Watermelon snow
Encyclopedia
Watermelon snow, also called snow algae, red snow, or blood snow, is snow
that is reddish or pink in color, with the slight scent of a fresh watermelon
. Watermelon snow is caused by the presence mainly of 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. 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.
The first accounts of watermelon snow are in the writings of Aristotle
. Watermelon snow has puzzled mountain climbers, explorers, and naturalist
s 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:
A follow-up article three days later erroneously concluded that the coloration was caused by meteoric iron deposits:
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.
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.
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 bloom
s 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 glacier
s 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 gamete
s, fusing in pairs to form zygote
s.
Many species feed on C. nivalis, including protozoa
ns such as ciliate
s, rotifers, nematodes, ice worm
s and springtail
s.
Snow
Snow is a form of precipitation within the Earth's atmosphere in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. Since snow is composed of small ice particles, it is a granular material. It has an open and therefore soft structure, unless packed by...
that is reddish or pink in color, with the slight scent of a fresh watermelon
Watermelon
Watermelon is a vine-like flowering plant originally from southern Africa. Its fruit, which is also called watermelon, is a special kind referred to by botanists as a pepo, a berry which has a thick rind and fleshy center...
. Watermelon snow is caused by the presence mainly of Chlamydomonas nivalis, a species of green algae
Green algae
The green algae are the large group of algae from which the embryophytes emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic...
containing a secondary red carotenoid
Carotenoid
Carotenoids are tetraterpenoid organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some bacteria, and some types of fungus. Carotenoids can be synthesized fats and other basic organic metabolic building...
pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
(astaxanthin
Astaxanthin
Astaxanthin is a carotenoid. It belongs to a larger class of phytochemicals known as terpenes. It is classified as a xanthophyll, which means "yellow leaves". Like many carotenoids, it is a colorful, lipid-soluble pigment. Astaxanthin is found in microalgae, yeast, salmon, trout, krill, shrimp,...
) in addition to chlorophyll
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...
. Unlike most species of fresh-water algae, it is cryophilic
Psychrophile
Psychrophiles or cryophiles are extremophilic organisms that are capable of growth and reproduction in cold temperatures, ranging from −15°C to +10°C. Temperatures as low as −15°C are found in pockets of very salty water surrounded by sea ice. They can be contrasted with thermophiles, which...
(cold-loving) and thrives in freezing water. Its specific epithet, nivalis, is from Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
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
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
. 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
Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...
. Watermelon snow has puzzled mountain climbers, explorers, and naturalist
Natural history
Natural history is the scientific research of plants or animals, leaning more towards observational rather than experimental methods of study, and encompasses more research published in magazines than in academic journals. Grouped among the natural sciences, natural history is the systematic study...
s 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
Northwest Passage
The Northwest Passage is a sea route through the Arctic Ocean, along the northern coast of North America via waterways amidst the Canadian Arctic Archipelago, connecting the Atlantic and Pacific Oceans...
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
John Ross (Arctic explorer)
Sir John Ross, CB, was a Scottish rear admiral and Arctic explorer.Ross was the son of the Rev. Andrew Ross, minister of Inch, near Stranraer in Scotland. In 1786, aged only nine, he joined the Royal Navy as an apprentice. He served in the Mediterranean until 1789 and then in the English Channel...
noticed crimson snow that streaked the white cliffs like streams of blood as they were rounding Cape York
Cape York (Greenland)
Cape York is a cape on the northwestern coast of Greenland, in northern Baffin Bay. The cape, located west-south-west of the Savissivik settlement, delimits the northwestern end of Melville Bay, with the other end commonly defined as Wilcox Head, the western promontory on Kiatassuaq Island.-...
on the northwest coast of Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
. A landing party stopped and brought back samples to England. The Times
The Times
The Times is a British daily national newspaper, first published in London in 1785 under the title The Daily Universal Register . The Times and its sister paper The Sunday Times are published by Times Newspapers Limited, a subsidiary since 1981 of News International...
wrote about this discovery on December 4, 1818:
A follow-up article three days later erroneously concluded that the coloration was caused by meteoric iron deposits:
When Ross published his account of the voyage in 1818, it contained a botanical appendix by Robert Brown
Robert Brown (botanist)
Robert Brown was a Scottish botanist and palaeobotanist who made important contributions to botany largely through his pioneering use of the microscope...
. In it, Brown tentatively attributed the red snow to an alga.
The phenomenon was also reported from the Scottish Highlands
Scottish Highlands
The Highlands is an historic region of Scotland. The area is sometimes referred to as the "Scottish Highlands". It was culturally distinguishable from the Lowlands from the later Middle Ages into the modern period, when Lowland Scots replaced Scottish Gaelic throughout most of the Lowlands...
in the nineteenth century and subsequently recorded scientifically from a snowpatch in the Cairngorm Mountains in 1967.
Chlamydomonas nivalis
Carotenoid
Carotenoids are tetraterpenoid organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some bacteria, and some types of fungus. Carotenoids can be synthesized fats and other basic organic metabolic building...
pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
, which protects the chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
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 bloom
Algal bloom
An algal bloom is a rapid increase or accumulation in the population of algae in an aquatic system. Algal blooms may occur in freshwater as well as marine environments. Typically, only one or a small number of phytoplankton species are involved, and some blooms may be recognized by discoloration...
s 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
Red blood cell
Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...
. 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 glacier
Glacier
A glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation over many years, often centuries. At least 0.1 km² in area and 50 m thick, but often much larger, a glacier slowly deforms and flows due to stresses induced by its weight...
s 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
Flagellate
Flagellates are organisms with one or more whip-like organelles called flagella. Some cells in animals may be flagellate, for instance the spermatozoa of most phyla. Flowering plants do not produce flagellate cells, but ferns, mosses, green algae, some gymnosperms and other closely related plants...
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 gamete
Gamete
A gamete is a cell that fuses with another cell during fertilization in organisms that reproduce sexually...
s, fusing in pairs to form zygote
Zygote
A zygote , or zygocyte, is the initial cell formed when two gamete cells are joined by means of sexual reproduction. In multicellular organisms, it is the earliest developmental stage of the embryo...
s.
Many species feed on C. nivalis, including protozoa
Protozoa
Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...
ns such as ciliate
Ciliate
The ciliates are a group of protozoans characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagella but typically shorter and present in much larger numbers with a different undulating pattern than flagella...
s, rotifers, nematodes, ice worm
Ice worm
Ice worms are species of the worm genus Mesenchytraeus that live in glacial ice. They include Mesenchytraeus solifugus, M. harrimani, M. kuril, M. maculatus and M. obscurus....
s and springtail
Springtail
Springtails form the largest of the three lineages of modern hexapods that are no longer considered insects...
s.
See also
- Ice algaeIce algaeIce algae is a general term used to describe all the various types of algal communities encountered in annual and multi-year sea-ice. The ice algal communities play an important role in primary production and are therefore considered an important part of both Polar ecosystems.Sea-ice algal...
: algal communities encountered in annual and multi-year sea-ice. - Blood rainBlood rainBlood rain or red rain is a phenomenon in which blood is perceived to fall from the sky in the form of rain. Cases have been recorded since Homer's Iliad, composed ca eighth century BC, and are widespread. Before the 17th century it was generally believed that the rain was actually blood...