in antioxidant activity. [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]

The pink shrimpFarfantepenaeus brasiliensisis 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). [ABSTRACT FROM PUBLISHER]

A 10-day trial was conducted to evaluate the effect of temperature on the antioxidant system ofLitopenaeus vannameiin a biofloc technology system. Four treatments in triplicate tanks were assigned to the following temperatures: 15, 21, 27 (control), and 33 °C and the water quality parameters were monitored every day. For all enzyme assays, the hemolymph cells lysate of six shrimp per treatment was collected. Lipid peroxidation (LPO) was assessed by determining the content of thiobarbituric acid-reactive substances (TBARS); the activities of catalase (CAT) and glutathione-S-transferase (GST) were also evaluated. The results of TBARS showed that shrimp reared at 15 and 21 °C presented an increase of 407% (240 h) and 339% (120 h), respectively.L. vannameiexposed to 15 °C augmented in 186% (24 h) the activity of CAT. Moreover, shrimp of 21 °C group also increased CAT activity in 228% (6 h). GST presented the strongest variation reaching 1437% in shrimp of 15 °C for 6 h and 1425% of the 21 °C treatment at the same time. All these results were compared to the initial time (27 °C). Moreover, the antioxidant system was not sufficient to counteract LPO; therefore, the animals reared in 15 and 21 °C presented higher enzyme activities, suggesting that cold water can induce the oxidative stress inL. vannamei. [ABSTRACT FROM PUBLISHER]