Wikipedia

Snow algae

Snow algae are a group of freshwater micro-algae that grow in the alpine and polar regions of the Earth.[1] Snow algae have been found on every continent but are restricted to areas with temperatures between 0°C-10°C.[2] Snow algae are pigmented by chlorophyll and carotenoids and can be a variety of colors depending on the individual species, life stage, and topography/geography.[3][4] The pigmentation of snow algae reduces snow and ice albedo, which can stimulate the melting of perennial snow and ice and exacerbate the effects of climate change.[5] Snow algae are primary producers that form the basis of communities on snow or ice sheets that include microbes, tardigrades, and rotifers.[6][7] Snow algae have also been carried great distances by winds.[8]

An example of snow algae

Pigmentation

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Snow algae produce two main classes of pigment molecules: chlorophylls and carotenoids.[9] Carotenoids further split into two groups known as primary and secondary carotenoids and typically help give the snow algae cells their visible colors. Primary carotenoids, such as the yellow xanthophyll, are typically used in low concentrations for photosynthesis while still offering some UV protection.[10] Secondary carotenoids, such as the red astaxanthin, are used for UV protection by the cell and can be found in high or low concentrations depending on the strength of the UV light.[11]

Different taxa of snow algae produce differing amounts of primary and secondary carotenoids, meaning the color of a snow algae bloom can give some indication of the composition of algae found there. The alga Chlamydomonas nivalis is a very abundant component of red blooms due to its high concentrations of astaxanthin and its derivatives.[12] Many Chloromonas species are associated with green or orange-yellow snow due to the primary carotenoids they produce.[13] Similar colors of snow can also vary in composition by region, showing large scale biogeographical trends in the snow algae distribution.[14]

The algae's life stage may also play a large role in the color of the snow. Many blooms are higher in chlorophylls and primary carotenoids during early stages of the bloom, causing the snow to appear green or yellow.[15] Later in the summer, the bloom may switch to orange or red due high production of astaxanthin during low nutrient periods and the snow algae’s more stable cyst stage that they use to over-winter.[16]

Role in ecosystem

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Snow algae undergo oxygenic photosynthesis and are primary producers on the snow. This allows other organisms to live on the snow along with the algae and feed on them to obtain energy. Tardigrades and rotifers have been shown to grow preferentially on green blooms but have been found on many different snow algae blooms across the globe.[6]

Although the trophic webs of snow algae blooms are not generally complex, the microbial communities found in these blooms can play major roles in how nutrients are distributed in the environments they inhabit. These microbial and algal communities cycle globally significant amounts of carbon, nitrogen, iron, and sulfur.[7]

Effects on snow albedo and climate change

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The pigmentation of snow algae can significantly reduce snow albedo, stimulating the melting of ice and snow on ice sheets.[5] Larger snow grains allow light to penetrate further into the snow layer which increases light absorbance by snow algae and further reduces the albedo of the snow.[5] Snow algae drive greater changes in snow albedo later in the summer when algae are more abundant.[17] The different abundances of pigments present in snow algae, including chlorophyll and carotenoids, lead to differences in light absorption and therefore albedo changes based on algal community composition.[18] The presence of mineral and organic particle impurities on snow also reduces the albedo of snow, which can sometimes overshadow the effects of snow algal community dynamics on the albedo.[18] Under warmer conditions snow algae experience more growth, which can further reduce the albedo of snow and ice sheets. This positive feedback loop, similar to the ice-albedo feedback, can exacerbate the melting of perennial snow and ice by climate change.[5]

