Seasonal variations in the effect of temperature on the respiration of certain intertidal algae

Abstract

The intertidal algae Enteromorpha, Ulva, Fucus, Porphyra, Chondrus and Griffithsia are subjected to wide semi-diurnal fluctuations in temperature during the summer months. Measurements of the rate of respiration of such algae in the dark at a wide variety of temperatures have shown that during the summer the curve relating respiration to temperature (R. T curve) has a relatively shallow slope of Q10 < 1·2 between 10° and 20 °C. Algae collected during the autumn and winter show R. T curves which have a shallow slope in regions approximating to the temperature of the shore at the time of collection. Thus the respiration of such intertidal algae is relatively unaffected by temperature fluctuation within the normal environmental range. Further, the form of the R. T curve is not a fixed phenomenon which is characteristic of a particular species of alga, but appears to be modifiable in such a way that the shallow region of the R. T curve is appropriate to the temperatures prevailing in the habitat. In this way the effects of temperature fluctuation upon respiration are minimized.