3. Physiological Effects of CO2on Fish
3.1. Acid-Base Regulation
[8] Elevation of bloodPCO2
by environmental hypercapnia results in a transient but significant drop of the arterial pH,
even if ambient PCO2 remained at high levels. This drop of
blood pH is attenuated by chemical buffering by proteins and
other low-molecular-weight buffering substances, and subsequently compensated for within 3 – 24 hours by the transfer
of acid-base relevant ions with the surrounding water,
mainly through the gills [Heisler, 1986]. The transport of
HCO3
and/or H
+
across the body surface inevitably is
accompanied by the exchange of counterions to maintain
the electroneutrality of body fluids, but the precise mechanisms of, and the cell types responsible for, the transport
process remain obscure, especially in marine fish