Lethal effects of elevated pH and ammonia on juveniles of neotropical fish Colosoma macropomum (Pisces, Caracidae).
Ammonia is the main nitrogenous waste material excreted by gills, then is oxided first to nitrite and then to nitrate. The proportion of ionized-un-ionized ammonia depends on pH and temperature, when this variables increase in a solution containing ammonia the equation goes to left, so the proportion of NH3 increases and the solution becomes more toxic. The purpose of this study was to investigate the acute lethal effects of elevated pH and ammonia on tambaqui juveniles. With a constant ammonia concentration of 5.0 mg/l NH3, there was no mortality a pH of 6.0 (control) and 7.0; but was of 10-20% a pH of 8.0 and 100% at 9.0. The lethal effects of elevated pH and un-ionized ammonia should be recognized as a potential factor contributing to the variable success of tambaqui production ponds, but this species is highly resistant in comparison with other freshwater fish.
National Institute of Limnology (INALI), National Council of Technical and Scientific Research (CONICET) and National University of Litoral (UNL), Jose Macia 1933, (3016) Santo Tome City, Santa Fe Province, Argentine Republic. julietaparma@arnet.com.ar
Parma
P
de Croux
Maria
M
Julieta
Alicia
A
Loteste
D000367:Age Factors; D000641:Ammonia / Q000737:chemistry / Q000633:toxicity*; D000818:Animals; D001826:Body Fluids / Q000187:drug effects* / Q000378:metabolism; D005399:Fishes; D005618:Fresh Water; D005880:Gills / Q000187:drug effects* / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007928:Lethal Dose 50; D017672:Nitrogen Compounds / Q000378:metabolism; D014873:Water Pollutants / Q000633:toxicity*
D007477:Ions; D017672:Nitrogen Compounds; D014873:Water Pollutants; D000641:Ammonia