The influence of hypoxia, hyperoxia and temperature on the oxygen consumption, heart rate and ventilation frequency of the intertidal rockpool fish Gobius cobitis Pallas were investigated to examine the respiratory adaptations of this species to intertidal conditions.
The standard mass-specific oxygen consumption (MOO2 × m−1) during normoxia, calculated for a 50-g fish, averaged 1.27 mmol O2kg−1h−1 at 12.5°C and 3.62mmol O2kg−1h−1 at 25°C. The Q10 value for oxygen consumption averaged 2.3.
During a stepwise reduction of oxygen partial pressure (POO2) the oxygen consumption was maintained down to a critical oxygen tension, Pc, of approximately 43 Torr (1 Torr = 133.3 Pa). Ventilatory frequency increased progressively while heart rate remained constant until the POO2 was reduced below 16 Torr.
During hyperoxic exposure (POO2 = 150–450 Torr), oxygen consumption remained constant at 12.5 and at 25°C (Q10 = 2.3). Hyperoxia had no effect on heart rate, although ventilation frequency decreased with increasing POO2 (to the same extent at both temperatures), indicating the overriding effect of hyperoxia on ventilatory frequency.
Gobius cobitis appears to be well-adapted to the respiratory stresses which occur on a daily basis within intertidal rockpools.