Effect of temperature and dissolved oxygen on heart rate, ventilation rate and oxygen consumption of spangled perch, Leiopotherapon unicolor (Guenther 1859), (Percoidei, Teraponidae)

Cardio-respiratory responses to temperature and dissolved oxygen follow the typical teleost pattern, with bradycardia, increased ventilation rate and reduced oxygen consumption occurring during hypoxia. However, ventilation rate did not increase at 15 degree C and below. Ventilation rate showed a slower response to increasing temperature than heart rate and oxygen consumption. Leiopotherapon unicolor is unable to survive prolonged hypoxia by utilising anaerobic metabolism, but has a large gill surface area which presumably facilitates oxygen uptake in hypoxic environments. Periodic ventilation during normoxia in resting L. unicolor may improve ventilation efficiency by increasing the oxygen diffusion gradient across the gills.