|Pink snow algae growing on summer
slopes. When the winter snow and ice begins
to melt, water flows carrying
with it dissolved nutrients. This gives the
algae the boost it needs to make the most of extra energy from
summer light and the relative warmth.
This is a predominantly
red-coloured species. There are over 300 species of such
algae that live in such harsh and cold conditions. The red colour is
a protective chemical (a carotenoid such as astaxanthin) that
protects against the exceptionally high concentrations of visible and ultra
violet light that could become harmful and destructive.
are also found in many mountainous regions across the world, where extra ultra violet light due to the thinner atmosphere and again increased
light scattering by ice and snow requires protection by similar pigments.
Walking across such an area
will leave behind red footprints as the algae are concentrated by the
walker as the snow is crushed, and sometimes there will be a a faint
smell of fresh watermelon.
copyright Paul Ward