ACUTE TOXICITY OF AMMONIA TO JUVENILE SEA BASS (DICENTRARCHUS-LABRAX L) AT DIFFERENT AERATION LEVELS

Acute toxicity of ammonia to juvenile sea bass at three aeration level s of test tanks is expressed as median lethal time (LT50). Two statist ically significant components were distinguished by principal componen t analyses (PC) between the chemical parameter (pH, O2 concentration a nd un-ionized ammonia) and their interactions in each tank. The first PC describes the phase properties of pH, O2 concentration and NH3. The second PC describes the toxicity due to the dissociation of added NH4 Cl to experimental tanks. It is negatively correlated with pH and posi tively correlated with NH3.LC50 is highly negatively correlated with t he second PC whereas the correlation with the first is negative and co nsiderably poorer.