Is there a synergistic effect between steady‐state exercise and water acidification in carp?

Abstract

Carp (Cyprinus carpio) fitted with arterial catheters were trained to swim in a swim tunnel. While constantly swimming at two body lengths per second, they were subjected to gradual water acidification (from pH 7-6 to 4 0 in 4 h), and monitored subsequently over 24 h. It was hypothe sized that exercise would expose the gills to a larger extent and that consequently the effect of water acidification would be greater in exercising than in resting carp. In contrast to our earlier study with resting carp we found a constant decline of plasma pH, and of plasma Na f and Cl concen tration, indicating ionoregulatory failure. While plasma catecholamines remained at control levels, the plasma cortisol showed a three-to four-fold increase over the first 7h. This was followed by a slow decline. We conclude that there is a synergistic effect between moderate exercise and gradual water acidification.