Plínio S. Furtado

Acute effects of extreme pH and its influences on the survival and biochemical biomarkers of juvenile White Shrimp, Litopenaeus vannamei

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 juvenile L. 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 pH50 at 24, 48, 72 and 96 h for juvenile L. vannamei had 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.

Chronic effect of nitrite on the rearing of the white shrimp Litopenaeus vannamei in two salinities

Abstract The aim of this study was to determine the effects of nitrite on the growth and survival of the white shrimp L. vannamei in 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 juvenile L. 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 of L. vannamei in salinities of 8 and 24 g/L, respectively.

The Effect of Ammonia, Nitrite, and Nitrate on the Oxygen Consumption of Juvenile Pink Shrimp Farfantepenaeus brasiliensis (Latreille, 1817) (Crustacea: Decapoda)

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).

Acute toxicity of carbon dioxide to juvenile marine shrimp Litopenaeus vannamei (Boone 1931)

ABSTRACT 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 CO2 in 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 CO2 for juvenile white shrimp Litopenaeus 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 LC50 values 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 CO2 levels should be kept below the safety level obtained in this study.