The effects of nitrite and hypercapnia combination on acid – base regulation and hematology swamp, eel

Abstract

This study was conducted to determine the effects of nitrite with high levels of CO2 on acid-base regulation at different stages of the eel. The swamp eel (Monopterus albus) has intensively been farm in Mekong Delta, Vietnam. The study was carried out on eels (30±0,5 g individual weight) in 96-h. with 5 treatments including 30 mmHg CO2+23.57 mM NO2-, 14 mmHg CO2+23.57 mM NO2-, 23.57 mM NO2-, 14 mmHg CO2 and control (0 mmHg CO2+0 mM NO2-). Each treatment was triplicated. Blood samples were collected at 0, 24, 48, 72, 96 hours, each times 3eels/tank. After 24-h, the value of pH blood highly decreased (<7.01) in treatment 30 mmHg CO2+23.57mM NO2-, pCO2 increased steadily (33 mmHg) and metHb highest raised (34%) in compare with the other treatments (p<0.05). However, the treatment of 14 mmHg CO2+23.57mM NO2- as well as the 23.57 mM NO2- treatment, the pH decreased slightly, not significant difference if compared to the control; and pCO2 and HCO3- increased softly. The value of pH could not absolutely recover in the combined environment of 3.57 mM NO2-and 30 mmHg CO2 after 96-h showed NO2- absorption. In addition, significantly reduced content in Na+, Cl- ions as well as osmolality plasma; indicating that the passive transport of ions at gills. The criteria of hematology including red blood cell, white blood cell and Hct showed no significantly different in the combine group NO2- and CO2. The result showed that swamp eel absolutely has able to adapt in the harsh environment (high NO2- and hypercapnia).