Abstract

One of the key factors that determine an animal's distribution and abundance is environmental temperature. This factor affects all the components of an organism's energy budget and fitness. In this study, we tested the effect of water temperature and starvation on patterns of space use in the intertidal fish Girella laevifrons. We postulated that starved animals would select cold temperatures as a mechanism of energy conservation while fed animals would prefer higher temperatures as a mechanism to facilitate digestive processes. In a thermal gradient tank, fishes, irrespective of treatment (fed and starved), actively selected temperatures between 15 and 18°C. Starvation did not affect temperature selection, although it did alter the time and number of visits to thermal gradient extremes. Starved fishes stayed longer in, and visited the warmer temperatures of the gradient more frequently. In contrast, fed fishes stayed longer in, and visited cold temperatures more frequently. We discuss the ecological consequences of temperature selection and the possible relationship between water temperature, food selection and digestive processes.