Effects of hypercapnia on the buffer capacity and haematological values in Salmo salar (L.)

The effects of high environmental carbon dioxide tension (PCO₂) on buffering status, pH, haematocrit, red blood cell (RBC) count, mean corpuscle volume (MCV), and chloride (Cl^–) distribution in the blood of young salmon were investigated after 30 min and 24 h. An increase in blood buffering capacity was observed after 24 h. As compared to the preacclimation situation, haematocrit, RBC, MCV and Cl^– content of the erythrocytes increased after 30 min but decreased if hypercapnia was sustained for 24 h. However the plasma bicarbonate (HCO₃) content increased over the whole experimental period. Plasma Cl^– content was decreased after 24 h, but the ratio of Cl^– between erythrocytes and plasma increased at the onset of hypercapnia, then remained unchanged during the rest of the investigation period.