Ventilatory response of rainbow trout (Salmo gairdneri) to increased H+ ion concentration in blood and water

Abstract 1. 1. Ventilation amplitude and rate, inspired P co 2 - and arterial pH were measured in rainbow trout exposed to environmental acidification (pH 4.0) in hard and soft water to show the short term (45 min) and long term (5 day) ventilatory response to acidification with and without transient hypercapnia. 2. 2. Unless accompanied by transient hypercapnia there were no short term changes in ventilation or arterial pH,and no long term changes in ventilation despite increasing acidaemia. 3. 3. The results show that without hypercapnia, and whilst oxygen transport is adequate, there is no ventilatory response to increased internal or external H + ion concentration.