The influence of gradual water acidification on the oxygen consumption pattern of fish

Abstract

1. Carp (Cyprinus carpio) and tilapia (Oreochromis mossambicus) were kept in a flow-through respirometer for a week, while continuous oxygen consumption measurements were carried out, at a constant water O₂ concentration.

2. Our measurements showed that tilapia decreased its standard metabolic rate (SMR), its average oxygen consumption, and its maximum metabolic rate in acid water (pH 4.0), whereas carp did not.

3. It is proposed, based on our results, that carp and tilapia probably have different strategies to survive pH depression episodes: whereas tilapia avoids the additional stress of exercise, carp tries to escape the acid conditions.