ATTACHMENT AND GROWTH OF ANTARCTIC SOIL CYANOBACTERIA AND ALGAE ON NATURAL AND ARTIFICIAL SUBSTRATA

The attachment to artificial substrata (carborundum paper) of cyanobacteria and algae isolated from Antarctic fellfield soils was investigated using a simulated flow apparatus. Generally, the rugosity of the substratum was less important than the morphology and extent of mucilage production of the microflora in determining attachment success. However, the smoothest grades of substratum did increase the retention of the fine filaments of the cyanobacterium Pseudanabaena and decrease the retention of the large filaments of the chlorophyte Zygnema. Filaments of the motile cyanobacterium Phormidium and cells of the motile diatom Pinnularia showed good retention on all grades of paper, with that of Phormidium being the highest of all taxa at 90-100%. The coccoid chlorophyte Planktosphaerella was poorly retained on all grades of substratum. Growth rates of the same organisms on fellfield soils were little affected by soil rugosity, although the largest soil particles (1-2 mm) did cause a decrease in the growth rate of Phormidium and increase in that of Planktosphaerella. These results indicate the importance of the cyanobacterial-algal flora, and especially the motile component, in the stabilization of fellfield soils.