Photosynthetic energy storage efficiency in biofilms determined by photoacoustics

Abstract

Biofilms formed on solid biotic and abiotic substrata, deployed for a certain time period in the coastal waters of the Baltic, were studied with a photoacoustic spectroscopy (PA) technique. Since periphyton appears to be an effective indicator of water quality and stands for a photosynthetic system with a variety of pigments, the aim of the study was to determine biofilm colony photosynthetic apparatus properties (photosynthetic energy storage (ES), PA amplitude and phase spectra) which exhibited a seasonal variability. Nutrient limitation and antrophogenic eutrophication are among the most important factors determining the overall status of water bodies which can be followed by ES efficiency of biofilm cultures. ES turned out to be inversely correlated to biogenic elements concentrations (N (R=-0.76); P (R=-0.81); O (R=-0.67), and positively correlated to primary production (R=0.86) and Chl. a concentration (R= 0.82) in the Baltic (seawater parameters data available at http://satbaltyk.iopan.gda.pl). Photoacoustics can be used to estimate the concentration of photosynthetic pigments in cultures, the efficiency of ES by periphyton photosynthesis can be directly determined by photoacoustics, the effects of environmental stressors: temperature, nutrient limitation, high/dim light and pollutants on the photosynthetic capacity of biofilm colonies can be evaluated.