Avaliação do consumo de oxigênio e excreção de amônia de Astyanax altiparanae (Garutti & Britiski, 2000) submetidos a diferentes concentrações de amônia não ionizada

Abstract

In aquaculture the availability and quality of water are fundamental factors because it is in the aquatic environment that all activity is developed and where fish live and develop, so the amount of oxygen dissolved in water is of vital importance to fish, make capture of this gas from the water through the gills to carry out the cellular respiration and the amount of ammonia available in the environment, because besides being the main product of exception of the aquatic organisms the no ionized ammonia is toxic to the fish. In this sense, the objective of this work is to evaluate the metabolism of fish of the species Astyanax altiparanae by the oxygen consumption after submitted to different concentrations of non-ionized ammonia. For the experiment 75 specimens of lambari-do-tails (A. altiparanae) were used, with a mean size of 6.2 cm of total length and average weight of 3.22 g. The treatments consisted in exposing fish for 24 h in non - ionized ammonia at concentrations of 1.0; 0.75; 0.5; 0.25 mg / L beyond the control (0.0 mg / L) and subsequent evaluation of the consumption of dissolved oxygen and ammonia excretion for one hour. The oxygen consumption data of the fish were obtained through measurements using a digital oximeter. For the ammonia excretion data of the fish, both for the exposure period and for the period maintained in the respirometer, water samples were analyzed by the spectrophotometric method, following the Ammonia protocol - Adapted from the INDOTEST Alfakit Kit. For the oxygen and ammonia data, statistical regression analyzes were performed. The results showed that the oxygen consumption for the species decreased and the ammonia excretion increased as the ammonia (NH3) concentrations increased in the treatments.