Cyanobacteria and algae are the major photosynthetic organisms in deserts because they survive desiccation, high solar radiation and extreme temperature fluctuations better than other plants. Under favourable conditions, desert cyanobacteria and algae evidently photosynthesise. However, our understanding of whether each group modulates this metabolic process in response to preceding harsh conditions remains limited. To find out the effect of aridity on the photosynthetic activity of desert cyanobacteria and algae, we compared their cellular biovolume-specific carbon dioxide (CO2) fixation in the hyper-arid and arid regions of a typical hot desertâthe central Negev Desert. We found that the biovolume-specific CO2 fixation of both cyanobacteria and algae was highly variable rather than being constant.







