Comparison of chlorophyll far-red and rea fluorescence excitation spectra with photo-synthetic oxygen action spectra for photo-system II in algae

Abstract

The shapes of excitation spectra for chlorophyll a fluorescence in the far-red were compared under physiological conditions to those for chlorophyll a fluorescence in the red and to action spectra for photosynthetic oxygen production in diversely pigmented algae. Species examined as representatives of the prominent oceanic light harvesting systems were Chaetoceros gracilis, Glenodinium sp., Ulva sp., Porphyridium cruentum and Chroomonas sp. Qualitatively, for any one alga, all 3 action spectra exhibited broadly similar spectral features, suggesting initial light harvesting for photosynthesis by the same major pigments, i.e. those commonly associated with photosystem II. As such, measurement of F sub(730) fluorescence may provide a useful and facile alternative to oxygen action spectra in assessing the full photosynthetic spectral performance of individual phytoplankton species or assemblages.