Thermally-induced changes in the metabolism of the eye of the crayfish Paranephrops planifrons: respiration and substrate utilization at three distinct temperatures.

The effect of temperature on the metabolism of 10 isolated eyes taken from 5 lake-dwelling specimens of the crayfish Paranephrops planifrons was examined by measuring oxygen uptake and carbon dioxide production at 3 temperatures. The mean values for oxygen utilization at 3 degrees C, 13 degrees C, and 23 degrees C, expressed in microM O2 g-1 min-1, were 15.40 +/- 1.36, 21.91 +/- 1.20, and 22.52 +/- 2.47, respectively. The resulting Q10 values for respiration rate were 1.43 +/- 0.05 for the 3-13 degrees C range and 1.03 +/- 0.07 for the environmental range of 13-23 degrees C, indicating immediate compensation within the definition presented by Hazel and Prosser (16). The ability of this tissue to undergo immediate thermal compensation reflects the physiological adaptations of intertidal invertebrates, and is significant in terms of the feeding strategy that this animal adopts. Calculations of respiratory quotients for the 3 measurement temperatures indicate a switching in substrate utilization: at 13 degrees C lipid or lipid/protein oxidation and, at the extremes of 3 degrees C and 23 degrees C, carbohydrates or a carbohydrate/protein mixture.