Snow Algae
Snowball made of red algae snow.
DB: This is Earth and Sky, with a listener’s question.
JB: He writes, “This time of year in the mountains . . . there are still patches of snow that haven’t completely melted off. On some of these patches . . .you sometimes see a red (or pink) algae (or mold) growing. Everyone I’ve talked to says you should never eat it, but no one seems to know exactly what it is.”
DB: There are fungi, mold and some insects that have adapted the extreme cold on mountain tops. But what you saw was probably algae. There are more than 350 different kinds of algae that live in snow. The best known is chlamydomonas nivalis which appears to turn snow red.
JB: These are actually green algae. That is, when new cells form they’re green, but they quickly turn red to protect themselves from bright light in a snowy environment. During the dark and cold of winter, these algae are dormant. In spring and early summer, they reproduce very quickly – and can make large patches of snow appear pink or red.
DB: And you’d be right to leave them alone. Many blue-green algae can also be snow algae – and some are highly toxic. Special thanks today to the Bureau of Land Management and to the National Fish and Wildlife Foundation – supporting the conservation of native fish, wildlife, plants and their habitats. We’re Block and Byrd for Earth and Sky.
The following people were interviewed for today’s program. Our thanks to:
Dr. Grant G. Mitman
Assistant Professor and Greenhouse Director
Department of Biological Sciences
Montana Tech of the University of Montana
Butte, Montana
Richard Armstrong
National Snow and Ice Data Center
Author’s Notes:
The conditions become right for the growth of these algae when the snow begins to melt. This is because the thin layer of water carries nutrients to the algae and permits them to swim and reproduce. Often this happens only two or three days out of the year. Too much water, for some reason, is not ideal.
Dr. Mitman says that one organization he is in discourages people from eating the blue-green algae sold in health food stores. They claim it is possible for unwanted (toxic) strains to mix in with the desired ones.
A passage in the 1997 encyclopedia Britanica talked of red, brown, green, yellow and black snow, all caused by different types of algae. Dr. Mitman hadn’t heard of many of them, but commented that algae have accessory pigments which can make them turn just about any color. He noted that other plants do too. Carrots, for example, would be green if you grew them in the light. Red maple leaves are actually green underneath.
Additional Teacher Resources
The National Geographic Society, National Geographic News.:“Snow Algae Shade Most (Not All) Colored Snow”:http://news.nationalgeographic.com/news/2005/06/0607_050607_snowalgae.html
This article explores the “how and why” of snow algae existence, probing its life cycle, geographical distribution, and color schemes. The site also provides links to more information on snow algae.
The Science News, Articles: Red Snow, Green Snow?Snow Algae
This site is a good resource for explanation of the life cycle of snow algae, and how that life cycle differs based on the different colors of snow algae. The article also touches on theories of why certain snow algae are the color they are.
Wayne’s Word: Watermelon Snow; A Strange Phenomenon Caused By Algal Cells of the Chlorophyta
This site is an excellent source for all questions students may have about colored snow algae. The report is extensive and presented with images and languages that students of all ages will be able to understand. There are also links provided to more information.
