Observations on the snow algae of the South Orkney Islands

Abstract

One of the most abundant algal species found in snow on the South Orkney Islands is a unicellular chrysophycean not hitherto reported from this region. Investigations both by direct counts and by in situ determinations of metabolic activity by a radiocarbon technique suggest that growth of snow algae is, in general, slow. Their primary productivity is estimated as being of the order of 10 mg carbon fixed m-2 snow surface day-1. The sudden appearance of patches of these algae seems to be due to mechanical accumulation at the surface, as ablation of the snow proceeds, of cells previously distributed sparsely through its thickness. There appear to be no great differences either in species composition or in metabolic activity between green, yellow and red snow. The greater population densities and absence of red resting spores characteristic of green snow are perhaps attributable to greater availability of liquid water.