Acute effect of nitrate on Mugil platanus (Pisces: Mugilidae) fingerlings

Abstract

Nitrate was used to be considered not toxic for aquatic animals; however, in closed water culture system, this substance can accumulate high concentrations that could become potentially toxic for fish and crustacean. The aim of the present work was to determine the median lethal concentrations (LC₅₀) of nitrate for mullet (Mugil platanus) fingerlings, and to establish the safe level for the culture of the species. Short-term bioassay was carried out through 96 hours. Mullet fingerlings (average weight of 0.19 g) were exposed to concentrations of 0; 125; 250; 500; 750; 1,000; 1,250; 1,500; 1,750; 2,000; 2,500; and 3,000 mg/L of N-NO₃. The LC₅₀ was estimated based on mortality in the bioassays and their values were 2,287.4 and 1,522.4 mg/L, after 24 and 96 hours, respectively. Safe level was estimated in 152.2 mg/L of N-NO₃. Results demonstrate that M. platatus is highly tolerant to nitrate, and data contribute positively for its culture.