Effect of Fluctuations in Temperature on the Metabolism of Intertidal Invertebrates

SVNOPSIS. Compensatory changes in the level of activity of intertidalorganisms may occur in response to the thermal conditions whichprevail in the habitat. These involve an increase in the activityof those animals subjected to low temperatures and a correspondingsuppression of activity in those animals subjected to high temperaturesso that organisms with a wide geographical range, or livingover a range of shore levels, have comparable rates of activity.However, the rate of activity varies markedly with short-termfluctuations in temperature, as does the rate of respirationof active animals. Recent evidence suggests that the rate ofrespiration of quiescent animals is relatively independent oftemperature over the normal environmental range, and thus themetabolism is well-suited to an environment where rapid fluctuationsin temperature occur. Further, the extent of the thermal rangeover which metabolism is relatively independent of temperatureis modifiable according to season and storage-temperature. Similarchanges occur in the respiration of cell-free homogenates ofcertain intertidal organisms. Acclimation in such organismsinvolves not only a modification in the level of the activeand standard rates of metabolism but also an alteration in theform of the rate/temperature curve such that the range of temperature-independentmetabolism is appropriate to the thermal conditions prevailingin the habitat.