Behavioral thermoregulation in the intertidal fish Girella laevifrons (Kyphosidae): The effect of starvation

One of the key factors that determine an animal's distribution and abundanc e is environmental temperature. This factor affects all the components of a n 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 intert idal fish Girella laevifrons. We postulated that starved animals would sele ct cold temperatures as a mechanism of energy conservation while fed animal s would prefer higher temperatures as a mechanism to facilitate digestive p rocesses. In a thermal gradient tank, fishes, irrespective of treatment (fe d and starved), actively selected temperatures between 15 and 18 degrees C. Starvation did not affect temperature selection, although it did alter the time and number of visits to thermal gradient extremes. Starved fishes sta yed longer in, and visited the warmer temperatures of the gradient more fre quently. In contrast, fed fishes stayed longer in, and visited cold tempera tures more frequently. We discuss the ecological consequences of temperatur e selection and the possible relationship between water temperature, food s election and digestive processes.