Effects of ambient PO2 and temperature on oxygen uptake in Nautilus pompilius.

This study employs closed-circuit respirometry to evaluate the effect of declining ambient oxygen partial pressure (PO2) and temperature on mass specific rates of oxygen uptake (VO2) in Nautilus pompilius. At all temperatures investigated (11, 16, and 21 degrees C), VO2 is relatively constant at high PO2 (oxyregulation) but declines sharply at low PO2 (oxyconformation). The critical PO2 below which oxyconformation begins (Pc) is temperature dependent, higher at 21 degrees C (49 mmHg) than at 11 degrees C or 16 degrees C (21.