PHOTOSYNTHETIC TEMPERATURE RESPONSES OF FRESH-WATER AND BRACKISH-WATER MACROPHYTES - A REVIEW

Data on the temperature dependence of photosynthesis and respiration f rom 10 different species were reviewed from the literature. A mathemat ical model incorporating a thermal inactivation equilibrium of an esse ntial enzyme as a controlling factor of the modelled rates [Johnson, F .H., Eyring, H., Stover, B.J., 1974. The theory of rate processes in b iology and medicine. Wiley-Interscience, New York, pp. 175-272.] succe ssfully fitted all large data sets, showing that thermal inactivation is a mechanistic description consistent with the observed patterns in irradiance-saturated photosynthesis (P-m) and dark respiration (DR). G eneral trends could not be observed for the apparent quantum yield (al pha) and light half-saturation constant (K-0.5). We found a positive c orrelation between latitude and optimal temperature for P-m, which we attributed to the shift in life-cycle (from winter-to summer-active li fe-cycles) displayed by the waterplants when moving from subtropical t o temperate latitudes. Finally, the effect of acclimation on the seaso nal extrapolation of parameter estimates was briefly examined. Contrar y to what we expected, neither of the two datasets reviewed from the l iterature supported the existence of a significant seasonal widening o f the temperature response curve due to acclimation. (C) 1997 Elsevier Science B.V.