Overview

Comprehensive Description

Description of Chlamydomonas nivalis

Psychrophilic green alga, forms pink blooms in ice and snow.
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Evolution and Systematics

Functional Adaptations

Functional adaptation

Red pigment protects against UV rays: snow algae
 

Snow algae protects against UV damage via a red carotenoid pigment.

   
  "Other algae manage to exist in the snow itself. They live in a similar way between the individual flakes just below the surface. Their chlorophyll is masked by a red pigment. This protection against damaging ultra-violet rays is more important for them than for the sandstone algae, for sunlight shines more strongly through snow than it does through quartz. During the summer, the sun is warm enough to cause a slight melting of the surface layers, and this provides the algae with the liquid water they need. Dust, brought by the wind, supplies the necessary minerals. The algae themselves manufacture a kind of anti-freeze which keeps the contents of their bodies liquid even when the temperature of the snow falls to several degrees below zero. During the winter, the tiny cells remain largely invisible some distance below the surface, but when summer comes, they propel themselves with microscopic beating hairs and move up towards the surface, the light and the warmth. So in summer, some parts of the snow fields of both the Arctic and the Antarctic blush pink." (Attenborough 1995:246-247)
  Learn more about this functional adaptation.
  • Attenborough, D. 1995. The Private Life of Plants: A Natural History of Plant Behavior. London: BBC Books. 320 p.
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Functional adaptation

Algae protects from freezing: snow algae
 

The liquid cell contents of snow algae are kept liquid in freezing temperatures because the algae manufacture their own antifreeze.

   
  "Other algae manage to exist in the snow itself. They live in a similar way between the individual flakes just below the surface. Their chlorophyll is masked by a red pigment. This protection against damaging ultra-violet rays is more important for them than for the sandstone algae, for sunlight shines more strongly through snow than it does through quartz. During the summer, the sun is warm enough to cause a slight melting of the surface layers, and this provides the algae with the liquid water they need. Dust, brought by the wind, supplies the necessary minerals. The algae themselves manufacture a kind of anti-freeze which keeps the contents of their bodies liquid even when the temperature of the snow falls to several degrees below zero. During the winter, the tiny cells remain largely invisible some distance below the surface, but when summer comes, they propel themselves with microscopic beating hairs and move up towards the surface, the light and the warmth. So in summer, some parts of the snow fields of both the Arctic and the Antarctic blush pink." (Attenborough 1995:246-247)
  Learn more about this functional adaptation.
  • Attenborough, D. 1995. The Private Life of Plants: A Natural History of Plant Behavior. London: BBC Books. 320 p.
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Wikipedia

Watermelon snow

Watermelon snow, also called snow algae, pink snow, red snow, or blood snow, is 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, it is cryophilic (cold-loving) and thrives in freezing water.[1] Its specific epithet, nivalis, is from Latin and refers to snow.

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 pinkish pant cuffs.

History[edit]

Watermelon snow streaks.

The first accounts of watermelon snow are in the writings of Aristotle. Watermelon snow has puzzled mountain climbers, explorers, and naturalists for thousands of years, some speculating that it was caused by mineral deposits or oxidation products that were leached from rocks.

In May 1818, four ships sailed from England to search for the Northwest Passage and chart the Arctic coastline of North America. Severe weather made them finally turn the ships back, but the expedition made valuable contributions to science. Captain John Ross noticed crimson snow that streaked the white cliffs like streams of blood as they were rounding Cape York on the northwest coast of Greenland. A landing party stopped and brought back samples to England. The Times wrote about this discovery on December 4, 1818:[2]

A follow-up article three days later erroneously concluded that the coloration was caused by meteoric iron deposits:[3]

When Ross published his account of the voyage in 1818, it contained a botanical appendix by Robert Brown. In it, Brown tentatively attributed the red snow to an alga.[4]

The phenomenon was also reported from the Scottish Highlands in the nineteenth century and subsequently recorded scientifically from a snowpatch in the Cairngorm Mountains in 1967.[5]

Chlamydomonas nivalis[edit]

Unusual watermelon snow pits, superimposed with an orange-ish bootprint
Tracks made by sliding on watermelon snow in Utah's Uinta Mountains

Chlamydomonas nivalis is a green alga that owes its 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, including protozoans such as ciliates, rotifers, nematodes, ice worms and springtails.

See also[edit]

References[edit]

  1. ^ William E. Williams, Holly L. Gorton, and Thomas C. Vogelmann (January 21, 2003). "Surface gas-exchange processes of snow algae". Proceedings of the National Academy of Sciences of the United States of America 100 (2): 562–566. Bibcode:2003PNAS..100..562W. doi:10.1073/pnas.0235560100. PMC 141035. PMID 12518048. 
  2. ^ "Red snow from the Arctic regions". The Times. December 4, 1818. p. 2. 
  3. ^ "The King's health". The Times. December 7, 1818. p. 2. 
  4. ^ Brown, Robert (1818). "List of Plants collected by the Officers, &c., in Captain Ross's voyage, on the coasts of Baffin's Bay". 
  5. ^ A snow microflora in the Cairngorm Mountains, Scotland http://pdfserve.informaworld.com/370009__780343798.pdf
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