Estimation of routine metabolic rate in a penaeid prawn, Penaeus esculentus Haswell

Abstract

Metabolic rates in the juvenile tiger prawn, Penaeus esculentus Haswell were related to decreasing oxygen tensions, 24-h activity, size, temperature and the moulting cycle, using automated, microprocessorcontrolled apparatus. Routine metabolic rate was redefined as the mean 24-h rate, with the animal behaving as it would naturally. While resting, the prawn was oxygen-independent down to ≈25% saturation, but when swimming was oxygen-dependent almost up to full saturation. Oxygen consumption at night was markedly higher than by day, so that for comparative purposes measurements had to be made over at least 24 h. Metabolic rate during the moulting cycle did not change until late premoult, when it increased by 55% 3 days prior to ecdysis and fell to previous levels 1 day afterwards. Using red light, a red-sensitive camera and time-lapse video recorder, metabolic rates were related to nocturnal levels of activity, and these in turn to natural 24-h behaviour. Mean routine metabolic rate, as redefined, was estimated as 8–12% above the resting rate. There was a log-log relationship between metabolic rate and temperature, so that on a In metabolic rate/ln size plot, the displacement due to temperature was linear. Equations were derived relating whole animal metabolic rate, or weight-specific metabolic rate to size, temperature and 24-h normal activity.