Light environment within dense algal populations: cell size influences on self-shading

The influence of algal cell size on the light environment withindense phytoplankton populations was analysed in cultures of11 freshwater algae (mostly Chlorophyta) varying widely in cellsize and growing at saturated (220 µM m² s^–1) andlimited (11 µM m^–2 s^–1) irradiances Chlorophyll-a-specificabsorbance coefficients did not bear any obvious relationshipto cell size and, as expected from previous analyses, were stronglyinfluenced by the light intensity at which the algae were grown.However, biomass (fresh weight)-specific absorbance coefficientsdecreased as algal cell volume increased regardless of the incomingirradiance Intracellular chlorophyll a concentration (c₁), whichdecreased as algal cell size increased, explained a substantialfraction of the variance in biomass (fresh weight)-specifjcabsorbance coefficients. Thus, this study supports the notionthat reduced serf-shading allows large algae to support greatermaximal biomass than smaller algae.