Discriminating between phytoplankton taxa by photoacoustics

We present here an application of the photoacoustic method for studying and discriminating between important phytoplankton taxa in suspension. The photosynthetic activity was studied by measuring the photoacoustic signal with and without background illumination. A linear dependence of the photoacoustic signal on the biomass of different algae was observed along with wavelength-dependent differences between the various phytoplankton taxa. The photoacoustic signals from mixtures of pairs of taxa were measured at different ratios of the mixture components and at selected wavelengths at which the differences in absorption among the species were maximal. A linear dependence of the photoacoustic signal on the composition of each pair at the wavelengths studied was found. The results indicate the potential of the procedure for determining the composition of phytoplankton communities and following the effects of environmental parameters such as irradiance and nutrient status on the photosynthetic activity of phytoplankton.