Fig. 3. (A) The effects of increasing arterial CO₂ partial pressures Pa_CO2 on arterial total O₂ content (Ca_O2), expressed as the percentage change relative to normocapnia, in eels exposed either to chronic (black symbols) or acute (white symbols) hypercapnia. (B) The relationship between arterial blood pH (pHa) and Ca_O2 in eels exposed to either chronic (black symbols) or acute (white symbols) hypercapnia. Chronic hypercapnia implies at least 6 weeks exposure to water CO₂ partial pressures (Pw_CO2) of approx. 2mmHg (ambient control), 15±1 mmHg, 30±1 mmHg or 45±1 mmHg; acute hypercapnia implies sequential 30 min exposures to a Pw_CO2 of 5, 10, 20, 40, 60 and 80 mmHg (1 mmHg=approx. 0.01316 kPa). Data for acute hypercapnia are replotted from McKenzie et al. (2002). Values are means ± S.E.M., N=5–7 determinations.

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