LIGHT-ABSORPTION BY CYANOBACTERIA - IMPLICATIONS OF THE COLONIAL GROWTH FORM

We assessed differences in the light absorption characteristics of nine species of cyanobacteria, colonial and single-celled, and four species of eucaryotic phytoplankton species. The results indicated that the positive scaling of light absorption by both single cells and cyanobacteria colonies to their size and Chl a content is similar to that of eucaryotic algae, but the large differences in the extent of pigment packaging within single-celled cyanobacteria (i.e. c(i)) were unrelated to their size. Cyanobacteria colonies, in contrast, could avoid increased self-shading with increasing size by reducing their internal pigment concentration as colony size increased, as do eucaryotic cells. The results indicated that cyanobacteria colonies act as distinct optical units, rather than as the sum of their component cells. The ability of many cyanobacteria species to develop colonies may help explain their ability to develop nuisance blooms.