Tolerance of juvenile black sea bass Centropristis striata to acute ammonia and nitrite exposure at various salinities

摘要

Experiments were conducted to determine the acute tolerance of juvenile (mean weight±standard error, 9.9±0.9 g) black sea bass Centropristis striata to environmental un-ionized ammonia-nitrogen (NH3?N) and nitrite-nitrogen (NO2?N) exposure at various salinities. Specifically, median lethal concentrations (LC50 values) of NH3?N and NO2?N at 24, 48 and 96 h of exposure were determined at salinities of 10, 20 and 30 g/L at 22°C. With the exception of LC50 values determined at 48 h, median lethal concentrations of NH3?N to black sea bass were not influenced by environmental salinity; 24, 48, and 96 h LC50 values ranged from 0.81 to 0.85, 0.65–0.77, and 0.46–0.54 mg?NH3?N/L, respectively. In contrast, tolerance of black sea bass to environmental NO2?N was compromised at reduced salinities. Median lethal concentrations of NO2?N to fish at 24, 48 and 96 h of exposure ranged from 288.3 to 429.0, 258.4 to 358.8 and 190.0 to 241.9 mg?NO2?N/L, respectively. Results indicate that while juvenile black sea bass are relatively sensitive to acute NH3?N exposure, they are highly resistant to NO2?N exposure.