Ventilation and oxygen extraction in the little penguin ( Eudyptula minor), at different temperatures in air and water

Abstract

Oxygen consumption, (V̇ O2), carbon dioxide production (V̇ CO2) and ventilation were measured in little penguins ( Eudyptula minor) in air and water over a range of ambient temperatures. Barometrically measured minimum ventilation was very low (112 ± 23 ml·min −1 over the range 15–20°C, n=9), principally due to a lower than predicted respiratory frequency (f) (6.9±1.1 min −1). This low ventilation resulted in a very high oxygen extraction (E O2) and low air convection requirement ( V̇i/V̇ O 2 ). Despite large increases in metabolic rate in birds in cold water, V̇ i/V̇ O 2 and hence E O 2 did not vary in non-heat exposed penguins over a range of air and water temperatures. Mean extraction was 53.2±10.8% (n=82) corresponding to an air convection requirement of 1.13±2.5L·L −1. Above thermoneutrality there was a dramatic increase in ventilation and fall in E O2 resulting from increases in both f and tidal volume ( Vt). Eng-expired gases were measuerd at thermoneutrality and during heat exposure. At thermoneutrality Fe CO 2 ′ was 0.074±0.005, and Fe O 2 ′ 0.115±0.009. During heat exposure end expired gases approached atmospheric levels.