Acute toxicity of ammonia in juvenile brazilian sardine Sardinella brasiliensis

Abstract

The Brazilian sardine (Sardinella brasiliensis) is the main fishery resource in Brazil, holding directly the canning industry, as raw material, and indirectly, as the tuna fishing, because juveniles are used as live bait. The UFSC through Live-Bait Project is developing production techniques of Brazilian sardine in captive aimed at the sustainable use of the resource, however, there is no information about the toxicity of nitrogenous compounds in the culture of this species. This study was conducted to estimate the acute toxicity of ammonia (NH₃-N) on the juvenile Brazilian sardine. Groups of five fish (1.04 ± 0.20 g) were exposed to five concentrations of NH₃-N (0.60 to 1.47 mg L^-1) for 96 h plus control group in three replicates. Tests were run using a standard semi-static system with 100% daily renewal of water and toxicants. The results were based on mortality data registered for the different concentrations tested, using the software Trimmed Spearman Karber method. The median lethal concentration (LC₅₀) after 96 h of exposure to NH₃-N was estimated at 0.74 (0.61-0.90) mg L^-1. The results indicate that the juvenile Brazilian sardine is relatively sensitive to ammonia compared to other marine fish and that particular attention must be given to this compound in culture systems.