Effect of Fluctuations in Temperature on the Metabolism of Intertidal Invertebrates

Abstract

SVNOPSIS. Compensatory changes in the level of activity of intertidal organisms may occur in response to the thermal conditions which prevail in the habitat. These involve an increase in the activity of those animals subjected to low temperatures and a corresponding suppression of activity in those animals subjected to high temperatures so that organisms with a wide geographical range, or living over a range of shore levels, have comparable rates of activity. However, the rate of activity varies markedly with short-term fluctuations in temperature, as does the rate of respiration of active animals. Recent evidence suggests that the rate of respiration of quiescent animals is relatively independent of temperature over the normal environmental range, and thus the metabolism is well-suited to an environment where rapid fluctuations in temperature occur. Further, the extent of the thermal range over which metabolism is relatively independent of temperature is modifiable according to season and storage-temperature. Similar changes occur in the respiration of cell-free homogenates of certain intertidal organisms. Acclimation in such organisms involves not only a modification in the level of the active and standard rates of metabolism but also an alteration in the form of the rate/temperature curve such that the range of temperature-independent metabolism is appropriate to the thermal conditions prevailing in the habitat.