Acute tolerance of juvenile Florida pompano, Trachinotus carolinus L., to ammonia and nitrite at various salinities

Abstract

The acute tolerance of juvenile Florida pompano Trachinotus carolinus L. (mean weight±SE=8.1±0.5 g) to environmental unionized ammonia-nitrogen (NH3-N) and nitrite-nitrogen (NO2-N) at various salinities was determined via a series of static exposure trials. Median-lethal concentrations (LC50 values) of NH3-N and NO2-N at 24, 48, and 96 h of exposure were calculated at salinities of 6.3, 12.5 and 25.0 g L−1 at 28 °C (pH=8.23–8.36). Tolerance of pompano to acute NH3-N exposure was not affected by salinity, with 24, 48 and 96 h LC50 values ranging from 1.05 to 1.12, 1.00 to 1.08 and 0.95 to 1.01 mg NH3-N L−1 respectively. Regarding NO2-N, tolerance of pompano to this environmental toxicant was compromised at reduced salinities. Median-lethal concentrations of NO2-N to pompano at 24, 48 and 96 h of exposure ranged from 67.4 to 220.1, 56.9 to 140.7 and 16.7 to 34.2 mg NO2-N L−1 respectively. The results of this study indicate that juvenile Florida pompano are relatively sensitive to acute NH3-N and NO2-N exposure, and in the case of the latter, especially at lower salinities.