Summary
Around 145 different non-marine algae have been identified from the Windmill Islands region, Antarctica. About 24 of these occur in the snow. Nearly half of these, which includes all the dominant snow algae, complete their life cycles in the snow and do not grow elsewhere. Many of their closest relatives are soil or aerial algae found in warmer climes. Their local distribution is governed by pH, salinity and nutrient levels. Most of the snow algae are obligately cold adapted. At least two species have been found to have UV-protecting compounds; iron tannin in Mesotaenium berggrenii fo., red-pigmented lipids in Chloromonas rubroleosa. Two new Desmotetra spp. and a new Chlorococcum sp. all have diffuse pyrenoids. The majority of the snow algae form resistant spores, an important over-wintering adaptation. Many of the snow algae secrete large amounts of mucilage which help the algae adhere to ice particles and prevent them from being washed away by meltwater. The mucilage also delays desiccation and it may have an additional UV-protecting function. Snow algae may be sensitive monitors of global climate changes.