Abstract

The energy storage efficiency of photosynthesis is a sensitive diagnostic tool for probing the physiological status of phytoplankton in the laboratory and in nature. Furthermore, it is also a key factor in determining the economics of photobioreactors and algal mass culture ponds for the production of biodiesel and related applications. Photoacoustics allows direct determination of the energy storage efficiency of photosynthesis as the ratio of energy stored in the photosynthetic process, and not dissipated as heat, to the total light energy absorbed by the photosynthetic apparatus. The aim of the present study was to compare our novel, photoacoustics-based method with an oxygen-evolution–based calculation of photosynthetic energy storage. We also illustrate and discuss the use of photoacoustics for generating photosynthesis versus energy relationship curves. The photoacoustic efficiencies were always higher than the oxygen-based ones, and this difference in results is discussed. Our results show the power of photoacoustics as a tool in the research of various aspects of phytoplankton physiology.

Key words: Efficiency of photosynthesis, photoacoustics, light pipette, phytoplankton.