EFFECTS OF TEMPERATURE ON GROWTH, LIGHT-ABSORPTION, AND QUANTUM YIELD IN DUNALIELLA-TERTIOLECTA (CHLOROPHYCEAE)

The effects of growth temperature on the marine chlorophyte Dunaliella tertiolecta Butcher were studied to provide a more mechanistic understanding of the role of environmental factors in regulating bio-optical properties of phytoplankton. Specific attention was focused on quantities that are relevant for modeling of growth and photosynthesis. Characteristics including chlorophyll a (chi a)-specific light absorption (a(ph)*(lambda)), C:chl a ratio, and quantum yield for growth (phi(mu)) varied as functions of temperature under conditions of excess light and nutrients. As temperature increased over the range examined (12 degrees-28 degrees C), intracellular concentrations of chl a increased by a factor of 2 and a(ph)*(lambda) values decreased by more than 50% at blue to green wavelengths. The lower values of a(ph)*(lambda) were due to both a decrease in the abundance of accessory pigments relative to chi a and an increase in pigment package effects arising from higher intracellular pigment concentrations. Intracellular pigment concentration increased as a consequence of higher cellular pigment quotas combined with lower cell volume. At high growth temperatures, slightly more light was absorbed on a per-cell-C basis, but the dramatic increases in growth rate from mu = 0.5 d(-1) at 12 degrees C to mu = 2.2 d(-1) at 28 degrees C were primarily due to an increase in phi(mu) (0.015-0.041 mol C (mol quanta)(-1)). By comparison with previous work on this species, we conclude the effects of temperature on a(ph)*(lambda) and phi(mu) are comparable to those observed for light and nutrient limitation. Patterns of variability in a(ph)*(lambda) and phi(mu) as a function of growth rate at different temperatures