Photosynthetic characteristics of planktonic blue-green algae: Changes in photosynthetic capacity and pigmentation ofOscillatoria redekeivan Goor under high and low light

Publisher Website
Google Scholar
Abstract
The photosynthetic characteristics and pigment contents of O. redekei van Goor were measured under a range of photoperiods (6:18 light-dark to continuous light) and irradiances (13-260 .mu.E [einsteins] m-2 s-1) at 15.degree. C. The light saturated rate of photosynthesis (Pmax) per cell protein was comparatively constant under different light regimes but cells grown under low irradiances and/or short light-dark (LD) cycles showed marked increases in the efficiency with which they harvested low light. The increase in efficiency under low light doses corresponded to an increase in the phycocyanin and chlorophyll [Chl] a content of the cultures but phycocyanin content increased by a greater proportion than Chl a. The increase in the ratio of phycocyanin to Chl a was highly correlated with increases in the efficiency of light harvesting. Cells grown under 6:18 LD cycles had a pigment composition similar to low light cultures grown under continuous light. Because of wide differences in the pigment content of continuous light cultures, the light saturation characteristic Ik varied over a wide range from 77-462 .mu.E m-2 s-1, compared to a range of 78-140 .mu.E m-2 s-1 for cells grown under a 6:18 LD cycle. The range of compensation irradiances for continuous light cells was 4-82 .mu.E m-2 s-1 compared to 3-6 .mu.E m-2 s-1 for 6:18 LD cells. The large difference between continuous light and LD cells was due in part to the high respiration rates of continuous light cells.