title: Surface gas-exchange processes of snow algae.
abstract: The red-colored chlorophyte Chlamydomonas nivalis is commonly found in summer snowfields. We used a modified Li-Cor gas-exchange system to investigate surface gas-exchange characteristics of snow colonized by this alga, finding rates of CO(2) uptake up to 0.3 micromol.m(-2).s(-1) in dense algal blooms. Experiments varying the irradiance resulted in light curves that resembled those of the leaves of higher plants. Red light was more effective than white and much more effective than green or blue, because of the red astaxanthin that surrounds and masks the algal chloroplasts. Integrating daily course measurements of gas exchange showed CO(2) uptake around 2,300 micromol.m(-2).day(-1) in heavily colonized patches, indicating that summer snowfields can be surprisingly productive.
authors.affiliation: Biology Department, St. Mary's College of Maryland, 18952 East Fisher Road, St. Mary's City, MD 20680, USA. WEWilliams@smcm.edu
authors.forename: William E
authors.initials: WE
authors.lastname: Williams
authors.forename: Holly L
authors.initials: HL
authors.lastname: Gorton
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Vogelmann
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000032:analysis / Q000378:metabolism; D002696:Chlamydomonas / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D008027:Light; D008396:Maryland; D000461:Rhodophyta / Q000302:isolation & purification; D024341:Xanthophylls; D019207:beta Carotene / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D024341:Xanthophylls; D019207:beta Carotene; D002245:Carbon Dioxide; C005948:astaxanthine