Temperature influences whole-animal rates of metabolism but not protein synthesis in a temperate intertidal isopod

Abstract

The effects of temperature on two important biological rate processes, whole-body rates of oxygen uptake (ṀO2) and protein synthesis (ks), were investigated in the temperate intertidal isopod Ligia oceanica at two different times of the year. Animals were collected in January (winter) and June (summer) and either subjected to an acute temperature change after 24 h (acclimatized) or acclimated to various temperatures for 4 wk. In both cases, ṀO2 increased with temperature, with a Q 10 of 2.2 between 5° and 20°C, but increased in thermal sensitivity at 25°C. Winter isopods were characterized by significantly higher ṀO2 levels, greater thermal sensitivities, and lower thermal tolerances than summer animals. Seasonal differences in ṀO 2 persisted after acclimation, indicating that temperature alone was not responsible for the changes. In sharp contrast, whole-body ks showed no variation with temperature, although overall rates decreased upon acclimation. In acclimatized animals, ks was higher in the summer than in the winter. After acclimation, a compensatory increase in RNA capacity in winter animals reversed this situation. The temperature independence of whole-body ks in L. oceanica could ensure survival in a highly liable thermal environment, as thermal tolerances of intertidal invertebrates are thought to be more closely related to protein than to energy metabolism. © 2005 by The University of Chicago. All rights reserved.