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Surface gas-exchange processes of snow algae.
William E Williams1, Holly L Gorton, Thomas C Vogelmann
1Biology Department, St. Mary's College of Maryland, 18952 East Fisher Road, St. Mary's City, MD 20680, USA. WEWilliams@smcm.edu
Summary
Chlamydomonas nivalis, an alga in snowfields, actively absorbs carbon dioxide (CO2). This research shows that snow algae can be highly productive, similar to higher plants, especially under red light.
Area of Science:
- * Snow ecology
- * Photosynthetic microorganisms
- * Algal physiology
Background:
- * The alga Chlamydomonas nivalis causes red snow, a common phenomenon in summer snowfields.
- * Understanding the gas exchange of snow-dwelling algae is crucial for assessing ecosystem productivity.
Purpose of the Study:
- * To investigate the surface gas-exchange characteristics of snow colonized by Chlamydomonas nivalis.
- * To determine the photosynthetic response of snow algae to varying light conditions and wavelengths.
Main Methods:
- * Utilized a modified Li-Cor gas-exchange system to measure CO2 uptake in snow algae.
- * Conducted experiments with varying irradiance levels and light wavelengths (red, white, green, blue).
- * Integrated daily measurements of gas exchange to estimate overall CO2 assimilation.
Main Results:
- * Observed significant CO2 uptake rates, reaching up to 0.3 micromol.m(-2).s(-1) in dense algal blooms.
- * Light response curves were similar to those of higher plants.
- * Red light was the most effective wavelength for CO2 uptake, followed by white, green, and blue light, due to the presence of red astaxanthin pigment.
Conclusions:
- * Summer snowfields colonized by Chlamydomonas nivalis exhibit surprisingly high productivity.
- * Daily CO2 uptake can reach approximately 2,300 micromol.m(-2).day(-1) in heavily colonized areas.
- * The pigment astaxanthin influences light absorption and photosynthetic efficiency in snow algae.