ABSTRACT: Spontaneous fluctuations in oxygen consumption (R) and ventilation frequency (VF) of stoplight parrotfish Sparisoma viride were measured simultaneously in small flow-through respirometers to establish the relationship 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 proportion of the variance in respiration could be explained by the equation: R = 0.00035 x VF^(1.369) x W^(1.118) (r^(2) = 93.1%, n = 380, p < 0.001), with R in mg O₂ 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 concentrations showed that correction for [O₂] hardly affected the predictions. No important differences were found between the 3 life phases, and inter-individual differences were no larger than the variation between replicate measurements. We conclude that the equation above appears quite robust and can therefore be used to predict the metabolic rate of undisturbed fish in their natural environment.

KEY WORDS: Metabolism . Oxygen concentration . Reef fish . Respirometry . Scaridae . Gill beat frequency

Published in MEPS Vol. 132 (1996) on February 29
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1996