Effects of Ambient Nitrite on Amazon River Prawn,Macrobrachium amazonicum,larvae |
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| Authors: | Liliam A Hayd Daniel Lemos Wagner C Valenti |
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| Abstract: | The effects of nitrite concentration on larval development of Amazon river prawn, Macrobrachium amazonicum, were studied in laboratory. In Experiment 1, larvae were reared in 600‐mL glass beakers filled with 300‐mL water with nitrite concentration of 0, 0.2, 0.4, 0.8 and 1.6 mg/L NO2‐N. In Experiment 2, total ammonia nitrogen (TAN, NH3‐N + NH4‐N) excretion were analyzed in zoea (Z) I, III, VII and IX exposed to 0, 0.4, 0.8 and 1.6 mg/L NO2‐N. In both experiments each treatment was conducted in five replicates. The experiments were carried out in test solutions at 10 salinity, constant temperature 30 C and 12:12 h daylight : darkness regime. Survival, productivity, weight gain and larval stage index decreased linearly with increasing ambient nitrite concentration. However, there was no significant difference among larvae reared at concentration ranging from 0 to 0.8 mg/L NO2‐N by ANOVA in all variables. Individual ammonia‐N and mass‐specific ammonia‐N excretion increased in ZI and ZIX, was almost constant in ZIII and decreased in ZVII from 0 to 1.6 mg/L NO2‐N. The relationship between individual TAN and body mass suggested that 1.6 mg/L NO2‐N stress the larvae. Despite of the effects of nitrite on larvae follow a dose‐dependent response and shows large variability among individuals, levels below 0.8 mg/L may be used as a general reference in commercial hatcheries, which should be applied carefully. |
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