high-light-acclimated cells appear to outperform the low-light-acclimated cells at high
light intensities. When the rates of photosynthesis are normalized to cell number (Fig.
3.7b), it is clear that low-light-acclimated cells have higher rates of photosynthesis at
low light intensities, while high-light-acclimated cells have higher rates of
photosynthesis at high light intensities. Finally, when photosynthesis is normalized to
cell carbon (Fig. 3.6c), the low-light-acclimated cells have higher rates of
photosynthesis than high-light-acclimated cells at all light intensities. This last
approach has the advantage of showing the effect of variations in the P vs. E curve on
the rate of incorporation of carbon into cell biomass under some conditions.
Fig. 3.7 P vs. E response curves for high-light (1200 μmol photons m−2 s−1) and low-
light (50 μmol photons m−2 s−1) acclimated nutrient-replete cultures of the diatom
Skeletonema costatum. (a) Chl-a-specific photosynthesis. (b) Cell-specific
photosynthesis. (c) Carbon-specific photosynthesis.
(^) (After MacIntyre et al. 2002.)