Қызыл балқыған қар құбылысы

Red coloration effect caused by algae

Watermelon snow, also called snow algae, pink snow, red snow, or blood snow, is a phenomenon caused by Chlamydomonas nivalis, a species of green algae containing a secondary red carotenoid pigment (astaxanthin) in addition to chlorophyll. Unlike most species of fresh water algae, this species appears to be cryophilic (cold loving) and thrives in freezing water. This type of snow is common during the summer in alpine and coastal polar regions worldwide, such as the Sierra Nevada of California. Here, at altitudes of 10,000 to 12,000 feet (3,000–3,600 m), the temperature is cold throughout the year, and so the snow has lingered from winter storms. Compressing the snow by stepping on it or making snowballs leaves it looking red. Walking on watermelon snow often results in getting bright red soles and pink trouser cuffs. Snow algae dominates glacial biomass immediately after the onset of melting, and its pigmentation can significantly darken the surface of a glacier. This plays a substantial role in glacial melt.

The name Chlamydomonas nivalis has been associated with the phenomenon of red snow for the last 200 years, yet, a latest study shows that the alga responsible for most of the red snow fields on our earth does not belong to the genus Chlamydomonas, but had to be placed in a separate, new genus, Sanguina. This genus contains two species, S. nivaloides producing red snow, and S. aurantia causing orange snow. All snow algae producing red or orange snow are actually green alga that owe their red color to a bright red carotenoid pigment, which protects the chloroplast from intense visible and also ultraviolet radiation, as well as absorbing heat, which provides the alga with liquid water as the snow melts around it. Algal blooms may extend to a depth of 25 cm (10 inches), with each cell measuring about 20 to 30 micrometers in diameter, about four times the diameter of a human red blood cell. It has been calculated that a teaspoon of melted snow contains a million or more cells. The algae sometimes accumulate in "sun cups", which are shallow depressions in the snow. The carotenoid pigment absorbs heat and as a result it deepens the sun cups, and accelerates the melting rate of glaciers and snowbanks. During the winter months, when snow covers them, the algae become dormant. In spring, nutrients, increased levels of light and meltwater, stimulate germination. Once they germinate, the resting cells release smaller green flagellate cells which travel towards the surface of the snow. Once the flagellated cells reach the surface, they may lose their flagellae and form aplanospores, or thick walled resting cells, or they may function as gametes, fusing in pairs to form zygotes. Many species feed on C. nivalis/Sanguina spp., including protozoans such as ciliates, rotifers, nematodes, ice worms and springtails.