Extracellular Acid-Base Balance in Aquatic Animals as a Function of the Ionic Composition and the Acid-Base Balance of the Ambient Water

Abstract

Because of their high ventilatory flow rate and the necessary thinness of their respiratory epithelium, aquatic animals are always in close contact with their ambient medium. Water and solute exchanges maintaining their osmotic and ionic balance take place mainly at the gills. Since the acid-base status of a given system depends on the independent variable [SID], which may be changed by altering its ionic composition (Chap. 1), it is not surprising that the extracellular acid-base balance of aquatic animals can be affected by the ionic characteristics of the ambient water. This raises many problems which are specific to aquatic species and of which one should be aware when undertaking acid-base measurements in such animals.