Characterization of the community of snow algae and their photochemical performance in situ in the Giant Mountains, Czech Republic

Abstract

The Czech Republic's Giant Mountains are a unique locality for studying snow algae because representatives of both significant genera, Chlamydomonas and Chloromonas (Chlorophyta), are regularly found there and are capable of completing their life cycle in several weeks. Physical and chemical environmental characteristics of two sites were measured in June 2008 and the photochemical processes of the snow algae were studied using variable chlorophyll fluorescence techniques. Correlations between the environmental conditions and the rapid light curve parameters were evaluated. The environment was characterized by stable snow temperature (Tsnow; -0.6 to -0.3 °C) but variable air temperature (Tair; 4.3 to 15.3 °C), photosynthetically active radiation (PAR; maximum of approximately 2000 mol m-2 s -1), and ultraviolet radiation (UVR; 0.135 to 2.27 mW cm -2). The snow chemical composition at both experimental sites was similar, regardless of whether snow algae were present or not, and the nutrient concentrations resembled mesotrophic to eutrophic water. Only concentration of P-PO43- was significantly higher in the presence of algae. Vegetative and mating cells of Chloromonas cf. nivalis were observed on the snow surface down to a depth of 6 cm. The maximum quantum yield in a range from 0.479 to 0.624 indicated only minor or no stress conditions. While the relative electron transfer rate (142 to 241) and the initial slope (0.287 to 0.505 mol -1 m2 s1) were negatively related to Tair, PAR, and UVR, the saturation irradiance values were very stable (350 to 489 mol m-2 s-1). Various strategies of acclimation to high PAR and/or UVR at different stages of the life cycle are proposed. © 2010 Regents of the University of Colorado.