Scaling of oxygen consumption of Lake Magadi tilapia, a fish living at 37°C

Abstract

Rates of oxygen consumption were measured in the geothermal, hot spring fish, Oreochromis alcalicus grahami by stopped flow respirometry. At 37° C, routine oxygen consumption followed the allometric relationship: V o 2 =0.738 M 0.75 , where V o 2 is ml O 2 h −1 and M is body mass (g). This represents a routine metabolic rate for a 10 g fish at 37° C of 0.415 ml O 2 g −1 h −1 (16.4 μmol O 2 g −1 h −1 ). Acutely increasing the temperature from 37 to 42° C significantly elevated the rate of O 2 consumption from 0.739 to 0.970 ml O 2 g −1 h −1 ( Q 10 =l.72). In the field, O. a. grahami was observed to be ‘gulping’ air from the surface of the water especially in hot springs that exceeded 40° C. O. a. grahami may utilize aerial respiration when O 2 requirements are high.