Oxygen consumption in the fathead minnow ( Pimephales promelas rafinesque)-I : Effects of weight, temperature, group size, oxygen level and opercular movement rate as a function of temperature 1

Abstract

1. 1. A relationship is evident between oxygen consumption (OC in cm 3/hr) and weight (WT in g) such that: OC = −0.580 (WT) 1.053 2. 2. Fathead minnows failed to exhibit immediate rate compensation as a result of acute temperature changes. Minnows showed an exponential increase in weight-specific oxygen consumption with temperature (in °C), resulting in a Q 10 of over three. The equation is: OC = 10 0.0482 (Temp.) − 1.268. 3. 3. Minnows acclimated to water temperatures of 5–21°C showed a steady increase in opercular movement rates (OMR) (ventilation rates) as expressed by the equation: OMR = 0.1968 (Temp.) 2 + 1.064. 4. 4. Grouping more than two fish per chamber resulted in an increase in oxygen consumption. The relationship of group size (GS) to oxygen consumption is: OC = 0.04059 (GS) 2 − 0.2017 (GS) + 0.5353. 5. 5. Oxygen consumption is a function of dissolved oxygen level. This relationship is shown by the equation: OC = 0.003049 (OL) 3 − 0.06359 (OL) 2 + 0.4211 (OL) − 0.4020 where OL is oxygen level. Due to high variability, it is statistically impossible to determine oxygen level ranges in which they conformed and those in which they regulated.