Estimating oxygen uptake rate from ventilation frequency in the reef fish Sparisoma viride

ABSTRr: Spontaneous fluctuations in oxygen consumption (R) and ventilation frequency (VF) of stoplight parrotfish Sparisoma virjde were measured simultaneously in small flow-through respirometers to establish the relationship between these variables. Respiration of l l fish of varying size (14 to 1052 g) and life phase (juveniles, initial and terminal phasc adults) was measured at naturally fluctuating temperatures A large proportion of the variance In respiration could be explained by the equation: R = 0. 00035 X V F ' 3b% W ' '!"r2 = 93. 1 n = 380, p < 0 001), with R in mg O2 h-', V F in beats min-l and flsh weight (W) in g. Oxygen concentration in the respiration chambers could drop below natural levels Cornpanson of the R-VF relationships at different concentrations showed that correction for 02 hardly affected the predictions. No important differences were found between the 3 life phases, and inter-individual d~fferences were no larger than the variation between replicate measurements. We conclude that the equation above appears quite robust and can therefore b e used to predict the metabolic rate of undisturbed fish in their natural environment.