ESTIMATING OXYGEN-UPTAKE RATE FROM VENTILATION FREQUENCY IN THE REEF FISH SPARISOMA VIRIDE

Spontaneous fluctuations in oxygen consumption (R) and ventilation fre quency (VF) of stoplight parrotfish Sparisoma viride were measured sim ultaneously in small now-through respirometers to establish the relati onship between these variables. Respiration of 11 fish of varying size (14 to 1052 g) and life phase (juveniles, initial and terminal phase adults) was measured at naturally fluctuating temperatures. A large pr oportion of the variance in respiration could be explained by the equa tion: R = 0.00035 x VF1.369 x W-1.118 (r(2) = 93.1%, n = 380, p < 0.00 1), with R in mg O-2 h(-1), VF in beats min(-1) and fish weight (W) in g. Oxygen concentration in the respiration chambers could drop below natural levels. Comparison of the R-VF relationships at different conc entrations showed that correction for [O-2] hardly affected the predic tions. No important differences were found between the 3 life phases, and inter-individual differences were no larger than the variation bet ween replicate measurements. We conclude that the equation above appea rs quite robust and can therefore be used to predict the metabolic rat e of undisturbed fish in their natural environment.