Effects of temperature and size on the routine rate of oxygen consumption and on the relative scope for activity in larval cyprinids

Abstract

1. Routine and maximum rates (after stimulation with weak electrical pulses) of oxygen consumption were determined in the larvae of three cyprinid species. 2. In all three species the mass-specific routine rate decreases exponentially after hatching. 3. Routine and maximum rates of oxygen consumption follow the same temperature relationship, with an indication of lowered temperature sensitivity between 16 and 20°C as compared with the ranges 12–16 and 20–24°C. 4. The relative factorial scope for activity, i.e. the ratio\(\dot V_{{\text{O}}_2 } \max /\dot V_2 \) routine, ranges from 2.4 to 2.9 at the four experimental temperatures employed, but none of the differences between temperatures are significant. Equally, within the weight range studied, the regression of scope on body weight is indistinguishable from zero at all four experimental temperatures. 5. It is argued that larval fish have escaped the constraints of small size on aerobic scope for activity, a typical feature of larger poikilotherms, by a combination of morphological, physiological and biochemical adaptations. 6. The development of the routine rate of oxygen consumption in cyprinids during larval life is compared with that in a coregonid and a salmonid species (Fig. 3). At 10°CCoregonus sp. consumes about twice as much oxygen per g body weight as the representatives of the other two families of freshwater fish.