Compromises between ionic regulation and acid–base regulation in aquatic animals

Abstract

To compensate for various sorts of acid–base disturbances, animals must sometimes make large changes in the concentration of [Formula: see text] in both intra- and extra-cellular fluids. As [Formula: see text] concentration is dependent upon several other solution parameters, including the so-called strong ions, there must often be compromises between compensation of acid–base disturbances and the requirements for ionic and osmotic homeostasis. Data showing that partial compensation of hypercapnia may represent such a compromise have been gathered from both fish and crabs. Traditional approches to acid–base regulation emphasize the [Formula: see text] system changes, but more recently an approach based on electrolytes has been promoted. The similarities between these two approaches are illustrated with experimental data and theoretical studies. Practical limitations prevent the routine use of the electrolyte (strong ion) approach.