THERMALLY-INDUCED CHANGES IN THE METABOLISM OF THE EYE OF THE CRAYFISH PARANEPHROPS PLANIFRONS - RESPIRATION AND SUBSTRATE UTILIZATION AT 3DISTINCT 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 degree s C, 13 degrees C, and 23 degrees C, expressed in mu M O-2 g(-1) min(- 1), were 15.40 +/- 1.36, 21.91 +/- 1.20, and 22.52 +/- 2.47, respectiv ely. 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 r ange of 13-23 degrees C, indicating immediate compensation within the definition presented by Hazel and Prosser (16). The ability of this ti ssue to undergo immediate thermal compensation reflects the physiologi cal adaptations of intertidal invertebrates, and is significant in ter ms of the feeding strategy that this animal adopts. Calculations of re spiratory quotients for the 3 measurement temperatures indicate a swit ching in substrate utilization: at 13 degrees C lipid or lipid/protein oxidation and, at the extremes of 3 degrees C and 23 degrees C, carbo hydrates or a carbohydrate/protein mixture. (C) 1997 Elsevier Science Inc.