References

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  1. ^ Leya, Thomas (2013), Seckbach, Joseph; Oren, Aharon; Stan-Lotter, Helga (eds.), "Snow Algae: Adaptation Strategies to Survive on Snow and Ice", Polyextremophiles: Life Under Multiple Forms of Stress, Cellular Origin, Life in Extreme Habitats and Astrobiology, vol. 27, Dordrecht: Springer Netherlands, pp. 401–423, doi:10.1007/978-94-007-6488-0_17, ISBN 978-94-007-6488-0, retrieved 2022-03-03
  2. ^ Hoham, Ronald W.; Remias, Daniel (April 2020). "Snow and Glacial Algae: A Review 1". Journal of Phycology. 56 (2): 264–282. Bibcode:2020JPcgy..56..264H. doi:10.1111/jpy.12952. ISSN 0022-3646. PMC 7232433. PMID 31825096.
  3. ^ Spijkerman, Elly; Wacker, Alexander; Weithoff, Guntram; Leya, Thomas (2012). "Elemental and fatty acid composition of snow algae in Arctic habitats". Frontiers in Microbiology. 3: 380. doi:10.3389/fmicb.2012.00380. ISSN 1664-302X. PMC 3482990. PMID 23112797.
  4. ^ Thomas, William H.; Duval, Brian (November 1995). "Sierra Nevada, California, U.S.A., Snow Algae: Snow Albedo Changes, Algal-Bacterial Interrelationships, and Ultraviolet Radiation Effects". Arctic and Alpine Research. 27 (4): 389. doi:10.2307/1552032. ISSN 0004-0851. JSTOR 1552032.
  5. ^ a b c d Onuma, Yukihiko; Takeuchi, Nozomu; Tanaka, Sota; Nagatsuka, Naoko; Niwano, Masashi; Aoki, Teruo (2020-06-29). "Physically based model of the contribution of red snow algal cells to temporal changes in albedo in northwest Greenland". The Cryosphere. 14 (6): 2087–2101. Bibcode:2020TCry...14.2087O. doi:10.5194/tc-14-2087-2020. ISSN 1994-0416.
  6. ^ a b Ono, Masato; Takeuchi, Nozomu; Zawierucha, Krzysztof (2021-03-16). "Snow algae blooms are beneficial for microinvertebrates assemblages (Tardigrada and Rotifera) on seasonal snow patches in Japan". Scientific Reports. 11 (1): 5973. Bibcode:2021NatSR..11.5973O. doi:10.1038/s41598-021-85462-5. ISSN 2045-2322. PMC 7971028. PMID 33727649.
  7. ^ a b Hotaling, Scott; Hood, Eran; Hamilton, Trinity L. (August 2017). "Microbial ecology of mountain glacier ecosystems: biodiversity, ecological connections and implications of a warming climate". Environmental Microbiology. 19 (8): 2935–2948. Bibcode:2017EnvMi..19.2935H. doi:10.1111/1462-2920.13766. ISSN 1462-2912. PMID 28419666.
  8. ^ Hoham, Ronald W.; Remias, Daniel (April 2020). "Snow and Glacial Algae: A Review 1". Journal of Phycology. 56 (2): 264–282. Bibcode:2020JPcgy..56..264H. doi:10.1111/jpy.12952. ISSN 0022-3646. PMC 7232433. PMID 31825096.
  9. ^ Takaichi, Shinichi (June 2011). "Carotenoids in Algae: Distributions, Biosyntheses and Functions". Marine Drugs. 9 (6): 1101–1118. doi:10.3390/md9061101. ISSN 1660-3397. PMC 3131562. PMID 21747749.
  10. ^ Tanabe, Yukiko; Shitara, Tomofumi; Kashino, Yasuhiro; Hara, Yoshiaki; Kudoh, Sakae (2011-02-23). "Utilizing the Effective Xanthophyll Cycle for Blooming of Ochromonas smithii and O. itoi (Chrysophyceae) on the Snow Surface". PLOS ONE. 6 (2): e14690. Bibcode:2011PLoSO...614690T. doi:10.1371/journal.pone.0014690. ISSN 1932-6203. PMC 3044130. PMID 21373183.
  11. ^ Remias, Daniel Lütz (2007-07-01). "Characterisation of esterified secondary carotenoids and of their isomers in green algae: a HPLC approach". Algological Studies. 124: 85–94. doi:10.1127/1864-1318/2007/0124-0085.
  12. ^ Remias, Daniel; Pichrtová, Martina; Pangratz, Marion; Lütz, Cornelius; Holzinger, Andreas (2016-02-15). "Ecophysiology, secondary pigments and ultrastructure ofChlainomonassp. (Chlorophyta) from the European Alps compared withChlamydomonas nivalisforming red snow". FEMS Microbiology Ecology. 92 (4): fiw030. doi:10.1093/femsec/fiw030. ISSN 1574-6941. PMC 4815433. PMID 26884467.
  13. ^ Kvíderová, Jana (2010). "Characterization of the Community of Snow Algae and Their Photochemical Performance in situ in the Giant Mountains, Czech Republic". Arctic, Antarctic, and Alpine Research. 42 (2): 210–218. Bibcode:2010AAAR...42..210K. doi:10.1657/1938-4246-42.2.210. ISSN 1523-0430. JSTOR 40801691.
  14. ^ Lutz, Stefanie; Anesio, Alexandre M.; Edwards, Arwyn; Benning, Liane G. (February 2017). "Linking microbial diversity and functionality of arctic glacial surface habitats". Environmental Microbiology. 19 (2): 551–565. Bibcode:2017EnvMi..19..551L. doi:10.1111/1462-2920.13494. ISSN 1462-2912. PMID 27511455.
  15. ^ Remias, Daniel; Lütz-Meindl, Ursula; Lütz, Cornelius (August 2005). "Photosynthesis, pigments and ultrastructure of the alpine snow alga Chlamydomonas nivalis". European Journal of Phycology. 40 (3): 259–268. Bibcode:2005EJPhy..40..259R. doi:10.1080/09670260500202148. ISSN 0967-0262.
  16. ^ Hoham, Ronald W.; Blinn, Dean W. (June 1979). "Distribution of cryophilic algae in an arid region, the American Southwest". Phycologia. 18 (2): 133–145. Bibcode:1979Phyco..18..133H. doi:10.2216/i0031-8884-18-2-133.1. ISSN 0031-8884.
  17. ^ Takeuchi, Nozomu (January 2009). "Temporal and spatial variations in spectral reflectance and characteristics of surface dust on Gulkana Glacier, Alaska Range". Journal of Glaciology. 55 (192): 701–709. Bibcode:2009JGlac..55..701T. doi:10.3189/002214309789470914. ISSN 0022-1430.
  18. ^ a b Takeuchi, Nozomu (2013). "Seasonal and altitudinal variations in snow algal communities on an Alaskan glacier (Gulkana glacier in the Alaska range)". Environmental Research Letters. 8 (3): 035002. doi:10.1088/1748-9326/8/3/035002.
 

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