What is Ice algae?
[[File:Snow Algae Textures.jpg|thumb|200px|Snow algae.]] [[File:Green algal.jpg|thumb|right|200px|''Chlamydomonas nivalis'' <br/>Thin section [[electron microscope]] photo; color artificially added. ]] '''Ice algae''' and '''snow algae''' are [[algae]] and [[cyanobacteria]] which grow on long-lasting [[snow]] and [[ice]] fields like glaciers. When [[liquid]] water is available between the snow and ice crystals, they may color the surface green, yellow or red during the summer months. The red pigment of some species is an intracellular protection against excessive visual light and [[ultraviolet radiation]] of the sun, which otherwise can cause photoinhibition of [[photosynthesis]] or [[mutation]]s. Without it, the algae at the surface would suffer [[chromosome]] breaks and [[DNA]] mutations. There are also ice algal communities on sea [[ice]]. These algae (mainly [[diatoms]]) are important in [[polar climate|polar]] [[ecosystem]]s (especially [[Antarctica]]) because they provide food for [[krill]]. Krill scrape off the algae from the underside of the ice, which is colored brown by the algae. The algae may be found between ice [[crystal]]s or attached to them, in the water or [[brine|saltwater]] channels between ice crystals. == ''Chlamydomonas nivalis'' == ''Chlamydomonas nivalis'' is a green microalga which causes, besides other closely relative species, Watermelon snow.<ref>{{cite journal | title = Surface gas-exchange processes of snow algae | author = William E. Williams, Holly L. Gorton, and Thomas C. Vogelmann | journal = Proceedings of the National Academy of Sciences | date = 2003 | volume = 100 | issue = 2 | pages = 562–566 | doi = 10.1073/pnas.0235560100 | pmid = 12518048 | pmc = 141035 | bibcode = 2003PNAS..100..562W | doi-access = free }}</ref> Watermelon snow is snow that is reddish or pink in color, and that can have a [[Odor|smell]] similar to a fresh [[watermelon]]. This type of snow is common during the summer in alpine and coastal polar regions, such as the [[Sierra Nevada (US)|Sierra Nevad