Effect of Combined Non‐ionized Ammonia and Dissolved Oxygen Levels on the Survival of Juvenile Dourado,Salminus brasiliensis (Cuvier) |
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| Authors: | Raphael De Leão Serafini Evoy Zaniboni‐Filho Bernardo Baldisserotto |
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| Institution: | 1. Laboratory of Freshwater Fish Biology and Culture, Department of Aquaculture, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil;2. Department of Physiology and Pharmacology, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil |
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| Abstract: | The aim of this study was to assess the mean lethal concentration (LC50) of dissolved oxygen in high ammonia concentration and also the LC50 of ammonia under hypoxic conditions for juveniles of dourado, Salminus brasiliensis. In the first experiment, the non‐ionized ammonia (NH3) concentrations were: 0.026, 0.447, 0.612, 0.909, and 1.334 mg/L, and the dissolved oxygen concentration was maintained at approximately 1.65 mg/L. In the second experiment, the dissolved oxygen concentrations were: 1.64, 1.99, 3.33, 5.10, and 7.77 mg/L, and the non‐ionized ammonia concentration was kept at approximately 0.927 mg/L. The mean lethal concentrations of non‐ionized ammonia varied from 0.584 to 0.577 mg/L, indicating that LC50 values were almost unaffected by exposure time. The estimated LC50 of dissolved oxygen varied from 4.02 to 5.02 mg/L, indicating a slight increase in the mean lethal concentrations as the exposure time increased. Results from this study indicate that interaction between these two parameters increases mortality and also suggest that dourado is susceptible to the combination of high ammonia with low dissolved oxygen concentrations. |
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